A test device and method for simulating high-speed cyclic shearing-seepage of rock fractures

Abstract

The application discloses a kind of test device and method of simulating rock fissure high-speed cyclic shearing-seepage, belong to rock mass engineering test field;Device includes shearing and guiding system, excitation loading system, shearing box sealing system and normal partition loading system;Shearing and guiding system realizes large displacement shearing, excitation loading system adopts three degrees of freedom high-speed cyclic excitation platform, can be in shearing process simultaneously superimposed three-dimensional cyclic excitation, shearing box sealing system realizes the dynamic stability of high-pressure seepage by end face main sealing and side dynamic sealing, normal partition loading system realizes non-uniform normal loading and sample deflection inhibition by independent controllable pressurizing head.The present application solves the technical problems that the existing device cannot realize high-speed shearing-multidimensional vibration coupling loading, seepage sealing reliability is poor under dynamic condition, and cannot simulate non-uniform stress field, provides accurate and reliable test means for the evolution mechanism research of rock mass fissure under the action of dynamic-seepage coupling.

Description

Technical Field

[0001] This invention relates to the field of rock mass engineering testing technology, and more particularly to a rock fracture shear-seepage coupling test device and method, and more specifically, to a test device and method for simulating high-speed cyclic shear-seepage in rock fractures. Background Technology

[0002] In rock engineering, scenarios such as fault activation, rock slope instability, deep rock hydraulic fracturing, and blasting excavation disturbance all involve high-speed shear sliding and abrupt changes in seepage characteristics of rock fissures under complex stress conditions. In actual engineering, dynamic loads such as seismic wave propagation, mechanical vibration, and blasting impact cause rock fissures to simultaneously endure multi-field coupling effects of cyclic shear, normal stress fluctuation, multi-dimensional horizontal vibration, and high-pressure seepage. The shear mechanics characteristics and seepage evolution laws of the fissures directly determine the stability and disaster prevention effectiveness of rock engineering projects.

[0003] In existing technologies, conventional rock fracture direct shear-seepage test devices can only simulate quasi-static shear processes in a single direction, and have the following core technical defects: First, they cannot achieve synchronous coupling of high-speed shear with large displacement and multi-dimensional cyclic vibration. The vibration loading and shear loading of traditional devices are independent of each other, and cannot reproduce the real stress state of fractures simultaneously subjected to three-dimensional vibration during high-speed shear under dynamic conditions such as earthquakes and blasting. The test conditions are seriously out of touch with engineering reality. Second, the reliability of seepage sealing is poor under dynamic conditions. Conventional static sealing structures are prone to sealing failure and seepage boundary instability under the coupling effect of high-speed shear and high-frequency vibration. They cannot maintain stable boundary conditions for high-pressure seepage tests, resulting in excessive errors in seepage parameter testing. Third, the normal loading method is singular. Existing devices mostly adopt integral normal loading, which cannot effectively offset the bending moment generated during shearing, suppress sample deflection, or simulate the non-uniform stress distribution characteristics that are widely present in natural strata, and cannot reproduce the real occurrence environment of the rock mass.

[0004] The aforementioned technical bottlenecks severely restrict in-depth research on the evolution mechanism of rock fractures under dynamic-seepage coupling. Therefore, it is urgent to develop a rock fracture shear-seepage test device and method that can simultaneously achieve high-speed shear-multidimensional vibration superposition, reliable sealing under dynamic conditions, and partitioned non-uniform normal loading, in order to solve many defects in the existing technology. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides an experimental device and method for simulating high-speed cyclic shear-seepage in rock fractures. This method can solve the technical problems in the prior art, such as the inability to simultaneously superimpose multidimensional cyclic excitation during high-speed shearing, poor reliability of seepage sealing under dynamic conditions, inability to simulate non-uniform normal stress distribution, and inability to suppress sample shear deflection. It can accurately reproduce the complex stress and seepage environment of rock fractures in engineering practice, and provide a reliable experimental means for studying the dynamic-seepage coupling evolution mechanism of rock fractures.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a test device for simulating high-speed cyclic shear-seepage in rock fissures, comprising a frame matrix, a shear box, a seepage control system, a shear and guiding system, an excitation loading system, a shear box sealing system, and a normal zonal loading system; wherein the shear box is used to place rock samples; the rock samples include a lower rock sample, an upper rock sample, and the fissure between the two.

[0007] The shearing and guiding system includes a lower horizontal slide rail, an upper horizontal slide rail, a lower tangential loading head, an upper left tangential loading head, and an upper right tangential loading head. The lower and upper horizontal slide rails are both fixedly installed on the frame base. The lower tangential loading head is mounted on the sliding component of the lower horizontal slide rail and is rigidly connected to the shear box, used to drive the rock sample to perform large displacement shearing motion in the horizontal direction. The upper left and upper right tangential loading heads are both mounted on the sliding component of the upper horizontal slide rail, used to apply tangential loading forces in different directions to the rock sample.

[0008] The excitation loading system includes a three-degree-of-freedom high-speed cyclic excitation table mounted on a lower horizontal slide rail sliding component, which can apply excitation in different directions to the rock sample while performing large displacement shear motion.

[0009] The shear box sealing system is installed around the fractures in the rock sample and is connected to the seepage control system to maintain a stable seepage boundary in the fractures under dynamic shearing and vibration conditions.

[0010] The normal zonal loading system includes at least two independent and controllable zonal normal loading heads, with the loading ends of the zonal normal loading heads facing the side of the sample, for zonal normal loading of the side of the sample.

