Multifunctional seepage consolidation test equipment and method

Abstract

The invention discloses multifunctional seepage consolidation test equipment and a multifunctional seepage consolidation test method. The multifunctional seepage consolidation test equipment comprises a support frame body, an axial pressurizing device, a consolidation seepage device, a variable head device, a control system and a pore water pressure measuring device, a sample is placed in the consolidation seepage device; the variable water head device is communicated with the interior of the consolidation seepage device and is used for introducing distilled water into the consolidation seepage device, and a water head saturates the sample; the axial pressurizing device is mounted on the supporting frame body and is used for applying a vertical load to the sample; the pore water pressure measuring device is used for recording excess pore water pressure change at the bottom of the sample during consolidation; and the control system is used for controlling the axial pressurizing device, recording the change of the vertical stress and the change of the vertical displacement when the sample is consolidated, and is in communication connection with the pore water pressure measuring device. According to the invention, a plurality of traditional tests such as graded loading consolidation test, consolidation seepage test, equal strain rate consolidation test, equal stress rate consolidation test and the like can be carried out in a laboratory.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical engineering, and in particular to a multifunctional seepage consolidation test device and method. Background Art

[0002] Currently, the most commonly used consolidation test instrument in geotechnical laboratories is the manually operated lever-type oedometer. While simple to operate, soil sample deformation during the test can easily cause the lever to tilt, affecting the loading accuracy of the soil sample. Furthermore, manual loading and unloading of weights is labor-intensive, and the degree of automation is low, resulting in relatively limited test data accuracy. Direct determination of soil permeability is typically performed using traditional constant / variable head permeability testing equipment, the most significant drawback of which is its inability to measure the permeability coefficient under specific pressure during consolidation.

[0003] Conventional graded loading consolidation test is the most commonly used consolidation test method. Its advantages are mainly simple equipment, standardized test steps and data compilation, but it also has shortcomings, mainly: it takes too long, the test data is small and discontinuous, and the effective stress is prone to uneven distribution during the test. The continuous loading consolidation test is to continuously load the sample during the consolidation test, and measure the vertical pressure, vertical deformation and pore water pressure of the sample at the bottom of the sample at any time, which can overcome the above-mentioned shortcomings in the conventional consolidation test. The consolidation-permeability combined test refers to a permeability test carried out during the consolidation test, directly measuring the permeability coefficient of the sample under various levels of consolidation pressure. The permeability coefficient thus measured avoids the error in the traditional one-dimensional linear consolidation theory, which first measures the consolidation coefficient and then reversely deduces the permeability coefficient. The current consolidation seepage test equipment is the GDS advanced consolidation instrument, but the equipment is expensive, the test cost is high, and it is seldom used in domestic laboratories. Therefore, there is a need for a multifunctional consolidation seepage test equipment and method suitable for conventional geotechnical laboratories, which is low-cost, simple in equipment, and easy to operate. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a multifunctional seepage consolidation test equipment and method, which has low cost and simple equipment, and can be used to carry out various tests in the laboratory, such as traditional graded loading consolidation test, consolidation seepage test, constant strain rate consolidation test (CRS), constant stress rate consolidation test (CRL), etc.

[0005] The present invention solves the technical problem by adopting the following technical solutions:

[0006] A multifunctional seepage consolidation test device, comprising: a support frame, an axial pressure device, a consolidation seepage device, a water head variable device, a control system and a pore water pressure measuring device;

[0007] The consolidation seepage device is placed on the support frame, and a sample is placed inside;

[0008] The variable head device is internally connected to the consolidation seepage device and is used to introduce distilled water into the consolidation seepage device to saturate the specimen with water head.

[0009] The axial loading device is installed on the support frame and is used to apply a vertical load to the specimen.

[0010] The pore water pressure measuring device records the change of excess pore water pressure at the bottom of the specimen during consolidation.

[0011] The control system is used to control the axial loading device, record the change of vertical stress and the change of vertical displacement during specimen consolidation, and is communicatively connected to the pore water pressure measuring device.

