Mechanical expansion type lateral pressure apparatus and test method

Abstract

This invention discloses a mechanically extended pressure meter and its testing method, belonging to the field of in-situ testing technology in geotechnical engineering. The pressure meter mainly includes a water storage tank, a telescopic rod, a sleeve rod, a spring, an extension plate, a linkage rod, a water level scale marking system, and a water level height reading system. Water pressure is applied to the water storage tank through a water pipe, driving the telescopic rod and sleeve rod to generate relative movement, which is then converted into horizontal mechanical expansion of the extension plate via the linkage rod mechanism, thereby compressing the surrounding soil. During the test, pressure and volume change data are simultaneously and automatically recorded using a water pressure sensor and a vision-based water level height reading system. This invention replaces the traditional flexible membrane with a rigid mechanical expansion, solving the problems of nonlinear deformation, easy damage, and limited testing range of flexible membranes, significantly improving the accuracy, reliability, and adaptability of testing in complex strata such as gravelly soil and soft soil.

Description

Technical Field

[0001] This invention belongs to the field of in-situ testing technology in geotechnical engineering, specifically relating to a mechanical extended pressure meter and testing method, which is particularly suitable for geological scenarios such as gravelly soil and soft soil. Background Technology

[0002] In-situ testing in geotechnical engineering is an effective means of accurately obtaining the characteristic parameters of geotechnical mechanics. Pressuremeter testing is a test technique used to obtain the horizontal lateral pressure state of soil. Its basic principle is to apply horizontal pressure to the pressuremeter probe in the test soil layer, and indirectly obtain the relationship between soil pressure and volume change based on the relationship between horizontal pressure and pressuremeter probe deformation, and calculate geotechnical mechanics parameters such as soil pressuremeter modulus.

[0003] Existing pressure gauges primarily consist of a flexible diaphragm probe. Applying water pressure to the diaphragm causes it to expand horizontally, compressing the soil. Pressure gauge probes typically consist of single, double, or triple chambers. Existing pressure gauges have the following drawbacks:

[0004] Because horizontal soil is expanded using a flexible membrane, but the flexible membrane is a non-linear deformation material, there is a mismatch between the expanded and pressurized states during the test, resulting in significant hysteresis and data distortion. Furthermore, flexible membranes are typically made of materials such as rubber, which are frequently damaged by gravelly soils during testing, leading to test failures. In addition, due to the limited lateral expansion volume of the flexible membrane, existing pressuremeters have a small testing range and are only suitable for shallow, hard soil sites. Their testing capabilities are limited when facing ultra-deep high-pressure overburden layers, especially in gravelly or soft soil scenarios.

[0005] In addition, the existing pressure gauge has a small water tank range and unclear water level scale, requiring intermittent manual reading and recording during the test, and human error affects the accuracy of the test results.

[0006] Through years of practical experience, the inventors have concluded that the stress-strain relationship of flexible membranes is complex, exhibiting material hysteresis and creep. This leads to a lack of synchronization and nonlinearity between the applied pressure (water pressure), the actual pressure on the soil (contact stress), and the change in probe volume, resulting in inherent data distortion and lag. Traditional flexible membrane manometers are considered indirect measurement systems. They input water pressure, couple with the soil through the complex and volatile "black box" of the flexible membrane, and output a distorted deformation signal. Moreover, the flexible membrane is easily punctured or scratched in gravelly soils and gravelly soil layers, leading to test failures and short probe lifespan. In establishing digital twin experiments, the flexible membrane expands into a "drum shape," resulting in uneven contact pressure with the soil—higher in the middle and lower at both ends—which restricts the accurate inversion of the original lateral pressure state of the soil. Based on this, the applicant conceived and proposed a rigidly connected manometer probe device. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a mechanically extended pressure meter and testing method. This device is applicable to strata with unfavorable particle conditions such as gravelly soil, as well as strata with large horizontal deformation such as soft soil. It can also acquire horizontal extension displacement and water pressure in real time, which greatly improves the accuracy of test data.

[0008] The technical problem to be solved by the present invention is achieved through the following technical solution:

[0009] A mechanically extended pressure gauge includes:

[0010] The water storage tank is connected to the ground water pressure loading system via water pipes to receive and transmit water pressure; a water pressure sensor is embedded in the inner wall of the upper cover plate of the water storage tank to monitor the water pressure inside the tank in real time.

