CN108663249B - Preparation device and preparation method of non-cohesive soil sample for geotechnical test - Google Patents

Preparation device and preparation method of non-cohesive soil sample for geotechnical test Download PDF

Info

Publication number
CN108663249B
CN108663249B CN201810849926.6A CN201810849926A CN108663249B CN 108663249 B CN108663249 B CN 108663249B CN 201810849926 A CN201810849926 A CN 201810849926A CN 108663249 B CN108663249 B CN 108663249B
Authority
CN
China
Prior art keywords
sample
pair
compaction
open molds
soil
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201810849926.6A
Other languages
Chinese (zh)
Other versions
CN108663249A (en
Inventor
章丽莎
张世民
王霄
孙银锁
邢丽
崔允亮
孙苗苗
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zhejiang University City College ZUCC
Original Assignee
Zhejiang University City College ZUCC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Zhejiang University City College ZUCC filed Critical Zhejiang University City College ZUCC
Priority to CN201810849926.6A priority Critical patent/CN108663249B/en
Publication of CN108663249A publication Critical patent/CN108663249A/en
Application granted granted Critical
Publication of CN108663249B publication Critical patent/CN108663249B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/286—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q involving mechanical work, e.g. chopping, disintegrating, compacting, homogenising
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/36—Embedding or analogous mounting of samples
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/36—Embedding or analogous mounting of samples
    • G01N2001/366—Moulds; Demoulding

Landscapes

  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Sampling And Sample Adjustment (AREA)

Abstract

The invention discloses a preparation device and a preparation method of a geotechnical test non-clay sample, wherein the device comprises a sample filling part, a sample compacting part, a sample presaturation part and a vacuumizing part; the sample filling part comprises a first pair of open molds, a second pair of open molds, a bottom collar, a top collar, two annular hoops, two rubber rings and a rubber membrane; according to the invention, the rubber film is flatly clung to the inner walls of the first pair of open molds and the second pair of open molds by a vacuumizing method, so that the defects of the side surfaces of the samples are reduced, and the uniform and flat side surfaces of the samples are ensured; the bottom collar improves the bottom stability of the sample filling part, and the top collar is beneficial to reducing the soil sample quality loss and the pollution to a geotechnical test device in the sample preparation process of the top sample; the presaturation part and the vacuumizing part have universality, and can be used for non-cohesive soil sample preparation of different precise geotechnical tests after the sizes of the sample filling part and the sample compacting part are adjusted according to the geotechnical test device and the sample size.

