Method for testing shear creep characteristics of rock mass structural surface in near-dam area and medium

Abstract

The invention discloses a test method for shear creep characteristics of a rock mass structural surface in a near-dam area and a medium. The test method comprises the following steps: collecting corresponding geological exploration data and annual change data of an underground water level after water storage of a dam; designing a test load based on the collected data; designing an artificial sawtooth structural surface based on a rock surface topography instrument; carrying out a rock mass structural surface shear-seepage coupling test, and determining the shear strength of the structural surface under the action of the maximum seepage pressure and the corresponding maximum shear load; carrying out a rock mass structural plane shear creep-seepage coupling test under the dam water storage condition, controlling the shear load to be constant in the test, gradually applying seepage pressure, and recording the creep deformation of the structural plane; a rock mass structural plane shear creep-circulating seepage coupling test is carried out under the dam water storage condition, in the test, the shear load is controlled to be constant, the reciprocating seepage pressure is gradually applied, the structural plane creep deformation is recorded, and the influence of the circulating action of the seepage pressure on the rock mass structural plane shear creep characteristic after dam water storage is simulated.

Description

Technical Field

[0001] This application belongs to the technical field of analysis of reservoir bank deformation driving mechanism after dam impoundment and testing technology of rock mass structural surface shear creep-seepage coupling test, and particularly relates to a test method and medium for the shear creep characteristics of rock mass structural surface near the dam area. Background Technology

[0002] The problem of reservoir bank deformation caused by dam impoundment is becoming increasingly prominent, posing a major challenge in the field of dam safety. Taking a certain ultra-high arch dam as an example, after more than ten years of operation, the reservoir bank deformation in the dam area has not yet converged, and the mechanism remains unclear. Currently, the academic community generally believes that the shear displacement of the controlling rock mass structural planes near the dam area induced by dam impoundment under the combined action of horizontal tectonic stress and cyclic seepage pressure increments is one of the main reasons for the large reservoir bank deformation, and that this process is accompanied by a significant time effect. However, this hypothesis still lacks effective verification through physical experiments.

[0003] At the experimental technology level, while existing rock joint shear-seepage coupling test systems are becoming increasingly sophisticated, their loading paths often employ a fixed pattern of "first applying normal stress and osmotic pressure, then shearing in stages." This method is unable to simulate the cyclic osmotic pressure load caused by the periodic rise and fall of actual reservoir water levels, nor can it reproduce the true mechanical process of rock mass surfaces initially bearing high-level tectonic stress and subsequently experiencing incremental osmotic pressure. Therefore, existing experimental methods cannot accurately reflect the mechanical behavior of rock mass surfaces under dam impoundment operation conditions, thus limiting their support for research on reservoir bank deformation mechanisms.

[0004] To address the aforementioned technical bottlenecks, this invention proposes an experimental method, equipment, and medium for simulating the shear creep characteristics of rock mass structures near the dam area under cyclic seepage pressure after dam impoundment. The aim is to accurately reproduce the actual stress environment of the rock mass near the dam area after impoundment, providing crucial technical support for revealing the intrinsic mechanism of reservoir bank deformation and ensuring the long-term safe operation of the dam. Summary of the Invention

[0005] The purpose of this application is to overcome the problems of the prior art by disclosing a test method and medium for the shear creep characteristics of the rock mass structural surface near the dam area. This application truly reflects the shear creep characteristics of the controlling rock mass structural surface near the dam area under the combined action of the reciprocating osmotic pressure increment and high-level tectonic stress after the dam is impounded, providing technical support for the analysis of the deformation mechanism of the reservoir bank during the dam impoundment period.

[0006] The objective of this application is achieved through the following technical solution: A test method for the shear creep characteristics of rock mass structural planes near the dam area, the test method comprising: S1: Collect relevant geological exploration data and annual groundwater level variation data after the dam is impounded for the rock mass structure of the dam and the area near the dam to be studied; S2: Design test loads based on collected data; S3: Based on a rock surface topography instrument, design artificial sawtooth structure surfaces; S4: Conduct shear-seepage coupling tests on rock mass structural surfaces to determine the shear strength of the structural surfaces and the corresponding maximum shear load under maximum osmotic pressure. S5: Conduct shear creep-seepage coupling test on rock mass structural surface under dam impoundment conditions. In the test, the shear load is kept constant, the seepage pressure is gradually applied, and the creep deformation of the structural surface is recorded. The shear load can be set to different values ​​to simulate the effect of the increase in seepage pressure on the shear creep characteristics of the structural surface under different levels of tectonic stress. S6: Conduct a coupled test of shear creep and cyclic seepage on the rock mass structural surface under dam impoundment conditions. In the test, the shear load is kept constant, and the cyclic seepage pressure is gradually applied. The creep deformation of the structural surface is recorded to simulate the effect of the cyclic seepage pressure on the shear creep characteristics of the rock mass structural surface after dam impoundment.

