CN115928684A - Device and method for mounting pore water pressure gauge in soft soil layer - Google Patents
Device and method for mounting pore water pressure gauge in soft soil layer Download PDFInfo
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- CN115928684A CN115928684A CN202211670468.2A CN202211670468A CN115928684A CN 115928684 A CN115928684 A CN 115928684A CN 202211670468 A CN202211670468 A CN 202211670468A CN 115928684 A CN115928684 A CN 115928684A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention discloses a device and a method for mounting a pore water pressure gauge in a soft soil layer, wherein the device comprises the steps of mounting the pore water pressure gauge in a mounting cylinder and assembling the pore water pressure gauge, and inserting a mounting rod into the mounting cylinder; the installation cylinder is lowered into a drilled embedding drill hole along with the installation rod, a drilling machine is used for applying downward pressure to the installation rod, and the installation cylinder is pressed into a soft soil layer at the bottom of the hole until the embedding depth of the lowest side monitoring point is reached; fixing the installation rope on the ground, and simultaneously lifting the installation rod section by section to automatically separate the installation cylinder from the installation rod, wherein the installation cylinder is installed to a preset monitoring depth; and (4) putting the hole sealing soil column between adjacent pore water pressure gauges, plugging and tamping soil between upper and lower adjacent monitoring points of the drilled hole in a layering manner, and then backfilling the drilled hole. The device is convenient to install and operate, can be suitable for monitoring the pore water pressure of a soft soil layer as a lower soil layer, can effectively isolate the communication of adjacent pore water pressure meters, and has high monitoring accuracy.
Description
Technical Field
The invention belongs to the technical field of geotechnical engineering monitoring, and particularly relates to a device and a method for mounting a pore water pressure gauge in a soft soil layer.
Background
The pore water pressure is an important monitoring index and an information source which need to be referred to when deformation and stability analysis is carried out in the engineering of filling foundations, roadbeds, dams and side slopes. The common instrument for observing the pore water pressure is a pore water pressure gauge, and the pore water pressure gauge needs to be installed and embedded at a monitoring position in a soil layer when in use. If reliable pore water pressure observation data is needed, not only a monitoring instrument with reliable quality but also a corresponding reliable installation and embedding technology is needed, so that the embedding quality of the pore water pressure meter is ensured, and the observation effect is influenced or not, even the observation fails. The key of the success or failure of the installation and embedding work of the pore water pressure gauge is to solve the following three key factors: firstly, accurately positioning a pore water pressure meter; (2) Secondly, smooth water seepage around the probe of the pore water pressure gauge is ensured; (3) And thirdly, the isolation and hole sealing between adjacent pore water pressure gauge probes are solved. When the drilling hole gap water pressure meter is buried by drilling, the problems of hole collapse and hole shrinkage generally do not occur in unsaturated soil above the underground water level, the pore water pressure meter probe can be directly hung to the monitoring depth in the drilling hole, the periphery of the pore water pressure meter probe is backfilled by coarse sand, and the hole is sealed by air-dried bentonite or high-disintegration clay balls between the upper and lower pore water pressure meter probes, but when the soft soil layers such as saturated soft clay, silt or peat soil, organic soil, peat and the like are encountered, the hole drilling and hole shrinkage are serious, and the installation and burying of the pore water pressure meter at the moment face the following problems: (1) Firstly, a pore water pressure gauge probe is difficult to be installed to a preset monitoring depth; (2) Secondly, a water seepage filter layer is difficult to form on the periphery of the probe of the pore water pressure gauge, and a permeable stone on the probe is easy to be blocked by mud, so that the water inlet of the probe is not smooth, and the sensitivity and the measured value reliability of the probe are influenced; (3) Thirdly, the upper and lower pore water pressure gauge probes are difficult to be sealed or are not sealed, so that the upper and lower pore water pressure gauge probes are communicated with each other, and the pore water pressure gauge measurement value is inaccurate. Therefore, it is necessary to improve the embedding method of the pore water pressure gauge to realize reliable embedding of the pore water pressure gauge and ensure the accuracy of the measured value.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a device and a method for installing pore water pressure gauges in a soft soil layer aiming at the defects in the prior art, so that a plurality of pore water pressure gauges are longitudinally embedded at different depths of the same drill hole in the soft soil layer.