[0012] Furthermore, the support frame includes a test bench, an upper cross beam, a moving cross beam, columns and a loading rod; two columns are connected to the top of the test bench, the upper cross beam is connected to the tops of the two columns, the moving cross beam is slidably arranged between the two columns and is located below the upper cross beam.

[0013] Furthermore, the consolidation seepage device includes a specimen base, a specimen sleeve, an upper cover plate, a permeable stone, filter paper and a sealing ring; the specimen base is placed on the top of the test bench, the specimen sleeve is placed on the specimen base, the specimen is placed in the specimen sleeve, permeable stones are arranged below and above the specimen, filter paper is arranged between the permeable stone and the specimen, the upper cover plate is placed above the permeable stone, and the sealing ring is placed at the edge position between the specimen and the permeable stone; a drainage channel is arranged inside the upper cover plate, and a channel outlet valve is arranged on the drainage channel; a base inlet valve, a base outlet valve and a pore water pressure sensor connection valve are arranged on the specimen base.

[0014] Furthermore, the variable head device includes a variable head tube, a water supply bucket, a water guide pipe, a tube inlet valve and a tube outlet valve; both the tube inlet valve and the tube outlet valve are arranged at the bottom end of the variable head tube, the tube outlet valve is connected to the base inlet valve through the water guide pipe, and the tube inlet valve is connected to the water supply bucket through the water guide pipe.

[0015] Furthermore, the axial loading device includes a servo motor, a servo controller, an optical encoder, a displacement sensor and a force sensor; the optical encoder is installed on the servo motor, and the output end of the servo motor drives the moving cross beam to move up and down through a driving member; the displacement sensor is arranged inside the moving cross beam, the top end of the force sensor is installed on the moving cross beam, and the bottom end is connected to the loading rod; the servo motor is electrically connected to the servo controller.

[0016] Further, the pore water pressure measuring device includes a pore water pressure sensor and a data acquisition system. The pore water pressure sensor is connected to a pore water pressure sensor connection valve, and the pore water pressure sensor is communicatively connected to the data acquisition system.

[0017] Further, the control system includes a single-chip microcontroller and a computer. The single-chip microcontroller is communicatively connected to the servo controller, the photoelectric encoder, the displacement sensor, the force sensor, and the computer respectively, and the computer is communicatively connected to the data acquisition system.

[0018] Further, the single-chip microcontroller has two modes of stress and strain control, and can perform automatic control of constant load, constant strain rate, and constant stress rate loading.

[0019] A multifunctional seepage consolidation test method includes the following steps:

[0020] Step S1, specimen preparation: Use a ring cutter to cut an undisturbed specimen or use a compaction method to prepare a remolded specimen;

[0021] Step S2, preparation and installation of the specimen before consolidation;

[0022] Connect the specimen base to the water supply bucket, open the base inlet valve and the base outlet valve, remove the air bubbles in the specimen base, place the specimen sleeve, place a permeable stone, a filter paper, and a rubber ring on the specimen base in sequence, press the ring cutter specimen into the specimen sleeve, and place a filter paper, a permeable stone, and a rubber ring on the upper part of the specimen in sequence. Place the upper cover plate on the permeable stone; contact the upper cover plate with the pressure rod, start the axial pressure application device, control the computer pressure application program, apply a vertical load of 2 kPa to make the consolidation seepage device tightly connected to prevent water leakage and air leakage; open the pipe inlet valve to inject water into the variable head pipe, close the base outlet valve, open the base inlet valve, open the channel outlet valve, and the specimen starts to be saturated with water head. When the water flowing out of the channel outlet valve is stable, the saturation ends and the consolidation test starts;

[0023] Step S3, consolidation test;

[0024] S31, conventional staged loading consolidation test:

[0025] Use the axial pressure application device to provide a constant load, apply vertical pressure in stages, close the base outlet valve and the base inlet valve, and the specimen drains only from the top of the channel drain valve. The one-way drainage pressure application time is 24 h. After each stage of pressure application, use the variable head device to saturate the specimen, and the computer records the vertical displacement;

[0026] S32, consolidation-permeability combined measurement test:

