Unsaturated soil vibration device considering multi-suction mechanism and damage evaluation method

Abstract

The invention discloses an unsaturated soil vibration device considering a multi-suction mechanism and a damage evaluation method. The unsaturated soil vibration device comprises a basic vibration three-axis inner-outer pressure chamber device, a balance weight, a surface humidity control device, a load control device, a pressure adjusting device and a data acquisition device, aiming at the unsaturated vibration triaxial test, the surface humidity control device is used for controlling solution infiltration, capillary suction force and adsorption suction force, the problems of serious moisture redistribution and difficult sample loading after sample freezing are solved by quickly freezing a high-moisture-content sample, and the problem of long suction force balance time is solved by suction force pre-balance; aiming at dynamic damage evaluation of soil, a multi-factor comprehensive evaluation standard is provided, the complex mechanism of dynamic damage of the soil body is disclosed from multiple dimensions, the comprehensive state of the soil body is reflected, the defects of a traditional method are overcome, and a more scientific theoretical basis is provided for design and safety evaluation of an engineering structure.

Description

Technical Field

[0001] The invention belongs to the technical field of civil engineering, and particularly relates to an unsaturated soil vibration device considering multiple suction mechanisms. Background Technique

[0002] From the evolution of earthquake disasters, earthquake action causes the groundwater level to rise, and the water content of the soil layer above the groundwater level increases, even reaching a saturated state. In unsaturated soil, the absorption of water by low water content soil is dominated by adsorption suction, and the absorption of water by high water content soil is dominated by capillary suction. The change of suction when the soil water content increases directly affects the effective stress of soil particles, and further affects the dynamic strength of the soil mass. Therefore, the unsaturated vibration triaxial considering multiple suction mechanisms plays an extremely significant role in promoting the research of unsaturated soil and secondary disasters caused by earthquake disasters. Summary of the Invention

[0003] The purpose of the invention is to provide an unsaturated soil vibration device considering multiple suction mechanisms to solve the problems raised in the above background technique.

[0004] To achieve the above purpose, the invention provides the following technical solution: An unsaturated soil vibration device considering multiple suction mechanisms, comprising: a basic vibration triaxial inner-outer pressure chamber device, a balance weight, a surface humidity control device, a load control device, a pressure regulating device, and a data acquisition device; the basic vibration triaxial inner-outer pressure chamber device includes an inner pressure chamber and an outer pressure chamber sleeved outside the inner pressure chamber, the shells of the inner pressure chamber and the outer pressure chamber are of a sealed structure, and the inner pressure chamber is used for containing a test sample; the balance weight is fixedly connected to the base inside the inner pressure chamber; the surface humidity control device is communicated with the inside of the inner pressure chamber through a conduit; the load control device includes a load vibrator, a pressure shaft, and a load sensor, the load vibrator is fixedly connected to the base, the lower end of the pressure shaft is vertically fixedly arranged in the inner pressure chamber and a top cap is arranged at the lower end of the pressure shaft, the top cap abuts against the upper surface of the test sample, and the load sensor is fixedly connected to the pressure shaft for detecting the pressure load received by the test sample; the pressure regulating device includes a confining pressure controller, a back pressure controller, and a gas pressure control device, and the confining pressure controller, the back pressure controller, and the gas pressure control device are connected to the sample through a conduit, and a channel communicating with the pressure source media of the inner pressure chamber and the confining pressure controller is arranged on the balance weight; the data acquisition device is connected to the sample placed inside the inner pressure chamber through a conduit and a sensor for performing confining pressure acquisition, back pressure acquisition, gas pressure acquisition, pore pressure acquisition, load acquisition, and strain acquisition.

[0005] Preferably, the surface humidity control device includes a peristaltic circulation pump and a saturated salt solution container, and the peristaltic circulation pump, the saturated salt solution container, and the upper and lower surfaces of the sample are connected through a circulation pipeline.

[0006] Preferably, an empty container is connected to the circulation pipeline between the peristaltic circulation pump, the saturated salt solution container and the specimen.

[0007] The reverse flow of the saturated salt solution is prevented by setting an empty container.

[0008] Preferably, a high air intake value clay plate is arranged above the base, and the test specimen is placed on the high air intake value clay plate.