[0011] Furthermore, the three-degree-of-freedom high-speed cyclic vibration table includes a normal excitation unit, a first horizontal excitation unit, a second horizontal excitation unit, and a three-phase excitation connecting block. The three-phase excitation connecting block is rigidly connected to the lower part of the shear box. The normal excitation unit, the first horizontal excitation unit, and the second horizontal excitation unit are respectively connected to different surfaces of the three-phase excitation connecting block. While the lower tangential loading head performs large-displacement shearing motion, at least one of the normal excitation unit, the first horizontal excitation unit, and the second horizontal excitation unit is independently driven to perform high-speed cyclic excitation, and the excitation load is transferred to the rock sample and the fracture surface, realizing the synchronous superposition of three-dimensional vibrations during the shearing process. This structure allows the three-degree-of-freedom high-speed cyclic vibration table to be adjusted from one-dimensional to three-dimensional vibration as needed, ensuring the stability of the experiment.

[0012] Furthermore, the normal excitation unit is connected to one surface of the three-phase excitation connecting block via a first horizontal guide rail and a second horizontal guide rail, allowing the normal excitation unit to move to different positions on that surface for normal excitation. The first horizontal excitation unit is connected to one surface of the three-phase excitation connecting block via a normal guide rail and a second horizontal guide rail, allowing the first horizontal excitation unit to move to different positions on that surface for first horizontal excitation. The second horizontal excitation unit is connected to one surface of the three-phase excitation connecting block via a normal guide rail and a first horizontal guide rail, allowing the second horizontal excitation unit to move to different positions on that surface for second horizontal excitation. Each of the normal excitation unit, the first horizontal excitation unit, and the second horizontal excitation unit is externally equipped with a centering airbag to suppress sample eccentricity and lateral sway during high-frequency excitation. This structure allows the normal excitation unit to perform excitation at different positions as needed, meeting the requirements of diversified experiments.

[0013] Furthermore, the shear box sealing system includes an end face sealing structure and a side sealing structure; the end face sealing structure includes a seepage chamber pad, an embedded concave sealing gasket, a waterproof pad, a fixed block, and a movable pad; the embedded concave sealing gasket is disposed between the seepage chamber pad and the end faces of the upper and lower rock samples, and by applying a horizontal preload to the fixed block and the movable pad, the seepage chamber pad and the embedded concave sealing gasket are driven to press against the end faces of the upper and lower rock samples to form a surface contact seal; the waterproof pad is sandwiched between the seepage chamber pads corresponding to the end faces of the upper and lower rock samples. The chamber blocks, together with the surrounding spacers, form a seepage chamber communicating with the cracks in the rock sample. Normal pressure is applied to the seepage chamber blocks via a loading head to achieve end-face sealing. The side sealing structure includes a flexible sealing strip, a transverse airbag-type compression side plate, and a U-shaped reaction side plate. The flexible sealing strip is attached to the cracks on the side of the rock sample. The transverse airbag-type compression side plate has an airbag receiving cavity on the sample-facing side, and adjustable compression force is applied to the flexible sealing strip by airbag expansion. The U-shaped reaction side plate is connected to a movable spacer, providing reverse support for the transverse airbag-type compression side plate. This structure further improves the sealing effect of the shear box sealing system, effectively ensuring the stable conduct of high-speed cyclic shear-seepage tests and obtaining accurate test data.

[0014] Furthermore, an L-shaped water injection channel is provided inside the seepage chamber pad, and an arc-shaped guide hole is provided on the movable pad. The seepage chamber is connected to the seepage control system through the L-shaped water injection channel and the arc-shaped guide hole. A waist-shaped hole is provided on the U-shaped reaction side plate to accommodate the limited horizontal displacement of the movable pad during shearing.

[0015] Furthermore, the normal zonal loading system includes four independently adjustable zonal normal pressure heads and a normal friction-reducing component that cooperates with the zonal normal pressure heads. The four zonal normal pressure heads are arranged in a row on the side of the specimen. Each zonal normal pressure head is independently set with a loading load. By differentially adjusting the load of each zonal section, the bending moment generated during shearing is offset, or the load is set according to a preset spatial distribution to achieve a non-uniform normal loading test of the rock fracture. The normal friction-reducing component is used to ensure the normal free movement of the upper rock specimen during shearing. With this structure, the normal zonal loading system can meet the loading requirements of different regions individually or in combination, according to the test needs.

[0016] Furthermore, the pipeline of the seepage control system is sequentially equipped with an inlet pressure sensor, an inlet flow meter, and a fluid collection device for real-time monitoring and control of the pressure and flow parameters of the fissure seepage.

[0017] A test method for simulating high-speed cyclic shear-seepage in rock fractures, using the above-mentioned test apparatus, includes the following steps:

[0018] S1. Rock sample installation and system assembly: Install the rock sample in the shear box and assemble the shear box sealing system on both ends of the rock sample to complete the end face sealing. At the same time, connect the cracks in the rock sample to the seepage control system. Then, assemble the shear and guiding system, the vibration loading system, and the normal zone loading system in sequence.

[0019] S2. System preload and sealing verification: The sample side is subjected to zonal normal loading according to the settings through the normal zonal loading system. The seepage control system is turned on and adjusted to the set seepage conditions. The consistency of inlet and outlet water flow and system sealing are checked. After confirming that there is no leakage, the test stage is entered.