The invention is realized by the following technical scheme:
a device for installing a pore water pressure gauge in a soft soil layer comprises,
the device comprises an installation cylinder, an installation rod, an installation rope and a hole sealing soil column;
the mounting cylinder comprises a connecting piece and a bottom pressure head, and the connecting piece and the bottom pressure head are spliced and connected through a reducing joint; the mounting cylinder is filled with coarse sand, the pore water pressure gauge is mounted inside the bottom pressure head, and the coarse sand is filled around the pore water pressure gauge; the mounting rod is inserted in the inner cavity of the connecting piece; the mounting rope is connected with the connecting piece, the hole sealing soil column and the mounting cylinder are both mounted in the drilled hole, and the hole sealing soil column is placed on the mounting cylinder.
Preferably, the outer side wall of the connecting piece is provided with a fixing ring for fixing and installing the rope, and the wall of the connecting piece is provided with a wire outlet hole for penetrating through a cable of the pore water pressure gauge.
Preferably, the connecting piece, the reducing joint and the bottom pressure head are fixedly connected through bolts.
Preferably, a blocking head is installed in a central inner hole of the connecting piece.
Preferably, the barrel body of the bottom pressure head is provided with water permeable holes, the aperture of each water permeable hole is 3-4 mm, the aperture ratio is 10% -15%, and the inner wall of the barrel of the bottom pressure head is provided with a filter screen.
Preferably, the hole sealing soil column is manufactured by arranging air-dried soil balls in a high-strength plastic net, and is hung and placed at a preset position in a hole drill hole through a steel wire rope; the diameter of the hole sealing soil column is (d-2) cm to (d-5) cm, and d is the diameter of a drilling hole forming drilling tool. (ii) a
Preferably, when the hole sealing earth pillar is installed, one end of the installation rod, which is close to the hole sealing earth pillar, is provided with a flexible top plate.
Preferably, the bottom of the bottom pressure head is a cone, the mounting rod is a segmented connecting rod, and the mounting rod is made of a drilling machine drill rod or a galvanized steel pipe.
Preferably, the installation rope is a steel wire rope with the diameter of 3-4 mm; the connecting piece is an H-shaped cylinder.
An installation method of a device for installing a pore water pressure gauge in a soft soil layer comprises the following steps,
step one, installing a pore water pressure gauge in an installation cylinder and assembling, and inserting an installation rod into the installation cylinder;
step two, the installation barrel is lowered into a drilled hole along with the installation rod, the installation rope is lifted upwards in the lowering process to enable the installation rod and the installation barrel not to be separated, a drilling machine is used for applying downward pressure to the installation rod, and the installation barrel is pressed into a soft soil layer at the bottom of the hole until the embedding depth of the lowest monitoring point is reached; fixing the installation rope on the ground, and lifting the installation rod section by section at the same time to automatically separate the installation cylinder from the installation rod, wherein the installation cylinder is installed to a preset monitoring depth;
and step three, placing the hole sealing soil column between adjacent pore water pressure gauges, plugging and tamping soil bodies between upper and lower adjacent monitoring points of the drilled hole in a layering manner, and then backfilling the drilled hole.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention provides a device and a method for mounting a pore water pressure gauge in a soft soil layer, wherein the pore water pressure gauge is mounted inside a bottom pressure head, and coarse sand is filled around the pore water pressure gauge, so that slurry blockage can be effectively prevented, smooth water seepage inside and outside a mounting cylinder is ensured, and the sensitivity of a probe and the reliability of a measured value are improved; the installation pole is inserted and is established in the inner chamber of connecting piece, the installation rope is connected with the connecting piece, hole sealing earth pillar and installation section of thick bamboo are all installed in drilling, the hole sealing earth pillar is placed on the installation section of thick bamboo, the hole sealing earth pillar is placed into between the adjacent pore water pressure gauge after, inside granule absorbs water and disperses, disintegrate into fragment and crumble, the intercommunication between the pore water pressure gauge has been avoided, the shutoff is effectual, the accuracy of value is measured to the assurance, realize vertically burying a plurality of pore water pressure gauges underground at the different degree of depth of same drilling in weak soil layer, the device simple structure, and convenient for operation, bury effectually underground, ensure that the measured value of different degree of depth pore water pressure gauges is accurate. The device disclosed by the invention is reasonable in design, convenient to install and operate, and suitable for monitoring the pore water pressure of the soft soil layers with the lower soil layers of saturated soft clay, silt or peat soil, organic soil, peat and the like, can effectively isolate the communication of adjacent pore water pressure meters, and is high in monitoring accuracy.