[0009] A method for evaluating the vibration failure of unsaturated soil of an unsaturated soil vibration device considering multiple suction mechanisms includes the following steps:

[0010] S1: Select an undisturbed soil specimen or a remolded soil specimen according to the actual situation and prepare the undisturbed soil or remolded soil specimen in accordance with the standard GB-T50123-2019;

[0011] S2: Saturate the specimen prepared in S1, and select the air extraction saturation method, the water head saturation method or the back pressure saturation method according to the type of different soil samples in accordance with the standard GB-T50123-2019;

[0012] S3: Control the suction of the saturated specimen to achieve suction pre-equilibrium with reference to the pressure plate method or the saturated salt solution method in the soil-water characteristic curve test in the standard T / CECS1337-2023. Among them, in the pressure plate method, when the volume of water discharged within 24 hours is less than 0.1 mL, it is regarded as suction balance, and in the saturated salt solution method, when the mass change rate is less than 0.1% / d, it is regarded as suction balance;

[0013] S4: Place the specimen after suction pre-equilibrium into the unsaturated soil vibration device considering multiple suction mechanisms, apply a predetermined air pressure, confining pressure, back pressure, and axial pressure for further suction balance. When the drainage volume is less than 12 mm within 2 hours 3 it is regarded as suction balance;

[0014] S5: Keep the air pressure and back pressure unchanged, and increase the confining pressure until the effective confining pressure reaches the predetermined effective confining pressure for consolidation;

[0015] S6: Close the back pressure, keep the confining pressure constant, and turn on the load control device for vibration shear;

[0016] S7: Disassemble the specimen, observe the specimen state, sort out the experimental data, draw the stress-strain curve, the dynamic pore water pressure time history curve, the dynamic strain time history curve, the dynamic elastic modulus ratio curve, and comprehensively consider the dynamic strain, dynamic pore water pressure, and dynamic elastic modulus ratio to judge the failure vibration times and failure types of the specimen.

[0017] Preferably, in step S3, when controlling the adsorption suction balance, a saturated salt solution method is used to perform suction pre-balancing, and when controlling the capillary suction balance, a pressure plate method is used to perform suction pre-balancing.

[0018] Preferably, in step S4, when soft soil is loaded, the soft soil sample to be loaded is quickly frozen for no less than 3 hours, and the sample is loaded when the sample is frozen and not melted. This ensures that when the sample is loaded into the unsaturated soil vibration device considering multiple suction mechanisms, it will not be crushed, bent, or otherwise damaged, thereby reducing the impact on the test.

[0019] Preferably, in step S4, when carrying out the unsaturated soil vibration test for controlling adsorption suction, the pre-balanced sample is placed in the unsaturated soil vibration device considering multiple suction mechanisms, the peristaltic circulation pump is turned on to circulate the saturated salt solution vapor on the upper and lower surfaces of the sample to balance the saturated salt solution vapor, and the saturated salt solution vapor is always kept circulating on the upper and lower surfaces of the sample during the consolidation process; when carrying out the unsaturated soil vibration test for controlling capillary suction, the experimental sample is placed in the unsaturated soil vibration device considering multiple suction mechanisms, the capillary suction is rebalanced under the required air pressure and water pressure difference, isotropic confining pressure is applied step by step, and consolidation is carried out; when carrying out the saturated or quasi-saturated soil vibration test for controlling solute suction, the sample is saturated with a saturated salt solution, placed in the unsaturated soil vibration device considering multiple suction mechanisms, the peristaltic pump is turned on to circulate the saturated salt solution vapor on the upper and lower surfaces of the sample, and isotropic consolidation is carried out while the saturated salt solution vapor is always kept circulating on the upper and lower surfaces of the sample.