[0020] S3, Shear-Vibration-Seepage Coupling Test: The rock sample is sheared at a constant speed along the horizontal direction by a shear and guiding system at a set rate. At the same time, the corresponding excitation unit of the three-degree-of-freedom high-speed cyclic excitation table is driven to work according to the test conditions. Different excitation conditions are superimposed synchronously during the shearing process to realize shear-vibration-seepage multi-field coupled loading.

[0021] S4. Synchronous acquisition and processing of experimental data: During the experiment, shear mechanical parameters, normal loading parameters, excitation force parameters and seepage characteristic parameters are acquired simultaneously to obtain the mechanical response and seepage evolution data of rock fractures under multi-field coupling.

[0022] Furthermore, in step S3, the excitation conditions include single-channel independent excitation, dual-channel synchronous excitation, and three-channel coupled excitation, and the excitation frequency, amplitude, and phase can all be adjusted independently.

[0023] Furthermore, in steps S3 and S4, based on the sample deflection data collected during the test, the loading load of the normal pressure head in each zone is adjusted differentially in real time to dynamically suppress the deflection and bending moment during the sample shearing process, or to dynamically adjust the non-uniform normal stress distribution.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. This invention achieves synchronous coupling loading of high-speed shearing with large displacement and high-speed cyclic excitation with three degrees of freedom. By integrating the three-degree-of-freedom high-speed cyclic excitation table onto the sliding path of the shearing motion, the excitation table can complete synchronous large displacement motion with the shearing loading, and can also independently output three-dimensional high-speed cyclic excitation. It realistically reproduces the complex stress state of rock mass fissures simultaneously bearing normal and bidirectional horizontal vibrations during high-speed shearing under dynamic loads such as earthquakes and blasting. It solves the core problem that traditional devices cannot synchronously couple shearing and vibration loading, and greatly improves the fit between experimental conditions and engineering practice.

[0026] 2. This invention designs a composite sealing system of end face main pressure seal + side dynamic seal. The end face seal forms a bidirectional surface contact seal through lateral tightening and normal pressure, while the side seal achieves dynamic adaptive sealing through an airbag-type flexible sealing strip. Under the coupled dynamic conditions of high-speed shearing and high-frequency vibration, it can always maintain a stable sealing effect around the crack, effectively solving the problems of easy failure and high-pressure seepage boundary instability of traditional sealing structures under dynamic conditions, and significantly improving the accuracy and reliability of seepage parameter testing.

[0027] 3. This invention employs a multi-channel, independently controllable, partitioned normal loading system. On the one hand, it can actively counteract the bending moment generated during shearing by differentially adjusting the loading load of each partition, effectively suppressing the shear deflection of the specimen and ensuring the stability of the test boundary conditions. On the other hand, it can flexibly set the load distribution of each partition, accurately simulate the non-uniform stress field that is widely present in natural strata, restore the real occurrence environment of the rock mass, and solve the defect that traditional integral normal loading cannot adapt to complex stress conditions.

[0028] 4. The device of this invention has a high degree of integration and strong controllability of test parameters. The shear rate, excitation dimension and parameters, seepage pressure, and normal load distribution can all be adjusted independently. It can cover the full range of working condition test requirements from quasi-static to high-speed shear, static to high-frequency dynamic excitation, atmospheric pressure to high-pressure seepage, and uniform to non-uniform normal loading. It provides a comprehensive, accurate and reliable test method for studying the evolution mechanism, strength degradation law, and seepage mutation characteristics of rock fractures under dynamic-seepage coupling. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0030] Figure 2 This is a front view of the shear box sealing system in this invention.

[0031] Figure 3 This is a top view of the shear box sealing system in this invention.

[0032] Figure 4 This is a schematic diagram of the assembly structure of the shear box sealing system in this invention.

[0033] Figure 5 This is an assembly diagram of the end face sealing structure in this invention.

[0034] Figure 6 This is an assembly diagram of the side sealing structure in this invention.

[0035] Figure 7 This is a front view schematic diagram of the three-degree-of-freedom high-speed cyclic excitation table in this invention.

[0036] Figure 8This is a front view schematic diagram of the three-degree-of-freedom high-speed cyclic excitation table in this invention.

[0037] In the diagram: 101-Lower horizontal slide rail; 102-Upper horizontal slide rail; 103-Lower tangential loading head; 104-Upper left tangential loading head; 105-Upper right tangential loading head; 106-Partitioned normal pressure head; 107-Padded block loading head; 108-Normal friction reduction component; 201-Three-degree-of-freedom high-speed cyclic vibration table; 202-Z-direction normal vibration unit; 203-X-direction horizontal vibration unit; 204-Y-direction horizontal vibration unit; 205-Centering airbag; 206-Three-directional vibration connecting block; 207-X-guide rail; 208-Y-guide rail; 209-Z-guide rail; 301-Upper rock test Sample; 302-Lower rock sample; 303-Fissure; 304-Fixing block; 305-Horizontal through threaded hole; 306-Movable pad; 307-Arc-shaped guide hole; 308-Seepage chamber pad; 309-L-shaped water injection channel; 310-Seepage chamber; 311-Imperceptible pad; 312-Embedded concave sealing gasket; 313-Flexible sealing strip; 314-Transverse airbag compression side plate; 315-Airbag receiving cavity; 316-U-shaped reaction side plate; 317-Oval hole; 401-Seepage control system; 402-Inlet water pressure sensor; 403-Inlet water flow meter; 404-Fluid collection device. Detailed Implementation

[0038] The present invention will be further described below.