[0011] The telescopic rod and the sleeve rod are provided. The upper end of the telescopic rod is connected to the lower cover plate of the water storage tank, and the lower part of the telescopic rod is sleeved in the sleeve rod. A spring is provided between the telescopic rod and the sleeve rod. The water pressure change in the water storage tank drives the lower cover plate to move the telescopic rod relative to the sleeve rod, and compresses or releases the spring.

[0012] An extension plate is symmetrically arranged on both sides of the pressure gauge;

[0013] The linkage rod has its two ends hinged to the inner side of the extension plate and the connection point between the telescopic rod and the sleeve rod, respectively; the relative movement between the telescopic rod and the sleeve rod is converted into the horizontal expansion or contraction movement of the extension plate through the linkage rod.

[0014] A water level marking system, connected to the water storage tank, is used to display changes in water level caused by changes in the volume of the water storage tank.

[0015] A water level reading system is used to identify and record the water level information of the water level scale marking system in real time.

[0016] Furthermore, the water level marking system includes a scale that can be accurately identified by a computer and a built-in water tank, the volume of which matches the volume change of the water storage tank.

[0017] Furthermore, the water level reading system includes a camera and PC-based visual recognition software; the camera is aimed at the scale of the water level marking system to obtain image information, and the PC-based visual recognition software is used to process the image information and obtain real-time water level data.

[0018] A test method for a mechanically extended pressure meter, using the mechanically extended pressure meter as described above, includes the following steps:

[0019] S11. Calibration steps: Before the test, the water storage tank and water pressure sensor of the pressure gauge are calibrated to obtain the correspondence between the change in the volume of the water storage tank and the change in the water level scale of the water level scale marking system; and the visual recognition mapping relationship of the water level height reading system is established.

[0020] S12. Installation and initial recording steps: Insert the probe of the pressure meter into the soil layer to be tested, and record the initial pressure reading of the water pressure sensor and the initial water level scale value of the water level scale marking system at this time.

[0021] S13, Staged loading and synchronous data acquisition steps: The first stage of pressure loading is carried out through the ground water pressure loading system connected by the water pipe; at the same time as loading, the water pressure sensor collects the water pressure data in the chamber in real time, and the corresponding water level data is collected in real time through the water level reading system.

[0022] S14. Continuous loading judgment step: After the data under the current loading level stabilizes, the next level of pressure loading is carried out, and the data acquisition process of step S13 is repeated until the horizontal displacement of the expansion plate shows a non-linear increasing trend.

[0023] S15. Unloading and Recycling Steps: After the test, the water pressure of the ground water pressure loading system is removed; the water storage tank recovers its volume under the rebound of the spring, causing the expansion plate to shrink to its initial state, and then the pressure gauge probe is removed from the soil.

[0024] Furthermore, in step S11, based on the volume change of the water storage tank obtained from calibration and combined with the geometric relationship of the linkage rod, the theoretical horizontal displacement of the extension plate is calculated.

[0025] Furthermore, in steps S13 and S14, the collected water pressure data and water level data are recorded simultaneously to analyze the correlation between the water pressure data P inside the tank, the vertical displacement ΔL of the water storage tank, and the horizontal displacement ΔS of the expansion plate.

[0026] A method for calculating test results of a mechanically extended pressure meter, based on data obtained by the test method described above, includes the following steps:

[0027] S21. Based on the collected water pressure data P inside the storage tank, calculate the vertical sliding displacement ΔL of the storage tank caused by the lower cover plate using the formula: ;

[0028] In the formula, This is the vertical sliding displacement. The inner diameter of the sealed cylindrical chamber. The spring constant is... The moving plate slides downwards. For the water pressure data inside the tank under the condition of vertical displacement ΔL generated by the expansion plate, The data represents the water pressure inside the chamber in the initial state of the expansion plate.

[0029] S22. Based on the calculated vertical sliding displacement ΔL, calculate the horizontal extension displacement ΔS of the extension plate using the formula: In the formula, For horizontal extension displacement, For the length of a single extension bar, This is the distance between the rotating shafts when the shafts are in the closed state.

[0030] S23. Substitute the formula into the formula to establish a direct mathematical relationship model between the water pressure data P in the chamber and the horizontal displacement ΔS of the expansion plate.

[0031] ;

[0032] The pressure modulus can be directly calculated from the horizontal displacement ΔS of the extended plate. :

[0033] ;

[0034] In the formula, The calibration coefficients, which are related to the device geometry and the Poisson's ratio of the soil, were determined through calibration tests. This represents the increment of the horizontal displacement of the expansion plate when the water pressure inside the tank reaches its maximum value. This refers to the pressure data corresponding to the maximum pressure value of the water inside the tank.