Furthermore, the mounting cylinder adopted by the invention has the advantages of simple structure, reasonable design, simple and convenient mounting and arrangement and lower input cost.
Further, the installation section of thick bamboo lower part that adopts constitutes the closed cavity, and the hole of permeating water is evenly seted up to bottom pressure head lateral wall, and the inside lining filter screen, and fill the coarse sand around the pore water pressure gauge, constitute multiple filtration system, form the infiltration passageway, can effectively prevent mud jam, guarantee that the inside and outside infiltration of installation section of thick bamboo is unobstructed, improve probe sensitivity and survey value reliability.
Furthermore, the adopted hole sealing soil column contains air-dried bentonite balls or clay balls with high disintegration, after the hole sealing soil column is placed between adjacent pore water pressure meters, internal particles absorb water and disperse and disintegrate into fragments and particles, and then the fragments and the particles are subjected to layered plugging and tamping by a compactor and a core-penetrating hammer or a perforated pipe hammer.
Furthermore, the installation rod and the installation barrel are connected by means of lifting the installation rope on the fixed ring, the installation rope is only required to be loosened by separating the installation rod from the installation barrel, and the installation rod is simple and convenient to operate, fast and efficient.
Furthermore, the flexible top plate used for pressing the hole sealing soil column downwards can deform and has small rigidity, so that the cable can be prevented from being damaged, and the survival rate of the pore water pressure gauge is improved.
Furthermore, the cable of the pore water pressure gauge can be automatically pushed to the embedded hole wall of the drilled hole when the hole sealing soil column is pressed down, and the situation that the cable is damaged by compaction equipment during layered plugging and tamping and other installation cylinders in the lowering process is avoided.
Furthermore, each pore water pressure gauge is fixed to the ground through an installation rope on the fixing ring, so that the multiple pore water pressure gauges can be accurately installed to a preset monitoring depth in the same drilling hole, and the accuracy of a measured value is guaranteed.
Drawings
FIG. 1 is a schematic structural view of the mounting barrel of the present invention;
FIG. 2 is a top view of the construction of the mounting cartridge of the present invention;
FIG. 3 is a schematic view of the construction state of the probe of the present invention pressed into place;
FIG. 4 is a schematic structural diagram of the hole sealing soil column of the present invention;
FIG. 5 is a schematic diagram of the construction state of the present invention for installing a pore water pressure gauge in a soft soil layer;
FIG. 6 is a schematic diagram of the state of the present invention for automatic monitoring after installation of a pore water pressure gauge in a soft soil layer is completed;
FIG. 7 is a block flow diagram of a method of the present invention.
In the figure; 1-connecting piece; 1-a fixed ring; 1-2-outlet holes; 2-plugging head; 3, a reducer union; 4, a bolt; 5, pressing a bottom head; 5-1-water permeable holes; 6, filtering the net; 7-pore water pressure gauge; 8, coarse sand; 9-a cable; 10, installing a rope; 11-mounting the cylinder; 12-mounting a rod; 13, drilling; 14-saturated soft soil; 15-unsaturated soil; 16-ground; 17-a steel wire rope; 18-hole sealing soil column; 18-1-air drying the soil balls; 18-2-high strength plastic net; 19-a flexible top plate; 20-backfilling; 21-automatic monitoring system; 21-1 — a data acquisition system; 21-2-solar panel.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The technical problem to be solved by the invention is to provide a device and a method for installing pore water pressure gauges in a soft soil layer aiming at the defects in the prior art, so that a plurality of pore water pressure gauges are longitudinally embedded at different depths of the same drill hole in the soft soil layer.