[0039] Example 1: The experimental apparatus in this example is as follows Figure 1 As shown, it includes four core modules: shearing and guiding system, vibration loading system, shear box sealing system and normal zoning loading system, and is equipped with shear box, seepage control system 401 and data acquisition system.

[0040] The shearing and guiding system provides bidirectional shearing guidance and drive for the device, including a lower horizontal slide rail 101, an upper horizontal slide rail 102, a lower tangential loading head 103, an upper left tangential loading head 104, and an upper right tangential loading head 105. The lower horizontal slide rail 101 and the upper horizontal slide rail 102 are both fixedly installed on the rigid frame base of the device by high-strength bolts. The two sets of slide rails are arranged in parallel. The first horizontal direction (shear direction) is set as the X direction, and the extension direction of the slide rail is consistent with the X direction. The lower tangential loading head 103 is driven by a servo hydraulic loading cylinder. The lower tangential loading head 103 is connected to the sliding slider on the lower horizontal slide rail 101. It can drive the slider to complete a large displacement constant speed shearing motion of 0~500mm / s along the X direction. The upper left tangential loading head 104 and the upper right tangential loading head 105 are both driven by servo hydraulic cylinders. The two sets of loading heads are symmetrically arranged. They can perform bidirectional clamping, positioning and centering adjustment of the upper rock sample 301. If necessary, they can drive the upper rock sample 301 to complete the reverse shearing motion to realize the bidirectional cyclic shearing test.

[0041] The excitation loading system is used to achieve synchronous superposition of three-dimensional vibrations during shearing. Its core is a three-degree-of-freedom high-speed cyclic excitation table 201, the structure of which is as follows: Figure 7 , Figure 8 As shown, the second horizontal direction is defined as the Z-axis, and the normal direction is defined as the Z-axis. The base of the three-degree-of-freedom high-speed cyclic vibration table 201 is fixed to the sliding block of the lower horizontal slide rail 101 by high-strength bolts. Driven by the lower tangential loading head 103, the slider can perform synchronous large-displacement shearing motion along the X-axis. The three-degree-of-freedom high-speed cyclic vibration table 201 integrates a Z-axis normal vibration unit 202, an X-axis horizontal vibration unit 203, and a Y-axis horizontal vibration unit 204. All three vibration units use high-frequency servo vibrators with a rated vibration frequency of 0~200Hz and a maximum vibration acceleration of ±10g. They can work independently or collaboratively. The three-degree-of-freedom high-speed cyclic vibration table 201 also includes... X-guide rail 207, Y-guide rail 208, Z-guide rail 209 and triaxial excitation connecting block 206, Z-direction normal excitation unit 202, X-direction horizontal excitation unit 203 and Y-direction horizontal excitation unit 204 are respectively connected to the triaxial excitation connecting block 206 through corresponding guide rails. The top of the triaxial excitation connecting block 206 is rigidly connected to the lower part of the shear box, which can transfer the three-dimensional excitation load to the surface of the lower rock sample 302 and the crack 303 without loss. Each of the Z-direction normal excitation unit, X-direction horizontal excitation unit and Y-direction horizontal excitation unit is equipped with a centering airbag 205 to suppress the eccentricity and lateral sway of the sample during high-frequency excitation and improve the stability of the test.

[0042] The shear box sealing system is used to maintain a stable seepage boundary of the fracture under dynamic conditions. The shear box sealing system is installed around the fracture 303 between the upper rock sample 301 and the lower rock sample 302 to maintain a stable seepage boundary of the fracture under dynamic shear and vibration conditions.

[0043] The normal zonal loading system includes two independently controllable zonal normal loading heads 106. The loading ends of the zonal normal loading heads 106 are set towards the side of the sample and are used to perform zonal normal loading on the side of the sample.

[0044] The seepage control system 401 adopts a servo constant pressure and constant flow pump station with a rated water supply pressure of 0~20MPa. The pipeline is equipped with an inlet pressure sensor 402, an inlet flow meter 403, and a fluid collection device 404 in sequence. It can monitor and control the pressure and flow parameters of the fissure seepage in real time. The data acquisition system can simultaneously collect all parameters such as shear force, shear displacement, zoned normal load, excitation frequency / amplitude / acceleration, seepage pressure, and seepage flow rate. The sampling frequency can reach up to 1MHz.

[0045] Example 2: The test apparatus in this example is based on Example 1, with further optimization of the shear box sealing system. The specific structure includes an end face sealing structure and a side face sealing structure. The overall assembly structure is as follows: Figures 2 to 6 As shown.

[0046] The end-face sealing structure includes a seepage chamber pad 308, an embedded concave sealing gasket 312, a waterproof pad 311, a fixing block 304, and a movable pad 306. The fixing block 304 is fixed to both ends of the shear box by high-strength bolts. Multiple rows of horizontal through-threaded holes 305 are provided along the height direction on the fixing block 304. A long through-bolt passes through the horizontal through-threaded holes 305 and pushes the movable pad 306 at its end. The embedded concave sealing gasket 312, made of wear-resistant and highly elastic polyurethane material, is positioned between the seepage chamber pad 308 and the end faces of the upper and lower rock samples. The movable pad 306 is fixedly connected to the seepage chamber pad 308. Through the pushing action of the long through-bolt, the seepage chamber pad 308 and the embedded concave sealing gasket 312 are driven to press against the end faces of the upper and lower rock samples, forming a... The initial seal is formed by surface contact; the impermeable pad 311 is made of high-strength stainless steel and is sandwiched between the seepage chamber pads 308 corresponding to the end faces of the upper and lower rock samples, and the three form a seepage chamber 310 that communicates with the crack 303; the pad loading head 107 is a servo hydraulic cylinder, and its loading end applies Z-direction pressure to the upper seepage chamber pad 308 to further press the contact surface and complete the end face main pressure seal; an L-shaped water injection channel 309 is opened in the seepage chamber pad 308, and an arc-shaped guide hole 307 is opened on the movable pad 306. The seepage inlet and outlet water pipelines that communicate with the seepage chamber 310 are led out through the L-shaped water injection channel 309 and the arc-shaped guide hole 307, respectively, and are connected to the seepage control system 401. The arc-shaped guide hole 307 can adapt to the angle change of the pipeline during the shearing process to avoid pipeline bending and blockage.

[0047] The side sealing structure includes a flexible sealing strip 313, a transverse airbag compression side plate 314, and a U-shaped reaction side plate 316. The flexible sealing strip 313 is made of water-swellable rubber and is attached to the periphery of the cracks 303 on both the front and rear sides of the rock sample. The transverse airbag compression side plate 314 has a strip-shaped airbag receiving cavity 315 on the side facing the rock sample, which contains a high-pressure airbag. After the airbag is inflated, it can apply a uniform and adjustable linear compression force to the flexible sealing strip 313 to achieve dynamic adaptive sealing. The U-shaped reaction side plate 316 has waist-shaped holes 317 at both ends, which are connected to the movable pad 306 by connecting bolts to provide rigid reverse support for the transverse airbag compression side plate 314. The waist-shaped holes 317 can adapt to the limited X-direction displacement of the movable pad 306 during shearing, avoiding damage to the sealing structure by shear force and forming a three-dimensional stable reaction sealing frame.

[0048] Example 3: Based on Example 2, the test apparatus in this example further optimizes the normal zoning loading system to better achieve non-uniform normal loading and specimen deflection suppression. The specific structure includes four independently adjustable zoning normal pressure heads 106 and a normal friction-reducing component 108 that cooperates with the zoning normal pressure heads 106. All four zoning normal pressure heads 106 are driven by servo hydraulic cylinders and arranged in a single row from left to right along the top side of the specimen, allowing for independent setting of the loading load. The normal friction-reducing component 108 uses a linear rolling guide pair and is equipped with... Between the upper rock sample 301 and the upper left and upper right tangential loading heads respectively, the sliding friction during the shearing process can be converted into rolling friction, with a friction coefficient of less than 0.005, ensuring that the upper rock sample 301 can move freely in the normal direction during the shearing process and avoiding interference of the normal load with the shearing motion. During the test, by differentially adjusting the loads of the four partition normal pressure heads 106, the bending moment generated during the shearing process can be offset, actively suppressing the deflection of the sample. Alternatively, the loads of each partition can be set according to the preset spatial distribution to accurately simulate the non-uniform normal stress field.

[0049] Example 4: Quasi-static unidirectional shear-normal single-channel excitation-uniform normal loading-atmospheric pressure seepage coupling test.

[0050] The experiment in this embodiment is based on the experimental apparatus described in the previous embodiment. It is used to simulate the working condition of rock fractures under quasi-static shearing under the coupling effect of normal vibration and normal pressure seepage during conventional excavation disturbance of deep rock masses. The specific implementation steps are as follows:

[0051] S1. Rock sample installation and system assembly:

[0052] S1.1 Specimen Bottom Installation and Initial End-Face Sealing: A standard cylindrical granite specimen, 50mm in diameter and 100mm in height, is used. A single fracture is pre-fabricated along the middle of the specimen using the Brazilian splitting method, with a fracture surface roughness of JRC=8~10. The specimen is then divided into an upper rock specimen 301 and a lower rock specimen 302. The lower rock specimen 302 is placed in a shear box for centering and fixing. Embedded concave sealing gaskets 312 and [other sealing elements] are sequentially installed on the inlet and outlet ends of the specimen. The flow chamber pad 308 and the movable pad 306 are connected by passing a long through bolt through the horizontal through thread hole 305 of the fixed block 304 and tightening the bolt evenly to push the movable pad 306, so that the flow chamber pad 308 and the embedded concave sealing gasket 312 are tightly fitted to the end face of the lower rock sample 302, thus completing the initial sealing of the end face; at the same time, the inlet and outlet water pipelines are led out through the L-shaped water injection channel 309 and the arc-shaped guide hole 307 respectively, and connected to the corresponding interface of the seepage control system 401.

[0053] S2.2, Upper installation of the sample and main pressure sealing of the end face: Place the upper rock sample 301 on top of the lower rock sample 302, adjust the position of the sample to accurately align the fracture surfaces of the upper and lower rock samples, and clamp the upper rock sample 301 in both directions through the upper left tangential loading head 104 and the upper right tangential loading head 105 to complete the centering and positioning; place an impermeable pad 311 between the seepage chamber pads 308 corresponding to the end faces of the upper and lower rock samples, start the pad loading head 107 to apply the set Z-direction pressure to the seepage chamber pads 308 of the upper rock sample 301, press the contact surface to complete the main pressure sealing of the end face, so that the fracture 303 and the seepage chamber 310 form a closed seepage space.

[0054] S2.3 Dynamic sealing assembly of the sample side: Flexible sealing strips 313 are attached and pasted around the cracks 303 on both the front and rear sides of the upper and lower rock samples. Transverse airbag compression side plates 314 are installed so that the airbag receiving cavity 315 is aligned with the flexible sealing strips 313. U-shaped reaction side plates 316 are installed and fixedly connected to the movable pads 306 at both ends by connecting bolts to form a three-dimensional reaction frame. High-pressure gas at a set pressure is filled into the airbag in the airbag receiving cavity 315 so that the airbag expands and presses the flexible sealing strips 313, thus completing the dynamic sealing of the rock sample side.

[0055] S2. System Preload and Sealing Verification: Activate the four zoned normal pressure heads 106. With the cooperation of the normal friction reduction component 108, apply the set zoned preload to the top side of the sample. The load of each pressure head is set to 5kN, and the total normal load is 20kN. Turn on the seepage control system 401 and gradually increase the seepage water pressure to 1MPa (normal pressure). Hold the pressure for 30 minutes and monitor the flow data of the inlet flow meter 403 and the outlet in real time. Verify that the deviation between the inlet and outlet flow rates is less than 2%. At the same time, check that there is no visible leakage in the sealing structure. After confirming that the system sealing is qualified, proceed to the formal test stage.

[0056] S3. Shear-Vibration-Seepage Coupling Test: Start the lower tangential loading head 103, set the shear rate to 0.5 mm / min (quasi-static shear), and the total shear displacement to 10 mm. Drive the three-degree-of-freedom high-speed cyclic excitation table 201 along the lower horizontal slide rail 101 to perform constant-speed shearing in the X direction at the shear rate set in the test. Use a single-channel independent excitation mode, set the excitation frequency to 5 Hz, the excitation amplitude to ±0.2 mm, and the excitation acceleration to ±0.2 g. Synchronously superimpose normal cyclic excitation throughout the shearing process to achieve coupled loading of quasi-static shear-normal excitation-normal pressure seepage.

[0057] S4. Synchronous Acquisition and Processing of Test Data: Throughout the test, the data acquisition system simultaneously acquires data on shear force, shear displacement, normal load, excitation parameters, seepage pressure, and flow rate at a sampling frequency of 10kHz. This allows for the acquisition of the shear strength degradation law and seepage evolution characteristics of granite fissures under the coupled action of quasi-static shear and normal excitation. After the test, the seepage control system 401 is shut down and the pressure is released. Then, the excitation loading system and shear loading system are shut down in sequence to remove the normal load and sealing pressure. The device is then disassembled and the sample is removed to complete the test.

[0058] Example 5: High-speed cyclic bidirectional shear-horizontal dual-channel synchronous excitation-gradient non-uniform normal loading-medium pressure seepage coupling test.

[0059] The experiment in this embodiment is based on the experimental apparatus described in the previous embodiment. It is used to simulate the working conditions of a rock slope under seismic cyclic loading, where the fractured rock mass is subjected to cyclic shearing, bidirectional horizontal vibration, non-uniform stress, and the coupling effect of medium-pressure groundwater seepage. The specific implementation steps are as follows:

[0060] S1. Rock sample installation and system assembly: A rectangular sandstone sample with dimensions of 150mm×100mm×100mm is used. A pre-fabricated sawtooth-shaped structural surface crack is used, with a crack surface undulation difference of 5mm. The sample is divided into upper and lower parts and then installed in the shear box. The sealing system assembly is completed according to the steps of Example 4, wherein the side sealing airbag is pressurized to 1.5MPa, the end face sealing pressure is set to 5MPa, and the seepage pipeline is reliably connected to the seepage control system 401.

[0061] S2. System preload and sealing verification: Start the four zoned normal pressure heads 106, set the gradient non-uniform normal load, and set the loads of the four pressure heads from left to right to 3kN, 6kN, 9kN and 12kN respectively to simulate the gradient geostress field of the slope rock mass; turn on the seepage control system 401, set the seepage pressure to 3MPa (medium pressure), maintain the pressure for 60min, monitor the stability of the inflow and outflow, check that the deviation of the inflow and outflow is less than 3%, and confirm that the sealing system is qualified under non-uniform load.

[0062] S3. Shear-excitation-seepage coupling test: Start the lower tangential loading head 103, the upper left tangential loading head 104, and the upper right tangential loading head 105. Set the cyclic shear rate to 10 mm / s, the shear displacement amplitude to ±20 mm, and the number of cycles to 50 for bidirectional cyclic shearing. Simultaneously start the X-direction horizontal excitation unit 203 and the Y-direction horizontal excitation unit 204 of the three-degree-of-freedom high-speed cyclic excitation table 201. Use the dual-channel synchronous excitation mode. Set the excitation frequency of both channels to 10 Hz, the excitation amplitude to ±0.5 mm, and the phase difference to 0°. Simultaneously superimpose bidirectional horizontal excitation throughout the cyclic shearing process to simulate the horizontal vibration effect of seismic waves and realize multi-field coupled loading of high-speed cyclic shearing, bidirectional horizontal excitation, non-uniform normal loading, and medium-pressure seepage.

[0063] S4. Synchronous acquisition and processing of test data: Throughout the test, full parameter data are synchronously acquired at a sampling frequency of 50kHz. At the same time, the deflection data of the specimen is monitored in real time. When the deflection angle of the specimen exceeds 0.1°, the load of the four zone normal pressure heads is differentially adjusted to dynamically correct the non-uniform load distribution and suppress the specimen deflection. After the test, the pressure is released, the machine is stopped, and the device is disassembled in the specified order to obtain the shear fatigue characteristics and seepage channel evolution law of the sandstone structural surface under the coupled action of cyclic shear and horizontal bidirectional excitation.

[0064] Example 6: Large displacement high-speed shear-three-degree-of-freedom coupled excitation-dynamic deflection suppression-high pressure seepage coupled test.

[0065] The experiment in this embodiment is based on the experimental apparatus described in the previous embodiment. It is used to simulate the conditions under extreme working conditions such as fault activation and seismic displacement, where rock fractures undergo large displacement and high-speed shearing simultaneously under three-dimensional vibration, high-pressure groundwater seepage, and complex geostress. The specific implementation steps are as follows:

[0066] S1. Rock Sample Installation and System Assembly: Marble samples taken from deep fault zones are processed into cuboid samples with dimensions of 200mm×150mm×100mm. The samples are split into upper and lower parts along the natural fracture surface, and the fracture surface is filled with 2mm thick fault gouge. The samples are then installed in the shear box. The sealing system is assembled according to the steps in Example 4, wherein the side sealing airbags are pressurized to 2.5MPa and the end face sealing pressure is set to 10MPa to ensure the sealing reliability under high pressure seepage conditions.

[0067] S2. System preload and sealing verification: Start the four zone normal pressure heads 106, initially set a uniform normal load, with each pressure head having a load of 15kN and a total normal load of 60kN; turn on the seepage control system 401, gradually increase the seepage pressure to 6MPa (high pressure), maintain the pressure for 120min, monitor the stability of the inlet and outlet water flow, check that the deviation of the inlet and outlet water flow is less than 2%, and there is no leakage, thus confirming the stability of the sealing system under high pressure conditions.

[0068] S3. Shear-Vibration-Seepage Coupling Test: The lower tangential loading head 103 is activated, and the shear rate is set to 200 mm / s (high-speed shear), with a total shear displacement of 100 mm, to perform large-displacement unidirectional high-speed shear. Simultaneously, the Z-direction normal excitation unit 202, X-direction horizontal excitation unit 203, and Y-direction horizontal excitation unit 204 of the three-degree-of-freedom high-speed cyclic excitation table 201 are activated, using a three-channel coupled excitation mode. The X-direction excitation frequency is 15 Hz with an amplitude of ±0.3 mm, the Y-direction excitation frequency is 15 Hz with an amplitude of ±0.2 mm, and the Z-direction excitation frequency is 30 Hz with an amplitude of ±0.1 mm. The phase difference of the three channels can be independently adjusted according to the test requirements. Three-dimensional cyclic excitation is synchronously superimposed throughout the high-speed shear process to realistically reproduce the three-dimensional seismic vibration effect during fault displacement.

[0069] S4. Synchronous Acquisition and Processing of Test Data: Throughout the entire test, full parameter data were synchronously acquired at the highest sampling frequency of 1MHz. Simultaneously, the deflection and bending moment data of the specimen were acquired in real time. The loading load of the four zone normal pressure heads was adjusted in real time through closed-loop control. When the specimen showed a deflection trend, the load of the corresponding pressure head was increased or decreased in real time to keep the specimen deflection angle within 0.05° throughout the test, thus eliminating the interference of shear bending moment on the test results. After the test, the seepage control system 401 was shut down and the pressure was released. Then, the excitation loading system and shear loading system were shut down, the normal load and sealing pressure were removed, the device was disassembled and the specimen was cleaned, and the strength mutation law and seepage disaster evolution characteristics of the rock fractures in the fault zone under the coupled action of high-speed shear-three-dimensional excitation-high-pressure seepage were obtained.

Claims

1. A test device for simulating high-speed cyclic shearing-seepage of rock fractures, comprising a frame base body, a shearing box and a seepage control system, characterized in that, It also includes a shearing and guiding system, a vibration loading system, a shear box sealing system, and a normal zone loading system; The shearing and guiding system includes a lower horizontal slide rail, an upper horizontal slide rail, a lower tangential loading head, an upper left tangential loading head, and an upper right tangential loading head. The lower and upper horizontal slide rails are both fixedly installed on the frame base. The lower tangential loading head is mounted on the sliding component of the lower horizontal slide rail and is rigidly connected to the shear box, used to drive the rock sample to perform large displacement shearing motion in the horizontal direction. The upper left and upper right tangential loading heads are both mounted on the sliding component of the upper horizontal slide rail, used to apply tangential loading forces in different directions to the rock sample. The excitation loading system includes a three-degree-of-freedom high-speed cyclic excitation table mounted on a lower horizontal slide rail sliding component. It can apply excitation in different directions to the rock sample while performing large displacement shearing motion. The three-degree-of-freedom high-speed cyclic excitation table includes a normal excitation unit, a first horizontal excitation unit, a second horizontal excitation unit, and a three-phase excitation connecting block. The three-phase excitation connecting block is rigidly connected to the lower part of the shear box. The normal excitation unit, the first horizontal excitation unit, and the second horizontal excitation unit are respectively connected to different surfaces of the three-phase excitation connecting block. While the lower tangential loading head is performing large displacement shearing motion, at least one of the normal excitation unit, the first horizontal excitation unit, and the second horizontal excitation unit is independently driven to perform high-speed cyclic excitation and the excitation load is transferred to the rock sample and the fracture surface to achieve synchronous superposition of three-dimensional vibration during the shearing process. The rock sample includes an upper rock sample, a lower rock sample, and the fracture between the two; The shear box sealing system is installed around the fractures of the rock sample and is connected to the seepage control system to maintain a stable seepage boundary of the fracture under dynamic shear and vibration conditions. The shear box sealing system includes an end face sealing structure and a side face sealing structure. The end face sealing structure includes a seepage chamber pad, an embedded concave sealing gasket, an impermeable pad, a fixed block, and a movable pad. An embedded concave sealing gasket is positioned between the seepage chamber pad and the end faces of the upper and lower rock samples. A horizontal preload is applied to the fixed block and the movable pad, driving the seepage chamber pad and the embedded concave sealing gasket to press against the end faces of the upper and lower rock samples to form a surface contact seal. An impermeable pad is sandwiched between the corresponding seepage chamber pads on the end faces of the upper and lower rock samples, and the three together form a seepage chamber communicating with the cracks in the rock sample. A normal pressure is applied to the seepage chamber pad through the pad loading head. The side sealing structure includes a flexible sealing strip, a transverse airbag compression side plate, and a U-shaped reaction side plate. The flexible sealing strip is attached to the cracks on the side of the rock sample. The transverse airbag compression side plate has an airbag receiving cavity on the side facing the sample, and an adjustable compression force is applied to the flexible sealing strip by the expansion of the airbag. The U-shaped reaction side plate is connected to the movable pad, providing reverse support for the transverse airbag compression side plate. The normal zonal loading system includes at least two independent and controllable zonal normal loading heads, with the loading ends of the zonal normal loading heads facing the side of the sample, for zonal normal loading of the side of the sample.