[0020] Preferably, the step S7 comprises:

[0021] Step S71, extracting the axial displacement h in the consolidation stage according to the experimental data g , pore pressure p in the consolidation stage g ; Axial pressure F during vibration stage d , axial displacement h of the vibration stage d , dynamic pore pressure p in the vibration stage d ;

[0022] Step S72: subtract the axial displacement h during the consolidation stage from the height of the sample before consolidation. g Calculate the height h of the sample after consolidation c , and then use the axial displacement h of the vibration stage d Calculate the axial dynamic strain ε d , the formula is: Among them, h d is the axial displacement during the vibration phase, h g The axial displacement in the consolidation stage, Δh is the axial dynamic deformation, ε d is the axial dynamic strain;

[0023] Step S73: Using the axial pressure F during the vibration stage d , according to the cross-sectional area A of the test specimen, through the formula calculate the dynamic deviator stress σ during the vibration stage d ;

[0024] Step S74: Using the dynamic pore pressure value p during the vibration stage d subtract the pore pressure value p at the end of consolidation in sequence g , to obtain the cumulative value p of the dynamic pore pressure during the vibration stage a ;

[0025] Step S75: Taking the cycle period as the group order, perform correction processing on the dynamic deviator stress σ d and the axial dynamic strain value ε d for each cycle period. First, find the average value of the dynamic deviator stress d σ of the dynamic deviator stress value σ d and the dynamic strain value ε of each cycle period and the average value of the dynamic strain Immediately afterwards, use the dynamic deviator stress value σ d and the dynamic strain value ε d of each cycle period to subtract the average value of the dynamic deviator stress and the average value of the dynamic strain of each cycle period respectively, to obtain the corrected dynamic deviator stress value σ' d and the corrected dynamic strain value ε' d .

[0026] Step S76: Select the maximum corrected dynamic deviator stress value σ' d and the maximum corrected dynamic strain value ε' d from the corrected dynamic deviator stress value σ' max and the corrected dynamic strain value ε' max in the cycle period, and calculate the dynamic elastic modulus E of the cycle period through the formula ; d ;

[0027] Step S77: Calculate the ratio of the dynamic elastic modulus for each cycle period. The ratio of the dynamic elastic modulus is the ratio of the maximum elastic modulus E max in Step S76 to the dynamic elastic modulus E d of each cycle period;

[0028] Step S78: Plot the dynamic strain time history curve, the dynamic stress-dynamic strain curve, the cumulative value time history curve of dynamic pore water pressure, and the dynamic elastic modulus ratio time history curve. Find the number of vibrations N1 when the dynamic strain reaches 3%, and check whether the cumulative value of dynamic pore water pressure rises to 20% of the effective confining pressure at the N1th vibration; the number of vibrations N2 when the dynamic strain reaches 5%; the number of vibrations N3 when the dynamic elastic modulus ratio drops to 10%. If two of the above three conditions are met, it is regarded as the failure vibration number N f 。

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. The present invention controls the infiltration solution, capillary suction, and adsorption suction for the unsaturated vibration triaxial test. By quickly freezing the high water content specimen, it solves the problem of serious water redistribution and difficult specimen installation after specimen freezing. By suction pre-balancing, it solves the problem of long suction balance time;

[0031] 2. While controlling the comprehensive suction of the specimen, the present invention can control the solute composition of the specimen through the surface humidity control device, and can perform an efficient suction balance shear test, improving the application range of the dynamic triaxial test;

[0032] 3. For the dynamic failure evaluation of soil, the present invention proposes a multi-factor comprehensive evaluation criterion, revealing the complex mechanism of soil dynamic failure from multiple dimensions, reflecting the comprehensive state of the soil, making up for the deficiencies of traditional methods, and providing a more scientific theoretical basis for the design and safety assessment of engineering structures. Description of the Drawings

[0033] Figure 1 is the overall structural schematic diagram of the unsaturated soil vibration device considering multiple suction mechanisms provided by the embodiment of the present invention;

[0034] Figure 2 is the dynamic stress-dynamic strain curve (hysteresis curve) provided by the embodiment of the present invention;

[0035] Figure 3 is the dynamic strain time history curve provided by the embodiment of the present invention;

[0036] Figure 4 is the dynamic stress time history curve provided by the embodiment of the present invention;

[0037] Figure 5 is the cumulative dynamic pore water pressure time history curve provided by the embodiment of the present invention;

[0038] Figure 6 is the dynamic elastic modulus time history curve provided by the embodiment of the present invention;

[0039] Figure 7 is the dynamic elastic modulus ratio time history curve provided by the embodiment of the present invention;