[0007] According to a preferred embodiment, step S2 includes: S21: The test normal load is determined based on the burial depth of the rock mass structural plane. The calculation formula is shown below:

[0008] In the formula, P v For testing normal loads, γ The average unit weight of the overlying rock mass on the structural surface. h A1 is the depth of the structural surface and A1 is the area of ​​the normal compression surface of the specimen. S22: The experimental shear load is determined based on the horizontal tectonic stress from geological exploration. The calculation formula is shown below:

[0009] In the formula, P h To test shear load, σ h The horizontal tectonic stress near the structural plane obtained from geological exploration. A 2 represents the tangential stress area of ​​the specimen; S23: Based on the key control points of the annual groundwater level variation curve near the rock mass structural plane after dam impoundment, a stepped osmotic pressure loading curve is designed. The maximum and minimum osmotic pressures of the test are calculated from the actual water level elevation, and the calculation formula is as follows:

[0010]

[0011] In the formula, P w1 and P w2 To test the maximum and minimum osmotic pressure, h 1 represents the maximum water level elevation during the dam's impoundment period. h 2 represents the minimum water level elevation during the dam's impoundment period; The loading and unloading rates of the osmotic pressure test are controlled by the loading equipment, and the relative rates of loading and unloading are consistent with the actual water level change curve, i.e., they satisfy the following formula:

[0012] In the formula, t 1,p and t 2,p These represent the time periods for water level rise and fall during the dam's impoundment cycle. t 1,m and t 2,m These represent the times corresponding to the loading and unloading of osmotic pressure during the test.

[0013] According to a preferred embodiment, the method for designing artificial sawtooth structural surfaces in step S3 includes: S31: Conduct mix proportion tests of cement, standard sand and water to ensure that the physical and mechanical properties of the specimen materials are consistent with those of the corresponding rock mass in the geological exploration data; S32: Using a rock surface profilometer, the actual rock mass structural surface of borehole samples is scanned, and the roughness JRC of the actual rock mass structural surface is calculated using the following formula:

[0014] In the formula, Z2 is the root mean square value of the slope of the two-dimensional joint profile obtained based on the scanning points; S33: Artificial sawtooth-shaped structural surfaces are used to simulate the shear characteristics of rock mass structural surfaces. Based on the roughness of the real rock mass structural surfaces, the sawtooth climbing angle, single tooth length, and sawtooth number parameters of the artificial structural surfaces are adjusted to make the roughness of the sample structural surfaces consistent with that of the real rock mass structural surfaces.

[0015] According to a preferred embodiment, steps S4 to S6 are implemented based on a multifunctional rock joint shear-seepage coupling test system. The multifunctional rock joint shear-seepage coupling test system includes: a host and servo loading unit (1), a seepage shear box and its sealing unit (2), a seepage servo control unit (3), and a data measurement and acquisition unit (4). The seepage servo control unit (3) can realize cyclic seepage loading.

[0016] According to a preferred embodiment, step S4 includes: S41: Place the saturated specimen in the shear box of the seepage shear box and its sealing unit (2) and apply pressure to the side sealing capsule to seal it; S42: First apply normal stress, and after the normal stress reaches the set value, apply the permeation water pressure; S43: When both the normal stress and the permeation water pressure reach the preset values, apply shear loads in stages until the specimen fails under shear loads. S44: After the specimen is damaged, first unload the permeation water pressure to 0, then unload the normal stress to 0, and finally unload the shear stress to 0. Remove the damaged specimen and export the test data for processing.

[0017] According to a preferred embodiment, step S5 includes: S51: Place the saturated specimen in the shear box of the seepage shear box and its sealing unit (2) and apply the side sealing capsule pressure seal; S52: First apply normal stress. After the normal stress reaches the set value, apply initial seepage water pressure, and then apply shear load to the set value and keep it unchanged. S53: Gradually increase the permeation water pressure to the set value and carry out the creep test, recording the creep deformation of the sample; S54: After the shear creep deformation rate of the specimen meets the convergence requirement, first unload the permeation water pressure to 0, then unload the normal stress to 0, and finally unload the shear stress to 0. Remove the specimen and export the test data for processing.