[0035] Furthermore, it also includes:

[0036] S24. Before the test, the relationship between the calibrated horizontal displacement ΔS of the expansion plate and the water pressure data P in the chamber was used to obtain the calibration coefficient K.

[0037] S25. During the experiment, plot the curve showing the relationship between the horizontal displacement ΔS of the expansion plate and the water pressure P inside the chamber, and take the inflection point of the straight line segment as the baseline. and Based on this, the side pressure modulus is calculated according to formula (4). .

[0038] The mechanically extended pressure gauge and testing method proposed in this invention have the following advancements and advantages over previous technologies:

[0039] 1. When the rigid expansion plate compresses the lateral soil, the force applied at both ends is more uniform, resulting in more accurate capture of the horizontal lateral pressure. A pressure-side probe actuated by a connecting rod provides real-time feedback on horizontal pressure and soil deformation, ensuring high data accuracy. (Horizontal displacement of the rigid expansion plate) Vertical displacement of the water storage tank Precise and calculable geometric functional relationships are formed through linkage mechanisms. The applied water pressure P is linearly related to the spring force. Therefore, the horizontal displacement of the soil... A deterministic and calibrable mathematical model was established between the applied pressure P and the data feedback. This makes the data feedback real-time, linear, and computable, fundamentally eliminating errors caused by the nonlinearity and hysteresis of the flexible membrane.

[0040] 2. By designing springs with different stiffness coefficients and connecting rods of different lengths, the force-displacement characteristics of the device can be flexibly adjusted, so that it can adapt to the large deformation requirements of soft soil and cope with the high pressure environment of hard soil or deep soil, effectively expanding the pressure and deformation range of the test.

[0041] 3. The rigid extension plate has extremely high impact and wear resistance, and can completely resist the cutting of gravel, so that the pressure meter test can be carried out safely and reliably in coarse-grained strata such as gravel layers and rockfill bodies that were previously impossible to conduct, thereby improving the service life of the pressure meter probe.

[0042] 4. Through machine vision recognition system and high-precision water level scale marking system, the test process data is recorded in real time, and the data integrity is significantly improved. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of a mechanically extended pressure meter according to the present invention;

[0044] Figure 2 This is a cross-sectional view of a mechanically extended pressure gauge according to the present invention;

[0045] Figure 3 This is a diagram showing the changes of the invention during the testing process;

[0046] Figure 4 This is a software interface diagram of the mechanical extended pressure gauge of the present invention connected to the digital twin system and the water level scale visual recognition system;

[0047] Figure 5 The following is a graph showing the data results of the indoor calibration test of the mechanical extended pressure meter of the present invention: (a) is the instrument parameter table, (b) is the calibration curve of three soil pressures and horizontal displacements, and (c) is the machine vision recognition accuracy calibration.

[0048] Figure 6This is a flowchart of the automated data acquisition process of the mechanical extended pressure gauge of the present invention through a visual recognition system.

[0049] In the diagram: 1—Telescopic rod; 2—Sleeve rod; 3—Spring; 4—Water storage tank; 5—Extension plate; 6—Linkage rod; 7—Water pressure sensor; 8—Water inlet; 9—Water pipe; 10—Water level scale marking system; 11—Water level reading system. Detailed Implementation

[0050] The technical solutions of the present invention will now be clearly and completely described with reference to the accompanying drawings.

[0051] See Figures 1-4 This invention provides a mechanically extended pressure gauge, including a telescopic rod 1, a sleeve rod 2, a spring 3, a water storage tank 4, an extension plate 5, a linkage rod 6, a water pressure sensor 7, a water inlet, a water pipe 9, a water level scale marking system 10, and a water level height reading system 11.

[0052] The telescopic rod 1 is connected to the upper sleeve rod 2 and the water storage tank 3, and a spring 3 is embedded between the telescopic rod 1 and the sleeve rod 2.

[0053] The extension plate 5 is connected to the telescopic rod 1 and the sleeve rod 2 via the linkage rod 6.

[0054] The water storage tank 4 obtains different water pressures through the water pipe 9, which causes the spring 3 inside the sleeve rod 2 to compress and push the telescopic rod 1 to move. The relative movement between the sleeve rod 2 and the telescopic rod 1 causes the linkage rod 6 to move, thereby realizing the horizontal expansion or contraction of the extension plate 5.