The invention is realized by adopting the following technical scheme: the device for installing the pore water pressure gauge in the soft soil layer as shown in the figures 1 and 2 comprises a connecting piece 1, a reducer union 3 and a bottom pressure head 5, wherein the three parts are spliced and fixed into an installation cylinder 11 through bolts 4;
the installation cylinder is made of metal or high-strength plastic and consists of three parts, namely a connecting piece, a reducer union and a bottom pressure head. The upper connecting piece is an H-shaped cylinder, the outer side wall of the cylinder is provided with a fixing ring, the upper cylinder is a pressing cavity, the center of the connecting piece is provided with a hole and contains an internal thread, the connecting piece can be screwed and sealed by a plugging head, the lower cylinder is provided with a cable outlet hole of the pore water pressure gauge, and a bolt hole is reserved at the bottom; the middle reducing joint is used for connecting the upper part and the lower part, the inner side of the middle reducing joint is provided with a bearing block, and reserved bolt holes are drilled on the upper side and the lower side; the bottom pressure head is internally provided with a pore water pressure gauge, the barrel body of the bottom pressure head is a cylinder, a bolt is reserved on the upper part of the bottom pressure head for drilling, the barrel wall is uniformly provided with water permeable holes, the aperture is (3-4) mm, the aperture ratio is 10% -15%, the bottommost side of the bottom pressure head is a cone, and the bottom pressure head is lined with a filter screen.
The mounting rod is a sectional connecting rod and can be directly made of a drilling machine drill rod or a galvanized steel pipe; the installation barrel 11 is pushed to move downwards by inserting the installation barrel into the upper pressure cavity of the connecting piece 1 and applying pressure to the installation rod 12 by a drilling machine, and the pore water pressure gauge 7 is lowered to a preset monitoring depth; meanwhile, when the hole sealing soil column 18 is lowered, a flexible top plate 19 is assembled at the head of the mounting rod 12 under the condition of plugging of a buried drill hole, and the hole sealing soil column 18 is pressed downwards, so that the cable of the pore water pressure gauge can be prevented from being damaged;
the mounting rope is made of a thin steel wire rope with the diameter of 3-4 mm and is fixed on a fixing ring on the outer side wall of the mounting cylinder;
the hole sealing soil column is made by filling a columnar mesh bag made of high-strength plastic materials into a bentonite ball or a high-disintegrability clay ball. The hole sealing earth pillar 18 is externally provided with a high-strength plastic net 18-2 which is a columnar net bag made of high-strength plastic, an air-dried earth ball 18-1 made of bentonite balls or high-disintegrability clay balls is filled in the hole sealing earth pillar, the diameter of the hole sealing earth pillar is (d-2) cm to (d-5) cm, and d is the diameter of a drilling hole forming drilling tool. In order to facilitate the sinking of the hole sealing soil column to a preset position, the lower part of the hole sealing soil column is processed into a closed cone shape. In order to facilitate the sinking operation and the sinking efficiency of the hole sealing soil column, the length of a single hole sealing soil column is processed into 0.5-1.0 m; the clay with high disintegrability preferably has a clay content of 20-40%, a plasticity index of greater than 17, and a clay ball density of greater than 1.40g/cm 3 The diameter is preferably (2-3) cm, and the composition should be air-dried.
