Device and method for testing dynamic compression modulus and damping ratio of soil body under action of cyclic load of seismic compression waves

Abstract

The invention discloses a device and method for testing the dynamic compression modulus and damping ratio of a soil body under the cyclic load effect of seismic compression waves, and belongs to the technical field of geotechnical tests. The loading mechanism is arranged on the bearing platform and is used for applying a dynamic load to the sample; the fixing mechanism is arranged on the loading mechanism and is used for fixing the sample; the drainage mechanism is arranged on the fixing mechanism and is used for draining internal water in the process of applying the back pressure and saturating the sample; and the computer is respectively connected with the loading mechanism and the drainage mechanism and is used for controlling the loading mechanism and the drainage mechanism to operate. The dynamic lateral confinement compression modulus of the soil body is tested through the combination of the cyclic lateral confinement compression and the piezoelectric ceramic crystal oscillator, and the problem that the dynamic characteristics of the soil body caused by vertical seismic actions are not tested by using a laboratory method at present is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of geotechnical testing, and in particular relates to a testing device and method for the dynamic compression modulus and damping ratio of soil under the action of earthquake compression wave cyclic load. Background Art

[0002] When an earthquake occurs, the site effect of the surface soil significantly affects the propagation characteristics of seismic waves, thereby intensifying the amplification effect of ground motion and causing greater damage to structures. Previous earthquake observations have shown that the amplification effect of seismic waves is closely related to the nonlinear behavior of soil. In particular, the nonlinear response of soil under strong earthquakes is one of the important factors that cause site effects.

[0003] Most existing studies focus on the nonlinear behavior of soil under shear waves (S waves), especially the nonlinear changes in shear modulus and damping ratio. These studies provide theoretical support for understanding the mechanical behavior of soil under earthquakes and have been widely used in site response analysis. However, actual seismic waves include not only horizontal shear waves, but also vertical compression waves (P waves). The impact of vertical seismic motion on structures and soil layers is often overlooked, but studies have shown that vertical seismic motion plays a vital role in causing structural damage and ground instability.

[0004] In the study of nonlinear behavior of soil, laboratory testing is a common method to obtain shear-related nonlinear modulus and damping ratio. However, due to the lack of specialized experimental equipment, there are relatively few experimental studies on the dynamic characteristics of soil under compression waves, and relevant experimental data are relatively scarce.

[0005] Based on the above, in view of the fact that the existing technology and test schemes are unable to test the dynamic characteristics of soil under compression wave cyclic loads, the present invention aims to provide a device and method that can test the lateral confinement compression modulus and damping ratio of soil in the full strain range. Summary of the invention

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A testing device for dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave, comprising:

[0008] platform;

[0009] A loading mechanism, the loading mechanism is arranged on the support platform and is used to apply a dynamic load to the sample;

[0010] A fixing mechanism, which is arranged on the loading mechanism and is used to fix the sample;

[0011] A drainage mechanism, the drainage mechanism is arranged on the fixing mechanism and is used to discharge the internal water during the process of applying back pressure and saturating the sample;

[0012] A computer is connected to the loading mechanism and the drainage mechanism respectively, and is used to control the operation of the loading mechanism and the drainage mechanism.

[0013] Furthermore, the loading mechanism includes a lifting platform, a loading cap, a horn sleeve, a piston screw rod, a loading frame and a displacement sensor;

[0014] The lifting platform is arranged on the supporting platform, and a base is arranged at one end of the lifting platform away from the supporting platform; the fixing mechanism is arranged on the base;

[0015] The displacement sensor is arranged on a side of the base away from the fixing mechanism;

[0016] The loading frame is connected to the support platform through a connecting screw rod and is located above the base;

[0017] The loading cap is connected to one end of the piston screw rod, and the other end of the piston screw rod is connected to the loading frame through a fixing bolt; wherein the loading cap is located directly above the base, and a vertical pressure sensor is also provided in the loading cap;

[0018] The horn sleeve is connected to the fixing mechanism and is located directly below the loading cap;

[0019] The lifting platform, the displacement sensor and the vertical pressure sensor are connected to the computer.