[0040] In the figure, 1 is the basic vibration triaxial inner-outer pressure chamber device, 2 is the balance weight, 3 is the surface humidity control device, 4 is the load control device, 5 is the pressure regulating device, 6 is the test specimen, 11 is the inner pressure chamber, 12 is the outer pressure chamber, 31 is the peristaltic circulation pump, 32 is the saturated salt solution container, 33 is the empty container, 41 is the load vibrator, 42 is the pressure shaft, 43 is the load sensor, 111 is the base, 112 is the high air-entry value ceramic plate, and 421 is the top cap. Specific implementation mode

[0041] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0042] Please refer to Figures 1 - 3 , the present invention provides a technical solution: a non-saturated soil vibration device considering multiple suction mechanisms, including: a basic vibration triaxial inner-outer pressure chamber device 1, a balance weight 2, a surface humidity control device 3, a load control device 4, a pressure regulating device 5 and a data acquisition device.

[0043] The basic vibration triaxial inner-outer pressure chamber device 1 includes an inner pressure chamber 11 and an outer pressure chamber 12 sleeved outside the inner pressure chamber 11. The shells of the inner pressure chamber 11 and the outer pressure chamber 12 are of a sealed structure, and the inner pressure chamber 11 is used to hold the test specimen 6.

[0044] The balance weight 2 is fixedly connected to the base 111 inside the inner pressure chamber 11. A high air-entry value ceramic plate 112 is arranged above the base 111, and the test specimen 6 is placed on the high air-entry value ceramic plate 112.

[0045] The surface humidity control device 3 includes a peristaltic circulation pump 31 and a saturated salt solution container 32. The peristaltic circulation pump 31, the saturated salt solution container 32 and the upper and lower surfaces of the specimen are connected through a circulation pipeline. In order to prevent the reverse flow of the saturated salt solution, an empty container 33 is arranged on the flow pipeline where the saturated salt solution flows to the specimen;

[0046] The load control device 4 includes a load vibrator 41, a pressure shaft 42 and a load sensor 43. The load vibrator 41 is fixedly connected to the base 111. The lower end of the pressure shaft 42 is vertically fixedly penetrated through the inner pressure chamber 11, and a top cap 421 is arranged at the lower end of the pressure shaft 42. The top cap 421 abuts against the upper surface of the test specimen 6. The load sensor 43 is fixedly connected to the pressure shaft 42 to detect the pressure load received by the test specimen 6;

[0047] The pressure regulating device 5 includes a confining pressure controller, a back pressure controller and a pneumatic control device, and the confining pressure controller, the back pressure controller and the pneumatic control device are connected to the specimen 6 through conduits. A channel communicating with the pressure source medium of the inner pressure chamber 11 and the confining pressure controller is provided on the balance weight 2; the data acquisition device is connected to the specimen 6 placed inside the inner pressure chamber 11 through conduits and sensors for confining pressure acquisition, back pressure acquisition, pneumatic pressure acquisition, pore pressure acquisition, load acquisition, and strain acquisition.

[0048] A method for evaluating the failure of an unsaturated soil vibration test of an unsaturated soil vibration device considering multiple suction mechanisms includes the following steps:

[0049] S1: In this embodiment, according to the natural density and natural water content of the landslide soil mass in Caotan Village, Minhe County, Haidong City, Qinghai Province, and in accordance with the specification GB-T50123-2019, the dry density ρ d = 1.42 g / cm 3 and ω = 12% disturbed soil specimens are prepared.

[0050] S2: The specimen prepared in S1 is subjected to saturation treatment. Since the specimen is silty clay, the water head saturation method or the back pressure saturation method takes a long time, and the confining pressure and back pressure after saturation are relatively large, which has a great impact on the soil sample. Therefore, according to the specification GB-T50123-2019, the air extraction saturation method is selected for saturation. The specimen is placed in a vacuum cylinder for 1 h of vacuum treatment, and then deionized water is injected until the specimen is completely submerged and the soaking time > 10 h.