[0055] The water storage tank 4 is connected to the ground water level scale marking system 10. A water pressure sensor 7 is embedded in the inner wall of the upper cover plate of the sealed water storage tank 4. When the lower cover plate of the water storage tank 4 is pressed down, the volume inside the tank changes. The water pressure sensor 7 records the real-time water pressure inside the tank, and the ground water level height reading system 11 records the water level fluctuation process in real time.

[0056] Figure 4 The water level scale marking system 10 described herein is a modification of the traditional Mena side pressure control box, including a scale that can be accurately identified by a computer and a built-in water tank corresponding to the volume of the water storage tank.

[0057] The water level reading system 11 includes PC-based visual recognition software 111 and a camera 112. The camera 112 acquires image information of the water level scale marking system 10 and transmits it to the PC-based visual recognition software 111 to obtain the water level height throughout the experiment.

[0058] This invention also provides a testing method for a mechanically extended pressure meter, using the mechanically extended pressure meter as described above, comprising the following steps:

[0059] S11. Calibration steps: Before the test, the water storage tank 4 and water pressure sensor 7 of the pressure gauge are calibrated to obtain the correspondence between the volume change of the water storage tank 4 and the water level scale change of the water level scale marking system 10; and the visual recognition mapping relationship of the water level height reading system 11 is established; wherein, based on the volume change of the water storage tank 4 obtained by calibration, combined with the geometric relationship of the linkage rod 6, the theoretical horizontal displacement of the extension plate 5 is calculated.

[0060] S12. Installation and initial recording steps: Insert the probe of the pressure meter into the soil layer to be tested, and record the initial pressure reading of the water pressure sensor 7 and the initial water level scale value of the water level scale marking system 10 at this time.

[0061] S13, Staged loading and data synchronous acquisition steps: The first stage of pressure loading is carried out through the ground water pressure loading system connected by the water pipe 9; at the same time as loading, the water pressure sensor 7 collects the water pressure data in the chamber in real time, and the water level reading system 11 collects the corresponding water level data in real time.

[0062] S14. Continuous loading judgment step: After the data under the current loading level stabilizes, the next level of pressure loading is carried out, and the data acquisition process of step S13 is repeated until the horizontal displacement of the expansion plate 5 shows a non-linear increasing trend.

[0063] S15. Unloading and recovery steps: After the test, the water pressure of the ground water pressure loading system is removed; the volume of the water storage tank 4 is restored under the rebound action of the spring 3, which drives the expansion plate 5 to retract to the initial state, and then the pressure meter probe is taken out of the soil.

[0064] In steps S13 and S14, the collected water pressure data and water level data are recorded synchronously to analyze the correlation between the water pressure data P inside the tank, the vertical displacement ΔL of the water storage tank, and the horizontal displacement ΔS of the expansion plate.

[0065] This invention also provides a method for calculating the test results of a mechanically extended pressure gauge, which, based on the data obtained by the above-described test method, includes the following steps:

[0066] S21. Based on the collected water pressure data P inside the storage tank, calculate the vertical sliding displacement ΔL of the storage tank caused by the lower cover plate using formula (1): (1);

[0067] In the formula, This is the vertical sliding displacement. The inner diameter of the sealed cylindrical chamber. The spring constant is... The moving plate slides downwards. For the water pressure data inside the tank under the condition of vertical displacement ΔL generated by the expansion plate, The data represents the water pressure inside the chamber in the initial state of the expansion plate.

[0068] S22. Based on the calculated vertical sliding displacement ΔL, calculate the horizontal extension displacement ΔS of the extension plate (5) using formula (2): (2);

[0069] In the formula, For horizontal extension displacement, For the length of a single extension bar, This is the distance between the rotating shafts when the shafts are in the closed state.

[0070] S23. Substitute formula (1) into formula (2) to establish a direct mathematical relationship model between the water pressure data P in the chamber and the horizontal displacement ΔS of the expansion plate;

[0071] (3);

[0072] The traditional method for calculating the pressure modulus based on the theory of cylindrical hole expansion is as follows:

[0073]

[0074] This invention utilizes the advantages of a rigid force transmission mechanism, its and The straight-line segment of the relationship curve has a wide range, so it is proposed to calculate it directly from the horizontal displacement ΔS of the extended plate. Simplified formula:

[0075] (4)

[0076] In the formula, The calibration coefficients, which are related to the geometry of the device and the Poisson's ratio of the soil, can be determined through calibration tests; ; The pressure data corresponding to the maximum pressure value of the water inside the tank.