[0020] Further, the fixing mechanism includes a sample base, a sample cap and a rigid mold;

[0021] The sample base is arranged on the top of the base, the sample is arranged on the top of the sample base, and the sample cap is arranged on the top of the sample; the side of the sample cap away from the sample is connected to the horn cover;

[0022] The rigid mold is sleeved outside the sample base, the sample and the sample cap.

[0023] Furthermore, a permeable stone is arranged between the sample, the sample base and the sample cap.

[0024] Furthermore, the sample base, the sample and the sample cap are collectively covered with a rubber film; the rigid mold is covered outside the rubber film, and rubber rings are provided between the two ends of the rubber film and the rigid mold.

[0025] Furthermore, the rigid mold is composed of two split rigid molds, and the cross-section of the split rigid mold is semicircular, which is used to limit the lateral deformation of the sample.

[0026] Furthermore, a piezoelectric ceramic crystal oscillator is provided in the sample cap and the sample base, and the piezoelectric ceramic crystal oscillator is connected to the computer.

[0027] Furthermore, the drainage mechanism includes a water pipe, a water inlet pipe and a water outlet pipe;

[0028] The sample base is provided with a back-pressure water inlet and outlet and a water inlet; the back-pressure water inlet and outlet pass through the rigid mold and are connected to the first end of the water pipe, and the second end of the water pipe is arranged on the support platform; the second end of the water pipe is also provided with a first valve and a pore pressure sensor; the water inlet passes through the rigid mold and is connected to the first end of the water inlet pipe, and the second end of the water inlet pipe is arranged on the support platform; the second end of the water inlet pipe is also provided with a third valve;

[0029] The sample cap is provided with a water outlet; the water outlet is connected to the first end of the water outlet pipe, the second end of the water outlet pipe is arranged on the support platform, and the second end of the water outlet pipe is also provided with a second valve;

[0030] The first valve, the second valve, the third valve and the pore pressure sensor are connected to the computer respectively.

[0031] A testing method for the testing device of soil dynamic compression modulus and damping ratio under the cyclic load of earthquake compression wave as described above comprises the following steps:

[0032] S1. Install the specimen on the specimen base, fasten the specimen with a rigid mold, install the specimen cap, and install the loading frame;

[0033] S2. Open the switch of the first valve and test the sealing performance of the rubber membrane according to the set back pressure;

[0034] S3. After the sealing test, close the first valve and apply a certain vertical stress without changing it; open the second valve and the third valve to saturate the water head of the sample;

[0035] S4. After the water head is saturated, close the second valve and the third valve, open the first valve, and use the loading mechanism to saturate the sample with back pressure;

[0036] S5. After the back pressure saturation is completed, the sample is loaded according to the set vertical stress and begins to consolidate;

[0037] S6. After consolidation is completed, the dynamic compression modulus and damping ratio of the soil under the cyclic load of earthquake compression waves are calculated and tested in the full strain range.

[0038] Furthermore, the method for calculating the dynamic compression modulus and damping ratio of soil under the cyclic load of earthquake compression waves in step S6 comprises the following steps:

[0039] S10, the specimen reaches the target vertical stress After that, the transmitter is used to generate an excitation signal to test the piezoelectric ceramic crystal oscillator and measure the compression wave velocity V p , calculate the small strain confined compression modulus M of the specimen 0 ;

[0040] M 0 =V p 2 ρ

[0041] Where ρ is the density of the sample;

[0042] S20, reconsolidating the sample after the piezoelectric ceramic crystal oscillator test, applying vertical stress to the target vertical stress, and applying dynamic load;

[0043] S30, lift the sample base by lifting the lifting platform to apply dynamic load to the sample, and the vertical pressure sensor records the vertical stress σ during the dynamic load process V , the displacement sensor records the vertical strain ε V , and the vertical stress-strain curve is obtained:

[0044] The confined compression modulus M of the specimen under the compression path C :

[0045] The confined compression modulus M of the specimen under the tensile path E :

[0046] Damping ratio λ:

[0047] in, is the vertical stress of the target strain of the compression path; is the vertical stress of the target strain of the tensile path; W D The area of ​​the hysteresis loop; W S polygon area;

[0048] S40, after the dynamic load is completed, the sample is re-consolidated and a dynamic load test of the next level of strain is performed.