Description

Preparation device and preparation method of non-cohesive soil sample for geotechnical test
Technical Field
The invention relates to the technical field of indoor geotechnical tests of geotechnical engineering, in particular to a device and a method for preparing a non-cohesive soil sample for geotechnical tests.
Background
The indoor geotechnical test is one of the main ways of revealing various physical and mechanical properties of soil, and can provide scientific basis for determining soil property parameters in engineering design, theoretical or numerical calculation and other processes.
The indoor geotechnical test is developed based on a proper soil unit body sample, and original soil can be directly obtained by a cutting method after in-situ sampling, but due to the fact that in-situ sampling disturbance is large, sampling difficulty is large, or the original soil is limited in quantity and difficult to transport and store in actual engineering practice and research projects, remolded soil is usually adopted to carry out comprehensive indoor geotechnical test research of a system.
The existing research shows that when remolded soil is adopted to carry out an indoor geotechnical test, the sample preparation quality of a soil unit body sample has obvious influence on the result and the precision of the precise geotechnical test, and particularly the indoor geotechnical test carried out by a precise soil unit body test device (such as a GDS advanced triaxial/dynamic triaxial test device, a GDS resonance column test device and the like). Because the cohesive soil generally has larger cohesive force, the remolded soil sample has good overall stability, the required cohesive soil sample preparation mould can be directly purchased, and the sample required by the geotechnical test can be obtained through a mature consolidation method or compaction method technology. However, the non-cohesive soil (such as sand) has little cohesive force, and the soil body has the characteristic of particle dispersion, so that the non-cohesive soil sample required for the indoor geotechnical test is difficult to obtain without adopting a scientific sample preparation mould and effective sample preparation measures. In addition, if a sample is prepared by separating the non-clay sample from the geotechnical sample device, the non-clay sample is extremely liable to be damaged to different degrees, and the quality of the sample preparation and the subsequent test accuracy are affected, so it is suggested that the non-clay sample is directly prepared on the sample mounting base of the geotechnical sample device.
Currently, there is no generally accepted device for preparing a sample of non-clay, and there are three disadvantages associated with the prior art devices for preparing a sample of non-clay in the literature and patents: (1) The adopted double-petal mould is directly sleeved on the sample mounting base of the geotechnical sample device, no protection measures are taken for the joint of the double-petal mould and the sample mounting base, and the influence of knocking the double-petal mould and compacting the sample on the connection of the double-petal mould and the sample mounting base in the process of preparing the sample by using the non-cohesive soil cannot be ensured, so that the uniformity of the bottom of the prepared sample and the coincidence connection of the sample and the central axis of the sample mounting base can be influenced; (2) In the non-cohesive soil sample preparation process, auxiliary compaction measures are not adopted, namely, the falling height of compaction cannot be guaranteed to be consistent, and the compaction area (possibly eccentric compaction) of a compaction hammer at each compaction time cannot be positioned, so that the uniformity of sample preparation is adversely affected; (3) The top of the double-petal mold is flush with the top of the sample, measures are not taken to assist in top soil sample preparation, and the casting height of the top soil exceeds the height of the double-petal mold during filling, so that on one hand, the quality of a soil sample cast in the compaction process can be lost and pollute a geotechnical test device, and on the other hand, in order to reduce the quality loss of the sample, the soil on the surface of the top layer of the sample can be cast in the top central area of the sample as much as possible, and the soil density of the top area of the sample is uneven. In fact, taking the GDS resonant column test as an example, both axial and radial displacement sensors of the sample are mounted on the top region of the sample, and the sample quality of the top layer of the sample will directly affect the test. In order to overcome the above drawbacks, it is necessary to develop a precise non-cohesive soil sample preparation device operatively connected to a sample mounting base of a geotechnical sample device and a preparation method thereof.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a device and a method for preparing a non-cohesive soil sample for geotechnical tests.
The technical scheme adopted for solving the technical problems is as follows: the preparation device of the non-cohesive soil sample for the geotechnical test comprises a sample filling part, a sample compacting part, a sample presaturation part and a vacuumizing part; the sample filling part comprises a first pair of open molds, a second pair of open molds, a bottom collar, a top collar, a first annular collar, a second annular collar, a first rubber ring, a second rubber ring and a rubber membrane; the inner walls of the first pair of open molds and the second pair of open molds are provided with air guide grooves; a vent hole is formed in the middle of the second pair of open molds; the first pair of open molds and the second pair of open molds are connected in an up-down alignment manner through the first annular hoop and the second annular hoop, and the section of the connected first pair of open molds and the section of the connected second pair of open molds are in a complete circle; the first pair of open molds and the second pair of open molds are vertically arranged on the geotechnical test instrument base around the soil unit body sample base through the bottom collar after being connected; the geotechnical test instrument base is provided with a valve communicated with the bottom of the sample; the top lantern ring is arranged at the top of the first pair of open molds and the second pair of open molds and is used for connecting the sample filling part and the sample compacting part;
The rubber film is flatly clung to the inner walls of the first pair of open molds and the second pair of open molds, one end of the rubber film is sleeved on the soil unit body sample base and is fixed through the first rubber ring, and the other end of the rubber film is sleeved on the outer walls of the tops of the first pair of open molds and the second pair of open molds and is fixed through the second rubber ring;
the sample compacting part comprises a compacting sleeve, a compacting hammer and a compacting rod; the compaction sleeve is provided with compaction sleeve graduation marks, and the compaction rod is provided with compaction rod graduation marks; the compaction sleeve zero graduation line is positioned at the bottom of the compaction sleeve graduation line, and the compaction rod zero graduation line is positioned at the top of the compaction rod graduation line; the bottom of the compaction sleeve is detachably connected with the top lantern ring; the compaction rod is orthogonally connected to the center of the compaction hammer; the compaction hammer can move up and down in a cavity formed by the compaction sleeve, the first pair of open dies and the second pair of open dies under the drive of the compaction rod so as to compact the sample; installing a soil unit body sample top cap on the top surface of the compacted sample, wherein a top cap through pipe is arranged on the soil unit body sample top cap;
the sample pre-saturation part consists of a vacuum pumping pre-saturation fitting, a water supplying pre-saturation fitting and a carbon dioxide gas tank; the vacuumizing presaturation accessory comprises a first organic glass cylinder, a first organic glass base, a first air inlet/water inlet valve, a first negative pressure meter, a cap, a vacuumizing valve and a vent; the first organic glass cylinder is in sealing connection with the cap through a rubber ring; the bottom of the first organic glass cylinder is connected with a first organic glass base, and the first organic glass base is provided with a first air inlet/water inlet valve and a first negative pressure meter; the first air inlet valve is connected with the top cap through pipe; the cap is provided with a vent and a vacuumizing valve;
The water-through presaturation accessory comprises a second organic glass cylinder, a second organic glass base, a second air inlet/water inlet valve and a second negative pressure meter; the top of the second plexiglas cylinder is open; the bottom of the second organic glass cylinder is connected with the second organic glass base; the second organic glass base is provided with a second air inlet/water inlet valve and a second negative pressure meter; the second air inlet valve is connected with a valve communicated with the bottom of the sample on the geotechnical test instrument base through a pipeline;
the carbon dioxide gas tank is connected with a valve communicated with the bottom of the sample on the geotechnical test instrument base through a pipeline;
the vacuumizing part comprises a vacuum pump with a vacuum pressure control valve, and the vacuum pump is respectively connected with the air guide grooves of the inner walls of the first pair of open molds and the second pair of open molds and the air vents on the cover cap.
Further, the section at the joint of the first pair of open molds and the second pair of open molds is smooth, and the joint of the first pair of open molds and the second pair of open molds is in sealing connection through the first annular hoop and the second annular hoop; the first annular hoop is arranged at a position which is 1/3 of the height of the bottom of the first pair of open molds and the second pair of open molds; the second annular collar is mounted 1/3 height adjacent the top of the first and second pairs of split dies.
Further, the materials of the first pair of open molds, the second pair of open molds, the bottom lantern ring and the top lantern ring are wear-resistant metals, including stainless steel and aluminum alloy; the first annular hoop and the second annular hoop are made of stainless steel; the compaction sleeve is made of transparent organic glass; the compaction hammer and the compaction rod are made of brass or stainless steel.
Further, the heights of the first pair of open molds and the second pair of open molds are the sum of the height of the sample and the height of the sample base of the soil unit body; the inner diameters of the first pair of open molds and the second pair of open molds with rubber films after being in butt joint are equal to the diameter of the sample; the bottoms of the first pair of open molds and the second pair of open molds are provided with notches for accommodating the soil unit body sample base and the first rubber ring, and the sizes of the notches are determined by the thickness of the rubber film and the diameter of the first rubber ring; the outer diameter of the first pair of open molds and the second pair of open molds in the height range close to the top is smaller than the outer diameter in the height range close to the bottom by 2/3;
the inner diameter of the bottom lantern ring is determined by the outer diameters of the bottoms of the first pair of split dies and the second pair of split dies after being in butt joint; the diameter of the opening of the top lantern ring is equal to the diameter of the sample; the inner diameter of the top lantern ring is determined by the outer diameters of the tops of the first pair of split dies and the second pair of split dies after being in butt joint and the thickness of the rubber film;
The inner diameter of the compaction sleeve is equal to the diameter of the sample; the bottom ring inner diameter of the compaction sleeve is equal to the outer diameter of the top collar; the internal height of the compaction sleeve is determined by the height of the sample, the height of the compaction hammer and the drop distance of the compacted sample; a round hole is formed in the center of the top of the compaction sleeve, and the diameter of the round hole is determined by the diameter of the sample, the diameter of the compaction hammer and the diameter of the compaction rod; the diameter of the compaction hammer is determined by the diameter of the test specimen.