2. The test device for simulating high-speed cyclic shear-permeability of rock fractures according to claim 1, wherein, The normal excitation unit is connected to one surface of the three-phase excitation connecting block via a first horizontal guide rail and a second horizontal guide rail, allowing the normal excitation unit to move to different positions on that surface for normal excitation. The first horizontal excitation unit is connected to one surface of the three-phase excitation connecting block via a normal guide rail and a second horizontal guide rail, allowing the first horizontal excitation unit to move to different positions on that surface for first horizontal excitation. The second horizontal excitation unit is connected to one surface of the three-phase excitation connecting block via a normal guide rail and a first horizontal guide rail, allowing the second horizontal excitation unit to move to different positions on that surface for second horizontal excitation. Each of the normal excitation unit, the first horizontal excitation unit, and the second horizontal excitation unit is externally equipped with a centering airbag to suppress sample eccentricity and lateral sway during high-frequency excitation.

3. The experimental apparatus for simulating high-speed cyclic shear-seepage in rock fractures according to claim 1, characterized in that, The seepage chamber pad has an L-shaped water injection channel, and the movable pad has an arc-shaped guide hole. The seepage chamber is connected to the seepage control system through the L-shaped water injection channel and the arc-shaped guide hole. The U-shaped reaction side plate has a waist-shaped hole to accommodate the limited horizontal displacement of the movable pad during shearing.

4. The apparatus of claim 1, wherein, The normal zonal loading system includes four independently adjustable zonal normal pressure heads and a normal friction reduction component that cooperates with the zonal normal pressure heads. The four zonal normal pressure heads are arranged in a row on the side of the sample. Each zonal normal pressure head is independently set with a loading load. The bending moment generated during shearing is offset by differential adjustment of the load of each zone, or the load is set according to a preset spatial distribution to realize the non-uniform normal loading test of rock fractures. The normal friction reduction component is used to ensure the normal free movement of the upper rock sample during shearing.

5. The apparatus of claim 1, wherein, The seepage control system is equipped with an inlet pressure sensor, an inlet flow meter, and a fluid collection device in sequence on the pipeline, which are used to monitor and control the pressure and flow parameters of the fissure seepage in real time.

6. A test method for simulating high-speed cyclic shear-permeation of rock fractures, characterized by, Based on the experimental apparatus according to any one of claims 1 to 5, the method includes the following steps: S1. Rock sample installation and system assembly: Install the rock sample in the shear box and assemble the shear box sealing system on both ends of the rock sample to complete the end face sealing. At the same time, connect the cracks in the rock sample to the seepage control system. Then, assemble the shear and guiding system, the vibration loading system, and the normal zone loading system in sequence. S2. System preload and sealing verification: The sample side is subjected to zonal normal loading according to the settings through the normal zonal loading system. The seepage control system is turned on and adjusted to the set seepage conditions. The consistency of inlet and outlet water flow and system sealing are checked. After confirming that there is no leakage, the test stage is entered. S3, Shear-Vibration-Seepage Coupling Test: The rock sample is sheared at a constant speed along the horizontal direction by a shear and guiding system at a set rate. At the same time, the corresponding excitation unit of the three-degree-of-freedom high-speed cyclic excitation table is driven to work according to the test conditions. Different excitation conditions are superimposed synchronously during the shearing process to realize shear-vibration-seepage multi-field coupled loading. S4. Synchronous acquisition and processing of experimental data: During the experiment, shear mechanical parameters, normal loading parameters, excitation force parameters and seepage characteristic parameters are acquired simultaneously to obtain the mechanical response and seepage evolution data of rock fractures under multi-field coupling.

7. The test method of claim 6, wherein, In step S3, the excitation conditions include single-channel independent excitation, dual-channel synchronous excitation, and three-channel coupled excitation, and the excitation frequency, amplitude, and phase can all be adjusted independently.

8. The test method of claim 6, wherein, In steps S3 and S4, based on the sample deflection data collected during the test, the loading load of the normal pressure head in each zone is adjusted differentially in real time to dynamically suppress the deflection and bending moment during the sample shearing process, or to dynamically adjust the non-uniform normal stress distribution.

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