CN109469124B - Layered pile foundation test device and test method adopting double air pressure films for vertical loading - Google Patents
Layered pile foundation test device and test method adopting double air pressure films for vertical loading Download PDFInfo
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- 238000005056 compaction Methods 0.000 abstract description 3
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D33/00—Testing foundations or foundation structures
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Abstract
The invention provides a layered pile foundation test device and a test method adopting double air pressure films for vertical loading, wherein the test method comprises the following steps: the model box consists of at least 1 layered model box and a model box bottom; the test pile testing device is arranged in the model box and consists of a test pile and detection sensing devices arranged on the inner side and the outer side of the test pile; the double-air-pressure film loading device is arranged above the test pile testing device and is used for loading load to the test pile; the layered pile foundation testing device adopts a method for assembling the layered model boxes into the integral model boxes, can prepare the compaction degree, the water content and the like of soil layers with different depths according to requirements, and simultaneously, the pile foundation design and construction can be scientifically guided by utilizing the characteristics of light weight, small volume, high sensitivity, electromagnetic interference resistance and the like of the fiber grating sensor.
Description
Technical Field
The invention relates to the technical field of pile foundation testing, in particular to a layered pile foundation testing device and a testing method adopting double air pressure films for vertical loading.
Background
The vertical bearing capacity test of the piles is extremely important for controlling the settlement of a building and ensuring the safety of the structure of the building.
The conventional pile vertical load test technology is more traditional, and is loaded through construction reaction pile loading or upper gravity test block stacking loading, and no matter the construction reaction pile or lifting gravity test block stacking loading, heavy machinery is required to carry out construction, so that a large construction site space is occupied, and preparation work is required for a long time. Meanwhile, the constructed counterforce pile is not wasted after the experiment is finished, so that the economical and resource waste is realized, the gravity test block is limited by the requirements of the stacking height and stability and can only be stacked to a certain height, and the pile foundation load range cannot meet the test requirement of the high-bearing-capacity pile foundation.
On the one hand, the pile foundation testing technology is more traditional, and the pile shaft axial force testing technology which is more commonly used adopts a vibrating wire type stress meter or a resistance strain gauge for monitoring. The test technologies are all single-point tests, and the electronic sensor signals have the characteristics of low precision, instability, easy interference, low acquisition frequency and the like, so that the advantages of light weight, small volume, high sensitivity, electromagnetic interference resistance, distributed measurement and the like are difficult to realize.
In addition, considering the specific pile foundation bearing capacity research problem, weak interlayer soil often appears in foundation soil due to the complexity of geological conditions, and the influence on pile foundation stress rules is obviously influenced. The existing test technology can not well solve the problem, the existing model box for pile foundation test has a complete design idea, and the sample preparation characteristics (including compactness, water content and the like) of a certain layer of soil can not be controlled in a targeted manner in the sample preparation process of foundation soil.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a layered pile foundation test device and a test method adopting double air pressure films for vertical loading.
The technical scheme is as follows:
in order to achieve the above object, the present invention provides a layered pile foundation testing device adopting dual pneumatic membranes for vertical loading, comprising:
a model box, which consists of at least 1 layered model box and a model box bottom,
the test pile testing device is arranged in the model box and consists of a test pile and detection sensing devices arranged on the inner side and the outer side of the test pile;
the double-air-pressure film loading device is arranged above the test pile testing device and is used for loading load to the test pile;
the double-air-pressure film loading device comprises a cylindrical positive-action air-pressure film, a pressure action plate connected with the cylindrical positive-action air-pressure film, a pressure transmission rod, an annular negative-action air-pressure film, a spherical hinge support and a pile cap, wherein the pressure action plate is connected with the cylindrical positive-action air-pressure film, the upper end of the pressure transmission rod is connected with the pressure action plate, the annular negative-action air-pressure film is coated on the outer side of the pressure transmission rod and clings to the pressure action plate, the spherical hinge support is connected with the lower end of the pressure transmission rod, the pile cap is connected with the spherical hinge support, and a displacement meter is arranged on the upper end face of the pile cap, and the lower end of the pile cap is connected with the test pile.
Preferably, in the above technical solution, the mold box is composed of five hollow layered mold boxes and one solid mold box bottom, and the material of the mold box is plexiglas.
Preferably, in the above technical solution, the layered model box is a cuboid formed by a piece of foundation soil in the model box and four pieces of solid organic glass box walls, and each solid organic glass box wall is provided with a bolt connection drilling hole, and a plurality of layered model boxes are assembled and connected by locking the bolt connection drilling holes into bolts for fixing the model box.
Preferably, in the above technical scheme, the detection sensing device comprises two optical fibers symmetrically paved on the test pile, a fiber grating strain gauge arranged on each optical fiber at a distance of 1.5 meters, a fiber grating temperature compensation meter arranged on each fiber grating strain gauge, four pile bottom soil pressure boxes symmetrically arranged on the pile bottom for testing pile bottom soil pressure, and two groups of two-way soil pressure boxes and pore water pressure meters symmetrically embedded on two sides of the pile circumference.
As another object of the present invention, there is provided a testing method of a layered pile foundation testing apparatus employing vertical loading of double air pressure membranes, comprising the steps of:
step one, preparing a layered model box soil sample and assembling the model box;
arranging and installing a test pile testing device in the test pile, and penetrating the test pile into foundation soil of the model box by adopting a filling method;
step three, installing a double-air-pressure film loading device, connecting a test pile testing device with a data acquisition system, debugging the system, and recording initial readings;
and step four, loading a test and monitoring in real time to finish the test.
Preferably, in the above technical solution, in step 1, the following simultaneous steps are included:
A. according to the research purpose and experimental requirements, confirming the preparation experimental requirements of soil layers in each model box, including physical and mechanical properties, compactness, water content and elastic modulus;
B. according to the set requirement of the potential weak soil layer, respectively completing the preparation of soil samples in each layered model box, wherein each layered model box is embedded with 1 group of bidirectional soil pressure boxes and pore water pressure gauges respectively, and the bidirectional soil pressure boxes and pore water pressure gauges are used for measuring the propagation rule of loads in surrounding foundation soil through pile-soil structure interaction in the pile foundation loading process;
C. the solid model box base is square on the ground, the layered model box is aligned to the model box bottom from bottom to top according to the design requirement of soil sample preparation, then 8 bolts for fixing the model box are locked into the bolts to be connected and drilled to the model box bottom, and nuts are screwed down, so that the model box assembly is completed.
In the second step, the optical fiber, the fiber grating strain gauge and the fiber grating temperature compensation meter are installed in the test pile, 4 pile bottom soil pressure boxes are installed at the bottom of the test pile in a cross mode, and the test pile with the detection test device installed and arranged is penetrated into foundation soil of the model box by adopting a filling method.
In the above technical scheme, in the fourth step, two vacuum pumps are started first, required air pressure is applied to the cylindrical positive-acting air pressure film and the annular negative-acting air pressure film respectively, air pressure difference generated by the two air pressure films acts on the pressure acting plate, the air pressure difference is transmitted to the pile caps below through the pressure transmission rod, the spherical hinge support above the pile caps enables load transmission to be distributed uniformly, and meanwhile, the displacement meter on the upper end face of the pile caps records pile top settlement in real time; meanwhile, the data acquisition system acquires sensing data of the fiber bragg grating strain gauge, the fiber bragg grating temperature compensation meter, the pore water pressure gauge, the bidirectional soil pressure box and the pile bottom soil pressure box in real time until the ultimate bearing capacity of the pile foundation is reached, and the test is finished.
Compared with the prior art, the invention has the following beneficial effects:
(1) The pile foundation test device has the advantages of portability, simplicity, high range, high precision, economy, rationality and the like, and the problems of large-area construction space occupation, long operation period, resource waste caused by construction reaction piles and the like caused by adopting a gravity test block in the traditional site load test method are solved by adopting a double-air-pressure-film vertical loading mode and a layered pile foundation test structure.
(2) The invention adopts the fiber grating sensor testing means, and utilizes the characteristics of light weight, small volume, high sensitivity, electromagnetic interference resistance and the like of the fiber grating sensor (fiber grating strain gauge, fiber grating temperature compensation meter and the like), so that the real-time and comprehensive pile foundation stress deformation rule can be obtained. The defects of discontinuous, non-real-time and low precision of the traditional measuring technology such as a vibrating wire type steel bar stress meter, a resistance strain gauge and the like in the traditional mode are overcome.
(3) The fiber grating temperature compensator is used for compensating the measurement data of the fiber grating strain gauge, and the influence of the temperature effect of the fiber grating on the strain measurement error is overcome.
(4) In the design of the model pile test scheme, the soil pressure test and the pore water pressure test of foundation soil are added, and the problem that the traditional single monitoring of pile foundation deformation stress can not completely reflect the transfer rule of load in soil is solved.
(5) A traditional model pile foundation soil sample preparation method is that a model box is compacted with whole foundation soil, and sample preparation control of weak interlayer soil with specific depth cannot be realized.
Drawings
FIG. 1 is a block diagram of a layered pile foundation testing apparatus employing dual air pressure membrane vertical loading in accordance with the present invention.
Fig. 2 is a schematic structural view of a dual pneumatic membrane loading device according to the present invention.
Fig. 3 is a schematic structural view of a single layer structure of a mold box according to the present invention.
The main reference numerals illustrate:
101-double air pressure film loading device, 102-test pile, 103-fiber bragg grating strain gauge, 104-fiber bragg grating temperature compensator, 105-two-way soil pressure box, 106-pore water pressure gauge, 107-pile bottom soil pressure box, 108-nut, 109-bolt, 110-weak soil layer, 111-solid organic glass box wall, 112-model box bottom and 113-layered model box;
201-cylindrical positive-acting air pressure film, 202-pressure acting plate, 203-annular negative-acting air pressure film, 204-pressure transmission rod, 205-displacement meter, 206-spherical hinge support, 207-pile cap and 209-vacuum pump;
301-foundation soil in a model box, 302-sealing waterproof latex films and 304-bolting drilling holes.
Detailed Description
The following detailed description of embodiments of the invention is, therefore, to be taken in conjunction with the accompanying drawings, and it is to be understood that the scope of the invention is not limited to the specific embodiments.
Throughout the specification and claims, unless explicitly stated otherwise, the term "comprise" or variations thereof such as "comprises" or "comprising", etc. will be understood to include the stated element or component without excluding other elements or components.
Fig. 1 shows a schematic structural view of a layered pile foundation testing apparatus employing dual pneumatic membranes for vertical loading according to a preferred embodiment of the present invention.
The layered pile foundation test device adopting double air pressure membranes for vertical loading as shown in fig. 1 comprises: the device comprises a model box, a test pile testing device, a double-air-pressure film loading device 101 and a data acquisition system;
referring to fig. 1, the mold box is composed of at least 1 layered mold box 113 and mold box bottom 112, each layered mold box 113 can be independently combined with the mold box bottom 112 to form a mold box, and in this embodiment, the mold box is composed of five hollow layered mold boxes 113 and a solid mold box bottom 112, and the material is preferably plexiglass, so that the test phenomenon of soil and piles in the box can be conveniently observed. As shown in fig. 3, the layered mold box 113 is a rectangular solid body composed of a foundation soil 301 and four solid organic glass walls 111 in one mold box, two bolt connection holes 304 traversing the solid organic glass walls 111 are formed in each solid organic glass wall 111, 8 bolt connection holes 304 are formed in total in a single layered mold box 113, and a plurality of layered mold boxes 113 are assembled and connected by locking bolts 109 for fixing the mold boxes in the bolt connection holes 304. Further, the organic glass surfaces of each layered mold box 113 are coated with a uniform sealing waterproof latex film 302 for preventing water leakage from the assembled mold boxes. And the layered model boxes 113 can flexibly prepare the compaction degree, the water content and the like of soil layers with different depths according to requirements, and the preparation of soil samples in each model box single layer is respectively completed by confirming the performance parameters of the soil layers in each layered model box 113, including the physical and mechanical properties, the compaction degree, the water content, the elastic modulus and the like of the soil. For example, the weak soil layer 110 is prepared separately in advance, and a single layered model box 113 containing the weak soil layer 110 is placed at the depth of the soil layer to be studied, so as to achieve the purpose of researching the weak interlayer pile foundation test.
With continued reference to FIG. 1, the test pile testing device of the present invention is disposed in a mold box and consists of a test pile 102 and detection sensing devices disposed inside and outside the test pile 102; the detection sensing device comprises two distributed optical fibers which are symmetrically paved on a test pile and connected in series, an optical fiber grating strain gauge 103 which is arranged on each optical fiber at a distance of 1.5 m, an optical fiber grating temperature compensation meter 104 which is specifically installed in the middle of the test pile 102 and symmetrically installed on the pile bottom, four pile bottom soil pressure boxes 107 which are symmetrically installed on the pile bottom and are used for testing the pile bottom soil pressure, and two groups of bidirectional soil pressure boxes 105 and pore water pressure meters 106 which are symmetrically embedded on two sides of the pile circumference. The fiber grating temperature compensator 104 is used for eliminating the error influence of temperature on the measurement strain of the fiber grating strain gauge so as to correct the reading of the fiber grating strain gauge, the detection sensing device adopts various multi-surface distributed test means of the fiber grating strain gauge, the fiber grating temperature compensator, the pile bottom soil pressure box, the bidirectional soil pressure box and the pore water pressure gauge, and utilizes the characteristics of light weight, small volume, high sensitivity, electromagnetic interference resistance and the like of the fiber grating strain gauge and the fiber grating temperature compensator, so that the invention can comprehensively realize the stress deformation rule of the pile foundation in real time and improve the measurement accuracy and the safety.
As another modification of the present invention, a double air pressure film loading device 101 is shown in fig. 2, which is disposed above a test pile testing device for loading load to a test pile 102; the dual-air pressure film loading device 101 is composed of a cylindrical positive-acting air pressure film 201, a pressure acting plate 202 connected with the cylindrical positive-acting air pressure film 201, a pressure transmission rod 204 with the upper end connected with the pressure acting plate 202, an annular negative-acting air pressure film 203 coated on the outer side of the pressure transmission rod 204 and tightly attached to the pressure acting plate 202, a spherical hinge support 206 connected with the lower end of the pressure transmission rod 204 and a pile cap 207 connected with the spherical hinge support 206 from top to bottom, wherein a displacement meter 205 is arranged on the upper end face of the pile cap 207, and the lower end of the pile cap 207 is connected with a test pile 102. By adopting the structure, the invention can apply the pressure difference generated by positive air pressure and negative air pressure to the pressure action plate by respectively loading the positive air pressure and the negative air pressure in the two air pressure films, and uniformly load the pressure action plate and the pile cap through the pressure transmission rod and the spherical hinge support, thereby achieving the test purpose of vertical loading. By adopting the method, when positive air pressure and negative air pressure are loaded, the vacuum pump 209 can be controlled to be connected with the uniform and slow air inflation or air suction, preferably the two vacuum pumps are respectively connected with the positive air pressure film and the negative air pressure film, on one hand, the loading force of the loading device is slowly balanced, on the other hand, the loading force can be flexibly adapted to the corner requirement in any direction, and under the interaction of the spherical hinge support 206 with the double funnel shape, the pressure transmission rod 204 (the pressure transmission rod 204 is preferably arranged above the center of the spherical hinge support 206) and the pile cap 207, the vibration is effectively reduced, the necking phenomenon of the force is avoided, the counterforces of the upper and lower junction structures, which are acted on the pressure plate 202, the spherical hinge support 206 and the like, are relatively uniform, and the problems of large-area construction space occupation, long operation period, resource waste caused by the construction pile and the like due to the adoption of the gravity test block in the traditional site load test method are overcome.
The invention also provides a testing method of the layered pile foundation testing device adopting double air pressure films for vertical loading, which comprises the following steps:
step one, preparing a layered model box soil sample and assembling the model box;
specifically, in step 1, the following simultaneous steps are included:
A. according to the research purpose and experimental requirements, confirming the preparation experimental requirements of soil layers in each model box, including physical and mechanical properties, compactness, water content and elastic modulus; especially, the weak soil layer is to be tested, namely, the weak soil layer can be prepared in advance, and a model box single layer containing the weak soil layer is placed at the depth to be researched, so that the purpose of researching the weak interlayer pile foundation test is achieved;
B. according to the set requirement of the potential weak soil layer, respectively completing the preparation of soil samples in each layered model box, wherein each layered model box is embedded with 1 group of bidirectional soil pressure boxes 105 and pore water pressure gauges 106 respectively, and the bidirectional soil pressure boxes and the pore water pressure gauges are used for measuring the propagation rule of loads in surrounding foundation soil through pile-soil structure interaction in the pile foundation loading process;
C. the solid model box base 112 is square on the ground, the layered model box is aligned to the model box bottom 112 from bottom to top according to the design requirement of soil sample preparation, then 8 bolts for fixing the model box are locked into the bolt connecting drilling holes 304 to the model box bottom 112, and the nuts 108 are screwed down, so that the model box assembly is completed;
arranging and installing a test pile testing device in the test pile, and penetrating the test pile into foundation soil of the model box by adopting a filling method;
in the second step, firstly, the optical fiber, the fiber grating strain gauge 103 and the fiber grating temperature compensation meter 104 are installed in the test pile 102, 4 pile bottom soil pressure boxes 107 are installed at the bottom of the test pile 102 in a cross shape, and the test pile 102 provided with the detection test device is penetrated into foundation soil of a model box by adopting a filling method;
step three, installing a double-air-pressure film loading device, connecting a test pile testing device with a data acquisition system, debugging the system, and recording initial readings;
and step four, loading a test and monitoring in real time to finish the test.
In step four, two vacuum pumps 209 are started first, the required air pressure is applied to the cylindrical positive-acting air pressure membrane 201 and the annular negative-acting air pressure membrane 203 respectively, the air pressure difference generated by the two air pressure membranes acts on the pressure acting plate 202, the air pressure difference is transmitted to the pile cap 207 below through the pressure transmission rod 204, the load transmission is uniformly distributed by the spherical hinge support 206 above the pile cap 207, and meanwhile, the pile top settlement is recorded in real time by the displacement meter 205 on the upper end surface of the pile cap 207; meanwhile, the data acquisition system acquires sensing data of the fiber bragg grating strain gauge, the fiber bragg grating temperature compensation meter 104, the pore water pressure gauge 106, the bidirectional soil pressure box 105 and the pile bottom soil pressure box 107 in real time until the ultimate bearing capacity of the pile foundation is reached, and the test is finished.
In summary, the pile foundation test device has the advantages of portability, simplicity, high range, high precision, economy, rationality and the like, and the problems of large-area construction space occupation, long operation period, resource waste caused by construction reaction piles and the like caused by the construction machinery requirement caused by the adoption of the gravity test block in the traditional site load test method are solved by adopting the double-air-pressure-film vertical loading mode and the layered pile foundation test structure.
The invention adopts the fiber grating sensor testing means, and utilizes the characteristics of light weight, small volume, high sensitivity, electromagnetic interference resistance and the like of the fiber grating sensor (fiber grating strain gauge, fiber grating temperature compensation meter and the like), so that the real-time and comprehensive pile foundation stress deformation rule can be obtained. The defects of discontinuous, non-real-time and low precision of the traditional measuring technology such as a vibrating wire type steel bar stress meter, a resistance strain gauge and the like in the traditional mode are overcome. In addition, the fiber grating temperature compensator is used for compensating the measurement data of the fiber grating strain gauge, so that the influence of the fiber grating temperature on the strain measurement error is overcome.
In the design of the model pile test scheme, the soil pressure test and the pore water pressure test of foundation soil are added, and the problem that the traditional single monitoring of pile foundation deformation stress can not completely reflect the transfer rule of load in soil is solved.
A traditional model pile foundation soil sample preparation method is that a model box is compacted with whole foundation soil, and sample preparation control of weak interlayer soil with specific depth cannot be realized.
The foregoing descriptions of specific exemplary embodiments of the present invention are presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application to thereby enable one skilled in the art to make and utilize the invention in various exemplary embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.
Claims (8)
1. Adopt vertical loaded layering pile foundation test device of dual air pressure membrane, its characterized in that includes:
a mold box consisting of at least 1 layered mold box (113) and a mold box bottom (112);
the test pile testing device is arranged in the model box and consists of a test pile (102) and detection sensing devices arranged on the inner side and the outer side of the test pile (102);
and a double air pressure film loading device (101) arranged above the test pile testing device and used for loading load to the test pile (102);
the double-air-pressure film loading device (101) comprises a cylindrical positive-action air-pressure film (201), a pressure action plate (202) connected with the cylindrical positive-action air-pressure film (201), a pressure transmission rod (204) with the upper end connected with the pressure action plate (202), an annular negative-action air-pressure film (203) which is coated on the outer side of the pressure transmission rod (204) and clings to the pressure action plate (202), a spherical hinge support (206) connected with the lower end of the pressure transmission rod (204) and a pile cap (207) connected with the spherical hinge support (206), wherein a displacement meter (205) is arranged on the upper end face of the pile cap (207), and the lower end of the pile cap (207) is connected with the test pile (102).
2. The layered pile foundation test device adopting double air pressure membranes for vertical loading according to claim 1, wherein the model box consists of five hollow layered model boxes (113) and one solid model box bottom (112), and the material of the model boxes is organic glass;
the layered model boxes (113) are used for respectively completing the preparation of soil samples in each model box single layer by confirming the performance parameters of soil layers in each layered model box (113).
3. The layered pile foundation test device adopting double air pressure membranes for vertical loading according to any one of claims 1 or 2, wherein the layered model boxes (113) are rectangular solids consisting of a foundation soil (301) and four solid organic glass box walls (111) in one model box, each solid organic glass box wall (111) is provided with a bolt connection drilling hole (304), and a plurality of layered model boxes (113) are assembled and connected by locking bolts (109) for fixing the model boxes into the bolt connection drilling holes (304);
the organic glass surfaces above and below each layered mold box (113) are coated with a uniform layer of sealing waterproof latex film (302).
4. The layered pile foundation test device adopting double air pressure membranes for vertical loading according to claim 1, wherein the detection sensing device comprises two optical fibers symmetrically paved on a test pile, an optical fiber grating strain gauge (103) arranged on each optical fiber at a distance of 1.5 meters, an optical fiber grating temperature compensation meter (104) arranged on the optical fiber grating strain gauge, four pile bottom soil pressure boxes (107) symmetrically arranged on the pile bottom for testing pile bottom soil pressure, and two groups of bidirectional soil pressure boxes (105) and pore water pressure gauges (106) symmetrically embedded on two sides of the pile circumference; the fiber grating temperature compensation meter (104) is used for eliminating the error influence of temperature on the measurement strain of the fiber grating strain gauge so as to correct the reading of the fiber grating strain gauge.
5. The test method of the layered pile foundation test device adopting double air pressure membranes for vertical loading according to claim 1, comprising the following steps:
step one, preparing a layered model box soil sample and assembling the model box;
arranging and installing a test pile testing device in the test pile, and penetrating the test pile into foundation soil of the model box by adopting a filling method;
step three, installing a double-air-pressure film loading device, connecting a test pile testing device with a data acquisition system, debugging the system, and recording initial readings;
and step four, loading a test and monitoring in real time to finish the test.
6. The testing method of the layered pile foundation testing device adopting double air pressure membranes for vertical loading according to claim 5, wherein in step 1, the following simultaneous steps are included:
A. according to the research purpose and experimental requirements, confirming the preparation experimental requirements of soil layers in each model box, including physical and mechanical properties, compactness, water content and elastic modulus;
B. according to the set requirement of the potential weak soil layer, respectively completing the preparation of soil samples in each layered model box, wherein each layered model box is embedded with 1 group of bidirectional soil pressure boxes (105) and pore water pressure gauges (106) respectively, and the bidirectional soil pressure boxes are used for measuring the propagation rule of loads in surrounding foundation soil through pile-soil structure interaction in the pile foundation loading process;
C. the solid model box bottom (112) is square on the ground, the layered model box is aligned to the model box bottom (112) according to the design requirement of soil sample preparation from bottom to top, then 8 bolts for fixing the model box are locked into the bolt connecting drilling holes (304) to the model box bottom (112), and the nuts (108) are screwed down, so that the model box assembly is completed.
7. The testing method of the layered pile foundation testing device adopting double air pressure membranes for vertical loading according to claim 5, wherein in the second step, the optical fiber, the fiber bragg grating strain gauge (103) and the fiber bragg grating temperature compensation meter (104) are firstly installed in the testing pile (102), 4 pile bottom soil pressure boxes (107) are installed at the bottom of the testing pile (102) in a cross mode, and the testing pile (102) with the detection testing device installed is penetrated into foundation soil of a model box by adopting a filling method.
8. The testing method of the layered pile foundation testing device adopting double air pressure membranes for vertical loading according to claim 5, wherein in the fourth step, two vacuum pumps (209) are started first, required air pressure is respectively applied to the cylindrical positive air pressure membrane (201) and the annular negative air pressure membrane (203), air pressure difference generated by the two air pressure membranes acts on the pressure acting plate (202), the air pressure difference is transmitted to a pile cap (207) below through the pressure transmitting rod (204), the load transmission is uniformly distributed by a spherical hinge support (206) above the pile cap (207), and meanwhile, pile top settlement is recorded in real time by a displacement meter (205) on the upper end surface of the pile cap (207); meanwhile, the data acquisition system acquires sensing data of the fiber bragg grating strain gauge, the fiber bragg grating temperature compensation meter (104), the pore water pressure meter (106), the bidirectional soil pressure box (105) and the pile bottom soil pressure box (107) in real time until the ultimate bearing capacity of the pile foundation is reached, and the test is finished.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910026974.XA CN109469124B (en) | 2019-01-11 | 2019-01-11 | Layered pile foundation test device and test method adopting double air pressure films for vertical loading |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201910026974.XA CN109469124B (en) | 2019-01-11 | 2019-01-11 | Layered pile foundation test device and test method adopting double air pressure films for vertical loading |
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| CN110018097B (en) * | 2019-03-27 | 2023-10-20 | 哈尔滨工业大学（深圳） | Bidirectional soil seepage test device and test method for multilayer detachable sample preparation and sampling |
| CN113218771A (en) * | 2021-03-16 | 2021-08-06 | 安徽理工大学 | Indoor model test loading and data acquisition system for geotechnical engineering |
| CN113404098B (en) * | 2021-06-10 | 2023-03-31 | 中国建筑第八工程局有限公司 | Pile sinking model test device and test method |
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