Further, the air guide grooves on the inner walls of the first pair of open molds and the second pair of open molds have the following two types of forms:
the first type of air guide grooves are annular air guide grooves which are arranged in parallel along the inner walls of the first pair of open molds and the second pair of open molds, and the annular air guide grooves are communicated with the vent holes through the straight line grooves.
The second type of air guide groove is a spiral air guide groove along the inner walls of the first pair of open molds and the second pair of open molds, and the spiral air guide groove passes through the vent holes.
The preparation method of the non-cohesive soil sample for the geotechnical test comprises the following steps:
(1) After the first pair of open molds and the second pair of open molds are aligned up and down, the side wall sealing connection is carried out through the first annular hoop and the second annular hoop;
(2) One end of a rubber film is fixed on a soil unit body sample base through a first rubber ring; then, vertically installing the butted first pair of open molds and the butted second pair of open molds on a geotechnical test instrument base around the soil unit body sample base through a bottom lantern ring; straightening the rubber film to enable the other end of the rubber film to be sleeved on the outer walls of the tops of the butted first pair of open molds and the butted second pair of open molds; the method comprises the steps that a vacuum pump is used for vacuumizing air guide grooves on the inner walls of a first pair of open molds and a second pair of open molds, so that a rubber film is flatly attached to the inner walls of the first pair of open molds and the second pair of open molds, and the other end of the rubber film is fixed on the outer walls of the tops of the first pair of open molds and the second pair of open molds which are well abutted by a second rubber ring;
(3) Horizontally mounting top lantern rings on the tops of the butted first pair of open molds and the second pair of open molds with the rubber film, so that the top lantern rings are tightly connected with the outer walls of the rubber film, the first pair of open molds and the second pair of open molds, and the mounting of the sample filling part is completed;
(4) Designing a test soil sample layered filling test scheme: filling in n layers, wherein the weight m=M/n of each layer of filled soil body sample, and the height l=L/n of each layer of filled soil body sample, wherein M is the total weight of the sample, and L is the height of the sample;
(5) Sequentially installing a compaction rod with a compaction hammer and a compaction sleeve on the sample filling part, and reading a scale reading a of the compaction rod corresponding to a zero scale mark of the compaction sleeve 1 The method comprises the steps of carrying out a first treatment on the surface of the Sequentially removing the compaction sleeve and the compaction rod with the compaction hammer, and pouring a first layer of soil sample with the weight of m into the sample filling part; installing the compaction rod with the compaction hammer and the compaction sleeve again, so that the inner wall of the compaction sleeve, the inner wall of the opening of the top lantern ring and the inner walls of the butted first pair of open molds and the butted second pair of open molds with rubber films are aligned; the compaction hammer contacts the top surface of the first layer of uncompacted filled soil body, and reads the scale reading b of the compaction rod corresponding to the zero scale line of the compaction sleeve 1+k K represents the number of compactions; taking k=0 before non-compaction, i.e. the scale reading of the compaction bar corresponding to the zero scale mark of the compaction sleeve is b 1 ；
(6) Compacting the first layer of filled soil body by adopting a compacting rod with a compacting hammer, wherein the falling distance of the compacting hammer is l when each time of compaction 0 I.e. the compaction bar corresponds to the scale (b) from the zero scale mark of the compaction sleeve 1+k +l 0 ) Falling down; when the first pressing is carried out, the scale corresponding to the zero scale mark of the compaction rod from the compaction sleeve is (b) 1 +l 0 ) Falling down; the final compaction height of the first layer of filled soil body after multiple compaction is l, namely when the compaction hammer contacts the top surface of the compacted first layer of filled soil body, the scale reading a of the compaction rod corresponding to the zero scale mark of the compaction sleeve 2 ＝a 1 +l; the top surface of the filled soil layer before and after each compaction is ensured to be uniform and horizontal;
(7) After the surface of the soil body filled in the first layer is scratched by bamboo sticks, pouring a second layer of soil sample with the weight of m into the sample filling part, compacting the second layer of filled soil body, and repeating the steps until the compaction of the sample with the height of L is completed;
(8) Sequentially removing the compaction sleeve, the compaction rod with the compaction hammer, the top sleeve ring and the second rubber ring, and then installing a soil unit body sample top cap on the top surface of the uniform horizontal sample so that the central axis of the soil unit body sample top cap coincides with the connecting line of the central axis of the sample; the rubber film sleeved on the outer walls of the tops of the first pair of open molds and the second pair of open molds is turned up to be sleeved on the top cap and fixed through the second rubber ring;
(9) Adopting a vacuumizing part and a vacuumizing pre-saturation fitting to assist in demolding, firstly closing a valve communicated with the bottom of a sample on a base of a geotechnical test instrument, connecting a first air inlet/water inlet valve at the bottom of the vacuumizing pre-saturation fitting with a top cap through pipe, and then connecting a vent at the top of the vacuumizing pre-saturation fitting with a vacuum pump with a vacuum pressure control valve; after the airless water is injected into the first organic glass cylinder, the first organic glass cylinder is connected with the cap in a sealing way through a rubber ring; closing the vacuum pressure control valve, opening the first air inlet/water inlet valve, the vacuumizing valve and the valve for controlling the top cap through pipe, starting the vacuum pump, and slowly adjusting the vacuum pressure control valve until the vacuum pressure is stably maintained at-20 kPa; after the sample is vertically stabilized by the applied negative pressure, respectively and sequentially removing the first annular hoop, the second annular hoop, the first pair of open molds, the second pair of open molds and the bottom lantern ring; the vacuum pressure is controlled by a vacuum pressure control valve to be stably maintained at-20 kPa, so that the sample is kept stable, and an unsaturated soil sample is prepared;
(10) Presaturation step: after a control valve of the carbon dioxide gas tank is connected with a valve communicated with the bottom of the sample on the geotechnical test instrument base, opening the control valve of the carbon dioxide gas tank and the valve communicated with the bottom of the sample on the geotechnical test instrument base, and slowly introducing carbon dioxide into the sample; adjusting a control valve of the carbon dioxide gas tank to make bubbles in the first organic glass cylinder uniform and slow; the vacuum pressure is controlled to be stably maintained at-20 kPa through a vacuum pressure control valve, and after continuously and slowly introducing carbon dioxide gas into the sample for 30min, a valve on the base of the geotechnical test instrument, which is communicated with the bottom of the sample, and a control valve of a carbon dioxide gas tank are closed;
Closing a second air inlet/water inlet valve at the bottom of the water-through presaturation accessory, injecting a sufficient amount of airless water into the second organic glass cylinder, removing gas in a connecting conduit, and connecting a valve on the geotechnical test instrument base, which is communicated with the bottom of the sample, with the second air inlet/water inlet valve through the connecting conduit; opening a valve on the geotechnical test instrument base, which is communicated with the bottom of the sample, and a second air inlet/water inlet valve, and slowly injecting airless water in a second organic glass cylinder into the sample under the action of vacuum pressure; the vacuum pressure is controlled by a vacuum pressure control valve to be stably maintained at-20 kPa, and airless water is continuously injected into the sample; after the bubbles in the first organic glass cylinder completely disappear, sequentially closing a valve communicated with the bottom of the sample, a valve for controlling a top cap through pipe, a first air inlet/water inlet valve, a second air inlet/water inlet valve and a vacuum pump on a base of the geotechnical test instrument to prepare a saturated soil sample.
Further, the rubber film is flatly attached to the inner walls of the first pair of open molds and the second pair of open molds in a mode of vacuumizing the air guide grooves of the inner walls of the first pair of open molds and the second pair of open molds through a vacuum pump; in the layered filling process of the sample, the rubber film continuously and flatly clings to the inner walls of the first pair of open molds and the second pair of open molds.
Further, in the soil sample compacting process, the central axes of the sample filling part and the sample compacting part and the connecting line of the central axes of the sample and the central axis of the sample base of the soil unit body are kept coincident; the sample was compacted in a quincuncial fashion.
Further, the calculation formula of the total mass of the sample is as followsWherein d, L, e, ω and d s The diameter, the height, the void ratio, the water content and the soil particle weight, ρ of the sample are respectively w Is the density of water; wherein, the value of omega is determined by a sample preparation method, and when preparing a saturated soil sample, if the sample is prepared by a wet ramming method, the omega is taken to be 5 percent; if a (dry sand) shakeout method is adopted for sample preparation, omega is 0; when (when)When preparing unsaturated soil samples, ω is the actual moisture content of the sample.
Further, when the scale reading of the compaction rod corresponding to the zero scale mark of the compaction sleeve exceeds the maximum scale a of the compaction rod max I.e. the maximum scale a of the compaction bar each time the compaction hammer enters the compaction sleeve, the final compaction height of the layered fill mass is determined by the compaction hammer contacting the top surface of the compacted layer of fill mass max The scale mark scale of the corresponding compaction sleeve is (a) n+1 ＝a n +l-a max ) Determining, wherein n represents the number of times of sample layered filling;
each time a soil sample is compacted, the compaction rod is moved from the maximum scale a of the compaction rod max The scale mark scale of the corresponding compaction sleeve is (b) 1+k +l 0 -a max ) Falling down.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the invention, the inner walls of the first pair of open molds and the second pair of open molds are provided with the communicated air guide grooves, and the rubber film is flatly clung to the inner walls of the first pair of open molds and the second pair of open molds by a vacuumizing method, so that the defects of the side surfaces of the samples are reduced, and the uniform and flat side surfaces of the samples are effectively ensured.
2. The bottom collar is arranged in the invention, so that the bottom stability of the sample filling part is improved, the tight connection of the double-petal die and the sample mounting base is facilitated, the influence of knocking the double-petal die and compacting the sample on the connection of the double-petal die and the sample mounting base in the non-cohesive soil sample preparation process is reduced, the uniformity of soil at the bottom of the sample is ensured, and the central axes of the sample and the sample mounting base are kept coincident in the preparation process.
3. The invention is provided with a top collar for connecting the sample filling part and the sample compacting part; on the other hand, as the heightening part of the sample filling part, the soil mass loss and the pollution to the geotechnical test device in the top sample preparation process can be reduced, the soil mass uniformity and flatness of the top sample area can be ensured, and the sample preparation quality of the top sample area can be improved; the top lantern ring, the bottom lantern ring and the variable cross-section design of the first pair of open dies and the second pair of open dies at the position close to the top 1/3 are arranged, so that the overall stability of the sample filling part is improved.