[0018] According to a preferred embodiment, step S6 includes: S61: Place the saturated specimen in a shear box and apply side-sealing capsule pressure to seal it; S62: First apply normal stress. After the normal stress reaches the set value, apply initial seepage water pressure, and then apply shear load to the set value and keep it unchanged. S63: Apply cyclic osmotic pressure step by step, conduct creep tests at the maximum and minimum osmotic pressure points, and record the creep deformation of the sample. S64: After the test, first unload the permeation water pressure to 0, then unload the normal stress to 0, and finally unload the shear stress to 0. Remove the specimen and export the test data for processing.

[0019] On the other hand, this application also discloses: A computer-readable storage medium for storing instructions that, when executed, cause the aforementioned method to be implemented.

[0020] The aforementioned main solution and its various further alternative solutions can be freely combined to form multiple solutions, all of which are solutions that can be adopted and are claimed in this application. Those skilled in the art, after understanding the solution of this application, will realize that there are many combinations based on the prior art and common general knowledge, all of which are technical solutions to be protected in this application, and will not be exhaustively listed here.

[0021] The beneficial effects of this application are: (1) This application uses the roughness of the real rock mass structure obtained by the rock morphology scanner to invert the design parameters of the artificial sawtooth structure, so as to ensure that the structure of the specimen can reflect the physical and mechanical properties of the real rock mass structure. (2) Unlike conventional tests that only use seepage pressure as a fixed boundary and apply normal stress and seepage pressure first, and then shear in stages, this application considers the real mechanical process of the rock mass structure near the dam after the dam is impounded. The loading method is set to control the normal and shear loads to be constant and gradually increase the seepage pressure. (3) Considering the cyclical changes in the permeability pressure of the rock mass structure surface after the dam impoundment and the change in reservoir water level, it can more realistically reflect the influence of dam impoundment on the shear creep characteristics of the rock mass structure surface near the dam area. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the test method for the shear creep characteristics of the rock mass structure near the dam area in this application; Figure 2 This is a schematic diagram of the method for determining the serrated surface parameters of the specimen in this application; Figure 3 This is a schematic diagram of the method for determining the test cycle osmotic pressure in this application; Figure 4 This is a schematic diagram of the multifunctional rock joint shear-seepage coupling test system of this application; Figure 5 This is a schematic diagram showing the influence of seepage water pressure and horizontal tectonic stress on the shear creep characteristics of rock mass structural surfaces after dam impoundment, obtained using the test method provided in this application. Figure 6 This is a schematic diagram illustrating the effect of cyclic seepage water pressure on the shear creep characteristics of rock mass structural surfaces, obtained using the experimental method provided in this application.

[0023] Among them, 1-host and servo loading unit, 2-seepage shear box and its sealing unit, 3-seepage servo control unit, and 4-data measurement and acquisition unit. Detailed Implementation

[0024] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0027] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0028] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0029] Furthermore, it should be noted that unless otherwise specified in this application, the specific structures, connections, positions, power sources, etc. involved are all things that a person skilled in the art can know without creative effort based on the prior art.

[0030] Example 1 refer to Figure 1 As shown in the figure, a test method for the shear creep characteristics of rock mass structural surfaces near the dam area is illustrated. The test method for the shear creep characteristics of rock mass structural surfaces near the dam area includes the following steps.

[0031] Step S1: Collect relevant geological exploration data and annual groundwater level variation data after the dam is impounded for the rock mass structure of the dam and the area near the dam.

[0032] Step S2: Design the test load based on the collected data, such as... Figure 2 As shown.