The outer side wall of the connecting piece 1 comprises a fixing ring 1-1 for fixing a mounting rope 10, an upper barrel body is a pressing cavity and is connected with a mounting rod 12, a hole is formed in the center of the connecting piece 1 and contains an internal thread, so that the mounting barrel 11 can be continuously filled with coarse sand 8 after connection is completed, a plugging head 2 can be used for screwing and sealing after filling is completed, a closed cavity is formed in the bottom pressing head 5, a wire outlet 1-2 is formed in the lower barrel wall of the connecting piece 1 and is used for penetrating out a cable 9 of a pore water pressure gauge 7, and a bolt is reserved in the lower barrel body for drilling and is used for connecting a reducing joint 3;
bolt drill holes are reserved on the upper portion and the lower portion of the reducing joint 3, and the upper connecting piece 1 and the bottom pressure head 5 are connected through tightening bolts 4 to form an installation cylinder 11; the reducer union is used for connecting and fixing the upper part and the lower part of the bolt, and the inner side of the reducer union is provided with a bearing block;
the bottom pressure head 5 is provided with water permeable holes 5-1 uniformly on the cylinder body, the cylinder wall is lined with a filter screen 6, a pore water pressure gauge 7 is placed in the center of the bottom pressure head 5, the periphery is filled with coarse sand 8, the inner side and the outer side of the probe can freely permeate water, and multiple filter layers are formed at the same time, so that the probe is prevented from being blocked by slurry; the bottom pressure head and the upper connecting piece jointly form a closed cavity barrel, the bottom of the barrel is a cone, the barrel can conveniently pass through and be pressed into saturated soft soil 14 of a soft soil layer, water permeable holes are uniformly formed in the barrel body, the aperture is (3-4) mm, the aperture ratio is 10% -15%, when the device is installed, a pore water pressure gauge is placed in the center of the bottom pressure head, a filter screen is lined, and coarse sand is filled around the pore water pressure gauge, so that water can freely seep inside and outside a probe of the pore water pressure gauge;
the installation rod 12 is a sectional connection rod, can be directly made of a drill rod of a drilling machine or a galvanized steel pipe, is inserted into a pressure cavity at the upper part of the connecting piece 1, and is used for applying pressure to the installation rod 12 by the drilling machine to push the installation cylinder 11 to move downwards and lowering the pore water pressure gauge 7 to a preset monitoring depth; meanwhile, when the hole sealing soil column 18 is lowered, a flexible top plate 19 is assembled at the head of the mounting rod 12 when the buried drill hole is blocked, and the hole sealing soil column 18 is pressed downwards.
As shown in FIG. 7, the invention also discloses a method for mounting the pore water pressure gauge in the soft soil layer, which has the advantages of simple steps, convenient operation, high detection precision and good use effect, and the method comprises the following steps:
step one, assembling a mounting device:
101, placing a filter screen 6 on the inner side wall of a bottom pressure head 5, placing a pore water pressure gauge 7 in the center of the bottom pressure head 5, and filling coarse sand 8 around the pore water pressure gauge 7 until the position of a reserved bolt hole is stopped;
102, sleeving the reducing joint 3 on the upper part of the bottom pressure head 5, and fixing the reducing joint 3 and the bottom pressure head 5 by using a bolt 4;
103, penetrating out a cable 9 of the pore water pressure gauge 7 through a wire outlet hole 1-2 at the lower part of the connecting piece 1, then placing the connecting piece 1 on a bearing grid of the reducer union 3, and fixing the reducer union 3 and the upper connecting piece 1 by using a bolt 4 to connect three parts of the mounting cylinder 11 into a whole;
step 104, continuing to fill coarse sand 8 into the installation cylinder 11 until the lower cylinder is filled, screwing down the plugging head 2, fixing the installation rope 10 to a fixing ring 1-1 on the side wall of the installation cylinder, and inserting the installation rod 12 into the upper pressure cavity of the installation cylinder 11 in a piston manner;
step two, burying and drilling a borehole:
in order to maintain the stability of the properties of the soft soil layer, the drill hole 13 is formed by a dry drilling method so as to prevent the original physical mechanical properties of the soft soil foundation structure from changing. Stopping drilling when the drilling machine drills to about 0.5m above the lowest monitoring point;