4. The compaction sleeve, the compaction sleeve graduation line and the compaction rod graduation line of the compaction part belong to auxiliary compaction measures, the compaction sleeve is used for guiding the compaction hammer and positioning the compaction region of the compaction hammer, the compaction sleeve graduation line and the compaction rod graduation line are used for determining the falling height of the compaction hammer, and the quincuncial compaction method is used for assisting, so that the uniformity of sample preparation is effectively ensured.
5. The pre-saturation step in the invention is beneficial to improving the sample preparation efficiency of the saturated soil sample, and effectively shortens the time required for sample saturation in the test.
6. The presaturation part and the vacuumizing part have universality, and the presaturation part and the vacuumizing part can be used for preparing samples of non-cohesive soil for different precise geotechnical tests after the sizes of the sample filling part and the sample compacting part are adjusted according to the sizes of geotechnical test devices and samples.
Drawings
FIG. 1 (a) is a top view of a first pair of split dies;
FIG. 1 (b) is a front view of a first pair of split dies;
FIG. 1 (c) is a side view of a first pair of split dies;
FIG. 2 (a) is a top view of a second split mold;
FIG. 2 (b) is a front view of a second split mold;
FIG. 2 (c) is a side view of a second split mold;
FIG. 3 is a schematic view of a first type of air guide slot;
FIG. 4 is a schematic view of a second type of air guide slot;
FIG. 5 (a) is a top view of the bottom collar;
FIG. 5 (b) is a front view of the bottom collar;
FIG. 5 (c) is a cross-sectional view of the bottom collar at section A-A;
FIG. 6 (a) is a top view of the top collar;
FIG. 6 (b) is a front view of the top collar;
FIG. 6 (c) is a section B-B of the top collar;
FIG. 7 is a schematic view of a compaction bar with a compaction hammer;
FIG. 8 (a) is a top view of a compaction sleeve;
FIG. 8 (b) is an elevation view of a compaction sleeve;
FIG. 8 (C) is a C-C cross-sectional view of a compaction sleeve;
FIG. 9 (a) is an exploded schematic view of an evacuated presaturation fitting;
FIG. 9 (b) is a front view of the vacuum pre-saturation fitting;
FIG. 9 (c) is a top view of the vacuum pre-saturation fitting;
FIG. 10 (a) is a front view of a water-passing pre-saturation fitting;
FIG. 10 (b) is a top view of the water-passing pre-saturation fitting;
FIG. 11 (a) is an elevation view of the specimen loading portion and the specimen compaction portion after assembly;
FIG. 11 (b) is a cross-sectional view of the assembled sample loading section and sample compacting section;
FIG. 12 is a schematic illustration of a sample with a top cap of the soil unit sample mounted prior to stripping;
in the figure: the sample filling part 1, the first pair of open molds 1-1, the second pair of open molds 1-2, the circular air guide groove 1-2-1, the straight line groove 1-2-2, the spiral air guide groove 1-2-3, the vent hole 1-2-4, the bottom lantern ring 1-3, the top lantern ring 1-4, the first annular hoop 1-5, the second annular hoop 1-6, the first rubber ring 1-7, the second rubber ring 1-8, the rubber film 1-9, the sample compacting part 2, the compacting sleeve 2-1, the compacting sleeve scale mark 2-2-1, the compacting sleeve zero scale mark 2-2-1, the compacting hammer 2-3, the compacting rod 2-4, the compacting rod scale mark 2-5, the compacting rod zero scale mark 2-5-1, the vacuum presaturation fitting 3, the first organic glass cylinder 3-1, the first organic glass base 3-2, the first air inlet/water inlet valve 3-3, the first negative pressure gauge 3-4, the cap 3-5, the vacuum valve 3-6, the vacuum valve 3-7, the presaturation valve 4, the second vent 4, the second water inlet valve 4, the second glass cylinder 1-4, the soil sample filling valve 1-4, the second glass base 4, the top glass base 4-4, the soil sample filling valve 1-4, the top soil sample filling unit.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples.
The invention provides a preparation device of a geotechnical test non-cohesive soil sample, which comprises a sample filling part 1, a sample compacting part 2, a sample presaturation part and a vacuumizing part; the sample filling part 1 comprises a first pair of open molds 1-1, a second pair of open molds 1-2, a bottom collar 1-3, a top collar 1-4, a first annular hoop 1-5, a second annular hoop 1-6, a first rubber ring 1-7, a second rubber ring 1-8 and a rubber membrane 1-9; as shown in fig. 1 (a) -1 (c) and fig. 2 (a) -2 (c), air guide grooves are formed in the inner walls of the first pair of open molds 1-1 and the second pair of open molds 1-2; the middle part of the second pair of open molds 1-2 is provided with vent holes 1-2-4; the first pair of open molds 1-1 and the second pair of open molds 1-2 are connected in an up-down aligned manner through a first annular hoop 1-5 and a second annular hoop 1-6, and the section of the connected first pair of open molds and the section of the connected second pair of open molds are in a complete circle; the first pair of open molds 1-1 and the second pair of open molds 1-2 are vertically arranged on the geotechnical test instrument base 7 around the soil unit body sample base 5 through the bottom lantern ring 1-3 after being connected, and the structure of the bottom lantern ring 1-3 is shown in the figures 5 (a) -5 (c); the geotechnical test instrument base 7 is provided with a valve communicated with the bottom of the sample; the top collar 1-4 is installed on top of the first and second pairs of open molds 1-1 and 1-2 for connection of the specimen loading portion 1 and the specimen compacting portion 2, and the bottom collar 1-3 is constructed as shown in fig. 6 (a) -6 (c).
The rubber film 1-9 is flatly and tightly attached to the inner walls of the first pair of open molds 1-1 and the second pair of open molds 1-2, one end of the rubber film is sleeved on the soil unit body sample base 5 and fixed through the first rubber ring 1-7, and the other end of the rubber film is sleeved on the outer walls of the tops of the first pair of open molds 1-1 and the second pair of open molds 1-2 and fixed through the second rubber ring 1-8.
The sample compacting part 2 comprises a compacting sleeve 2-1, a compacting hammer 2-3 and a compacting rod 2-4; the compaction sleeve 2-1 is provided with a compaction sleeve scale mark 2-2, and the compaction rod 2-4 is provided with a compaction rod scale mark 2-5; the compaction sleeve zero graduation mark 2-2-1 is positioned at the bottom of the compaction sleeve graduation mark 2-2, and the compaction rod zero graduation mark 2-5-1 is positioned at the top of the compaction rod graduation mark 2-5; the structure of the compaction sleeve 2-1 is shown in fig. 8 (a) -8 (c); the bottom of the compaction sleeve 2-1 is detachably connected with the top lantern ring 1-4; the compaction bar 2-4 is orthogonally connected to the center of the compaction hammer 2-3 as shown in fig. 7; the compaction hammer 2-3 can move up and down in a cavity formed by the compaction sleeve 2-1, the first pair of open dies 1-1 and the second pair of open dies 1-2 under the drive of the compaction rod 2-4 so as to compact a sample; fig. 11 (a) and 11 (b) show the structure after the sample loading section 1 and the sample compacting section 2 are assembled. A soil unit body sample top cap 6 is mounted on the top surface of the compacted sample, and a top cap through pipe 6-1 is arranged on the soil unit body sample top cap 6, as shown in fig. 12.
The sample pre-saturation part consists of a vacuumizing pre-saturation fitting 3, a water-introducing pre-saturation fitting 4 and a carbon dioxide gas tank; as shown in fig. 9 (a) -9 (c), the vacuum-pumping pre-saturation fitting 3 comprises a first organic glass cylinder 3-1, a first organic glass base 3-2, a first air inlet/water inlet valve 3-3, a first negative pressure meter 3-4, a cover cap 3-5, a vacuum-pumping valve 3-6 and a vent 3-7; the first organic glass cylinder 3-1 is connected with the cap 3-5 in a sealing way through a rubber ring; the bottom of the first organic glass cylinder 3-1 is connected with a first organic glass base 3-2, and the first organic glass base 3-2 is provided with a first air inlet/water inlet valve 3-3 and a first negative pressure meter 3-4; the first air inlet/water inlet valve 3-3 is connected with the top cap through pipe 6-1; the cap 3-5 is provided with a vent 3-7 and a vacuumizing valve 3-6.
As shown in fig. 10 (a) and 10 (b), the water-passing pre-saturation fitting 4 comprises a second plexiglas cylinder 4-1, a second plexiglas base 4-2, a second air inlet/water inlet valve 4-3 and a second negative pressure gauge 4-4; the top of the second plexiglas cylinder 4-1 is open; the bottom of the second organic glass cylinder 4-1 is connected with the second organic glass base 4-2; the second organic glass base 4-2 is provided with a second air inlet/water inlet valve 4-3 and a second negative pressure meter 4-4; the second air inlet/water inlet valve 4-3 is connected with a valve communicated with the bottom of the sample on the geotechnical test instrument base 7 through a pipeline.
The carbon dioxide gas tank is connected with a valve communicated with the bottom of the sample on the geotechnical test instrument base 7 through a pipeline.
The vacuumizing part comprises a vacuum pump with a vacuum pressure control valve, and the vacuum pump is respectively connected with an air guide groove on the inner wall of the first pair of open molds 1-1 and the second pair of open molds 1-2 and an air vent 3-7 on the cover cap 3-5.
Further, the section at the joint of the first pair of open molds 1-1 and the second pair of open molds 1-2 is smooth, and the joint of the first pair of open molds 1-1 and the second pair of open molds 1-2 is in sealing connection through the first annular hoop 1-5 and the second annular hoop 1-6; the first annular hoop 1-5 is arranged at a position which is close to the bottom 1/3 of the height of the first pair of open molds 1-1 and the second pair of open molds 1-2; the second annular collar 1-6 is mounted at a height of 1/3 of the top of the first and second pairs of split dies 1-1 and 1-2.
Further, the materials of the first pair of open molds 1-1, the second pair of open molds 1-2, the bottom lantern ring 1-3 and the top lantern ring 1-4 are wear-resistant metals, including stainless steel and aluminum alloy; the first annular hoop 1-5 and the second annular hoop 1-6 are made of stainless steel; the compaction sleeve 2-1 is made of transparent organic glass; the compaction hammer 2-3 and the compaction rod 2-4 are made of brass or stainless steel.
Further, the heights of the first pair of open molds 1-1 and the second pair of open molds 1-2 are the sum of the height of the sample and the height of the soil unit body sample base 5; the inner diameters of the first pair of open molds 1-1 and the second pair of open molds 1-2 with rubber films 1-9 after being in butt joint are equal to the diameter of the sample; the bottoms of the first pair of open molds 1-1 and the second pair of open molds 1-2 are provided with notches for accommodating the soil unit body sample base 5 and the first rubber ring 1-7, and the sizes of the notches are determined by the thickness of the rubber film 1-9 and the diameter of the first rubber ring 1-7; the outer diameter of the first pair of open molds 1-1 and the second pair of open molds 1-2 in the height range near the top 1/3 is smaller than the outer diameter in the height range near the bottom 2/3.
The inner diameter of the bottom lantern ring 1-3 is determined by the outer diameters of the bottoms of the first pair of split dies 1-1 and the second pair of split dies 1-2 after being in butt joint; the diameter of the opening of the top lantern ring 1-4 is equal to the diameter of the sample; the inner diameter of the top lantern ring 1-4 is determined by the top outer diameter of the first pair of split dies 1-1 and the second pair of split dies 1-2 after being in butt joint and the thickness of the rubber film 1-9.