[0051] S3: Since this specimen is a high water content specimen for controlling capillary suction, the suction control is carried out by referring to the pressure plate method in the soil-water characteristic curve test in the specification T / CECS1337-2023 to achieve suction pre-equilibrium for the saturated specimen. The saturated specimen is placed in a pressure membrane apparatus, a gas pressure of 45 kPa is applied to the pressure membrane apparatus, and the drain valve is opened to balance the suction of the specimen until the volume of water drained within 24 h is less than 0.1 mL, which is regarded as the suction being balanced.

[0052] S4: According to the soil-water characteristic curve obtained from the existing soil property tests, when the suction is 45 kPa, the saturation of the specimen is 90%. At this time, the dry density of the specimen is relatively low, presenting a softer state, and it is difficult to load the specimen. During the loading process, the specimen will be crushed by the top cap. Therefore, the soft soil specimen to be loaded is quick-frozen for no less than 3 h, and the specimen is loaded when it is frozen and not melted. In this way, it can be ensured that the specimen will not be crushed, bent or damaged when it is loaded into the unsaturated soil vibration device considering the multi-suction mechanism, thus reducing the influence on the test. Referring to the specification T / CECS1337-2023, when performing suction balance, a back pressure of 5 kPa needs to be applied to control the pore water pressure to 5 kPa. Since the suction of the soil sample is 45 kPa, and the suction is equal to the difference between the pore air pressure and the pore water pressure, an additional air pressure of 50 kPa needs to be applied. According to the specification, the inner and outer confining pressures should be greater than the air pressure by 20 kPa, that is, an additional inner and outer confining pressure of 70 kPa is applied. Finally, an axial pressure of about 75 kPa, which is greater than the confining pressure by 5 kPa, is applied for further suction balance. Among them, in unsaturated soil, when the water content is low, the adsorption suction plays a dominant role; when the water content is high, the capillary suction plays a dominant role; the solute suction plays a dominant role when the solute concentration is high. The test method of this test is to control the corresponding suction when the corresponding suction plays a dominant role. The specific control method is as follows: when conducting the unsaturated soil vibration test to control the adsorption suction, turn on the peristaltic circulation pump to make the saturated salt solution vapor circulate on the upper and lower surfaces of the specimen to balance the saturated salt solution vapor, and always keep the saturated salt solution vapor circulating on the upper and lower surfaces of the specimen during the consolidation process; when conducting the unsaturated soil vibration test to control the capillary suction, rebalance the capillary suction by adjusting the air pressure and water pressure difference, and perform consolidation by gradually applying isotropic confining pressure; when conducting the saturated or quasi-saturated soil vibration test to control the solute suction, saturate the specimen with a saturated salt solution, make the saturated salt solution vapor circulate on the upper and lower surfaces of the specimen through a peristaltic pump, and perform isotropic consolidation when keeping the saturated salt solution vapor always circulating on the upper and lower surfaces of the specimen. Finally, when the drainage volume is less than 12 mm within 2 h 3 it is regarded as suction balance;

[0053] S5: This case is a vibration triaxial test with an effective confining pressure of 50 kPa. Keep the air pressure and back pressure unchanged, and increase the effective confining pressure until 50 kPa, that is, control the confining pressure to increase to 100 kPa (effective confining pressure = confining pressure - pore air pressure) for consolidation;

[0054] S6: Turn off the back pressure, keep the confining pressure constant, and turn on the load control device for vibration shearing;

[0055] S7: Dismantle the sample, observe the state of the sample, organize the experimental data, plot the stress-strain curve, dynamic pore water pressure time history curve, dynamic strain time history curve, and dynamic elastic modulus ratio curve. Comprehensively consider the dynamic strain, dynamic pore water pressure, and dynamic elastic modulus ratio to determine the failure vibration times and failure types of the sample.

[0056] The specific steps are as follows:

[0057] Step S71, in this embodiment, extract the axial displacement h during the consolidation stage from the experimental data g = 2.873 mm, and the pore water pressure p during the consolidation stage g = -24.25 kPa; the axial pressure F during the vibration stage d , the axial displacement h during the vibration stage d , and the dynamic pore pressure p during the vibration stage d ;