[0049] Beneficial effects:

[0050] 1. The present invention tests the soil confinement compression modulus by combining cyclic confinement compression with a piezoelectric ceramic crystal oscillator, thus overcoming the problem that there is currently no research on testing the vertical seismic dynamic characteristics of soil using laboratory methods. Laboratory testing is the most commonly used method to obtain shear modulus, nonlinear modulus and damping ratio.

[0051] 2. The dynamic load of the lateral confinement compression test can test the soil strain range of 10 -4 ~10 -2 The test range of piezoelectric ceramic crystal oscillators can reach 10 -6 Therefore, combining the piezoelectric ceramic crystal oscillator with the lateral confined compression test can expand the range of soil strain tested by the instrument.

[0052] 3. Based on the asymmetry of the vertical stress-strain curve, a method for calculating the lateral confining compression modulus and damping ratio under compression and tension paths respectively is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a structural schematic diagram of a testing device for dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave according to the present invention;

[0054] Figure 2 It is a structural schematic diagram of the fixing mechanism of the present invention;

[0055] Figure 3 It is a structural schematic diagram of the rigid mold of the present invention;

[0056] Figure 4 This is a schematic diagram of calculating the confined compression modulus of the present invention;

[0057] Explanation of the accompanying drawings: 1-lifting platform, 2-displacement sensor, 3-first valve, 4-second valve, 5-pore pressure sensor, 6-water pipe, 7-back pressure inlet and outlet, 8-sample base, 9-rubber membrane, 10-sample, 11-permeable stone, 12-sample cap, 13-water outlet, 14-horn sleeve, 15-loading cap, 16-vertical pressure sensor, 17-loading frame, 18-fixing bolt, 19-piston screw rod, 20-vertical pressure sensor signal line, 21-connecting screw rod, 22-piezoelectric ceramic crystal oscillator signal line, 23-rubber ring, 24-piezoelectric ceramic crystal oscillator, 25-rigid mold, 26-water inlet, 27-base, 28-third valve, 29-support. DETAILED DESCRIPTION

[0058] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0059] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0060] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0061] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0062] Example 1

[0063] refer to Figure 1-Figure 3 , a testing device for dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave, comprising:

[0064] Platform 29;

[0065] A loading mechanism, which is disposed on the support platform 29 and is used to apply a dynamic load to the sample 10;

[0066] A fixing mechanism, which is arranged on the loading mechanism and is used to fix the sample 10;

[0067] A drainage mechanism, which is arranged on the fixing mechanism and is used to discharge the internal water during the process of applying back pressure and saturating the sample;

[0068] The computer is connected to the loading mechanism and the drainage mechanism respectively and is used for controlling the operation of the loading mechanism and the drainage mechanism.

[0069] Preferably, the loading mechanism includes a lifting platform 1, a loading cap 15, a horn sleeve 14, a piston screw rod 19, a loading frame 17 and a displacement sensor 2;

[0070] The lifting platform 1 is arranged on the supporting platform 29, and a base 27 is arranged at one end of the lifting platform 1 away from the supporting platform 29; a fixing mechanism is arranged on the base 27;

[0071] The displacement sensor 2 is arranged on a side of the base 27 away from the fixing mechanism;

[0072] The loading frame 17 is connected to the support platform 29 through the connecting screw rod 21 and is located above the base 27;

[0073] The loading cap 15 is connected to one end of the piston screw rod 19, and the other end of the piston screw rod 19 is connected to the loading frame 17 through a fixing bolt 18; wherein the loading cap 15 is located directly above the base 27, and a vertical pressure sensor 16 is also provided in the loading cap 15;

[0074] The speaker cover 14 is connected to the fixing mechanism and is located directly below the loading cap 15;

[0075] The lifting platform 1, the displacement sensor 2 and the vertical pressure sensor 16 are connected to the computer.

[0076] In this embodiment, the vertical pressure sensor 16 is connected to the computer via a vertical pressure sensor signal line 20 .

[0077] Preferably, the fixing mechanism includes a sample base 8, a sample cap 12 and a rigid mold 25;

[0078] The sample base 8 is arranged on the top of the base 27, the sample 10 is arranged on the top of the sample base 8, and the sample cap 12 is arranged on the top of the sample 10; the side of the sample cap 12 away from the sample 10 is connected to the horn cover 14;

[0079] The rigid mold 25 is sleeved outside the sample base 8 , the sample 10 and the sample cap 12 .