The inner diameter of the compaction sleeve 2-1 is equal to the diameter of the sample; the bottom ring inner diameter of the compaction sleeve 2-1 is equal to the outer diameter of the top collar 1-4; the internal height of the compaction sleeve 2-1 is determined by the height of the sample, the height of the compaction hammer 2-3 and the drop distance of the compacted sample; a round hole 2-1-1 is formed in the center of the top of the compaction sleeve 2-1, and the diameter of the round hole 2-1-1 is determined by the diameter of a sample, the diameter of a compaction hammer 2-3 and the diameter of a compaction rod 2-4; the diameter of the compaction hammer 2-3 is determined by the diameter of the sample.
Further, the air guide grooves on the inner walls of the first pair of open molds 1-1 and the second pair of open molds 1-2 have the following two types of forms:
as shown in FIG. 3, the first type of air guide grooves are annular air guide grooves 1-2-1 which are arranged in parallel along the inner walls of the first pair of open molds 1-1 and the second pair of open molds 1-2, and the annular air guide grooves 1-2-1 are communicated with the vent holes 1-2-4 through the linear grooves 1-2-2.
As shown in FIG. 4, the second type air guide groove is a spiral air guide groove 1-2-3 along the inner walls of the first pair of open molds 1-1 and the second pair of open molds 1-2, and the spiral air guide groove 1-2-3 passes through the vent holes 1-2-4.
The preparation method of the non-cohesive soil sample for the geotechnical test comprises the following steps:
(1) After the first pair of open molds 1-1 and the second pair of open molds 1-2 are aligned up and down, the side wall sealing connection is carried out through the first annular hoop 1-5 and the second annular hoop 1-6;
(2) One end of a rubber film 1-9 is fixed on a soil unit body sample base 5 through a first rubber ring 1-7; then, the first split mold 1-1 and the second split mold 1-2 which are well connected are vertically arranged on the geotechnical test instrument base 7 around the soil unit body sample base 5 through the bottom lantern ring 1-3; then straightening the rubber film 1-9, and sleeving the other end of the rubber film on the outer walls of the tops of the butted first pair of open molds 1-1 and the butted second pair of open molds 1-2; the method comprises the steps that a vacuum pump is used for vacuumizing air guide grooves on the inner walls of a first pair of open molds 1-1 and a second pair of open molds 1-2, so that a rubber film 1-9 is flatly attached to the inner walls of the first pair of open molds 1-1 and the second pair of open molds 1-2, and then the other end of the rubber film 1-9 is fixed on the outer walls of the tops of the first pair of open molds 1-1 and the second pair of open molds 1-2 which are well abutted by a second rubber ring 1-8;
(3) The top part of the first pair of open molds 1-1 and the top part of the second pair of open molds 1-2 with the rubber films 1-9 are horizontally provided with the top lantern ring 1-4, so that the top lantern ring 1-4 is tightly connected with the outer walls of the rubber films 1-9, the first pair of open molds 1-1 and the second pair of open molds 1-2, and the installation of the sample filling part 1 is completed;
(4) Designing a test soil sample layered filling test scheme: filling in n layers, wherein the weight m=M/n of each layer of filled soil body sample, and the height l=L/n of each layer of filled soil body sample are obtained, wherein M is the total weight of the sample, L is the height of the sample, and n=5 is generally taken;
(5) The compaction rod 2-4 with the compaction hammer 2-3 and the compaction sleeve 2-1 are sequentially arranged on the sample filling part 1, and the scale reading a of the compaction rod 2-4 corresponding to the zero scale mark 2-2-1 of the compaction sleeve is read 1 The method comprises the steps of carrying out a first treatment on the surface of the Sequentially removing the compaction sleeve 2-1 and the compaction rod 2-4 with the compaction hammer 2-3, and pouring a first layer of soil sample with the weight of m into the sample filling part 1; installing the compaction rod 2-4 with the compaction hammer 2-3 and the compaction sleeve 2-1 again, so that the inner wall of the compaction sleeve 2-1, the inner wall of the opening of the top lantern ring 1-4 and the inner walls of the butted first pair of open molds 1-1 and the second pair of open molds 1-2 with the rubber film 1-9 are aligned; the compaction hammer 2-3 contacts the top surface of the first layer of filling soil body which is not compacted, and the scale reading of the compaction rod 2-4 corresponding to the zero scale mark 2-2-1 of the compaction sleeve is read as b 1+k K represents the number of compactions; taking k=0 before non-compaction, namely the scale reading of the compaction rod 2-4 corresponding to the zero scale mark 2-2-1 of the compaction sleeve is b 1 ；
(6) Compacting the first layer of filled soil body by adopting a compacting rod 2-4 with a compacting hammer 2-3, wherein the falling distance of the compacting hammer 2-3 is l when each compaction is carried out 0 I.e. the scale of the compaction rod 2-4 corresponding to the zero scale mark 2-2-1 of the compaction sleeve is (b) 1+k +l 0 ) Falling down; on the first compaction, the scale of the compaction rod 2-4 corresponding to the zero scale mark 2-2-1 of the compaction sleeve is (b) 1 +l 0 ) Falling down; the final compaction height of the first layer of filled soil body after multiple compaction is l, namely when the compaction hammer 2-3 contacts the top surface of the compacted first layer of filled soil body, the scale reading a of the compaction rod 2-4 corresponding to the compaction sleeve zero scale mark 2-2-1 2 ＝a 1 +l; the top surface of the filled soil layer before and after each compaction is ensured to be uniform and horizontal;
(7) After the surface of the soil body filled in the first layer is scratched by bamboo sticks, pouring a second layer of soil sample with the weight of m into the sample filling part 1, compacting the second layer of filled soil body, and repeating the steps until the compaction of the sample with the height of L is completed;
(8) After the compaction sleeve 2-1, the compaction rod 2-4 with the compaction hammer 2-3, the top lantern ring 1-4 and the second rubber ring 1-8 are sequentially removed, the top cap 6 of the soil unit body sample is installed on the top surface of the even horizontal sample, so that the central axis of the top cap 6 of the soil unit body sample coincides with the connecting line of the central axis of the sample; the rubber film 1-9 sleeved on the outer walls of the tops of the first pair of open molds 1-1 and the second pair of open molds 1-2 is turned over and sleeved on the top cap 6 and fixed through the second rubber ring 1-8;
(9) Adopting a vacuumizing part and a vacuumizing pre-saturation fitting 3 to assist in demolding, firstly closing a valve communicated with the bottom of a sample on a geotechnical test instrument base 7, connecting a first air inlet/water inlet valve 3-3 at the bottom of the vacuumizing pre-saturation fitting 3 with a top cap through pipe 6-1, and then connecting a vent port 3-7 at the top of the vacuumizing pre-saturation fitting 3 with a vacuum pump with a vacuum pressure control valve; after airless water is injected into the first organic glass cylinder 3-1, the first organic glass cylinder 3-1 is connected with the cap 3-5 in a sealing way through a rubber ring; closing the vacuum pressure control valve, opening the first air inlet/water inlet valve 3-3, the vacuumizing valve 3-6 and the valve for controlling the top cap through pipe 6-1, starting the vacuum pump, and slowly adjusting the vacuum pressure control valve until the vacuum pressure is stably maintained at-20 kPa; after the sample is vertically stabilized by the applied negative pressure, respectively and sequentially removing the first annular hoop 1-5, the second annular hoop 1-6, the first pair of open dies 1-1, the second pair of open dies 1-2 and the bottom lantern ring 1-3; the vacuum pressure is controlled by a vacuum pressure control valve to be stably maintained at-20 kPa, so that the sample is kept stable, and an unsaturated soil sample with the water content of omega and the pore ratio of e is prepared;
(10) Presaturation step: after a control valve of the carbon dioxide gas tank is connected with a valve communicated with the bottom of the sample on the geotechnical test instrument base 7, opening the control valve of the carbon dioxide gas tank and the valve communicated with the bottom of the sample on the geotechnical test instrument base 7, and slowly introducing carbon dioxide into the sample; adjusting a control valve of the carbon dioxide gas tank to make bubbles in the first organic glass cylinder 3-1 uniform and slow; the vacuum pressure is controlled to be stably maintained at-20 kPa through a vacuum pressure control valve, and after continuously and slowly introducing carbon dioxide gas into the sample for 30min, a valve on the geotechnical test instrument base 7, which is communicated with the bottom of the sample, and a control valve of a carbon dioxide gas tank are closed;
Closing a second air inlet/water inlet valve 4-3 at the bottom of the water-through presaturation fitting 4, injecting a sufficient amount of airless water into the second organic glass cylinder 4-1, removing gas in a connecting conduit, and connecting a valve on the geotechnical test instrument base 7, which is communicated with the bottom of the sample, with the second air inlet/water inlet valve 4-3 through the connecting conduit; opening a valve on the geotechnical test instrument base 7, which is communicated with the bottom of the sample, and a second air inlet/water inlet valve 4-3, and slowly injecting airless water in a second organic glass cylinder 4-1 into the sample under the action of vacuum pressure; the vacuum pressure is controlled by a vacuum pressure control valve to be stably maintained at-20 kPa, and airless water is continuously injected into the sample; after the bubbles in the first organic glass cylinder 3-1 completely disappear, sequentially closing a valve communicated with the bottom of the sample, a valve for controlling a top cap through pipe 6-1, a first air inlet/water inlet valve 3-3, a second air inlet/water inlet valve 4-3 and a vacuum pump on a base 7 of the geotechnical test instrument to prepare a saturated soil sample with the aperture ratio of e.
Further, the rubber film 1-9 is flatly attached to the inner walls of the first split die 1-1 and the second split die 1-2 by vacuumizing the air guide grooves on the inner walls of the first split die 1-1 and the second split die 1-2 through a vacuum pump; in the sample layering filling process, the rubber film 1-9 continuously and flatly clings to the inner walls of the first pair of open molds 1-1 and the second pair of open molds 1-2.
Further, in the soil sample compacting process, the central axes of the components of the sample filling part 1 and the sample compacting part 2 and the connecting line of the central axes of the sample and the central axis of the sample base 5 of the soil unit body are kept coincident; the sample was compacted in a quincuncial fashion.
Further, the calculation formula of the total mass of the sample is as followsWherein d, L, e, ω and d s The diameter, the height, the void ratio, the water content and the soil particle weight, ρ of the sample are respectively w Is the density of water; wherein, the value of omega is determined by a sample preparation method, and when preparing a saturated soil sample, if the sample is prepared by a wet ramming method, the omega is taken to be 5 percent; if adopting a (dry sand) shakeout methodIn the sample, omega is 0; when preparing unsaturated soil samples, ω is the actual moisture content of the sample.
Further, when the scale reading of the compaction rod 2-4 corresponding to the compaction sleeve zero scale mark 2-2-1 exceeds the maximum scale a of the compaction rod 2-4 max I.e. the maximum scale a of the compaction rod 2-4 each time the compaction hammer 2-3 enters the compaction sleeve 2-1, the final compaction height of the layered filling soil body is according to the contact of the compaction hammer 2-3 with the top surface of the compacted layered filling soil body max The graduation mark of the corresponding compaction sleeve 2-1 is (a) n+1 ＝a n +l-a max ) Determining, wherein n represents the number of times of sample layered filling;
Each time a soil sample is compacted, the compaction rod 2-4 is moved from the maximum scale a of the compaction rod 2-4 max The graduation mark of the corresponding compaction sleeve 2-1 is (b) 1+k +l 0 -a max ) Falling down.
The technical principle of the present invention is described above in connection with the specific embodiments. The description is made for the purpose of illustrating the general principles of the invention and should not be taken in any way as limiting the scope of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of this specification without undue burden.