[0033] Preferably, step S2 includes: S21: The test normal load is determined based on the burial depth of the rock mass structural plane. The calculation formula is shown below:

[0034] In the formula, P v For testing normal loads, γ The average unit weight of the overlying rock mass on the structural surface. h A1 is the depth of the structural surface and A1 is the area of ​​the normal compression surface of the specimen. S22: The experimental shear load is determined based on the horizontal tectonic stress from geological exploration. The calculation formula is shown below:

[0035] In the formula, P h To test shear load, σ h The horizontal tectonic stress near the structural plane obtained from geological exploration. A 2 represents the tangential stress area of ​​the specimen; S23: Based on the key control points of the annual groundwater level variation curve near the rock mass structural plane after dam impoundment, a stepped osmotic pressure loading curve is designed. The maximum and minimum osmotic pressures of the test are calculated from the actual water level elevation, and the calculation formula is as follows:

[0036]

[0037] In the formula, P w1 and P w2 To test the maximum and minimum osmotic pressure, h 1 represents the maximum water level elevation during the dam's impoundment period. h 2 represents the minimum water level elevation during the dam's impoundment period; The loading and unloading rates of the osmotic pressure test are controlled by the loading equipment, and the relative rates of loading and unloading are consistent with the actual water level change curve, i.e., they satisfy the following formula:

[0038] In the formula, t 1,p and t 2,p These represent the time periods for water level rise and fall during the dam's impoundment cycle. t 1,m and t 2,m These represent the times corresponding to the loading and unloading of osmotic pressure during the test.

[0039] Step S3: Based on a rock surface topography instrument, design an artificial sawtooth structure surface, such as... Figure 3 As shown.

[0040] Preferably, the S3 method for designing artificial sawtooth structural surfaces includes: S31: Conduct mix proportion tests of cement, standard sand and water to ensure that the physical and mechanical properties of the specimen materials are consistent with those of the corresponding rock mass in the geological exploration data.

[0041] S32: Using a rock surface profilometer, the actual rock mass structural surface of borehole samples is scanned, and the roughness JRC of the actual rock mass structural surface is calculated using the following formula:

[0042] In the formula, Z2 is the root mean square value of the slope of the two-dimensional joint profile obtained based on the scanning points.

[0043] S33: Considering that borehole sampling is difficult to meet the standard specimen size requirements of the loading equipment, an artificial sawtooth structure surface is used to simulate the shear characteristics of the rock mass structure surface. Based on the roughness of the real rock mass structure surface, the sawtooth slope angle, single tooth length and sawtooth number parameters of the artificial structure surface are adjusted so that the roughness of the specimen structure surface is consistent with the real rock mass structure surface.

[0044] Step S4: Conduct shear-seepage coupling tests on rock mass structural surfaces using a multifunctional rock joint shear-seepage coupling test system to determine the shear strength of the structural surfaces and the corresponding maximum shear load under maximum osmotic pressure.

[0045] Preferably, the multifunctional rock joint shear-seepage coupling test system includes: a host and servo loading unit 1, a seepage shear box and its sealing unit 2, a seepage servo control unit 3, and a data measurement and acquisition unit 4. The seepage servo control unit 3 is capable of cyclic seepage loading.

[0046] Preferably, step S4 includes: S41: Place the saturated specimen in the shear box of the seepage shear box and its sealing unit 2 and apply pressure from the side sealing capsule to seal it.

[0047] S42: First apply normal stress, and then apply permeation water pressure after the normal stress reaches the set value.

[0048] S43: When both the normal stress and the permeation water pressure reach the preset values, apply shear loads in stages until the specimen fails under shear conditions.

[0049] S44: After the specimen is damaged, first unload the permeation water pressure to 0, then unload the normal stress to 0, and finally unload the shear stress to 0. Remove the damaged specimen and export the test data for processing.

[0050] Step S5: Conduct shear creep-seepage coupling tests on rock mass structural surfaces under dam impoundment conditions using a multifunctional rock joint shear-seepage coupling test system. During the test, the shear load is kept constant, and seepage pressure is gradually applied. The creep deformation of the structural surface is recorded. Different values ​​of shear load can be set to simulate the effect of increased seepage pressure on the shear creep characteristics of the structural surface under different levels of tectonic stress.

[0051] Preferably, step S5 includes: S51: Place the saturated specimen in the shear box of the seepage shear box and its sealing unit 2 and apply the side sealing capsule pressure seal.

[0052] S52: First apply normal stress. After the normal stress reaches the set value, apply initial seepage water pressure, and then apply shear load to the set value and keep it unchanged.

[0053] S53: Gradually increase the permeation water pressure to the set value to carry out the creep test and record the creep deformation of the sample.

[0054] S54: After the shear creep deformation rate of the specimen meets the convergence requirement, first unload the permeation water pressure to 0, then unload the normal stress to 0, and finally unload the shear stress to 0. Remove the specimen and export the test data for processing.