[0080] Preferably, a permeable stone is provided between the sample 10 and the sample base 8 and the sample cap 12 .

[0081] Preferably, a rubber film 9 is provided on the sample base 8 , the sample 10 and the sample cap 12 ; the rigid mold 25 is provided on the outside of the rubber film 9 , and rubber rings 23 are provided between the two ends of the rubber film 9 and the rigid mold 25 .

[0082] In this embodiment, the rubber film 9, the sample base 8 and the sample cap 12 form a sealed space, and the sample 10 is sealed in the sealed space.

[0083] In this embodiment, the rigid mold 25 and the rubber membrane 9 are connected to the base 27 via screws.

[0084] Preferably, the rigid mold 25 is composed of two split rigid molds, the cross-section of the split rigid mold is semicircular, and is used to limit the lateral deformation of the sample 10.

[0085] In this embodiment, the rigid mold 25 is fastened to the base 27 by bolts to ensure that the rigid mold does not move during the cyclic loading process.

[0086] In this embodiment, the bottom wall thickness of the split rigid mold is smaller than the upper wall thickness, which is used to place the rubber ring 23 for fastening the sample base 8; the rubber ring 23 at the bottom of the rubber membrane 9 is located between the rubber membrane 9 and the split rigid mold, and the rubber ring 23 at the top of the rubber membrane 9 is located at the top of the split rigid mold.

[0087] In this embodiment, the two split rigid molds are completely fitted with the rubber film 9 to completely wrap the rubber film 9; preferably, the two split rigid molds are clamped by wire locks to limit the lateral deformation of the sample 10.

[0088] Preferably, a piezoelectric ceramic crystal oscillator 24 is also provided in the sample cap 12 and the sample base 8 , and the piezoelectric ceramic crystal oscillator 24 is connected to a computer.

[0089] In this embodiment, the piezoelectric ceramic crystal oscillator 24 is connected to the computer via the piezoelectric ceramic crystal oscillator signal line 22 .

[0090] Preferably, the drainage mechanism includes a water pipe 6, a water inlet pipe and a water outlet pipe;

[0091] The sample base 8 is provided with a back-pressure water inlet and outlet 7 and a water inlet 26; the back-pressure water inlet and outlet 7 passes through the rigid mold 25 and is connected to the first end of the water pipe 6, and the second end of the water pipe 6 is arranged on the support 29; the second end of the water pipe 6 is also provided with a first valve 3 and a pore pressure sensor 5; the water inlet 26 passes through the rigid mold 25 and is connected to the first end of the water inlet pipe, and the second end of the water inlet pipe is arranged on the support 29; the second end of the water inlet pipe is also provided with a third valve 28;

[0092] The sample cap 12 is provided with a water outlet; the water outlet is connected to the first end of the water outlet pipe, the second end of the water outlet pipe is arranged on the support 29, and the second end of the water outlet pipe is also provided with a second valve 4;

[0093] The first valve 3, the second valve 4, the third valve 28 and the pore pressure sensor 5 are respectively connected to the computer.

[0094] In this embodiment, two through holes are provided at the bottom of the rigid mold 25, and the water inlet and the back-pressure water inlet and outlet 7 pass through the two through holes respectively.

[0095] Example 2

[0096] A testing method for a testing device for testing dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave as in Example 1 comprises the following steps:

[0097] S1. Install the specimen on the specimen base, fasten the specimen with a rigid mold, install the specimen cap, and install the loading frame;

[0098] S2. Open the switch of the first valve and test the sealing performance of the rubber membrane according to the set back pressure;

[0099] S3. After the sealing test, close the first valve and apply a certain vertical stress without changing it; open the second valve and the third valve to saturate the water head of the sample;

[0100] S4. After the water head is saturated, close the second valve and the third valve, open the first valve, and use the loading mechanism to saturate the sample with back pressure;

[0101] S5. After the back pressure saturation is completed, the sample is loaded according to the set vertical stress and begins to consolidate;

[0102] S6. After consolidation is completed, the dynamic compression modulus and damping ratio of the soil under the cyclic load of earthquake compression waves are calculated and tested in the full strain range.

[0103] In this embodiment, a back pressure controller is also included, and the back pressure controller is connected to the drainage mechanism, the fixing mechanism and the loading mechanism.

[0104] In this embodiment, step S6 includes the following steps:

[0105] During the specimen loading process, the back pressure controller was used to maintain the drainage condition loading, allowing the specimen to deform vertically;

[0106] The loading mechanism performs cyclic loading by setting the target strain. The cyclic loading stage includes compression and tension stages. The vertical stress corresponding to the target strain in the tension stage is not less than 20% of the consolidation vertical stress. After each level of strain loading is completed, the sample is re-consolidated and then the next level of strain loading is performed.

[0107] The displacement sensor and vertical pressure sensor transmit the detected data to the computer to record the vertical stress and vertical strain of the sample during the test process.

[0108] Example 3

[0109] refer to Figure 4 This embodiment is a method for calculating the dynamic compression modulus and damping ratio of soil under the action of earthquake compression wave cyclic load in step S6 of embodiment 2, comprising the following steps:

[0110] S10, the specimen reaches the target vertical stress After that, the transmitter is used to generate an excitation signal to test the piezoelectric ceramic crystal oscillator and measure the compression wave velocity V p , calculate the small strain confined compression modulus M of the specimen 0 ;

[0111] M 0 =V p 2 ρ

[0112] Where ρ is the density of the sample;

[0113] S20, reconsolidating the sample after the piezoelectric ceramic crystal oscillator test, applying vertical stress to the target vertical stress, and applying dynamic load;

[0114] S30, lift the sample base by lifting the lifting platform to apply dynamic load to the sample, and the vertical pressure sensor records the vertical stress ε during the dynamic load process V , the displacement sensor records the vertical strain ε V , and the vertical stress-strain curve is obtained:

[0115] The confined compression modulus M of the specimen under the compression path C :

[0116] The confined compression modulus M of the specimen under the tensile path E :

[0117] Damping ratio λ:

[0118] in, is the vertical stress of the target strain of the compression path; is the vertical stress of the target strain of the tensile path; W D The area of ​​the hysteresis loop; W S polygon area;

[0119] S40, after the dynamic load is completed, the sample is re-consolidated and a dynamic load test of the next level of strain is performed.

[0120] In this embodiment, after 5 minutes of reconsolidation, a dynamic load test of the next level of target strain is carried out.

[0121] The present invention can realize the subsequent cyclic confined compression test directly after the piezoelectric ceramic crystal oscillator test on the same sample, thereby effectively simulating the confined compression modulus and damping ratio of the soil in a wide strain range under the compression wave load, making up for the deficiency that the existing test equipment cannot test the dynamic modulus and damping ratio of the soil under the compression wave, and overcoming the relevant limitations in the prior art.

[0122] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A testing device for dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave, characterized in that: include: platform; A loading mechanism, the loading mechanism is arranged on the support platform and is used to apply a dynamic load to the sample; A fixing mechanism, which is arranged on the loading mechanism and is used to fix the sample; A drainage mechanism, the drainage mechanism is arranged on the fixing mechanism and is used to discharge the internal water during the process of applying back pressure and saturating the sample; A computer is connected to the loading mechanism and the drainage mechanism respectively, and is used to control the operation of the loading mechanism and the drainage mechanism.

2. The testing device for dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave according to claim 1 is characterized in that: The loading mechanism includes a lifting platform, a loading cap, a horn sleeve, a piston screw rod, a loading frame and a displacement sensor; The lifting platform is arranged on the supporting platform, and a base is arranged at one end of the lifting platform away from the supporting platform; the fixing mechanism is arranged on the base; The displacement sensor is arranged on a side of the base away from the fixing mechanism; The loading frame is connected to the support platform through a connecting screw rod and is located above the base; The loading cap is connected to one end of the piston screw rod, and the other end of the piston screw rod is connected to the loading frame through a fixing bolt; wherein the loading cap is located directly above the base, and a vertical pressure sensor is also provided in the loading cap; The horn sleeve is connected to the fixing mechanism and is located directly below the loading cap; The lifting platform, the displacement sensor and the vertical pressure sensor are connected to the computer.

3. The testing device for dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave according to claim 2, characterized in that: The fixing mechanism comprises a sample base, a sample cap and a rigid mold; The sample base is arranged on the top of the base, the sample is arranged on the top of the sample base, and the sample cap is arranged on the top of the sample; the side of the sample cap away from the sample is connected to the horn cover; The rigid mold is sleeved outside the sample base, the sample and the sample cap.

4. The testing device for dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave according to claim 3 is characterized in that: A permeable stone is arranged between the sample, the sample base and the sample cap.

5. The testing device for dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave according to claim 3, characterized in that: The sample base, the sample and the sample cap are collectively covered with a rubber film; the rigid mold is covered outside the rubber film, and rubber rings are arranged between the two ends of the rubber film and the rigid mold.

6. The testing device for dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave according to claim 5, characterized in that: The rigid mold is composed of two split rigid molds, the cross section of the split rigid mold is semicircular, and is used to limit the lateral deformation of the sample.

7. The testing device for dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave according to claim 3, characterized in that: The sample cap and the sample base are also provided with a piezoelectric ceramic crystal oscillator, and the piezoelectric ceramic crystal oscillator is connected to the computer.

8. The testing device for dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave according to claim 3, characterized in that: The drainage mechanism includes a water pipe, a water inlet pipe and a water outlet pipe; The sample base is provided with a back-pressure water inlet and outlet and a water inlet; the back-pressure water inlet and outlet pass through the rigid mold and are connected to the first end of the water pipe, and the second end of the water pipe is arranged on the support platform; the second end of the water pipe is also provided with a first valve and a pore pressure sensor; the water inlet passes through the rigid mold and is connected to the first end of the water inlet pipe, and the second end of the water inlet pipe is arranged on the support platform; the second end of the water inlet pipe is also provided with a third valve; The sample cap is provided with a water outlet; the water outlet is connected to the first end of the water outlet pipe, the second end of the water outlet pipe is arranged on the support platform, and the second end of the water outlet pipe is also provided with a second valve; The first valve, the second valve, the third valve and the pore pressure sensor are connected to the computer respectively.

9. A method for testing a device for testing dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Install the specimen on the specimen base, fasten the specimen with a rigid mold, install the specimen cap, and install the loading frame; S2. Open the switch of the first valve and test the sealing performance of the rubber membrane according to the set back pressure; S3. After the sealing test, close the first valve and apply a certain vertical stress without changing it; open the second valve and the third valve to saturate the water head of the sample; S4. After the water head is saturated, close the second valve and the third valve, open the first valve, and use the loading mechanism to saturate the sample with back pressure; S5. After the back pressure saturation is completed, the sample is loaded according to the set vertical stress and begins to consolidate; S6. After consolidation is completed, the dynamic compression modulus and damping ratio of the soil under the cyclic load of earthquake compression waves are calculated and tested in the full strain range.

10. The method for testing the dynamic compression modulus and damping ratio of soil under cyclic load of earthquake compression wave according to claim 9, characterized in that: The method for calculating the dynamic compression modulus and damping ratio of soil under the cyclic load of earthquake compression waves in step S6 comprises the following steps: S10, the specimen reaches the target vertical stress After that, the transmitter is used to generate an excitation signal to test the piezoelectric ceramic crystal oscillator and measure the compression wave velocity V p , calculate the small strain confining compression modulus M0 of the specimen; M0=V p 2 ρ Where ρ is the density of the sample; S20, reconsolidating the sample after the piezoelectric ceramic crystal oscillator test, applying vertical stress to the target vertical stress, and applying dynamic load; S30, lift the sample base by lifting the lifting platform to apply dynamic load to the sample, and the vertical pressure sensor records the vertical stress ε during the dynamic load process V , the displacement sensor records the vertical strain ε V , and the vertical stress-strain curve is obtained: The confined compression modulus M of the specimen under the compression path C : The confined compression modulus M of the specimen under the tensile path E : Damping ratio λ: in, is the vertical stress of the target strain of the compression path; is the vertical stress of the target strain of the tensile path; W D The area of ​​the hysteresis loop; W S polygon area; S40, after the dynamic load is completed, the sample is re-consolidated and a dynamic load test of the next level of strain is performed.

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