Claims (8)

1. The utility model provides a preparation facilities of geotechnical test non-clay soil sample which characterized in that: the device comprises a sample filling part (1), a sample compacting part (2), a sample presaturation part and a vacuumizing part; the sample filling part (1) comprises a first pair of open molds (1-1), a second pair of open molds (1-2), a bottom collar (1-3), a top collar (1-4), a first annular hoop (1-5), a second annular hoop (1-6), a first rubber ring (1-7), a second rubber ring (1-8) and a rubber membrane (1-9); the inner walls of the first pair of open molds (1-1) and the second pair of open molds (1-2) are provided with air guide grooves; the middle part of the second pair of open molds (1-2) is provided with vent holes (1-2-4); the first pair of open molds (1-1) and the second pair of open molds (1-2) are connected in an up-down alignment manner through a first annular hoop (1-5) and a second annular hoop (1-6), and the section of the connected first pair of open molds and the section of the connected second pair of open molds are in a complete round shape; the first pair of open molds (1-1) and the second pair of open molds (1-2) are vertically arranged on the geotechnical test instrument base (7) around the soil unit body sample base (5) through the bottom lantern ring (1-3) after being connected; the geotechnical test instrument base (7) is provided with a valve communicated with the bottom of the sample; the top lantern ring (1-4) is arranged at the top of the first pair of open molds (1-1) and the second pair of open molds (1-2) and is used for connecting the sample filling part (1) and the sample compacting part (2);
The rubber film (1-9) is flatly clung to the inner walls of the first pair of open molds (1-1) and the second pair of open molds (1-2), one end of the rubber film is sleeved on the soil unit body sample base (5) and fixed through the first rubber ring (1-7), and the other end of the rubber film is sleeved on the outer walls of the tops of the first pair of open molds (1-1) and the second pair of open molds (1-2) and fixed through the second rubber ring (1-8);
the sample compacting part (2) comprises a compacting sleeve (2-1), a compacting hammer (2-3) and a compacting rod (2-4); the compaction sleeve (2-1) is provided with a compaction sleeve scale mark (2-2), and the compaction rod (2-4) is provided with a compaction rod scale mark (2-5); the compaction sleeve zero graduation line (2-2-1) is positioned at the bottom of the compaction sleeve graduation line (2-2), and the compaction rod zero graduation line (2-5-1) is positioned at the top of the compaction rod graduation line (2-5); the bottom of the compaction sleeve (2-1) is detachably connected with the top lantern ring (1-4); the compaction rod (2-4) is orthogonally connected to the center of the compaction hammer (2-3); the compaction hammer (2-3) can move up and down in a cavity formed by the compaction sleeve (2-1), the first pair of open dies (1-1) and the second pair of open dies (1-2) under the drive of the compaction rod (2-4) to compact the sample; a soil unit body sample top cap (6) is arranged on the top surface of the compacted sample, and a top cap through pipe (6-1) is arranged on the soil unit body sample top cap (6);
The sample pre-saturation part consists of a vacuumizing pre-saturation fitting (3), a water-introducing pre-saturation fitting (4) and a carbon dioxide gas tank; the vacuumizing presaturation accessory (3) comprises a first organic glass cylinder (3-1), a first organic glass base (3-2), a first air inlet/water inlet valve (3-3), a first negative pressure meter (3-4), a cap (3-5), a vacuumizing valve (3-6) and an air vent (3-7); the first organic glass cylinder (3-1) is connected with the cap (3-5) in a sealing way through a rubber ring; the bottom of the first organic glass cylinder (3-1) is connected with a first organic glass base (3-2), and the first organic glass base (3-2) is provided with a first air inlet/water inlet valve (3-3) and a first negative pressure meter (3-4); the first air inlet/water inlet valve (3-3) is connected with the top cap through pipe (6-1); the cap (3-5) is provided with a vent (3-7) and a vacuumizing valve (3-6);
the water-through presaturation accessory (4) comprises a second organic glass cylinder (4-1), a second organic glass base (4-2), a second air inlet/water inlet valve (4-3) and a second negative pressure meter (4-4); the top of the second plexiglas cylinder (4-1) is open; the bottom of the second organic glass cylinder (4-1) is connected with the second organic glass base (4-2); the second organic glass base (4-2) is provided with a second air inlet/water inlet valve (4-3) and a second negative pressure meter (4-4); the second air inlet/water inlet valve (4-3) is connected with a valve communicated with the bottom of the sample on the geotechnical test instrument base (7) through a pipeline;
The carbon dioxide gas tank is connected with a valve communicated with the bottom of the sample on the geotechnical test instrument base (7) through a pipeline;
the vacuumizing part comprises a vacuum pump with a vacuum pressure control valve, and the vacuum pump is respectively connected with an air guide groove on the inner wall of the first pair of open molds (1-1) and the second pair of open molds (1-2) and an air vent (3-7) on the cover cap (3-5);
the section at the joint of the first split die (1-1) and the second split die (1-2) is smooth, and the joint of the first split die (1-1) and the second split die (1-2) is in sealing connection through the first annular hoop (1-5) and the second annular hoop (1-6); the first annular hoop (1-5) is arranged at a position which is 1/3 of the height of the bottom of the first pair of open molds (1-1) and the second pair of open molds (1-2); the second annular hoop (1-6) is arranged at a position which is 1/3 of the height of the top of the first pair of open molds (1-1) and the second pair of open molds (1-2);
the heights of the first pair of open molds (1-1) and the second pair of open molds (1-2) are the sum of the height of the sample and the height of the soil unit body sample base (5); the inner diameters of the first pair of open molds (1-1) and the second pair of open molds (1-2) with rubber films (1-9) after being in butt joint are equal to the diameter of the sample; the bottoms of the first pair of open molds (1-1) and the second pair of open molds (1-2) are provided with notches for accommodating the soil unit body sample base (5) and the first rubber ring (1-7), and the sizes of the notches are determined by the thickness of the rubber film (1-9) and the diameter of the first rubber ring (1-7); the outer diameter of the first pair of open molds (1-1) and the second pair of open molds (1-2) in the height range close to the top 1/3 is smaller than the outer diameter in the height range close to the bottom 2/3;
The inner diameter of the bottom lantern ring (1-3) is determined by the outer diameters of the bottoms of the first pair of split dies (1-1) and the second pair of split dies (1-2) after being in butt joint; the diameter of the opening of the top lantern ring (1-4) is equal to the diameter of the sample; the inner diameter of the top lantern ring (1-4) is determined by the top outer diameter of the first pair of split dies (1-1) and the second pair of split dies (1-2) after being in butt joint and the thickness of the rubber film (1-9);
the inner diameter of the compaction sleeve (2-1) is equal to the diameter of the sample; the inner diameter of the bottom ring of the compaction sleeve (2-1) is equal to the outer diameter of the top lantern ring (1-4); the internal height of the compaction sleeve (2-1) is determined by the height of the sample, the height of the compaction hammer (2-3) and the drop distance of the compacted sample; a round hole (2-1-1) is formed in the center of the top of the compaction sleeve (2-1), and the diameter of the round hole (2-1-1) is determined by the diameter of a sample, the diameter of a compaction hammer (2-3) and the diameter of a compaction rod (2-4); the diameter of the compaction hammer (2-3) is determined by the diameter of the sample.
2. The device for preparing a geotechnical test non-cohesive soil sample according to claim 1, wherein: the first pair of open molds (1-1), the second pair of open molds (1-2), the bottom lantern ring (1-3) and the top lantern ring (1-4) are made of wear-resistant metal, and comprise stainless steel and aluminum alloy; the first annular hoop (1-5) and the second annular hoop (1-6) are made of stainless steel; the compaction sleeve (2-1) is made of transparent organic glass; the compaction hammer (2-3) and the compaction rod (2-4) are made of brass or stainless steel.
3. The device for preparing a geotechnical test non-cohesive soil sample according to claim 1, wherein: the air guide grooves on the inner walls of the first pair of open molds (1-1) and the second pair of open molds (1-2) are in the following two types:
the first type of air guide grooves are annular air guide grooves (1-2-1) which are arranged in parallel along the inner walls of the first pair of open molds (1-1) and the second pair of open molds (1-2), and the annular air guide grooves (1-2-1) are communicated with the vent holes (1-2-4) through the straight line grooves (1-2-2);
the second type of air guide groove is a spiral air guide groove (1-2-3) along the inner walls of the first pair of open molds (1-1) and the second pair of open molds (1-2), and the spiral air guide groove (1-2-3) passes through the vent hole (1-2-4).
4. The preparation method of the non-cohesive soil sample for the geotechnical test is characterized by comprising the following steps of:
(1) After the first pair of open molds (1-1) and the second pair of open molds (1-2) are aligned up and down, the side wall sealing connection is carried out through the first annular hoop (1-5) and the second annular hoop (1-6);
(2) One end of a rubber film (1-9) is fixed on a soil unit body sample base (5) through a first rubber ring (1-7); then, vertically installing the butted first split mould (1-1) and second split mould (1-2) on a geotechnical test instrument base (7) around the soil unit body sample base (5) through a bottom lantern ring (1-3); straightening the rubber film (1-9) to ensure that the other end of the rubber film is sleeved on the outer walls of the tops of the butted first pair of split dies (1-1) and the butted second pair of split dies (1-2); the rubber film (1-9) is flatly attached to the inner walls of the first split die (1-1) and the second split die (1-2) by means of vacuumizing the air guide grooves on the inner walls of the first split die (1-1) and the second split die (1-2) through a vacuum pump, and then the other end of the rubber film (1-9) is fixed on the outer walls of the tops of the first split die (1-1) and the second split die (1-2) which are well abutted through the second rubber ring (1-8);