step three, pressing the probe in place:
301, lowering the installation barrel 11 along with the installation rod 12 section by section, and lifting the installation rope 10 connected to the installation barrel 11 upwards to prevent the installation barrel 11 and the installation rod 12 from being separated; in the necking part in the drill hole 13, a drilling machine applies downward pressure to the installation rod 12, and the installation rope 10 is synchronously lowered, so that the installation barrel 11 is gradually lowered;
step 302, after the installation barrel 11 is lowered to the bottom of the buried drill hole, a drilling machine is used for continuously applying downward pressure to the installation rod 12, and the installation barrel 11 is slowly pressed into saturated soft soil 14 of a soft soil layer at the bottom of the hole until the embedding depth of the lowest side monitoring point is reached;
step 303, stopping lifting the installation rope 10 upwards, fixing the installation rope 10 on the ground, lifting the installation rod 12 section by section at the same time, and automatically separating the installation cylinder 11 from the installation rod 12, wherein the installation cylinder 11 at the lowest side can be installed to a preset monitoring depth;
step four, placing and tamping the hole sealing soil column:
step 401, installing a flexible top plate 19 at the bottom of the installation rod to prevent the cable 9 of the pore water pressure gauge 7 from being damaged in the subsequent pressing process; the hole-sealing soil column 18 is hung in the hole by a steel wire rope 17 and is firstly sunk downwards by the dead weight of the hole-sealing soil column. When the hole is slightly blocked in the sinking process, applying downward pressure to the mounting rod by using a drilling machine, and pushing down the hole sealing soil column 18 by using a flexible top plate 19 until the upper side of the pressure of the first pore water is reached;
step 402, repeating the step 401, and plugging and tamping in a layered mode by using a compactor and a piercing hammer or a floral tube hammer, wherein the thickness of each layer is 0.5-1.0 m, and stopping hole sealing until the embedding depth of the probe of the next pore water pressure gauge is reached;
step five, installing other probes:
replacing a mounting rod without a flexible top plate, repeating the step 301, after the probe of the pore water pressure gauge is lowered to the next monitoring depth, fixing the mounting rope 10 on the ground, stopping lifting upwards, simultaneously lifting the mounting rod 12 section by section to automatically separate the mounting cylinder 11 from the mounting rod 12, and then repeating the step four to plug and tamp the soil body between the upper and lower adjacent monitoring points of the drill hole 13 in a layered manner;
step six, burying, drilling and backfilling:
and repeating the fifth step, backfilling from the deepest monitoring point of the deepest saturated soft soil 14 to a position 1m away from the embedded drilling hole through the unsaturated soft soil 15, then backfilling the embedded drilling hole to the elevation of the current ground 16 by using backfill 20, and tamping the backfill 20 in layers in the backfilling process, wherein the density of the tamped backfill 20 is not less than that of the soil body around the embedded drilling hole. Connecting all cables 9 of the pore water pressure gauge 7 into an automatic data acquisition system 21-1 to realize automatic monitoring; the data acquisition system 21-1 is powered by the solar panel 21-2, so that resource utilization is facilitated.
In this embodiment, all pore water pressure gauges 7 should be placed in the installation cylinder 11 at one time on the ground and assembled when the installation device is assembled in the first step.
In this embodiment, after the pore water pressure gauge probe at the lowest monitoring point reaches the bottom of the borehole 13, the installation rod 12 is used to slowly press the pore water pressure gauge probe to the monitoring depth, and the rest of the pore water pressure gauge probe burying methods are all placed at the corresponding monitoring depth according to step 301.
In this embodiment, in step 303, when the installation barrel 11 is lowered to the predetermined monitoring depth, the drilling machine should stop applying the downward pressure to the installation rod 12, and simultaneously the ground operator stops pulling the installation rope 10 upward, and fixes the installation rope 10 to the ground, so as to prevent the pore water pressure gauge probe from moving downward again along with the installation barrel 11 and deviating from the monitoring position due to the extrusion of the pore water pressure gauge probe by the sealing earth pillar 18.
In the embodiment, when the hole sealing earth pillar 18 is pushed down in the fourth step, the hole sealing earth pillar 18 firstly sinks downwards by means of self weight, the lower side drill hole 13 is contracted due to the gradual increase of the lateral earth pressure around the lower side drill hole, the mounting rod 12 additionally provided with the flexible top plate 19 is required to be pressed downwards from the top of the hole sealing earth pillar 18, meanwhile, the hole sealing earth pillar 18 can push the cable 9 of the pore water pressure gauge 7 to the side wall of the drill hole 13, and the phenomenon that the cable 9 is damaged by compaction equipment during the layered plugging tamping and the lowering process of the rest mounting cylinders 11 is avoided.
In the present embodiment, the grit 8 is medium grit having a particle size of 0.35 to 0.50mm, and in actual use, dry medium grit is further used for uniform filling.
In this embodiment, the mounting rod 12 is a segmented connecting rod, and can be made of a drill rod of a drilling machine or a galvanized steel pipe.
In the embodiment, the backfill soil is tamped by clay in layers, and the density of the tamped backfill soil is not less than that of the soil body around the embedded drill hole.
In this embodiment, the flexible top plate 19 is an ellipsoid, and may be made of a high-elastic thickened rubber material, so as to prevent the cable 8 of the pore water pressure gauge 6 from being damaged in the process of pressing down the hole sealing column 18.
In the embodiment, the adjacent pore water pressure meters are filled with the hole sealing soil columns to ensure the isolation and the plugging between the adjacent pore water pressure meters, and the hole sealing soil columns are plugged and tamped in a layered mode, so that the plugging is guaranteed to be compact, and the accuracy of a measured value is improved.
In this embodiment, after the hole sealing earth pillar is transferred between the adjacent pore water pressure gauge, inside granule absorbs water dispersion, disintegrates into fragment and crushed grain, adds the core-piercing hammer or floral tube hammer layering shutoff tamping again through the compactor, simultaneously owing to bury underground the drilling and receive the effect of side direction soil pressure, bury underground the drilling and can extrude inside shrink gradually, the aperture reduces, will install a section of thick bamboo around the soil body extrusion closely knit, above-mentioned combined action can effectively completely cut off adjacent pore water pressure gauge, avoid intercommunication each other to influence the measuring value accuracy.
In this embodiment, the pore water pressure gauge is placed in bottom pressure head center, fills with the coarse sand all around, and bottom pressure head inside lining filter screen forms multiple filter layer, prevents that the probe from blockking up by mud, guarantees simultaneously that the installation section of thick bamboo inside and outside infiltration is unobstructed.
In conclusion, the device has the advantages of reasonable design, simple structure, convenience in installation and arrangement and low investment cost, can be used for longitudinally embedding a plurality of pore water pressure meters at different depths of the same drilled hole in a soft soil layer, and is high in monitoring precision.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or intervening components may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner; the present invention may be readily implemented by those of ordinary skill in the art as illustrated in the accompanying drawings and described above; however, those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiments as a basis for designing or modifying other structures for carrying out the same purposes of the present invention without departing from the scope of the invention as defined by the appended claims; meanwhile, any changes, modifications, and evolutions of the equivalent changes of the above embodiments according to the actual techniques of the present invention are still within the protection scope of the technical solution of the present invention.
Claims (10)
1. A device for installing a pore water pressure gauge in a soft soil layer is characterized by comprising,
the device comprises an installation barrel (11), an installation rod (12), an installation rope (10) and a hole sealing soil column (18);
the mounting cylinder (11) comprises a connecting piece (1) and a bottom pressure head (5), and the connecting piece (1) is connected with the bottom pressure head (5) in a splicing manner through a reducing joint (3); the pore water pressure gauge (7) is arranged inside the bottom pressure head (5), and coarse sand (8) is filled around the pore water pressure gauge; the mounting rod (12) is inserted into the inner cavity of the connecting piece (1); the mounting rope (10) is connected with the connecting piece (1), the hole sealing soil column (18) and the mounting cylinder (11) are both mounted in the drill hole (13), and the hole sealing soil column (18) is placed on the mounting cylinder (11).