[0058] Step S72, subtract the axial displacement h during the consolidation stage from the height of the sample before consolidation (the height of the sample made in this embodiment before consolidation is 100 mm) g = 2.8738 mm to calculate the height h of the sample after consolidation c = 100 - 2.8738 = 97.1262 mm, and then use the axial displacement h during the vibration stage d to calculate the axial dynamic strain ε d , and the formula is: where h d is the axial displacement during the vibration stage, h g is the axial displacement during the consolidation stage, Δh is the axial dynamic deformation, and ε d is the axial dynamic strain. In this embodiment, the variation curve of ε d is as shown in Figure 3 ;

[0059] Step S73, use the axial pressure F during the vibration stage d , and according to the cross-sectional area A of the test sample. In this embodiment, A = 0.001963495 m 2 , calculate the dynamic deviator stress σ during the vibration stage through the formula , and in this embodiment, the variation curve of σ d is as shown in d Figure 4 ;

[0060] Step S74, subtract the pore pressure value p at the end of consolidation from the dynamic pore pressure value p during the vibration stage in sequence d to obtain the cumulative value p of the dynamic pore pressure during the vibration stage g , and in this embodiment, the variation curve of p a is as shown in a Figure 5 ; ;

[0061] Step S75. Since the data sampling frequency is once every 0.01 s and the amount of data is huge, code is written in Matlab to process the data. Taking the cycle period as the group sequence, for the dynamic deviator stress σ d and the axial dynamic strain value ε d in each cycle period, correction processing is carried out. First, find the average value of the dynamic deviator stress d σ and the dynamic strain value ε d in each cycle period and the average value of the dynamic strain Immediately, use the dynamic deviator stress value σ d and the dynamic strain value ε d in each cycle period to subtract the average value of the dynamic deviator stress and the average value of the dynamic strain in each cycle period respectively, to obtain the corrected dynamic deviator stress value σ′ d and the corrected dynamic strain value ε′ d ;

[0062] Step S76. Select the maximum corrected dynamic deviator stress value σ′ d and the maximum corrected dynamic strain value ε′ d from the corrected dynamic deviator stress value σ′ max and the corrected dynamic strain value ε′ max in the cycle period, and calculate the dynamic elastic modulus E of the cycle period through the formula d . In this embodiment, the variation curve of E d is as shown in Figure 6 ;

[0063] Step S77. Calculate the ratio of the dynamic elastic modulus of each cycle period. The ratio of the dynamic elastic modulus is the ratio of the maximum elastic modulus E d in Step S76 to the dynamic elastic modulus E max of each cycle period. In this embodiment, the variation curve of the ratio of the dynamic elastic modulus is as shown in Figure 7 ;

[0064] Step S78. Plot the time history curve of the dynamic strain, the dynamic stress - dynamic strain curve, the time history curve of the cumulative value of the dynamic pore water pressure, and the time history curve of the ratio of the dynamic elastic modulus, and find the number of vibrations when the dynamic strain reaches 3%. Among them, the vibration period set in this embodiment is 1 s, that is, the number of vibrations of the device per second is 1 time, as shown in Figure 3As shown, when the vibration frequency N1 = 9, the dynamic strain reaches 3%, and when checking the vibration frequency N2 = 7 at which the cumulative value of the dynamic pore water pressure rises to 20% of the effective confining pressure, it indicates that when the dynamic strain reaches 3%, the cumulative pore water pressure has risen to 20% of the effective confining pressure; the vibration frequency N3 = 10 when the dynamic strain reaches 5%; the vibration frequency N4 = 8 when the ratio of the dynamic elastic modulus drops to 10%. From the above three conditions, it can be inferred that at the 8th vibration, the ratio of the dynamic elastic modulus drops to 10% and when the dynamic strain reaches 3%, the cumulative pore water pressure has risen to 20% of the effective confining pressure, then the failure vibration frequency N f = 8.

[0065] It should be noted that the confining pressure controller, back pressure controller, air pressure control device in the pressure regulating device 5 and the sensors in the data acquisition device are all existing commodities that can be purchased on the market. Those skilled in the art can connect the confining pressure controller, back pressure controller and air pressure control device to the device of the technical solution of the present invention and realize the corresponding functions according to the product instructions and professional knowledge, so no further description will be given here.