(3) Installing a top collar (1-4) horizontally on top of the butted first pair of open molds (1-1) and the second pair of open molds (1-2) with rubber films (1-9), so that the top collar (1-4) is tightly connected with the outer walls of the rubber films (1-9), the first pair of open molds (1-1) and the second pair of open molds (1-2), and installing a sample filling part (1) is completed;
(4) Designing a test soil sample layered filling test scheme: filling in n layers, wherein the weight m=M/n of each layer of filled soil body sample, and the height l=L/n of each layer of filled soil body sample, wherein M is the total weight of the sample, and L is the height of the sample;
(5) A compaction rod (2-4) with a compaction hammer (2-3) and a compaction sleeve (2-1) are sequentially arranged on the sample filling part (1), and a scale reading a of the compaction rod (2-4) corresponding to a zero scale mark (2-2-1) of the compaction sleeve is read 1 The method comprises the steps of carrying out a first treatment on the surface of the Sequentially removing the compaction sleeve (2-1) and the compaction with the compaction hammer (2-3)After the solid rod (2-4), pouring a first layer of soil sample with the weight of m into the sample filling part (1); installing the compaction rod (2-4) with the compaction hammer (2-3) and the compaction sleeve (2-1) again, so that the inner wall of the compaction sleeve (2-1), the inner wall of the opening of the top lantern ring (1-4) and the inner walls of the first pair of open molds (1-1) and the second pair of open molds (1-2) which are in butt joint and provided with the rubber film (1-9) are aligned; the compaction hammer (2-3) contacts the top surface of the first layer of non-compacted filled soil body, and reads the scale reading b of the compaction rod (2-4) corresponding to the zero scale line (2-2-1) of the compaction sleeve 1+k K represents the number of compactions; taking k=0 before non-compaction, namely the scale reading of the compaction rod (2-4) corresponding to the zero scale mark (2-2-1) of the compaction sleeve is b 1 ；
(6) Compacting the first layer of filled soil body by adopting a compacting rod (2-4) with a compacting hammer (2-3), wherein the falling distance of the compacting hammer (2-3) is l when each compaction is carried out 0 Namely, the scale corresponding to the zero scale mark (2-2-1) of the compaction rod (2-4) from the compaction sleeve is b 1+k +l 0 Falling down; when compacting for the first time, the corresponding scale of the compacting rod (2-4) from the zero scale line (2-2-1) of the compacting sleeve is b 1 +l 0 Falling down; the final compaction height of the first layer of filled soil body after multiple times of compaction is l, namely when the compaction hammer (2-3) contacts the top surface of the compacted first layer of filled soil body, the scale reading a of the compaction rod (2-4) corresponding to the zero scale mark (2-2-1) of the compaction sleeve 2 ＝a 1 +l; the top surface of the filled soil layer before and after each compaction is ensured to be uniform and horizontal;
(7) After the surface of the soil body filled in the first layer is scratched by bamboo sticks, pouring a second layer of soil sample with the weight of m into the sample filling part (1), compacting the second layer of filled soil body, and repeating the steps until the compaction of the sample with the height of L is completed;
(8) After sequentially removing the compaction sleeve (2-1), the compaction rod (2-4) with the compaction hammer (2-3), the top sleeve ring (1-4) and the second rubber ring (1-8), installing a soil unit body sample top cap (6) on the top surface of the uniformly horizontal sample, so that the central axis of the soil unit body sample top cap (6) coincides with the connecting line of the central axis of the sample; the rubber film (1-9) sleeved on the outer walls of the tops of the first pair of open molds (1-1) and the second pair of open molds (1-2) is turned up and sleeved on the top cap (6) and fixed through the second rubber ring (1-8);
(9) Adopting a vacuumizing part and a vacuumizing pre-saturation fitting (3) to assist in demolding, firstly closing a valve communicated with the bottom of a sample on a geotechnical test instrument base (7), connecting a first air inlet/water inlet valve (3-3) at the bottom of the vacuumizing pre-saturation fitting (3) with a top cap through pipe (6-1), and then connecting a vent (3-7) at the top of the vacuumizing pre-saturation fitting (3) with a vacuum pump with a vacuum pressure control valve; after airless water is injected into the first organic glass cylinder (3-1), the first organic glass cylinder (3-1) is connected with the cap (3-5) in a sealing way through a rubber ring; closing the vacuum pressure control valve, opening the first air inlet/water inlet valve (3-3), the vacuumizing valve (3-6) and the valve for controlling the top cap through pipe (6-1), starting the vacuum pump, and slowly adjusting the vacuum pressure control valve until the vacuum pressure is stably maintained at-20 kPa; after the sample is vertically stabilized by the applied negative pressure, respectively and sequentially removing the first annular hoop (1-5), the second annular hoop (1-6), the first pair of open molds (1-1), the second pair of open molds (1-2) and the bottom lantern ring (1-3); the vacuum pressure is controlled by a vacuum pressure control valve to be stably maintained at-20 kPa, so that the sample is kept stable, and an unsaturated soil sample is prepared;
(10) Presaturation step: after a control valve of the carbon dioxide gas tank is connected with a valve communicated with the bottom of a sample on a geotechnical test instrument base (7), opening the control valve of the carbon dioxide gas tank and the valve communicated with the bottom of the sample on the geotechnical test instrument base (7), and slowly introducing carbon dioxide into the sample; adjusting a control valve of the carbon dioxide gas tank to make bubbles in the first organic glass cylinder (3-1) uniform and slow; the vacuum pressure is controlled to be stably maintained at-20 kPa through a vacuum pressure control valve, and after continuously and slowly introducing carbon dioxide gas into the sample for 30min, a valve on a geotechnical test instrument base (7) which is communicated with the bottom of the sample and a control valve of a carbon dioxide gas tank are closed;
Closing a second air inlet/water inlet valve (4-3) at the bottom of the water-through presaturation fitting (4), injecting a sufficient amount of airless water into the second organic glass cylinder (4-1), removing gas in a connecting conduit, and connecting a valve on a geotechnical test instrument base (7) communicated with the bottom of the sample with the second air inlet/water inlet valve (4-3) through the connecting conduit; opening a valve on a geotechnical test instrument base (7) communicated with the bottom of the sample and a second air inlet/water inlet valve (4-3), and slowly injecting airless water in a second organic glass cylinder (4-1) into the sample under the action of vacuum pressure; the vacuum pressure is controlled by a vacuum pressure control valve to be stably maintained at-20 kPa, and airless water is continuously injected into the sample; after bubbles in the first organic glass cylinder (3-1) completely disappear, sequentially closing a valve communicated with the bottom of the sample and a valve for controlling a top cap through pipe (6-1), a first air inlet/water inlet valve (3-3), a second air inlet/water inlet valve (4-3) and a vacuum pump on a geotechnical test instrument base (7) to prepare a saturated soil sample.
5. The method for preparing the geotechnical test non-cohesive soil sample according to claim 4, wherein the method comprises the following steps: the rubber film (1-9) is flatly attached to the inner walls of the first split die (1-1) and the second split die (1-2) in a mode of vacuumizing the air guide grooves on the inner walls of the first split die (1-1) and the second split die (1-2) through a vacuum pump; in the layered filling process of the sample, the rubber film (1-9) continuously and flatly clings to the inner walls of the first pair of open molds (1-1) and the second pair of open molds (1-2).
6. The method for preparing the geotechnical test non-cohesive soil sample according to claim 4, wherein the method comprises the following steps: in the soil sample compacting process, the central axes of the components of the sample filling part (1) and the sample compacting part (2) are kept coincident with the connecting line of the central axes of the sample and the central axis of the sample base (5) of the soil unit body; the sample was compacted in a quincuncial fashion.
7. The method for preparing the geotechnical test non-cohesive soil sample according to claim 4, wherein the method comprises the following steps: the calculation formula of the total mass of the sample is as followsWherein d, L, e, ω and d s The diameter, the height, the void ratio, the water content and the soil particle weight, ρ of the sample are respectively w Is the density of water; wherein, the value of omega is determined by a sample preparation method, and when preparing a saturated soil sample, if the sample is prepared by a wet ramming method, the omega is taken to be 5 percent; omega taking when adopting shakeout method to prepare sample0; when preparing unsaturated soil samples, ω is the actual moisture content of the sample.
8. The method for preparing the geotechnical test non-cohesive soil sample according to claim 4, wherein the method comprises the following steps: when the scale reading of the compaction rod (2-4) corresponding to the compaction sleeve zero scale mark (2-2-1) exceeds the maximum scale a of the compaction rod (2-4) max I.e. the compaction hammer (2-3) enters the compaction sleeve (2-1), the maximum scale a of the compaction rod (2-4) is reached each time the final compaction height of the layered filling soil body is according to the contact of the compaction hammer (2-3) with the top surface of the compacted layered filling soil body max The scale mark scale of the corresponding compaction sleeve (2-1) is a n+1 ＝a n +l-a max Determining, wherein n represents the number of times of sample layered filling;
each time a soil sample is compacted, the compaction rod (2-4) is moved from the maximum scale a of the compaction rod (2-4) max The scale mark scale of the corresponding compaction sleeve (2-1) is b 1+k +l 0 -a max Falling down.
CN201810849926.6A 2018-07-28 2018-07-28 Preparation device and preparation method of non-cohesive soil sample for geotechnical test Active CN108663249B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201810849926.6A CN108663249B (en) 2018-07-28 2018-07-28 Preparation device and preparation method of non-cohesive soil sample for geotechnical test