2. The device for installing the pore water pressure gauge in the soft soil layer according to claim 1, wherein a fixing ring (1-1) is arranged on the outer side wall of the connecting piece (1) and used for fixing and installing the rope (10), and a cable hole (1-2) is formed in the cylinder wall of the connecting piece (1) and used for penetrating through a cable (9) of the pore water pressure gauge (7).
3. The device for installing the pore water pressure gauge in the soft soil layer is characterized in that the connecting piece (1), the reducer union (3) and the bottom pressure head (5) are fixedly connected through bolts (4).
4. Device for installing a pore water pressure gauge in soft soil layers according to claim 1, characterized in that the central inner hole of the connecting piece (1) is provided with a plugging head (2).
5. The device for installing the pore water pressure gauge in the soft soil layer according to claim 1, wherein the barrel body of the bottom pressure head (5) is provided with water permeable holes (5-1), the pore diameter of the water permeable holes (5-1) is 3-4 mm, the aperture ratio is 10% -15%, and the inner wall of the barrel of the bottom pressure head (5) is provided with a filter screen (6).
6. The device for installing the pore water pressure gauge in the soft soil layer as claimed in claim 1, wherein the hole sealing soil column (18) is made of a high-strength plastic net (18-2) with air-dried soil balls (18-1) inside, and the hole sealing soil column (18) is hung and placed at a preset position in the drill hole (13) through a steel wire rope (17); the diameter of the hole sealing soil column is (d-2) cm to (d-5) cm, and d is the diameter of the drilling hole forming drilling tool.
7. Device for the installation of a pore water pressure gauge in soft soil layers according to claim 1, characterized in that when installing the column (18), the end of the installation rod (12) near the column is fitted with a flexible top plate (19).
8. The device for installing the pore water pressure gauge in the soft soil layer as claimed in claim 1, wherein the cylinder bottom of the bottom pressure head (5) is a cone, the installation rod (12) is a segmented connecting rod made of a drilling machine drill rod or a galvanized steel pipe, and the grain diameter of the coarse sand (8) is 0.35-0.50 mm.
9. The device for installing the pore water pressure gauge in the soft soil layer as claimed in claim 1, wherein the installation rope (10) adopts a steel wire rope with the diameter of 3-4 mm; the connecting piece (1) is an H-shaped cylinder.
10. A method for installing a device for installing a pore water pressure gauge in a soft soil layer, characterized in that the device for installing a pore water pressure gauge in a soft soil layer according to any one of claims 1 to 9 comprises,
step one, installing a pore water pressure gauge (7) in an installation cylinder (11) and assembling, and inserting an installation rod (12) into the installation cylinder (11);
step two, the installation barrel (11) is lowered into a drilled borehole along with the installation rod (12), in the lowering process, the installation rope (10) is lifted upwards, the installation rod (12) is not separated from the installation barrel (11), the installation rod (12) is pressed into a soft soil layer at the bottom of the hole by a drilling machine, and the installation barrel (11) is pressed into the soft soil layer until the embedding depth of the lowest monitoring point is reached; fixing the installation rope (10) on the ground, lifting the installation rod (12) section by section at the same time, enabling the installation cylinder (11) to be automatically separated from the installation rod (12), and installing the installation cylinder (11) to a preset monitoring depth;
and step three, the hole sealing soil column (18) is placed between the adjacent pore water pressure meters (7), the soil body between the upper and lower adjacent monitoring points of the drill hole is plugged and tamped in a layered mode, and then the drill hole is backfilled.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117198005A (en) * | 2023-10-17 | 2023-12-08 | 青海省环境地质勘查局 | Landslide hazard early warning equipment based on groundwater osmotic pressure monitoring |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117198005A (en) * | 2023-10-17 | 2023-12-08 | 青海省环境地质勘查局 | Landslide hazard early warning equipment based on groundwater osmotic pressure monitoring |
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