[0055] The effects of horizontal tectonic stress and seepage water pressure on the shear creep characteristics of rock mass structural surfaces after dam impoundment, obtained in step S5, are as follows: Figure 5 As shown, when the horizontal tectonic stress is small, the rock mass shear creep is not obvious. Under the same horizontal tectonic stress, the greater the seepage water pressure, the greater the rock mass shear creep deformation. Therefore, after the dam is impounded, the rock mass structural surface with a large initial horizontal tectonic stress is prone to shear creep deformation under a large increase in seepage pressure, which in turn leads to reservoir bank deformation.

[0056] Step S6: Conduct a shear creep-cyclic seepage coupling test on the rock mass structural surface under dam impoundment conditions using a multifunctional rock joint shear-seepage coupling test system. During the test, the shear load is kept constant, and cyclic seepage pressure is gradually applied. The creep deformation of the structural surface is recorded to simulate the effect of the cyclic seepage pressure on the shear creep characteristics of the rock mass structural surface after dam impoundment.

[0057] Preferably, step S6 includes: S61: Place the saturated specimen in a shear box and apply side-sealing capsule pressure to seal it; S62: First apply normal stress. After the normal stress reaches the set value, apply initial seepage water pressure, and then apply shear load to the set value and keep it unchanged. S63: Apply cyclic osmotic pressure step by step, conduct creep tests at the maximum and minimum osmotic pressure points, and record the creep deformation of the sample. S64: After the test, first unload the permeation water pressure to 0, then unload the normal stress to 0, and finally unload the shear stress to 0. Remove the specimen and export the test data for processing.

[0058] The effect of the number of osmotic pressure cycles obtained in step S6 on the shear creep characteristics of the rock mass structural surface is as follows: Figure 6 As shown, with the increase of the number of cyclic loading cycles, the damage to the rock mass structural surface intensifies, and the steady-state creep rate first gradually increases and then tends to stabilize.

[0059] To more clearly illustrate the advantages of the experimental method of this invention for simulating the shear creep characteristics of the rock mass structure near the dam area after cyclic seepage pressure after dam impoundment compared with existing methods, the researchers compared the method of this invention with the conventional shear (creep)-seepage coupling test method, and the comparison results are shown in Table 1.

[0060] Table 1

[0061] As shown in the table above, the test method for shear creep characteristics of rock mass structural surfaces near the dam area described in this application, compared with existing technologies, can simulate the real mechanical process of rock mass structural surfaces near the dam area after dam impoundment, and can consider the cyclical changes in osmotic pressure of rock mass structural surfaces with reservoir water level fluctuations after dam impoundment. All other unspecified parts belong to existing technologies.

[0062] Example 2 Based on Embodiment 1, this embodiment also discloses: a computer-readable storage medium for storing instructions that, when executed, cause the method described in Embodiment 1 to be implemented.

[0063] In some alternative embodiments, the present invention also provides that various aspects of the test method for the shear creep characteristics of rock mass structural surfaces near the dam area can also be implemented in the form of a program product, which includes program code that, when the program product is run on a device, causes the control device to perform the steps in the test method for the shear creep characteristics of rock mass structural surfaces near the dam area according to various exemplary embodiments of the present invention as described above.

[0064] It should be noted that although several units or sub-units of the apparatus have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to embodiments of the invention, the features and functions of two or more units described above can be embodied in one unit. Conversely, the features and functions of one unit described above can be further divided and embodied by multiple units. Furthermore, although the operation of the method of the invention is described in a specific order in the drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0065] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can be implemented in one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs) containing computer-usable program code. The form of a computer program product implemented on ROM, optical memory, etc.

[0066] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a server, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0067] Program code for performing the operations of this invention can be written using any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0068] In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0069] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0070] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