[0077] Embodiments of the present invention may further include the following steps:

[0078] S24. Before the test, the relationship between the horizontal displacement ΔS of the expansion plate and the applied water pressure P is calibrated to obtain the calibration coefficient K.

[0079] S25. During the experiment, plot the curve showing the relationship between the horizontal displacement ΔS of the expansion plate and the water pressure P inside the chamber, and take the inflection point of the straight line segment as the baseline. and Based on this, the side pressure modulus is calculated according to formula (4). .

[0080] Figure 5 These are the results of indoor calibration tests. They verified the core performance indicators of the mechanically extended pressure meter and demonstrated the technical advantages of this invention in solving the problems of traditional flexible membrane pressure meters. The mechanically extended pressure meter has a large linear range and is more applicable to clay, sand, and gravel layers.

[0081] Figure 6 The flowchart shows the automated data acquisition process using a visual recognition system. After the computer control program is started, the high-definition camera is turned on and aimed at the water level gauge, air pressure gauge, and water pressure gauge. During the experiment, the machine vision recognition system monitors the water level changes in real time and records the data. The water level data is imported into a 3D digital twin model, and the expansion status of the mechanical expander pressure meter is displayed in real time according to the established mapping relationship, including information such as the vertical slide rod displacement and the horizontal expansion plate displacement.

[0082] This invention has the following features and effects:

[0083] 1. High testing accuracy, eliminating hysteresis error: Based on a mechanical transmission system composed of telescopic rods, sleeve rods, springs, and linkage rods, water pressure (P) is linearly converted into the vertical displacement (ΔL) of the water storage tank through the springs, and then converted into the horizontal displacement (ΔS) of the expansion plate through the precise geometric relationship of the linkage rods, establishing a definite and calibrable mathematical model between "pressure and displacement". This overcomes the data distortion problem caused by the nonlinear deformation and hysteresis effect of traditional flexible membranes in principle, realizing real-time and linear feedback of soil stress and deformation.

[0084] 2. Adjustable range and strong site adaptability: By replacing springs 3 with different stiffness coefficients and linkage rods 6 with different lengths, the force-displacement characteristics of the entire device can be flexibly adjusted. This allows it to meet the needs of large deformation testing in soft soil, as well as adapt to the high-pressure environment of hard soil or deep soil, effectively expanding the pressure and deformation range of the pressuremeter test.

[0085] 3. Robust structure and excellent durability: The rigid extension plate 5 is used as the force-applying component that directly contacts the soil, replacing the easily damaged flexible membrane. This design gives it extremely strong impact and abrasion resistance, completely resisting the cutting of sharp particles in gravelly soils. This allows the pressuremeter test to be conducted safely and reliably in coarse-grained strata such as gravel layers and rockfill bodies, which were previously difficult to test, and significantly extends the service life of the probe.

[0086] 4. Automated and highly complete data acquisition: Through the water level scale marking system 10 and the water level height reading system 11 based on camera 112 and visual recognition software 111, the automatic, real-time and high-precision recording of water level changes (corresponding to volume changes) during the experiment is realized, avoiding errors and interruptions in manual reading and significantly improving the integrity and reliability of the data.

[0087] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A mechanically extended pressure gauge, characterized in that, include: The water storage tank (4) is connected to the ground water pressure loading system via a water pipe (9) to receive and transmit water pressure; A water pressure sensor (7) is embedded in the inner wall of the upper cover plate of the water storage tank (4) for real-time monitoring of the water pressure inside the tank; The telescopic rod (1) and the sleeve rod (2) are provided. The upper end of the telescopic rod (1) is connected to the lower cover plate of the water storage tank (4). The lower part of the telescopic rod (1) is sleeved in the sleeve rod (2). A spring (3) is provided between the telescopic rod (1) and the sleeve rod (2). The water pressure change in the water storage tank (4) drives the lower cover plate to move the telescopic rod (1) relative to the sleeve rod (2) and compress or release the spring (3). An extension plate (5) is symmetrically arranged on both sides of the pressure gauge; The linkage rod (6) has its two ends hinged to the inner side of the extension plate (5) and the connection part of the telescopic rod (1) and the sleeve rod (2), respectively; the relative movement between the telescopic rod (1) and the sleeve rod (2) is converted into the horizontal expansion or contraction movement of the extension plate (5) through the linkage rod (6); A water level scale marking system (10) is connected to the water storage tank (4) and is used to display the water level height change caused by the change in the volume of the water storage tank (4); A water level reading system (11) is used to identify and record the water level height information of the water level scale marking system (10) in real time.