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201810849926.6A CN108663249B (en) 2018-07-28 2018-07-28 Preparation device and preparation method of non-cohesive soil sample for geotechnical test

Publications (2)

Publication Number Publication Date
CN108663249A CN108663249A (en) 2018-10-16
CN108663249B true CN108663249B (en) 2023-08-18

Family

ID=63789729

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201810849926.6A Active CN108663249B (en) 2018-07-28 2018-07-28 Preparation device and preparation method of non-cohesive soil sample for geotechnical test

Country Status (1)

Country Link
CN (1) CN108663249B (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109752228B (en) * 2019-01-22 2024-03-01 北京交通大学 Sample preparation device and method for simulating composite stratum and reserving grouting holes
CN110553898A (en) * 2019-10-15 2019-12-10 中国矿业大学(北京) Cohesive soil sample preparation device for geotechnical test and use method
CN110987561A (en) * 2019-12-13 2020-04-10 中国海洋大学 Sand sample preparation device and method
CN111678754B (en) * 2020-07-03 2023-07-04 江苏开放大学（江苏城市职业学院） Static pressure and hammering combined sample preparation method and triaxial test device
CN113125221B (en) * 2021-04-08 2022-10-28 昆明理工大学 Triaxial test sample preparation device and sample preparation method thereof
CN113804523B (en) * 2021-08-26 2024-03-22 西安理工大学 Visual sealing sample preparation device, assembly method and sample preparation method for bulk materials

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010181232A (en) * 2009-02-04 2010-08-19 Kansai Electric Power Co Inc:The Method of preparing test sample for triaxial test
CN202126369U (en) * 2011-06-28 2012-01-25 宁波大学 Sample preparation instrument of sand triaxial test
CN104374624A (en) * 2014-11-19 2015-02-25 北京工业大学 Geotechnical triaxial test sample preparation split round mold and sample preparation method
CN104913959A (en) * 2015-06-10 2015-09-16 温州大学 High-airtightness sample preparation device and sample preparation method thereof
CN105181416A (en) * 2015-10-12 2015-12-23 北京工业大学 High-visualization geotechnical triaxial test sample device and manufacturing method
CN107101855A (en) * 2017-04-26 2017-08-29 桂林理工大学 Manipulated soil compaction in layers sample preparation device and its method for indoor triaxial test
CN107607385A (en) * 2017-08-02 2018-01-19 同济大学 Vacuum test device for three axle manipulated soil sample preparations
CN207066817U (en) * 2017-03-31 2018-03-02 浙江大学 Triaxial test disturbed soil sample preparation device
CN209086023U (en) * 2018-07-28 2019-07-09 浙江大学城市学院 A kind of preparation facilities of soil test cohesiveless soil sample

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9546940B2 (en) * 2015-06-03 2017-01-17 Ramesh Chandra Gupta Test device for determining three-dimensional consolidation properties of soils

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010181232A (en) * 2009-02-04 2010-08-19 Kansai Electric Power Co Inc:The Method of preparing test sample for triaxial test
CN202126369U (en) * 2011-06-28 2012-01-25 宁波大学 Sample preparation instrument of sand triaxial test
CN104374624A (en) * 2014-11-19 2015-02-25 北京工业大学 Geotechnical triaxial test sample preparation split round mold and sample preparation method
CN104913959A (en) * 2015-06-10 2015-09-16 温州大学 High-airtightness sample preparation device and sample preparation method thereof
CN105181416A (en) * 2015-10-12 2015-12-23 北京工业大学 High-visualization geotechnical triaxial test sample device and manufacturing method
CN207066817U (en) * 2017-03-31 2018-03-02 浙江大学 Triaxial test disturbed soil sample preparation device
CN107101855A (en) * 2017-04-26 2017-08-29 桂林理工大学 Manipulated soil compaction in layers sample preparation device and its method for indoor triaxial test
CN107607385A (en) * 2017-08-02 2018-01-19 同济大学 Vacuum test device for three axle manipulated soil sample preparations
CN209086023U (en) * 2018-07-28 2019-07-09 浙江大学城市学院 A kind of preparation facilities of soil test cohesiveless soil sample

Also Published As

Publication number Publication date
CN108663249A (en) 2018-10-16

Similar Documents

Publication Publication Date Title
CN108663249B (en) Preparation device and preparation method of non-cohesive soil sample for geotechnical test
CN104913959A (en) High-airtightness sample preparation device and sample preparation method thereof
CN105181416A (en) High-visualization geotechnical triaxial test sample device and manufacturing method
CN104634636A (en) Remolded soil layered sample impacting device and sample preparation method thereof
CN104374624A (en) Geotechnical triaxial test sample preparation split round mold and sample preparation method
CN107247010B9 (en) Method and device for measuring oxygen diffusion coefficient in cement-based material under different humidity
CN111624070A (en) Test sample and method for measuring external friction angle of saturated soil and structure by utilizing triaxial apparatus
CN103674643A (en) Method and equipment for preparing remolded soil specimen
CN109752304B (en) Variable water head soil permeability coefficient measuring device
CN109752305B (en) Constant head soil permeability coefficient measuring device
CN209745717U (en) triaxial hydraulic fracture test device
CN209086023U (en) A kind of preparation facilities of soil test cohesiveless soil sample
CN212275392U (en) A can inhale formula system appearance device for sandy soil triaxial experiment
CN116735844B (en) Device and method for rapidly measuring grouting rate of semi-flexible pavement
CN109283113B (en) Concrete impermeability test device and test method for eliminating horizontal hoop pressure
CN209979337U (en) Forming die for preparing triaxial compression test sample
CN112161908A (en) Triaxial apparatus continuous seepage test device and use method thereof
CN208705202U (en) A kind of equipment measuring intact loess Unsaturated Hydraulic Conductivity
CN213209687U (en) Controllable geotechnique triaxial soil sample saturation mould in route soaks
CN210690196U (en) Physical similar material test piece mould of variable volume
CN115290533A (en) Centrifugal model test device and method for simulating soil body permeation
CN210243315U (en) Sand resonance column test sample preparation device
CN210180783U (en) A test piece static pressure forming device for geotechnique triaxial compression test
CN209802929U (en) constant head soil permeability coefficient measuring device
CN113804523B (en) Visual sealing sample preparation device, assembly method and sample preparation method for bulk materials

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant