CN114136811A - Large multifunctional soil and structure interface shearing device and using method thereof - Google Patents
Large multifunctional soil and structure interface shearing device and using method thereof Download PDFInfo
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Abstract
The invention discloses a large multifunctional soil and structure interface shearing device.A power mechanism is arranged on a supporting structure, a shearing tank comprises a tank body, an upper mounting port and a lower mounting port are arranged on the tank body, a bag body is arranged in the tank body, two ends of the bag body extend to the upper mounting port and the lower mounting port respectively, a soil sample is filled in the bag body, two ends of a model pile penetrate through the soil sample, and detachable fixing components are arranged at the upper mounting port and the lower mounting port of the tank body respectively; a tension and compression sensor is hinged between the end part of an output rod of the power mechanism and the top end of the model pile; first high accuracy displacement meter and second high accuracy displacement meter are installed respectively to model pile top and bottom, and jar internal third high accuracy displacement meter who is used for measuring soil sample radial displacement of installing. The invention also discloses a use method of the large multifunctional soil and structure interface shearing device. The invention can solve the problem that the requirements of different types of shear tests cannot be met in the existing soil sample and structure interface shear test.
Description
Technical Field
The invention relates to the technical field of geotechnical testing, in particular to a large multifunctional soil and structure interface shearing device and a using method thereof.
Background
The problem of interaction between soil sample and structure has been an important issue for long-term research in the engineering field. The contact of the soil sample and the structure relates to aspects of soil mechanics, foundation engineering, support engineering, bridge engineering, tunnel engineering and the like, such as the contact of a sheet pile wharf structure and the soil sample, the contact of a pile foundation and the soil sample, the contact of a retaining wall and the soil sample, the contact of a dam and the soil sample, the contact of a tunnel lining and the soil sample and the like. The two materials have large difference in mechanical properties, and when the two materials are subjected to external load, the deformation difference of the two materials causes the contact surface of the soil sample and the structure to generate interaction force, so that discontinuous contact phenomena such as dislocation, slippage, spalling and the like are generated between the soil sample and the structure.
Meanwhile, in recent years, pile structures are widely applied to bridge engineering, foundation engineering, supporting engineering and port engineering construction, and pile foundations are applied to port-pearl australian bridges which are known as one of 'zuno-peak' and 'seven curiosities in the modern world' in the bridge industry and Beijing great-fun airports which are known as the first seven curiosities in the new world in great quantity. Taking foundation engineering as an example, the construction cost of the pile foundation in civil high-rise building engineering can be up to 30 percent of the total engineering cost. At present, the pile foundation design is mainly estimated by adopting an empirical formula and numerical simulation, and whether the bearing capacity of the pile foundation meets the requirement or not is verified by combining a field static load test, so that the design value of the pile foundation is often larger than the actual requirement of the engineering, the waste of engineering materials is generated, and the key for solving the problem is to accurately calculate the pile-soil interaction force. Therefore, the contact mechanical property of the soil sample and the pile is revealed, which is beneficial to defining the pile-soil interaction mechanism, improving the calculation accuracy of the bearing capacity of the pile foundation and the horizontal force resistance of the support pile structure, reducing the waste of engineering materials generated by the application of the pile structure and improving the economic benefit of the pile foundation in the engineering application.
However, the study of mechanical properties between soil samples and structures is premised on a precision earth test instrument. The existing soil sample and structure interface shearing equipment mainly uses an interface type shearing instrument, but the equipment has the defects of low simulated stress state, single stress path, uncertain main stress direction, reduction of the contact area of the soil sample and the structure along with the increase of shearing displacement and the like. Meanwhile, the conventional shearing equipment is small in size, the soil sample is difficult to prepare, the control precision of the relative density of the soil sample is low, and the accuracy of the preparation of the soil sample is the key for ensuring the accuracy of the measured test data. In addition, the conventional shearing equipment has relatively small shearing displacement and cannot meet the requirements of interface contact large deformation and cyclic load research, such as earth and rockfill dams, static pressure piles and the like. Therefore, research and development are carried out on the soil sample and structure interface shear test equipment to meet the test requirements of high stress state, complex stress path, large deformation problem of interface contact, cyclic load, improvement of soil sample preparation and control precision and the like. Therefore, reliable data are provided for further determining the mechanical characteristics of the contact interface between the soil sample and the structure.
Disclosure of Invention
The invention aims to provide a large multifunctional soil and structure interface shearing device and a using method thereof, which are used for solving the problems that in the existing soil sample and structure interface shearing test, the soil sample is difficult to prepare, the height-diameter ratio of the soil sample is inconvenient to adjust, the problem that pile-soil contact large deformation cannot be met, and the requirements of different types of shearing tests cannot be met.
In order to solve the problems, the invention adopts the following technical scheme:
a large multifunctional soil and structure interface shearing device comprises a supporting structure, a power mechanism, a control system and a data acquisition system, wherein the power mechanism is installed on the supporting structure, the shearing tank comprises a tank body, an upper installation port, a lower installation port, a pressurization port, a pressure relief port and a wire outlet hole are formed in the tank body, a bag body is installed in the tank body, the bag body is of a cylindrical structure, two ends of the bag body extend to the upper installation port and the lower installation port respectively, the diameter of the bag body is smaller than that of the upper installation port or the lower installation port, gas or liquid is filled between the bag body and the inner wall of the tank body, a soil sample is filled in the bag body, a model pile is placed in the soil sample, the axial direction of the model pile is consistent with the axial direction of the bag body, and two ends of the model pile penetrate through the soil sample;
the upper mounting opening and the lower mounting opening of the tank body are respectively provided with a detachable fixing component, the tank body forms a sealing structure after the fixing components are mounted on the tank body, two ends of the bag body are respectively fixed at the fixing components, one side surface of the fixing components, facing the interior of the tank body, is flush with the inner surface of the tank body, and two ends of the soil sample are respectively in surface contact with one side surface of the fixing components, facing the interior of the tank body, at the upper mounting opening and the lower mounting opening;
the top end and the bottom end of the model pile respectively extend out of the corresponding fixing components, an output rod of the power mechanism is coaxially arranged with the model pile, and a tension-compression sensor is hinged between the end part of the output rod of the power mechanism and the top end of the model pile;
the position that fixed subassembly was stretched out to model stake top is installed and is used for measuring the first high accuracy displacement meter of model stake axial displacement, the position that fixed subassembly was stretched out to model stake bottom is installed and is used for measuring the second high accuracy displacement meter of model stake axial displacement, jar internal third high accuracy displacement meter that is used for measuring soil sample radial displacement of installing, draw pressure sensor, first high accuracy displacement meter, second high accuracy displacement meter and third high accuracy displacement meter and be connected with data acquisition system through the wire respectively.
Optionally, the supporting structure is a steel frame, the steel frame is a door-shaped structure, the power mechanism is an electric cylinder, the electric cylinder is vertically installed on the steel frame, the control system is a servo control system, and the servo control system is connected with the electric cylinder.
Optionally, the fixing assembly comprises a flange plate, a base plate, a backing ring and a cover plate, the flange plate, the backing ring and the cover plate are all of an annular structure, the flange plate is detachably fixed at an upper mounting opening and/or a lower mounting opening of the tank body through bolts, a clamping step is fixed on the top of one side of the flange plate, which is located at the inner ring, along the circumferential direction, a hoop is mounted on the outer ring of the clamping step, the top end of the bag body is fixed between the clamping step and the hoop after passing through the clamping step, and the diameter of the inner ring of the flange plate is matched with the diameter of the bag body;
backing plate and backing ring are all placed in soil sample surface and all are located the utricule inboard, and the backing ring is arranged in the backing plate inner circle, backing ring inner circle and model pile periphery direct contact, the apron covers at backing plate and backing ring surface and passes through the bolt with the ring flange and can dismantle fixed connection, is equipped with the clearance between apron inner circle and the model pile periphery, and the periphery diameter of apron is greater than the diameter of backing plate.
Optionally, the axes of the measuring rods of the first high-precision displacement meter and the second high-precision displacement meter are arranged in parallel with the axis of the model pile, and the axis of the measuring rod of the third high-precision displacement meter is arranged perpendicular to the axis of the model pile;
the periphery of the part, extending out of the fixing component, of the top end of the model pile is fixedly connected with a horizontally arranged upper hoop rod, the first high-precision displacement meter is supported by the upper hoop rod, the upper hoop rod is fixed on a supporting structure, and a measuring rod of the first high-precision displacement meter is in contact with the upper hoop rod; the periphery of the part, extending out of the fixing component, of the bottom end of the model pile is fixedly connected with a lower hoop rod which is horizontally arranged, the second high-precision displacement meter is supported by the lower hoop rod, the lower hoop rod is fixed on the ground, and a measuring rod of the second high-precision displacement meter is in contact with the lower hoop rod;
an inner support rod is vertically fixed in the tank body, a plurality of third high-precision displacement meters are installed on the inner support rod from top to bottom, and the first high-precision displacement meter and the second high-precision displacement meter are symmetrically arranged two by two.
Optionally, a first floating joint is connected between one end of the tension and compression sensor and the top end of the model pile, a second floating joint is connected to the other end of the tension and compression sensor, and the second floating joint is connected with the end of the output rod of the power mechanism through a fisheye joint bearing.
Optionally, an adapter plate is mounted on the cover plate in the fixing assembly at the lower mounting opening, a linear bearing is mounted on the adapter plate, and the linear bearing is connected with the model pile in a sliding manner.
Optionally, a height-adjustable cushion block is arranged between the bottom of the inner side of the capsule body and the fixing assembly.
According to the interface shearing device for the large multifunctional soil and the structure, when a pile-soil interface shearing simulation test is carried out, the use method comprises the following steps:
step S1: installing a third high-precision displacement meter in the tank body, wherein a lead of the third high-precision displacement meter is connected out from a wire outlet hole of the tank body, and the wire outlet hole is sealed by adopting high-strength sealant after connection, selecting a fixing component and a bag body with the height-diameter ratio corresponding to that of a soil sample, installing the fixing component at an installation opening under the tank body, installing a flange plate and a hoop in the fixing component at an installation opening on the tank body, and fixing two ends of the bag body at the corresponding flange plates through the hoop respectively;
step S2: installing a model pile, enabling two ends of the model pile to penetrate through the fixing assemblies at two ends, and enabling the axial direction of the model pile to be consistent with the direction of the tension provided by the power mechanism;
step S3: according to the test requirement, filling a soil body into the bag body to obtain an annular soil sample, after the soil body is filled, installing a backing ring, a backing plate and a cover plate in the fixed assembly at an installation opening on the tank body, wherein the backing plate and the backing ring are both placed on the surface of the soil sample during installation, the inner ring of the backing ring is directly contacted with the periphery of the model pile, the cover plate covers the surfaces of the backing plate and the backing ring and is connected with a flange plate, and a gap is formed between the inner ring of the cover plate and the periphery of the model pile to complete packaging;
step S4: the method comprises the following steps that a power mechanism, a tension and compression sensor, a first high-precision displacement meter and a second high-precision displacement meter are sequentially installed, the power mechanism is connected with a control system, the tension and compression sensor, the first high-precision displacement meter, the second high-precision displacement meter and a third high-precision displacement meter are respectively connected with a data acquisition system through leads, and the data acquisition system is connected with a data storage system;
step S5: closing a valve at the pressure relief opening, applying air pressure or hydraulic confining pressure to the soil sample in the tank body through the pressure increasing opening, obtaining the soil sample confining pressure according to a measured value of a pressure gauge additionally arranged on the tank body, and then applying load to the model pile through a power mechanism to control the axial displacement of the model pile so as to realize pile-soil interface shear simulation;
step S6: the displacement of the model pile and the body strain of the soil sample in the interface shearing process of the soil sample and the model pile can be obtained through the first high-precision displacement meter, the second high-precision displacement meter and the third high-precision displacement meter; the shearing force in the shearing process can be obtained by pulling and pressing the sensor;
step S7: and stopping the power mechanism from loading when the displacement of the model pile reaches a preset value, and opening a valve at the pressure relief opening to relieve pressure after the test is finished.
According to the interface shearing device for the large multifunctional soil and the structure, when a simulation test of the static pressure pile is carried out, the interface shearing device comprises the following steps:
step S1: installing a third high-precision displacement meter in the tank body, wherein a lead of the third high-precision displacement meter is connected out from a wire outlet hole of the tank body, sealing the wire outlet hole by adopting high-strength sealant after connection, selecting a fixing component and a bag body with the height-diameter ratio corresponding to that of the soil sample, installing the fixing component at a lower installation opening of the tank body, replacing a backing ring and a backing plate in the fixing component at the lower installation opening with a disc-shaped whole backing plate to seal the bottom of the soil sample, installing a flange plate and a hoop ring in the fixing component at an installation opening on the tank body, and fixing two ends of the bag body at the corresponding flange plates through the hoop rings respectively;
step S2: according to the test requirement, filling a soil body into the bag body to obtain a cylindrical soil sample, after the soil body is filled, installing a backing ring, a backing plate and a cover plate in the fixing component at the installation opening on the tank body, wherein the backing plate and the backing ring are both placed on the surface of the soil sample during installation, the cover plate covers the surfaces of the backing plate and the backing ring and is connected with a flange plate, and a space for a model pile to penetrate into the soil sample is reserved in the centers of the backing plate, the backing ring and the cover plate in the fixing component at the installation opening on the tank body;
step S3: closing a valve at the pressure relief opening and zeroing a pressure gauge;
step S4: the power mechanism, the tension and compression sensor and the model pile are sequentially installed, the model pile is installed on the upper portion of the soil sample, the axial direction of the model pile is consistent with the direction of tension provided by the power mechanism, the power mechanism is connected with the control system, the tension and compression sensor and the end resistance in the model pile are respectively connected with the data acquisition system through wires, and the data acquisition system is connected with the data storage system;
step S5: applying air pressure or hydraulic confining pressure to the soil sample in the tank body through the pressurizing port, obtaining the confining pressure of the soil sample according to the measured value of a pressure gauge additionally arranged on the tank body, then applying load to the model pile through the power mechanism to control the model pile to penetrate into the soil sample at a certain speed, and realizing the simulation of the static pressure pile;
step S6: in the static pile pressing test process, a tension-compression sensor is adopted to measure the pile top pressure, and an end resistance meter in a model pile is adopted to measure the end resistance in the pile pressing process; simulating the proportion of end resistance and pile side friction force in the pile driving process of the static pressure pile at different soil layer depths by changing the confining pressure mode of the soil sample; calculating the penetration depth of the pile body before pile pressing, namely the difference between the height of the soil sample and the 8-10 times of the pile diameter of the model pile is the penetration depth of the simulated static pressure pile, and finishing the penetration of the static pressure pile when the pile tip of the model pile is 8-10 times of the pile diameter of the soil sample from the bottom of the model pile;
step S7: and after the test is finished, opening a valve at the pressure relief opening to relieve the pressure.
According to the interface shearing device for the large multifunctional soil and the structure, when a soil pressure cell calibration test is carried out, the interface shearing device comprises the following steps:
step S1: installing a third high-precision displacement meter in the tank body, wherein a lead of the third high-precision displacement meter is connected out from a wire outlet hole of the tank body, and the wire outlet hole is sealed by adopting high-strength sealant after connection, selecting a fixing component and a bag body with the height-diameter ratio corresponding to that of a soil sample, installing the fixing component at an installation opening under the tank body, installing a flange plate and a hoop in the fixing component at an installation opening on the tank body, and fixing two ends of the bag body at the corresponding flange plates through the hoop respectively;
step S2: embedding the miniature soil pressure box on the model pile, then installing the model pile in the shearing tank, enabling two ends of the model pile to penetrate through the fixing components at the two ends, and enabling the axial direction of the model pile to be consistent with the axial direction of the capsule body;
step S3: according to the test requirement, filling a soil body into the bag body to obtain an annular soil sample, after the soil body is filled, installing a backing ring, a backing plate and a cover plate in the fixed assembly at an installation opening on the tank body, wherein the backing plate and the backing ring are both placed on the surface of the soil sample during installation, the inner ring of the backing ring is directly contacted with the periphery of the model pile, and the cover plate covers the surfaces of the backing plate and the backing ring and is connected with a flange plate to complete encapsulation;
step S4: after the soil sample and the model pile are packaged, closing a valve at a pressure relief opening, applying air pressure or hydraulic confining pressure to the soil sample in the tank body through a pressurization opening, comparing the reading of a pressure gauge with the pressure measured by the soil pressure cell, and finally correcting the sensitivity coefficient of the soil pressure cell according to the reading of the pressure gauge so as to enable the data measured by the soil pressure cell to be consistent with the reading of the pressure gauge, thereby completing a calibration test of the soil pressure cell;
step S5: and after the test is finished, opening a valve at the pressure relief opening to relieve the pressure.
By adopting the technical scheme, the invention has the following advantages:
the shearing tank body is provided with the upper mounting opening and the lower mounting opening, and is sealed by the fixing assembly, so that a foundation is structurally provided for preparing a soil sample by adopting a rain falling method, the preparation difficulty of the soil sample is effectively reduced, and the preparation efficiency and the relative density control precision of the soil sample are obviously improved.
According to the invention, the two ends of the capsule are respectively fixed at the fixing assemblies, so that the stability of the capsule is effectively improved, the capsule is prevented from falling off in the pressurizing and shearing processes, the soil sample is completely in the pressure action range of the shearing tank due to the arrangement of the base plate, and the influence of the boundary effect of the two ends of the soil sample on the stress level is effectively reduced.
The shearing device provided by the invention is used for measuring the displacement of both ends of the model pile, not only can be used for measuring the displacement of the model pile, but also can be used for measuring the elongation or compression of the model pile under the action of the shearing force, so that the calculation accuracy of the shearing force of the contact interface of the soil body and the structure can be further improved.
The cushion ring made of acrylic material is contacted with the model pile, the advantage of high strength of the acrylic material is effectively utilized, the separation of the soil body and the model pile in the shearing process can be avoided, and the measurement precision of the shearing force of the contact interface of the soil body and the structure is improved.
According to the invention, by adopting the design of the flange plate and the cover plate, the height-diameter ratio of the soil sample can be adjusted by selecting the fixing component and the capsule body with the specifications corresponding to the height-diameter ratio of the soil sample, and the fixing component and the capsule body can be adjusted by matching with a mode of placing the cushion block at the bottom of the capsule body, so that the requirements of different sample sizes can be met under the condition of not replacing the shearing tank body, the flange plate and the cover plate have remarkable advantages in large sample tests, and the actual working conditions can be better simulated in geotechnical tests.
The invention adopts a servo control system to control the electric cylinder, and has a plurality of loading modes, such as: stress control, displacement control, monotonic load control, cyclic load control and the like, thereby providing favorable conditions for loading control in different modes, and meeting the test requirements of multiple modes, high stress, complex stress and the like.
The shear tank body of the present invention is made of steel or stainless steel and can be designed according to stress requirements, thereby facilitating the simulation of high stress and complex stress.
When the pile-soil interface shear test is carried out, the two ends of the model pile penetrate through the soil sample, so that the shear displacement of the structure is greatly improved, and the research on the problem of large deformation caused by pile-soil contact can be met. Meanwhile, by utilizing the shearing device disclosed by the invention, not only can a pile-soil interface shearing test be carried out, but also a static pressure pile test, a soil pressure cell calibration test, a coarse-grained soil and pile interface shearing test and the like can be carried out, so that the functions are diversified.
In conclusion, the power mechanism is controlled by the control system, the shearing displacement between the structure and the soil sample can be regulated, the soil sample is pressurized and controlled by inflating (or filling liquid) in the shearing tank, so that the normal stress of the contact surface of the soil body and the structure is controlled, the data acquisition system and the data storage system are used for data acquisition and storage, the multifunctional, multi-mode and automatic measurement can be realized, the measurement precision is high, the operation is simple, and the method has better economic benefit and wide application prospect.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic structural view of a fixing assembly according to the present invention;
FIG. 3 is an enlarged partial schematic view at A of FIG. 1;
FIG. 4 is an enlarged partial schematic view at B of FIG. 1;
fig. 5 is a schematic view of the mounting of the spacer block of the present invention.
Reference numerals: 1. a support structure 2 and a power mechanism; 3. the device comprises a tank body 31, an upper mounting port 32, a lower mounting port 33, a pressurizing port 34, a pressure relief port 35, a wire outlet hole 36, a pressure gauge 4, a bag body 5, a soil sample 6 and a model pile; 7. the device comprises a fixing component, 71, a flange plate, 72, a clamping step, 73, a hoop, 74, a backing plate, 75, a backing ring, 76, a cover plate, 8, a cushion block, 9, a tension and compression sensor, 91, a first floating joint, 92, a second floating joint, 93, a fisheye joint bearing, 10, a first high-precision displacement meter, 11, a second high-precision displacement meter, 12, a third high-precision displacement meter, 13, an upper hoop rod, 14, an upper support rod, 15, a lower hoop rod, 16, a lower support rod, 17, an inner support rod, 18, a linear bearing, 19, a control system, 20, a data acquisition system, 21 and a data storage system.
Detailed Description
In order to make the technical purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention are further described below with reference to fig. 1 to 5 and specific embodiments.
An embodiment of a large multifunctional soil and structure interface shearing device comprises:
a large multifunctional soil and structure interface shearing device comprises a supporting structure 1, a power mechanism 2, a control system 19 and a data acquisition system 20, wherein the power mechanism 2 is installed on the supporting structure 1, the control system 19 controls the operation of the power mechanism 2, the shearing tank comprises a tank body 3, an upper installation port 31, a lower installation port 32, a pressurization port 33, a pressure relief port 34 and a wire outlet hole 35 are arranged on the tank body 3, valves are respectively installed at the pressurization port 33 and the pressure relief port 34, a bag body 4 is installed in the tank body 3, the bag body 4 is of a cylindrical structure, the bag body 4 is made of silica gel or rubber, the size of the bag body 4 can be changed according to the size of a soil sample 5 required by a test, two ends of the bag body 4 respectively extend to the upper installation port 31 and the lower installation port 32, the diameter of the bag body 4 is smaller than that of the upper installation port 31 or the lower installation port 32, and gas or liquid is filled between the bag body 4 and the inner wall of the tank body 3, the tank body 3 is also provided with a pressure gauge 36 for monitoring the pressure in the tank body 3, the pressure gauge 36 is a high-precision pressure gauge 36, the pressure can be measured, the hydraulic pressure can be measured, and the pressure gauge 36 has recording and storing functions; the bag body 4 is filled with a soil sample 5, a model pile 6 is placed in the soil sample 5, the axial direction of the model pile 6 is consistent with the axial direction of the bag body 4, the model pile 6 is a structure, two ends of the model pile 6 penetrate through the soil sample 5, the normal force borne by a contact interface of soil and the structure is ensured to be always vertical to a contact surface of the soil and the structure, the area of the contact surface is ensured not to change along with the increase of shear displacement in the shearing process, the shear displacement of the structure is greatly improved, and therefore the research on the problem of large deformation caused by the contact of pile soil is met;
the upper mounting port 31 and the lower mounting port 32 of the tank body 3 are respectively provided with a detachable fixing component 7, and the fixing component 7 is arranged on the tank body 3 to form a sealing structure in the tank body 3.
As shown in fig. 2 and 3, the fixing assembly 7 includes a flange 71, a pad 74, a pad 75 and a cover plate 76, the flange 71, the pad 74, the pad 75 and the cover plate 76 are all of an annular structure, the flange 71 is detachably fixed at the upper mounting port 31 and/or the lower mounting port 32 of the tank 3 through bolts, a clamping step 72 is fixed at the top of one side of the flange 71 located at the inner ring along the circumferential direction, a hoop 73 is mounted on the outer ring of the clamping step 72, the top end of the capsule 4 is fixed between the clamping step 72 and the hoop 73 after passing through the clamping step 72, the capsule 4 and the hoop 73 are connected by high-strength adhesive, and the diameter of the inner ring of the flange 71 is matched with the diameter of the capsule 4;
the backing plate 74 and the backing ring 75 are both placed on the surface of the soil sample 5 and are both positioned on the inner side of the bag body 4, the backing ring 75 can be made of acrylic materials, the backing ring 75 is placed in the inner ring of the backing plate 74, the inner ring of the backing ring 75 is in direct contact with the periphery of the model pile 6, the influence of the backing ring 75 on the shearing force in the test can be eliminated in a filtering mode (in the device, whether the backing ring 75 influences the shearing force or not can be filtered by changing the height of the soil sample, whether the material of the backing ring 75 influences the shearing force or not can be changed, and the like, which belongs to the debugging process of test equipment), the cover plate 76 covers the surfaces of the backing plate 74 and the backing ring 75 and is detachably and fixedly connected with the flange plate 71 through bolts, a sealing adhesive and a rubber pad are arranged between the cover plate 76 and the flange plate 71, a gap is arranged between the inner ring of the cover plate 76 and the periphery of the model pile 6, so as to avoid the influence of the shearing force caused by the cover plate 76, the cover plate 76 has a peripheral diameter greater than the diameter of the backing plate 74.
The arrangement of the backing ring 75 can adapt to model piles 6 with different diameters, when the model piles 6 with different diameters are replaced, the backing ring 75 with corresponding size can be replaced firstly, and the utilization rate of the backing plate 74 can be effectively improved; in addition, the pad 74 can be added with a permeable stone and a pressure control device according to the test requirements;
further, as one embodiment of the present invention, as shown in fig. 5, a height-adjustable cushion block 8 is disposed between the bottom of the inner side of the capsule 4 and the fixing component 7, so as to further facilitate adjustment of the height-diameter ratio of the soil sample 5.
The height-diameter ratio of the soil sample 5 can be adjusted by replacing the fixing component 7 and the bag body 4 with different sizes, and the device can test the soil samples 5 with different sizes without replacing the tank body 3 with a new one.
The top end and the bottom end of the model pile 6 respectively extend out of the cover plates 76 corresponding to the fixing assemblies 7, the output rod of the power mechanism 2 is coaxially arranged with the model pile 6, and a tension-compression sensor 9 is hinged between the end part of the output rod of the power mechanism 2 and the top end of the model pile 6; the two ends of the tension and compression sensor 9 are respectively connected with the end part of the output rod of the power mechanism 2 and the top end of the model pile 6 through a hinged structure, so that the force measured by the tension and compression sensor 9 in the shearing test process can be prevented from being influenced by bending moment (or eccentric force), and the influence on the shearing force measurement when the axis of the model pile 6 is not completely coincided with the axis of the output rod (namely, the telescopic rod of the electric cylinder) of the power mechanism 2 is effectively avoided.
Specifically, as shown in fig. 4, the hinge mode of the tension/compression sensor 9 is as follows: a first floating joint 91 is connected between one end of the tension and compression sensor 9 and the top end of the model pile 6, the other end of the tension and compression sensor 9 is connected with a second floating joint 92, the second floating joint 92 is connected with the end part of the output rod of the power mechanism 2 through a fisheye joint bearing 93, the inner ring of the fisheye joint bearing 93 is fixedly connected with the end part of the output rod of the power mechanism 2 through a transfer shaft, and the outer ring of the fisheye joint bearing 93 is fixedly connected with the second floating joint 92.
The floating joint and the fisheye joint bearing 93 are conventional structures and are not described in detail.
The position that fixed subassembly 7 was stretched out on 6 tops of model pile installs the first high accuracy displacement meter 10 that is used for measuring 6 axial displacement of model pile, the position that fixed subassembly 7 was stretched out in 6 bottoms of model pile installs the second high accuracy displacement meter 11 that is used for measuring 6 axial displacement of model pile, install the third high accuracy displacement meter 12 that is used for measuring 5 radial displacement of soil sample in jar body 3, draw pressure sensor 9, first high accuracy displacement meter 10, second high accuracy displacement meter 11 and third high accuracy displacement meter 12 are connected with data acquisition system 20 through the wire respectively, data acquisition system 20 passes through the wire and links to each other with data storage system 21. The data acquisition system 20 has an automatic acquisition function, can effectively extract dynamic data in the whole shearing process, and the data storage system 21 is a computer host and a computer display.
The lead of the third high-precision displacement meter 12 is connected out from the outlet hole 35 of the tank body 3, and the outlet hole 35 is sealed by high-strength sealant after the lead is connected out.
The axes of measuring rods of the first high-precision displacement meter 10 and the second high-precision displacement meter 11 are arranged in parallel with the axis of the model pile 6, and the axis of a measuring rod of the third high-precision displacement meter 12 is arranged perpendicular to the axis of the model pile 6;
the periphery of the position, extending out of the fixing component 7, of the top end of the model pile 6 is fixedly connected with a horizontally arranged upper hoop rod 13, the first high-precision displacement meter 10 is supported by an upper support rod 14, the upper support rod 14 is fixed on a steel frame, and a measuring rod of the first high-precision displacement meter 10 is in contact with the upper hoop rod 13; the periphery of the part, extending out of the fixing component 7, of the bottom end of the model pile 6 is fixedly connected with a lower hoop rod 15 which is horizontally arranged, the second high-precision displacement meter 11 is supported by a lower supporting rod 16, the lower supporting rod 16 is fixed on the ground, and a measuring rod of the second high-precision displacement meter 11 is in contact with the lower hoop rod 15; in specific application, the upper support 14 and the lower support 16 can be magnetic gauge stands fixed on a steel frame, and the first high-precision displacement meter 10 or the second high-precision displacement meter 11 is installed on the magnetic gauge stands;
an inner support rod 17 is vertically fixed in the tank body 3, a plurality of third high-precision displacement meters 12 are installed on the inner support rod 17 from top to bottom, and the first high-precision displacement meter 10 and the second high-precision displacement meter 11 are symmetrically arranged in two respectively, so that the measurement is more accurate.
The first high-accuracy displacement meter 10, the second high-accuracy displacement meter 11, and the third high-accuracy displacement meter 12 may employ vibrating wire type or laser displacement sensors or the like.
Further, as one embodiment of the present invention, as shown in fig. 1, an adapter plate is installed on a cover plate 76 in the fixing assembly 7 located at the lower installation port 32, a linear bearing 18 is installed on the adapter plate, the linear bearing 18 is connected with the model pile 6 in a sliding manner, the linear bearing 18 can force the axis of the model pile 6 to coincide with the axis of the soil sample 5 so as to meet the requirement of the shear test on the perpendicularity of the model pile 6, and more accurate test data can be obtained.
Further, as one embodiment of the present invention, the supporting structure 1 is a steel frame, the steel frame is a door-shaped structure, the power mechanism 2 is an electric cylinder, the electric cylinder is vertically installed on the steel frame, the control system 19 is a servo control system 19, the servo control system 19 is connected to the electric cylinder, and the servo control system 19 has multiple loading modes, such as: stress control, displacement control, monotonic load control, cyclic load control and the like, thereby providing favorable conditions for loading control in different modes.
The servo control system 19 controls the power mechanism 2 to regulate and control the shearing displacement between the model pile 6 and the soil sample 5.
The servo control system 19, the electric cylinder, the tension and compression sensor 9, the data acquisition system 20, the data storage system 21 and the high-precision displacement meter are all conventional devices, and specific structures are not repeated.
The large multifunctional soil and structure interface shearing device can be used for not only performing pile-soil interface shearing tests, but also performing static pile tests, soil pressure cell calibration tests, coarse-grained soil and pile interface shearing tests and the like.
The pile-soil interface shear test process is as follows:
step S1: installing a third high-precision displacement meter 12 in the tank body 3, leading out a lead of the third high-precision displacement meter 12 from a wire outlet hole 35 of the tank body 3, sealing the wire outlet hole 35 by adopting high-strength sealant after the lead is out, selecting a fixing component 7 and a bag body 4 which have the height-diameter ratio corresponding to that of the soil sample 5, installing the fixing component 7 at a lower installation opening 32 of the tank body 3, further adjusting the height-diameter ratio of the soil sample 5 according to placing cushion blocks 8 with different sizes, installing a flange 71 and a hoop 73 in the fixing component 7 at an installation opening 31 on the tank body 3, and fixing two ends of the bag body 4 at the corresponding flange 71 through the hoop 73 respectively;
step S2: installing a model pile 6, enabling two ends of the model pile 6 to penetrate through the fixing assemblies 7 at two ends, and enabling the axial direction of the model pile 6 to be consistent with the direction of the tension provided by the power mechanism 2;
before the soil sample 5 is prepared, the perpendicularity of the model pile 6 needs to be ensured, and the axial direction of the model pile 6 is prevented from being consistent with the direction of the tension provided by the power mechanism 2.
Step S3: according to the test requirement, filling a soil body into the bag body 4 to obtain a circular soil sample 5, wherein the soil body filling mode can adopt a rain falling method, after the soil body filling is completed, a backing ring 75, a backing plate 74 and a cover plate 76 in the fixing component 7 are arranged at the mounting opening 31 on the tank body 3, when the circular soil sample 5 is mounted, the backing plate 74 and the backing ring 75 are both placed on the surface of the soil sample 5, the inner ring of the backing ring 75 is directly contacted with the periphery of the model pile 6, the cover plate 76 covers the surfaces of the backing plate 74 and the backing ring 75 and is connected with the flange plate 71, and a gap is formed between the inner ring of the cover plate 76 and the periphery of the model pile 6 to complete the packaging;
the device is convenient to prepare samples by adopting a rain falling method, the preparation difficulty of the soil sample 5 can be effectively reduced, the preparation efficiency and the relative density control precision of the soil body and the soil sample 5 are obviously improved, the rain falling method is a conventional sample preparation method in the rock and soil major, and the concrete sample preparation method is not repeated.
Step S4: the method comprises the following steps that a power mechanism 2, a tension and compression sensor 9, a first high-precision displacement meter 10 and a second high-precision displacement meter 11 are sequentially installed, the power mechanism 2 is connected with a control system 19, the tension and compression sensor 9, the first high-precision displacement meter 10, the second high-precision displacement meter 11 and a third high-precision displacement meter 12 are respectively connected with a data acquisition system 20 through leads, and the data acquisition system 20 is connected with a data storage system 21;
step S5: closing a valve at a pressure relief opening 34, applying air pressure or hydraulic confining pressure to the soil sample 5 in the tank body 3 through a pressure increasing opening 33, obtaining the confining pressure of the soil sample 5 according to the measured value of a pressure gauge 36 additionally arranged on the tank body 3, and then applying load to the model pile 6 through the power mechanism 2 to control the axial displacement of the model pile 6 so as to realize pile-soil interface shearing simulation;
step S6: the displacement of the model pile 6 and the body strain of the soil sample 5 in the interface shearing process of the soil sample 5 and the model pile 6 can be obtained through the first high-precision displacement meter 10, the second high-precision displacement meter 11 and the third high-precision displacement meter 12; the shearing force in the shearing process can be obtained by pulling and pressing the sensor 9;
step S7: and when the displacement of the model pile 6 reaches a preset value, the power mechanism 2 can stop loading, and after the test is finished, the valve at the pressure relief opening 34 is opened to relieve the pressure.
In this embodiment, according to the requirement of the test scheme, the power mechanism 2 may be stopped from being loaded when the displacement of the model pile 6 reaches a predetermined value. In other embodiments, the power mechanism 2 can apply cyclic load, so that the cyclic load test requirement can be met.
The shear test of the contact interface of coarse soil and the pile can be completed according to the steps, the requirement on the size of test equipment is high due to the fact that coarse soil particles are large, namely, a large-size soil sample 5 storage space, a large power device and large shear displacement are needed, the capsule body 4 of the device can be subjected to high-diameter ratio conversion according to the requirement, the load of an electric cylinder can be replaced according to the requirement, and the shear displacement can be regulated and controlled by regulating the stroke of the electric cylinder and the distance between the telescopic rod of the electric cylinder and the pile top of the model pile 6, so that the problems can be effectively solved.
The static pressure pile test process is as follows:
step S1: installing a third high-precision displacement meter 12 in the tank 3, leading out a lead of the third high-precision displacement meter 12 from a wire outlet hole 35 of the tank 3, sealing the wire outlet hole 35 by adopting high-strength sealant after the lead is out, selecting a fixing component 7 and a capsule 4 which have the height-diameter ratio corresponding to that of the soil sample 5, installing the fixing component 7 at a lower installation opening 32 of the tank 3, replacing a backing ring 75 and a backing plate 74 in the fixing component 7 at the lower installation opening 32 with a disc-shaped whole backing plate 74 to seal the bottom of the soil sample 5, further adjusting the height-diameter ratio of the soil sample 5 according to the placement of different-size backing blocks 8, installing a flange 71 and a hoop 73 in the fixing component 7 at an installation opening 31 on the tank 3, and fixing two ends of the capsule 4 at the corresponding flanges 71 through the hoop 73 respectively;
step S2: according to the test requirement, filling a soil body in the bag body 4 to obtain a cylindrical soil sample 5, wherein the soil body filling mode can adopt a rain falling method, after the soil body filling is completed, a backing ring 75, a backing plate 74 and a cover plate 76 in the fixing component 7 are arranged at the mounting opening 31 on the tank body 3, during the mounting, the backing plate 74 and the backing ring 75 are both arranged on the surface of the soil sample 5, the cover plate 76 covers the surfaces of the backing plate 74 and the backing ring 75 and is connected with a flange plate 71, and a space for the model pile 6 to penetrate into the soil sample 5 is reserved at the centers of the backing plate 74, the backing ring 75 and the cover plate 76 in the fixing component at the mounting opening 31 on the tank body 3;
step S3: closing the valve at the pressure relief port 34 and setting the pressure gauge 36 to zero;
step S4: sequentially installing a power mechanism 2, a tension and compression sensor 9 and a model pile 6, installing the model pile 6 on the upper part of a soil sample 5, enabling the axial direction of the model pile 6 to be consistent with the direction of tension provided by the power mechanism 2, connecting the power mechanism 2 with a control system 19, respectively connecting the tension and compression sensor 9 and end resistance in the model pile 6 with a data acquisition system 20 through leads, and connecting the data acquisition system 20 with a data storage system 21;
step S5: applying air pressure or hydraulic confining pressure to the soil sample 5 in the tank body 3 through the pressurizing port 33, obtaining the confining pressure of the soil sample 5 according to the measured value of a pressure gauge 36 additionally arranged on the tank body 3, and then applying load to the model pile 6 through the power mechanism 2 to control the model pile 6 to penetrate into the soil sample 5 at a certain speed so as to realize the simulation of the static pressure pile;
step S6: in the static pile pressing test process, a tension-compression sensor 9 is adopted to measure the pile top pressure, and an end resistance meter in a model pile 6 is adopted to measure the end resistance in the pile pressing process; simulating the proportion of end resistance and pile side friction force in the pile driving process of the static pressure pile at different soil layer depths by changing the confining pressure mode of the soil sample; calculating the penetration depth of the pile body before pile pressing, namely the difference between the height of the soil sample and the 8-10 times of the pile diameter of the model pile is the penetration depth of the simulated static pressure pile, and the penetration of the static pressure pile is finished when the pile tip of the model pile 6 is 8-10 times of the pile diameter from the bottom of the soil sample;
step S7: after the test is finished, the valve at the pressure relief port 34 is opened to relieve the pressure.
The soil pressure cell calibration test process is as follows:
step S1: installing a third high-precision displacement meter 12 in the tank body 3, leading out a lead of the third high-precision displacement meter 12 from a wire outlet hole 35 of the tank body 3, sealing the wire outlet hole 35 by adopting high-strength sealant after the lead is out, selecting a fixing component 7 and a bag body 4 which have the height-diameter ratio corresponding to that of the soil sample 5, installing the fixing component 7 at a lower installation opening 32 of the tank body 3, further adjusting the height-diameter ratio of the soil sample 5 according to placing cushion blocks 8 with different sizes, installing a flange 71 and a hoop 73 in the fixing component 7 at an installation opening 31 on the tank body 3, and fixing two ends of the bag body 4 at the corresponding flange 71 through the hoop 73 respectively;
step S2: embedding the miniature soil pressure box on a model pile 6, then installing the model pile 6 in a shearing tank, enabling two ends of the model pile 6 to penetrate through fixing assemblies 7 at two ends, and enabling the axial direction of the model pile 6 to be consistent with the axial direction of the capsule body 4;
step S3: according to the test requirement, filling a soil body into the bag body 4 to obtain a circular soil sample 5, wherein the soil body filling mode can adopt a rain falling method, after the soil body filling is completed, a backing ring 75, a backing plate 74 and a cover plate 76 in the fixing component 7 are arranged at the mounting opening 31 on the tank body 3, during the mounting, the backing plate 74 and the backing ring 75 are both placed on the surface of the soil sample 5, the inner ring of the backing ring 75 is directly contacted with the periphery of the model pile 6, and the cover plate 76 covers the surfaces of the backing plate 74 and the backing ring 75 and is connected with the flange plate 71 to complete the packaging;
step S4: after the soil sample 5 and the model pile 6 are packaged, closing a valve at a pressure relief port 34, applying air pressure or hydraulic confining pressure on the soil sample 5 in the tank body 3 through a pressurizing port 33, comparing the reading of a pressure gauge 36 with the pressure measured by the soil pressure cell, and finally correcting the sensitivity coefficient of the soil pressure cell according to the reading of the pressure gauge 36 so as to enable the data measured by the soil pressure cell to be consistent with the reading of the pressure gauge 36, thereby completing the calibration test of the soil pressure cell;
the method is a combined calibration method which is one of soil pressure cell calibration methods, and adopts a soil pressure cell calibration mode of combining a liquid marker and a sand marker when liquid confining pressure is applied to a shearing tank, and adopts a soil pressure cell calibration mode of combining a gas marker and a sand marker when the gas pressure is air pressure;
the method effectively utilizes the uniformity of the pressure exerted by the annular soil sample 5 on the surface of the pile body, can simultaneously calibrate a plurality of soil pressure cells, and can effectively improve the calibration efficiency of the soil pressure cells.
Step S5: after the test is finished, the valve at the pressure relief port 34 is opened to relieve the pressure.
The above embodiments are not intended to limit the shape, material, structure, etc. of the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.
Claims (10)
1. The utility model provides a large-scale multi-functional soil and structure thing interface shearing mechanism, includes bearing structure, power unit, control system and data acquisition system, and power unit installs on bearing structure, its characterized in that: the shearing tank comprises a tank body, an upper mounting port, a lower mounting port, a pressurizing port, a pressure relief port and a wire outlet hole are formed in the tank body, an airbag body is mounted in the tank body, the airbag body is of a cylindrical structure, two ends of the airbag body extend to the upper mounting port and the lower mounting port respectively, the diameter of the airbag body is smaller than that of the upper mounting port or the lower mounting port, gas or liquid is filled between the airbag body and the inner wall of the tank body, a soil sample is filled in the airbag body, a model pile is placed in the soil sample, the axial direction of the model pile is consistent with the axial direction of the airbag body, and two ends of the model pile penetrate through the soil sample;
the upper mounting opening and the lower mounting opening of the tank body are respectively provided with a detachable fixing component, the tank body forms a sealing structure after the fixing components are mounted on the tank body, two ends of the bag body are respectively fixed at the fixing components, one side surface of the fixing components, facing the interior of the tank body, is flush with the inner surface of the tank body, and two ends of the soil sample are respectively in surface contact with one side surface of the fixing components, facing the interior of the tank body, at the upper mounting opening and the lower mounting opening;
the top end and the bottom end of the model pile respectively extend out of the corresponding fixing components, an output rod of the power mechanism is coaxially arranged with the model pile, and a tension-compression sensor is hinged between the end part of the output rod of the power mechanism and the top end of the model pile;
the position that fixed subassembly was stretched out to model stake top is installed and is used for measuring the first high accuracy displacement meter of model stake axial displacement, the position that fixed subassembly was stretched out to model stake bottom is installed and is used for measuring the second high accuracy displacement meter of model stake axial displacement, jar internal third high accuracy displacement meter that is used for measuring soil sample radial displacement of installing, draw pressure sensor, first high accuracy displacement meter, second high accuracy displacement meter and third high accuracy displacement meter and be connected with data acquisition system through the wire respectively.
2. The interface shearing device for the large multifunctional soil and the structure according to claim 1, wherein the interface shearing device comprises: the supporting structure is a steel frame, the steel frame is a door-shaped structure, the power mechanism is an electric cylinder, the electric cylinder is vertically installed on the steel frame, the control system is a servo control system, and the servo control system is connected with the electric cylinder.
3. The interface shearing device for the large multifunctional soil and the structure according to claim 1, wherein the interface shearing device comprises: the fixing assembly comprises a flange plate, a base plate, a backing ring and a cover plate, the flange plate, the backing ring and the cover plate are all of annular structures, the flange plate is detachably fixed at an upper mounting opening and/or a lower mounting opening of the tank body through bolts, a clamping step is fixed at the top of one side of the flange plate, which is positioned at the inner ring, along the circumferential direction, a hoop is installed on the outer ring of the clamping step, the top end of the bag body is fixed between the clamping step and the hoop after turning over the clamping step, and the diameter of the inner ring of the flange plate is matched with that of the bag body;
backing plate and backing ring are all placed in soil sample surface and all are located the utricule inboard, and the backing ring is arranged in the backing plate inner circle, backing ring inner circle and model pile periphery direct contact, the apron covers at backing plate and backing ring surface and passes through the bolt with the ring flange and can dismantle fixed connection, is equipped with the clearance between apron inner circle and the model pile periphery, and the periphery diameter of apron is greater than the diameter of backing plate.
4. The interface shearing device for the large multifunctional soil and the structure according to claim 1, wherein the interface shearing device comprises: the axes of the measuring rods of the first high-precision displacement meter and the second high-precision displacement meter are arranged in parallel with the axis of the model pile, and the axis of the measuring rod of the third high-precision displacement meter is arranged perpendicular to the axis of the model pile;
the periphery of the part, extending out of the fixing component, of the top end of the model pile is fixedly connected with a horizontally arranged upper hoop rod, the first high-precision displacement meter is supported by the upper hoop rod, the upper hoop rod is fixed on a supporting structure, and a measuring rod of the first high-precision displacement meter is in contact with the upper hoop rod; the periphery of the part, extending out of the fixing component, of the bottom end of the model pile is fixedly connected with a lower hoop rod which is horizontally arranged, the second high-precision displacement meter is supported by the lower hoop rod, the lower hoop rod is fixed on the ground, and a measuring rod of the second high-precision displacement meter is in contact with the lower hoop rod;
an inner support rod is vertically fixed in the tank body, a plurality of third high-precision displacement meters are installed on the inner support rod from top to bottom, and the first high-precision displacement meter and the second high-precision displacement meter are symmetrically arranged two by two.
5. The interface shearing device for the large multifunctional soil and the structure according to claim 1, wherein the interface shearing device comprises: and a first floating joint is connected between one end of the tension and compression sensor and the top end of the model pile, the other end of the tension and compression sensor is connected with a second floating joint, and the second floating joint is connected with the end part of an output rod of the power mechanism through a fisheye joint bearing.
6. The interface shearing device for the large multifunctional soil and the structure according to claim 3, wherein the interface shearing device comprises: and the cover plate in the fixed assembly positioned at the lower mounting opening is provided with an adapter plate, the adapter plate is provided with a linear bearing, and the linear bearing is connected with the model pile in a sliding manner.
7. The interface shearing device for the large multifunctional soil and the structure according to claim 1, wherein the interface shearing device comprises: a cushion block with adjustable height is arranged between the bottom of the inner side of the bag body and the fixing component.
8. The use method of the large multifunctional soil and structure interface shearing device according to any one of claims 3 to 7, wherein the large multifunctional soil and structure interface shearing device comprises the following steps: the method comprises the following steps:
step S1: installing a third high-precision displacement meter in the tank body, wherein a lead of the third high-precision displacement meter is connected out from a wire outlet hole of the tank body, and the wire outlet hole is sealed by adopting high-strength sealant after connection, selecting a fixing component and a bag body with the height-diameter ratio corresponding to that of a soil sample, installing the fixing component at an installation opening under the tank body, installing a flange plate and a hoop in the fixing component at an installation opening on the tank body, and fixing two ends of the bag body at the corresponding flange plates through the hoop respectively;
step S2: installing a model pile, enabling two ends of the model pile to penetrate through the fixing assemblies at two ends, and enabling the axial direction of the model pile to be consistent with the direction of the tension provided by the power mechanism;
step S3: according to the test requirement, filling a soil body into the bag body to obtain an annular soil sample, after the soil body is filled, installing a backing ring, a backing plate and a cover plate in the fixed assembly at an installation opening on the tank body, wherein the backing plate and the backing ring are both placed on the surface of the soil sample during installation, the inner ring of the backing ring is directly contacted with the periphery of the model pile, the cover plate covers the surfaces of the backing plate and the backing ring and is connected with a flange plate, and a gap is formed between the inner ring of the cover plate and the periphery of the model pile to complete packaging;
step S4: the method comprises the following steps that a power mechanism, a tension and compression sensor, a first high-precision displacement meter and a second high-precision displacement meter are sequentially installed, the power mechanism is connected with a control system, the tension and compression sensor, the first high-precision displacement meter, the second high-precision displacement meter and a third high-precision displacement meter are respectively connected with a data acquisition system through leads, and the data acquisition system is connected with a data storage system;
step S5: closing a valve at the pressure relief opening, applying air pressure or hydraulic confining pressure to the soil sample in the tank body through the pressure increasing opening, obtaining the soil sample confining pressure according to a measured value of a pressure gauge additionally arranged on the tank body, and then applying load to the model pile through a power mechanism to control the axial displacement of the model pile so as to realize pile-soil interface shear simulation;
step S6: the displacement of the model pile and the body strain of the soil sample in the interface shearing process of the soil sample and the model pile can be obtained through the first high-precision displacement meter, the second high-precision displacement meter and the third high-precision displacement meter; the shearing force in the shearing process can be obtained by pulling and pressing the sensor;
step S7: and stopping the power mechanism from loading when the displacement of the model pile reaches a preset value, and opening a valve at the pressure relief opening to relieve pressure after the test is finished.
9. The use method of the large multifunctional soil and structure interface shearing device according to any one of claims 3 to 7, wherein the large multifunctional soil and structure interface shearing device comprises the following steps: the method comprises the following steps:
step S1: installing a third high-precision displacement meter in the tank body, wherein a lead of the third high-precision displacement meter is connected out from a wire outlet hole of the tank body, sealing the wire outlet hole by adopting high-strength sealant after connection, selecting a fixing component and a bag body with the height-diameter ratio corresponding to that of the soil sample, installing the fixing component at a lower installation opening of the tank body, replacing a backing ring and a backing plate in the fixing component at the lower installation opening with a disc-shaped whole backing plate to seal the bottom of the soil sample, installing a flange plate and a hoop ring in the fixing component at an installation opening on the tank body, and fixing two ends of the bag body at the corresponding flange plates through the hoop rings respectively;
step S2: according to the test requirement, filling a soil body into the bag body to obtain a cylindrical soil sample, after the soil body is filled, installing a backing ring, a backing plate and a cover plate in the fixed assembly at an installation opening on the tank body, wherein the backing plate and the backing ring are both placed on the surface of the soil sample during installation, and the cover plate covers the surfaces of the backing plate and the backing ring and is connected with the flange plate;
step S3: closing a valve at the pressure relief opening and zeroing a pressure gauge;
step S4: the power mechanism, the tension and compression sensor and the model pile are sequentially installed, the model pile is installed on the upper portion of the soil sample, the axial direction of the model pile is consistent with the direction of tension provided by the power mechanism, the power mechanism is connected with the control system, the tension and compression sensor and the end resistance in the model pile are respectively connected with the data acquisition system through wires, and the data acquisition system is connected with the data storage system;
step S5: applying air pressure or hydraulic confining pressure to the soil sample in the tank body through the pressurizing port, obtaining the confining pressure of the soil sample according to the measured value of a pressure gauge additionally arranged on the tank body, then applying load to the model pile through the power mechanism to control the model pile to penetrate into the soil sample at a certain speed, and realizing the simulation of the static pressure pile;
step S6: in the static pile pressing test process, a tension-compression sensor is adopted to measure the pile top pressure, and an end resistance meter in a model pile is adopted to measure the end resistance in the pile pressing process; simulating the proportion of end resistance and pile side friction force in the pile driving process of the static pressure pile at different soil layer depths by changing the confining pressure mode of the soil sample; calculating the penetration depth of the pile body before pile pressing, namely the difference between the height of the soil sample and the 8-10 times of the pile diameter of the model pile is the penetration depth of the simulated static pressure pile, and finishing the penetration of the static pressure pile when the pile tip of the model pile is 8-10 times of the pile diameter of the soil sample from the bottom of the model pile;
step S7: and after the test is finished, opening a valve at the pressure relief opening to relieve the pressure.
10. The use method of the large multifunctional soil and structure interface shearing device according to any one of claims 3 to 7, wherein the large multifunctional soil and structure interface shearing device comprises the following steps: the method comprises the following steps:
step S1: installing a third high-precision displacement meter in the tank body, wherein a lead of the third high-precision displacement meter is connected out from a wire outlet hole of the tank body, and the wire outlet hole is sealed by adopting high-strength sealant after connection, selecting a fixing component and a bag body with the height-diameter ratio corresponding to that of a soil sample, installing the fixing component at an installation opening under the tank body, installing a flange plate and a hoop in the fixing component at an installation opening on the tank body, and fixing two ends of the bag body at the corresponding flange plates through the hoop respectively;
step S2: embedding the miniature soil pressure box on the model pile, then installing the model pile in the shearing tank, enabling two ends of the model pile to penetrate through the fixing components at the two ends, and enabling the axial direction of the model pile to be consistent with the axial direction of the capsule body;
step S3: according to the test requirement, filling a soil body into the bag body to obtain an annular soil sample, after the soil body is filled, installing a backing ring, a backing plate and a cover plate in the fixed assembly at an installation opening on the tank body, wherein the backing plate and the backing ring are both placed on the surface of the soil sample during installation, the inner ring of the backing ring is directly contacted with the periphery of the model pile, and the cover plate covers the surfaces of the backing plate and the backing ring and is connected with a flange plate to complete encapsulation;
step S4: after the soil sample and the model pile are packaged, closing a valve at a pressure relief opening, applying air pressure or hydraulic confining pressure to the soil sample in the tank body through a pressurization opening, comparing the reading of a pressure gauge with the pressure measured by the soil pressure cell, and finally correcting the sensitivity coefficient of the soil pressure cell according to the reading of the pressure gauge so as to enable the data measured by the soil pressure cell to be consistent with the reading of the pressure gauge, thereby completing a calibration test of the soil pressure cell;
step S5: and after the test is finished, opening a valve at the pressure relief opening to relieve the pressure.
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