[0066] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An unsaturated soil vibration device considering multiple suction mechanisms, characterized in that: include: Foundation vibration triaxial internal-external pressure chamber device, counterweight, surface moisture control device, load control device, pressure regulating device and data acquisition device; The basic vibration three-axis internal-external pressure chamber device includes an internal pressure chamber and an external pressure chamber sleeved on the outside of the internal pressure chamber, the shells of the internal pressure chamber and the external pressure chamber are sealed structures, and the internal pressure chamber is used to hold the test sample; the balance hammer is fixedly connected to the base inside the internal pressure chamber; the surface humidity control device is connected to the interior of the internal pressure chamber through a conduit; the load control device includes a load vibrator, a pressure shaft and a load sensor, the load vibrator is fixedly connected to the base, the lower end of the pressure shaft is vertically fixed and penetrates the internal pressure chamber, and a top cap is provided at the lower end of the pressure shaft. The top cap abuts against the upper surface of the test sample, and the load sensor is fixedly connected to the pressure shaft to detect the pressure load on the sample; the pressure regulating device includes a confining pressure controller, a back pressure controller and an air pressure control device, and the confining pressure controller, the back pressure controller and the air pressure control device are connected to the sample through a conduit, and the balance hammer is provided with a channel connected to the pressure source medium of the inner pressure chamber and the confining pressure controller; the data acquisition device is connected to the sample placed in the inner pressure chamber through a conduit and a sensor for collecting confining pressure, back pressure, air pressure, pore pressure, load and strain.

2. The unsaturated soil vibration device considering multiple suction mechanisms according to claim 1 is characterized in that: The surface humidity control device comprises a peristaltic circulation pump and a saturated salt solution container. The peristaltic circulation pump, the saturated salt solution container and the upper and lower surfaces of the sample are connected through a circulation pipeline.

3. The unsaturated soil vibration device considering multiple suction mechanisms according to claim 2 is characterized in that: An empty container is connected to the circulation pipeline between the peristaltic circulation pump, the saturated salt solution container and the sample.

4. The unsaturated soil vibration device considering multiple suction mechanisms according to claim 3 is characterized in that: A high air intake value clay plate is arranged above the base, and the test sample is placed on the high air intake value clay plate.

5. A method for evaluating the damage of an unsaturated soil vibration test using an unsaturated soil vibration device considering multiple suction mechanisms according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Select the original soil sample or disturbed soil sample according to the actual situation and prepare the original soil sample or disturbed soil sample according to GB-T50123-2019; S2: Saturate the sample prepared in S1, and select the vacuum saturation method, water head saturation method or back pressure saturation method according to GB-T50123-2019 for different soil sample types; S3: For the saturated sample, the suction is controlled by the pressure plate method or saturated salt solution method in the soil-water characteristic curve test in the specification T / CECS1337-2023 to achieve suction pre-balance. In the pressure plate method, the volume of water discharged within 24 hours is less than 0.1mL, which is considered as suction balance. In the saturated salt solution method, the mass change rate is less than 0.1% / d, which is considered as suction balance. S4: The sample after suction pre-balance is placed in an unsaturated soil vibration device considering multiple suction mechanisms, and a predetermined air pressure, confining pressure, back pressure, and axial pressure are applied for further suction balance. When the drainage volume is less than 12 mm within 2 h, 3 Considered as suction balance; S5: Keep the air pressure and counter pressure unchanged, increase the confining pressure until the effective confining pressure reaches the predetermined effective confining pressure for consolidation; S6: turn off the back pressure, keep the confining pressure constant, and turn on the load control device for vibration shearing; S7: Remove the sample, observe the sample status, organize the experimental data, draw the stress-strain curve, dynamic pore water pressure time history curve, dynamic strain time history curve, dynamic elastic modulus ratio curve, and comprehensively consider the dynamic strain, dynamic pore water pressure, and dynamic elastic modulus ratio to determine the failure frequency and failure type of the sample.

6. The unsaturated soil vibration test failure evaluation method considering multiple suction mechanisms according to claim 5 is characterized in that: In step S3, when controlling the adsorption suction balance, a saturated salt solution method is used to perform suction pre-balance, and when controlling the capillary suction balance, a pressure plate method is used to perform suction pre-balance.

7. The unsaturated soil vibration test failure evaluation method considering multiple suction mechanisms according to claim 6 is characterized in that: In step S4, when the soft soil is sampled, the soft soil sample to be loaded is quickly frozen for no less than 3 hours, and the sample is loaded when the sample is frozen and not melted.

8. The unsaturated soil vibration damage evaluation method considering multiple suction mechanisms according to claim 7 is characterized in that: In step S4, when carrying out the unsaturated soil vibration test for controlling adsorption suction, the pre-balanced sample is placed in the unsaturated soil vibration device considering multiple suction mechanisms, the peristaltic circulation pump is turned on to circulate the saturated salt solution vapor on the upper and lower surfaces of the sample to balance the saturated salt solution vapor, and the saturated salt solution vapor is always kept circulating on the upper and lower surfaces of the sample during the consolidation process; when carrying out the unsaturated soil vibration test for controlling capillary suction, the experimental sample is placed in the unsaturated soil vibration device considering multiple suction mechanisms, the capillary suction is rebalanced under the required air pressure and water pressure difference, isotropic confining pressure is applied step by step, and consolidation is carried out; when carrying out the saturated or quasi-saturated soil vibration test for controlling solute suction, the sample is saturated with a saturated salt solution, placed in the unsaturated soil vibration device considering multiple suction mechanisms, the peristaltic pump is turned on to circulate the saturated salt solution vapor on the upper and lower surfaces of the sample, and isotropic consolidation is carried out while the saturated salt solution vapor is always circulated on the upper and lower surfaces of the sample.

9. The unsaturated soil vibration test failure evaluation method considering multiple suction mechanisms according to claim 7 is characterized in that: The step S7 comprises: Step S71, extracting the axial displacement h in the consolidation stage according to the experimental data g , pore pressure p in the consolidation stage g ; Axial pressure F during vibration stage d , axial displacement h of the vibration stage d , dynamic pore pressure p in the vibration stage d ; Step S72: subtract the axial displacement h during the consolidation stage from the height of the sample before consolidation. g Calculate the height h of the sample after consolidation c , and then use the axial displacement h of the vibration stage d Calculate the axial dynamic strain ε d , the formula is: Among them, h d is the axial displacement during the vibration stage, h g The axial displacement in the consolidation stage, Δh is the axial dynamic deformation, ε d is the axial dynamic strain; Step S73, using the axial pressure F during the vibration stage d , according to the cross-sectional area A of the test specimen, through the formula Calculate the dynamic deviator stress σ during the vibration stage d ; Step S74, using the dynamic pore pressure value p in the vibration stage d Subtract the pore pressure value p at the end of consolidation g , and the cumulative value of dynamic pore pressure p in the vibration stage is obtained a ; Step S75, grouping the dynamic deviator stress σ in each cycle according to the cycle period d and axial dynamic strain value ε d To perform correction processing, first calculate the dynamic deviator stress value σ for each cycle d and dynamic strain value ε d The average value of the dynamic deviator stress and the average dynamic strain Then, the dynamic deviator stress value σ of each cycle is used d and dynamic strain value ε d Subtract the average value of the dynamic deviator stress of each cycle and the average dynamic strain Get the modified dynamic deviator stress value σ′ of each cycle d and the modified dynamic strain value ε′ d . Step S76, select the corrected dynamic deviator stress value σ′ in the cycle d and the modified dynamic strain value ε′ d The maximum modified dynamic deviator stress value σ′ in max and the maximum modified dynamic strain value ε′ max , and by the formula Calculate the dynamic elastic modulus E of the cycle d ; Step S77, calculating the dynamic elastic modulus ratio of each cycle, the dynamic elastic modulus ratio is the maximum elastic modulus E in step S76 max The dynamic elastic modulus E per cycle d The ratio of Step S78, draw the dynamic strain time history curve, dynamic stress dynamic strain curve, dynamic pore water pressure cumulative value time history curve, dynamic elastic modulus ratio time history curve, find the vibration number N1 where the dynamic strain reaches 3% and check whether the dynamic pore water pressure cumulative value rises to 20% of the effective confining pressure under the vibration number N1; the vibration number N2 where the dynamic strain reaches 5%; the vibration number N3 where the dynamic elastic modulus ratio drops to 10%. If two of the above three conditions are met, it is considered as the failure vibration number N f .

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