2. The mechanically extended pressure gauge according to claim 1, characterized in that, The water level marking system (10) includes a scale (101) that can be accurately identified by a computer and a built-in water tank (102), the volume of which matches the volume change of the water storage tank (4).

3. The mechanically extended pressure gauge according to claim 2, characterized in that, The water level reading system (11) includes a camera (112) and PC-based visual recognition software (111); the camera (112) is aimed at the scale (101) of the water level scale marking system (10) to obtain image information, and the PC-based visual recognition software (111) is used to process the image information and obtain real-time water level data.

4. A test method for a mechanically extended pressure gauge, using the mechanically extended pressure gauge as described in any one of claims 1-3, characterized in that, Includes the following steps: S11. Calibration steps: Before the test, the water storage tank (4) and water pressure sensor (7) of the pressure gauge are calibrated to obtain the correspondence between the volume change of the water storage tank (4) and the water level scale change of the water level scale marking system (10); and the visual recognition mapping relationship of the water level height reading system (11) is established. S12, Installation and Initial Recording Steps: Insert the probe of the pressure meter into the soil layer to be tested, and record the initial pressure reading of the water pressure sensor (7) and the initial water level scale value of the water level scale marking system (10) at this time. S13, Step 1: Gradual loading and synchronous data acquisition: The first stage of pressure loading is carried out through the ground water pressure loading system connected by the water pipe (9); while loading, the water pressure data in the chamber is collected in real time through the water pressure sensor (7), and the corresponding water level data is collected in real time through the water level reading system (11). S14. Continuous loading judgment step: After the data under the current loading level is stable, the next level of pressure loading is carried out, and the data acquisition process of step S13 is repeated until the horizontal displacement of the expansion plate (5) is detected to show a nonlinear increasing trend. S15. Unloading and recovery steps: After the test, the water pressure of the ground water pressure loading system is removed; the water storage tank (4) recovers its volume under the rebound action of the spring (3), causing the expansion plate (5) to shrink to its initial state, and then the pressure gauge probe is taken out of the soil.

5. The test method according to claim 4, characterized in that, In step S11, based on the change in volume of the water storage tank (4) obtained from calibration, and combined with the geometric relationship of the linkage rod (6), the theoretical horizontal displacement of the extension plate (5) is calculated.

6. The test method according to claim 4, characterized in that, In steps S13 and S14, the collected water pressure data and water level data are recorded synchronously to analyze the correlation between the water pressure data P inside the tank, the vertical displacement ΔL of the water storage tank, and the horizontal displacement ΔS of the expansion plate.

7. A method for calculating test results of a mechanically extended pressure gauge, based on data obtained from the test method described in any one of claims 4-6, characterized in that, Includes the following steps: S21. Based on the collected water pressure data P inside the storage tank, calculate the vertical sliding displacement ΔL of the storage tank caused by the lower cover plate using formula (1): (1); where, This is the vertical sliding displacement. The inner diameter of the sealed cylindrical chamber. The spring constant is... The moving plate slides downwards. For the water pressure data inside the tank under the condition of vertical displacement ΔL generated by the expansion plate, The data represents the water pressure inside the chamber in the initial state of the expansion plate. S22. Based on the calculated vertical sliding displacement ΔL, calculate the horizontal extension displacement ΔS of the extension plate (5) using formula (2): (2); where, For horizontal extension displacement, For the length of a single extension bar, This is the distance between the rotating shafts when the shafts are in the closed state. S23. Substitute formula (1) into formula (2) to establish a direct mathematical relationship model between the water pressure data P in the chamber and the horizontal displacement ΔS of the expansion plate; （3）； The pressure modulus can be directly calculated from the horizontal displacement ΔS of the extended plate. : （4）； In the formula, The calibration coefficients, which are related to the device geometry and the Poisson's ratio of the soil, were determined through calibration tests. This represents the increment of the horizontal displacement of the expansion plate when the water pressure inside the tank reaches its maximum value. This refers to the pressure data corresponding to the maximum pressure value of the water inside the tank.

8. The test method according to claim 7, characterized in that, Also includes: S24. Before the test, the relationship between the calibrated horizontal displacement ΔS of the expansion plate and the water pressure data P in the chamber was used to obtain the calibration coefficient K. S25. During the experiment, plot the curve showing the relationship between the horizontal displacement ΔS of the expansion plate and the water pressure P inside the chamber, and take the data at the inflection point of the straight line segment as... and Based on this, the side pressure modulus is calculated according to formula (4). .

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