[0027] Using an axial pressure device for staged loading, the specimen drains unidirectionally through the channel drainage valve. The computer records the vertical displacement changes. After the vertical deformation of the specimen is stable or after 24 hours, the permeability test is started. The permeability test is the variable-head method, and the height of the variable-head tube does not exceed 2 m. Observe and record the change in the water head of the variable-head tube and record the time; perform staged loading in sequence. After each stage of load is applied, conduct the variable-head permeability test to complete the test;

[0028] S33, constant strain rate consolidation test:

[0029] Connect the pore water pressure sensor to the pore water pressure sensor connection valve and open the pore water pressure sensor connection valve. The computer controls the axial pressure device and selects the strain control mode to apply a constant strain rate load to the specimen. During the test, the pore water pressure generated at the bottom of the specimen is 3%-20% of the applied vertical stress; when the pore water pressure is too large, adjust the strain loading rate; when continuously loading until the expected stress or strain is reached, stop the constant strain rate loading, use the stress loading mode, keep the axial load unchanged and let the pore water pressure dissipate; when the pore water pressure dissipation ends, unload the specimen under the condition of the strain rate equal to that during loading. Close the pore water pressure measuring device during unloading, record the rebound deformation and the axial load. After unloading is completed, close the axial pressure device and disassemble the specimen to complete the test;

[0030] S34, constant stress rate consolidation test:

[0031] Connect the pore water pressure sensor to the pore water pressure sensor connection valve and open the pore water pressure sensor connection valve. Adopt the stress control mode of the axial pressure device to load the specimen at a constant stress growth rate, record the vertical strain, stress and the change in the pore water pressure at the bottom of the specimen during the test. During the test, the pore water pressure generated at the bottom of the specimen is 3%-20% of the applied vertical stress. When the pore water pressure is too large, adjust the stress loading rate; when the vertical stress is loaded to the predetermined pressure, keep the vertical pressure unchanged and continue to drain and consolidate until the pore water pressure dissipates; during unloading, unload the specimen under the condition of the stress rate equal to that during loading, record the rebound deformation. After unloading is completed, close the axial pressure device and disassemble the specimen to complete the test.

[0032] Advantages of the present invention:

[0033] (1) The present invention solves the problems existing in the traditional one-dimensional linear consolidation theory, where the consolidation coefficient is measured first and then the permeability coefficient is deduced inversely. It can combine the consolidation and seepage tests. The test device is simple and the specimen method is easy to implement.

[0034] (2) The present invention can conduct three types of one-dimensional saturated consolidation tests. Among them, the continuous loading consolidation test takes a short time, has many test data points, the effective stress distribution is uniform, the data is automatically collected, and the test results are accurate and reliable. Brief Description of the Drawings

[0035] Figure 1 is a schematic structural diagram of the present invention;

[0036] Figure 2 is a schematic structural diagram of the specimen base of the present invention.

[0037] Among them, in the figure:

[0038] 1 is a test bench, 2 is an upper cross beam, 3 is a moving cross beam, 4 is a column, 5 is a loading rod, 6 is a servo motor, 7 is a servo controller, 8 is an optical encoder, 9 is a displacement sensor, 10 is a force sensor, 11 is a single-chip microcontroller, 12 is a filter paper, 13 is a computer, 14 is a specimen sleeve, 15 is a specimen base, 16 is an upper cover plate, 17 is a permeable stone, 18 is a channel outlet valve, 19 is a water guide pipe, 20 is a variable head pipe, 21 is a water supply bucket, 22 is a pore water pressure sensor, 23 is a data acquisition system, 24 is a base inlet valve, 25 is a base outlet valve, 26 is a pore water pressure sensor connection valve. Detailed Embodiments

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] Referring to Figure 1-2 , the present invention provides a multifunctional seepage consolidation test device, including: a support frame body, an axial loading device, a consolidation seepage device, a variable head device, a control system, and a pore water pressure measuring device;

[0041] The consolidation seepage device is placed on the support frame body and a specimen is placed inside;

[0042] The variable head device is internally connected to the consolidation seepage device and is used to introduce distilled water into the consolidation seepage device to saturate the specimen with water head;

[0043] The axial loading device is installed on the support frame body and is used to apply a vertical load to the specimen;

[0044] The pore water pressure measuring device records the change of the excess pore water pressure at the bottom of the specimen during consolidation;

[0045] The control system is used to control the axial compression device, record the changes in the vertical stress and vertical displacement during the consolidation of the specimen, and is communicatively connected to the pore water pressure measuring device.

[0046] The support frame body includes a test bench 1, an upper cross beam 2, a moving cross beam 3, columns 4 and a force applying rod 5; two columns 4 are connected to the top end of the test bench 1, the upper cross beam 2 is connected to the top ends of the two columns 4, the moving cross beam 3 is slidably arranged between the two columns 4 and is located below the upper cross beam 2.

[0047] The consolidation and seepage device includes a specimen base 15, a specimen sleeve 14, an upper cover plate 16, a permeable stone 17, filter paper 12 and a sealing ring; the specimen base 15 is placed on the top of the test bench 1, the specimen sleeve 14 is placed on the specimen base 15, the specimen is placed in the specimen sleeve 14, permeable stones 17 are arranged below and above the specimen, filter paper 12 is arranged between the permeable stone 17 and the specimen, the upper cover plate 16 is placed above the permeable stone 17, and the sealing ring is placed at the edge position between the specimen and the permeable stone 17; a drainage channel is arranged inside the upper cover plate 16, and a channel water outlet valve 18 is arranged on the drainage channel; a base water inlet valve 24, a base water outlet valve 25 and a pore water pressure sensor connection valve 26 are arranged on the specimen base 15. The specimen base 15 is provided with a sealing ring, and sealing rings are placed at the edges of the upper permeable stone 17 to prevent lateral water leakage during the test. Vaseline is applied to the inner wall of the specimen sleeve 14 to reduce the friction generated during the compression deformation of the specimen. An undisturbed specimen is cut by a ring cutter or a remolded specimen is prepared. The ring cutter is a standard ring cutter with an inner diameter of 61.8 cm and a height of 40 cm.

[0048] The variable head device includes a variable head tube 20, a water supply bucket 21, a water guide pipe 19, a pipe water inlet valve and a pipe water outlet valve; both the pipe water inlet valve and the pipe water outlet valve are arranged at the bottom end of the variable head tube 20, the pipe water outlet valve is connected to the base water inlet valve 24 through the water guide pipe 19, and the pipe water inlet valve is connected to the water supply bucket 21 through the water guide pipe 19. Among them, the inner diameter of the variable head tube 20 is uniformly ired to supply water to the consolidation and seepage device through the water head difference.

[0049] The axial compression device includes a servo motor 6, a servo controller 7, an optoelectronic encoder 8, a displacement sensor 9, and a force sensor 10; the optoelectronic encoder 8 is installed on the servo motor 6, and the output end of the servo motor 6 drives the moving crossbeam 3 to move up and down through a driving member; the displacement sensor 9 is arranged inside the moving crossbeam 3, the top end of the force sensor 10 is installed on the moving crossbeam 3, and the bottom end is connected to a loading rod 5 to provide a vertical pressure for the consolidated specimen; the servo motor 6 is electrically connected to the servo controller 7. After the signal of the optoelectronic encoder 8 is received and calculated by the single-chip microcontroller 11, it is fed back to the servo controller 7, and then the servo motor 6 is controlled. The servo controller 7 selects a closed-loop servo system, which has better following accuracy and positioning accuracy. The force sensor 10 measures the change of the vertical stress during the consolidation of the specimen, and the displacement sensor 9 measures the change of the vertical displacement. The magnitude of the vertical load is measured by the S-type force sensor 10, and its measurement accuracy, stability, and output symmetry are better.

[0050] Further optimizing the technical solution, a convex cylindrical platform is provided in the middle of the upper cover plate 16, and the area of the cylindrical platform is the same as the bottom area of the loading rod 5.

[0051] The pore water pressure measuring device includes a pore water pressure sensor 22 and a data acquisition system 23. The pore water pressure sensor 22 is connected to a pore water pressure sensor connection valve 26, and the pore water pressure sensor 22 is communicatively connected to the data acquisition system 23.

[0052] The control system includes a single-chip microcontroller 11 and a computer 13. The single-chip microcontroller 11 is communicatively connected to the servo controller 7, the optoelectronic encoder 8, the displacement sensor 9, the force sensor 10, and the computer 13 respectively. The computer 13 is communicatively connected to the data acquisition system 23, and the computer 13 can control the loading stage program. The pore water pressure sensor 22 records the change of the excess pore water pressure at the bottom of the specimen during consolidation, and is displayed in real time through the data acquisition system 23 and the computer 13.

[0053] Further optimizing the technical solution, the single-chip microcontroller 11 has two control modes of stress and strain, and can perform automatic control of constant load, constant strain rate, and constant stress rate loading.

[0054] The present invention also provides a multifunctional seepage consolidation test method, including the following steps:

[0055] Step S1, specimen preparation: using a ring cutter to cut an undisturbed specimen or preparing a remolded specimen by the compaction method;

[0056] Step S2, preparation and installation of the specimen before consolidation;

[0057] Connect the specimen base to the water supply bucket, open the base inlet valve and the base outlet valve, remove the air bubbles in the specimen base, place the specimen sleeve, and successively place a permeable stone, a filter paper, and a rubber ring on the specimen base. Press the core cutter specimen into the specimen sleeve, and successively place a filter paper, a permeable stone, and a rubber ring on the upper part of the specimen. Place the upper cover plate on the permeable stone; make the upper cover plate contact the pressure rod, start the axial pressure application device, control the computer pressure application program, apply a vertical load of 2 kPa to tightly connect the consolidation and seepage device to prevent water leakage and air leakage; open the pipe inlet valve to fill water into the variable-head pipe, close the base outlet valve, open the base inlet valve, open the channel outlet valve, and the specimen starts water head saturation. When the water flowing out of the channel outlet valve is stable, the saturation ends and the consolidation test starts;

[0058] Step S3, consolidation test;

[0059] S31, conventional staged loading consolidation test:

[0060] Use the axial pressure application device to provide a constant load, apply vertical pressure in stages, close the base outlet valve and the base inlet valve. The specimen drains only from the top of the channel drain valve, and the one-way drainage pressure application time is 24 h. After each stage of pressure application, use the variable-head device to saturate the specimen, and the computer records the vertical displacement;

[0061] S32, consolidation-permeability combined determination test:

[0062] Use the axial pressure application device to apply load in stages. The specimen drains one-way from the channel drain valve, and the computer records the change in vertical displacement. After the vertical deformation of the specimen is stable or after 24 h, start the permeability test. The permeability test is the variable-head method, and the height of the variable-head pipe does not exceed 2 m. The experimenter observes and records the change in the water head of the variable-head pipe and records the time; Since the specimen is saturated during the permeability test, it is not necessary to saturate the specimen during the consolidation test of the next stage of loading. Apply load in stages successively, and perform the variable-head permeability test after the loading of each stage of load is completed to complete the test;

[0063] S33, constant strain rate consolidation test:

[0064] Connect the pore water pressure sensor to the pore water pressure sensor connection valve, and open the pore water pressure sensor connection valve. The computer controls the axial loading device, selects the strain control mode, and loads the specimen at a constant strain rate. During the test, the pore water pressure generated at the bottom of the specimen is 3%-20% of the applied vertical stress; when the pore water pressure is too high, adjust the strain loading rate; when continuously loading until the expected stress or strain is reached, stop the constant strain rate loading, use the stress loading mode, keep the axial load unchanged and let the pore water pressure dissipate; when the pore water pressure dissipation ends, unload the specimen under the condition of the strain rate equal to that during loading. Close the pore water pressure measuring device during unloading, record the rebound deformation and axial load. After the unloading is completed, close the axial loading device, disassemble the specimen, and complete the test;

[0065] S34, Constant stress rate consolidation test:

[0066] Connect the pore water pressure sensor to the pore water pressure sensor connection valve, and open the pore water pressure sensor connection valve. Adopt the stress control mode of the axial loading device and load the specimen at a constant stress growth rate. Record the vertical strain, stress and the change of pore water pressure at the bottom of the specimen during the test. During the test, the pore water pressure generated at the bottom of the specimen is 3%-20% of the applied vertical stress. When the pore water pressure is too high, adjust the stress loading rate; when the vertical stress is loaded to the predetermined pressure, keep the vertical pressure unchanged and continue the drainage consolidation until the pore water pressure dissipates; during unloading, unload the specimen under the condition of the stress rate equal to that during loading, record the rebound deformation. After the unloading is completed, close the axial loading device, disassemble the specimen, and complete the test.

[0067] The present invention solves the problems existing in the traditional one-dimensional linear consolidation theory, that is, first measuring the consolidation coefficient and then inversely calculating the permeability coefficient. It can be combined with the consolidation seepage test. The test device is simple and the specimen method is easy to implement. The present invention can conduct three types of one-dimensional saturated consolidation tests. Among them, the continuous loading consolidation test takes a short time, has many test data points, the effective stress distribution is uniform, the data is automatically collected, and the test results are accurate and reliable.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multifunctional seepage consolidation test device, characterized in that, Comprising: A support frame, an axial compression device, a consolidation seepage device, a variable head device, a control system, and a pore water pressure measuring device; The consolidation seepage device is placed on the support frame and a specimen is placed inside; The variable head device is connected to the inside of the consolidation seepage device and is used to introduce distilled water into the consolidation seepage device to saturate the specimen with water head; The axial compression device is installed on the support frame and is used to apply a vertical load to the specimen; The pore water pressure measuring device records the change of the excess pore water pressure at the bottom of the specimen during consolidation; The control system is used to control the axial compression device, record the change of the vertical stress and the change of the vertical displacement of the specimen during consolidation, and is communicatively connected to the pore water pressure measuring device.

2. The multifunctional seepage consolidation test device according to claim 1, characterized in that, The support frame includes a test bench, an upper cross beam, a moving cross beam, columns, and a loading rod; two columns are connected to the top of the test bench, the upper cross beam is connected to the tops of the two columns, the moving cross beam is slidably arranged between the two columns and is located below the upper cross beam.

3. The multifunctional seepage consolidation test device according to claim 2, wherein, The consolidation seepage device includes a specimen base, a specimen sleeve, an upper cover plate, a permeable stone, filter paper, and a sealing ring; the specimen base is placed on the top of the test bench, the specimen sleeve is placed on the specimen base, the specimen is placed inside the specimen sleeve, permeable stones are arranged below and above the specimen, filter paper is arranged between the permeable stone and the specimen, the upper cover plate is placed above the permeable stone, and the sealing ring is placed at the edge position between the specimen and the permeable stone; a drainage channel is arranged inside the upper cover plate, and a channel outlet valve is arranged on the drainage channel; a base inlet valve, a base outlet valve, and a pore water pressure sensor connection valve are arranged on the specimen base.

4. The multifunctional seepage consolidation test equipment according to claim 3, wherein The variable head device includes a variable head tube, a water supply bucket, a water guide pipe, a tube inlet valve, and a tube outlet valve; both the tube inlet valve and the tube outlet valve are arranged at the bottom end of the variable head tube, the tube outlet valve is connected to the base inlet valve through the water guide pipe, and the tube inlet valve is connected to the water supply bucket through the water guide pipe.

5. A multifunctional seepage consolidation test device according to claim 4, characterized in that, The axial compression device includes a servo motor, a servo controller, an optical encoder, a displacement sensor, and a force sensor; the optical encoder is installed on the servo motor, and the output end of the servo motor drives the moving cross beam to move up and down through a driving member; the displacement sensor is arranged inside the moving cross beam, the top end of the force sensor is installed on the moving cross beam, and the bottom end is connected to a loading rod; the servo motor is electrically connected to the servo controller.

6. The multifunctional seepage consolidation test device according to claim 5, wherein, The pore water pressure measuring device includes a pore water pressure sensor and a data acquisition system. The pore water pressure sensor is connected to the pore water pressure sensor connection valve, and the pore water pressure sensor is communicatively connected to the data acquisition system.

7. A multifunctional seepage consolidation test device according to claim 6, characterized in that, The control system includes a single-chip microcontroller and a computer. The single-chip microcontroller is communicatively connected to the servo controller, the optical encoder, the displacement sensor, the force sensor, and the computer respectively, and the computer is communicatively connected to the data acquisition system.

8. A multifunctional seepage consolidation test device according to claim 7, characterized in that, The single-chip microcontroller has two control modes of stress and strain control, and can perform automatic control of constant load, constant strain rate, and constant stress rate loading.

9. A multifunctional seepage consolidation test method, characterized in that, It includes the following steps: Step S1, specimen preparation: Use a ring cutter to cut undisturbed specimens or use a compaction method to prepare remolded specimens; Step S2, preparation and installation of the specimen before consolidation; Connect the specimen base to the water supply bucket, open the inlet valve and outlet valve of the base, remove the air bubbles in the specimen base, place the specimen sleeve, place a permeable stone, filter paper and rubber ring on the specimen base in sequence, press the ring cutter specimen into the specimen sleeve, and place filter paper, permeable stone and rubber ring on the upper part of the specimen in sequence, and place the upper cover plate on the permeable stone; Contact the upper cover plate with the loading rod, start the axial loading device, control the computer loading program, apply a vertical load of 2 kPa to make the consolidation seepage device tightly connected to prevent water leakage and air leakage; Open the pipe inlet valve to inject water into the variable head pipe, close the outlet valve of the base, open the inlet valve of the base, open the outlet valve of the channel, and the specimen starts to be saturated with water head. When the water at the outlet valve of the channel flows out stably, the saturation ends and the consolidation test starts; Step S3, consolidation test; S31, conventional staged loading consolidation test: Use the axial loading device to provide a constant load, load the vertical pressure in stages, close the outlet valve and inlet valve of the base, and the specimen drains only from the top of the channel drain valve. The one-way drainage pressurization time is 24 h. After each stage of pressurization, use the variable head device to saturate the specimen, and the computer records the vertical displacement; S32, consolidation-permeability combined determination test: Use the axial loading device to load in stages, and the specimen drains unidirectionally from the channel drain valve. The computer records the change in vertical displacement. After the vertical deformation of the specimen is stable or after 24 h, start the permeability test. The permeability test is the variable head method, and the height of the variable head pipe does not exceed 2 m. Observe and record the change in the water head of the variable head pipe and record the time; Load in stages in sequence, and conduct a variable head permeability test after the end of each stage of load, and complete the test; S33, constant strain rate consolidation test: Connect the pore water pressure sensor to the pore water pressure sensor connection valve, and open the pore water pressure sensor connection valve. The computer controls the axial loading device, selects the strain control mode, and loads the specimen at a constant strain rate. During the test, the pore water pressure generated at the bottom of the specimen is 3%-20% of the applied vertical stress; When the pore water pressure is too high, adjust the strain loading rate; When continuously loading to the expected stress or strain, stop the constant strain rate loading, use the stress loading mode, keep the axial load unchanged to dissipate the pore water pressure; When the dissipation of the pore water pressure ends, unload the specimen under the condition of the strain rate equal to that during loading. Close the pore water pressure measuring device during unloading, record the rebound deformation and axial load. After the unloading ends, close the axial loading device, disassemble the specimen, and complete the test; S34, constant stress rate consolidation test: Connect the pore water pressure sensor to the pore water pressure sensor connection valve, and open the pore water pressure sensor connection valve. Adopt the stress control mode of the axial compression device to load the specimen at a constant stress growth rate, record the vertical strain, stress and the change of pore water pressure at the bottom of the specimen during the test. During the test, the pore water pressure generated at the bottom of the specimen is 3%-20% of the applied vertical stress. When the pore water pressure is too large, adjust the stress loading rate; wait until the vertical stress is loaded to the predetermined pressure, keep the vertical pressure unchanged and continue the drainage consolidation until the pore water pressure dissipates; During unloading, the specimen is unloaded under the condition of the stress rate equal to that during loading, record the rebound deformation. After the unloading is completed, turn off the axial compression device and disassemble the specimen to complete the test.

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