Claims

1. A test method for the shear creep characteristics of rock mass structural surfaces near a dam area, characterized in that, The test methods for the shear creep characteristics of the rock mass structural planes near the dam area include: S1: Collect relevant geological exploration data and annual groundwater level variation data after the dam is impounded for the rock mass structure of the dam and the area near the dam to be studied; S2: Design test loads based on collected data; S3: Based on a rock surface topography instrument, design artificial sawtooth structure surfaces; S4: Conduct shear-seepage coupling tests on rock mass structural surfaces to determine the shear strength of the structural surfaces and the corresponding maximum shear load under maximum osmotic pressure. S5: Conduct shear creep-seepage coupling test on rock mass structural surface under dam impoundment conditions. In the test, the shear load is kept constant, the seepage pressure is gradually applied, the creep deformation of the structural surface is recorded, and the shear load is set to different values ​​to simulate the effect of the increase in seepage pressure on the shear creep characteristics of the structural surface under different levels of tectonic stress. S6: Conduct a coupled test of shear creep and cyclic seepage on the rock mass structural surface under dam impoundment conditions. In the test, the shear load is kept constant, and the cyclic seepage pressure is gradually applied. The creep deformation of the structural surface is recorded to simulate the effect of the cyclic seepage pressure on the shear creep characteristics of the rock mass structural surface after dam impoundment.

2. The test method for shear creep characteristics of rock mass structural surfaces near the dam area as described in claim 1, characterized in that, Step S2 includes: S21: The test normal load is determined based on the burial depth of the rock mass structural plane. The calculation formula is shown below: In the formula, P v For testing normal loads, γ The average unit weight of the overlying rock mass on the structural surface. h A1 is the depth of the structural surface and A1 is the area of ​​the normal compression surface of the specimen. S22: The experimental shear load is determined based on the horizontal tectonic stress from geological exploration. The calculation formula is shown below: In the formula, P h To test shear load, σ h The horizontal tectonic stress near the structural plane obtained from geological exploration. A 2 represents the tangential stress area of ​​the specimen; S23: Based on the key control points of the annual groundwater level variation curve near the rock mass structural plane after dam impoundment, a stepped osmotic pressure loading curve is designed. The maximum and minimum osmotic pressures of the test are calculated from the actual water level elevation, and the calculation formula is as follows: In the formula, P w1 and P w2 To test the maximum and minimum osmotic pressure, h 1 represents the maximum water level elevation during the dam's impoundment period. h 2 represents the minimum water level elevation during the dam's impoundment period; The loading and unloading rates of the osmotic pressure test are controlled by the loading equipment, and the relative rates of loading and unloading are consistent with the actual water level change curve, i.e., they satisfy the following formula: In the formula, t 1,p and t 2,p These represent the time periods for water level rise and fall during the dam's impoundment cycle. t 1,m and t 2,m These represent the times corresponding to the loading and unloading of osmotic pressure during the test.

3. The test method for shear creep characteristics of rock mass structural surfaces near the dam area as described in claim 2, characterized in that, S3's artificial sawtooth structure surface design method includes: S31: Conduct mix proportion tests of cement, standard sand and water to ensure that the physical and mechanical properties of the specimen materials are consistent with those of the corresponding rock mass in the geological exploration data; S32: Using a rock surface profilometer, the actual rock mass structural surface of borehole samples is scanned, and the roughness JRC of the actual rock mass structural surface is calculated using the following formula: In the formula, Z2 is the root mean square value of the slope of the two-dimensional joint profile obtained based on the scanning points; S33: Artificial sawtooth-shaped structural surfaces are used to simulate the shear characteristics of rock mass structural surfaces. Based on the roughness of the real rock mass structural surfaces, the sawtooth climbing angle, single tooth length, and sawtooth number parameters of the artificial structural surfaces are adjusted to make the roughness of the sample structural surfaces consistent with that of the real rock mass structural surfaces.

4. The test method for shear creep characteristics of rock mass structural surfaces near the dam area as described in claim 1, characterized in that, Steps S4 to S6 are implemented based on a multifunctional rock joint shear-seepage coupling test system. The multifunctional rock joint shear-seepage coupling test system includes: a host and servo loading unit (1), a seepage shear box and its sealing unit (2), a seepage servo control unit (3), and a data measurement and acquisition unit (4). The seepage servo control unit (3) can realize cyclic seepage loading.

5. The test method for shear creep characteristics of rock mass structural surfaces near the dam area as described in claim 4, characterized in that, Step S4 includes: S41: Place the saturated specimen in the shear box of the seepage shear box and its sealing unit (2) and apply pressure to the side sealing capsule to seal it; S42: First apply normal stress, and after the normal stress reaches the set value, apply the permeation water pressure; S43: When both the normal stress and the permeation water pressure reach the preset values, apply shear loads in stages until the specimen fails under shear loads. S44: After the specimen is damaged, first unload the permeation water pressure to 0, then unload the normal stress to 0, and finally unload the shear stress to 0. Remove the damaged specimen and export the test data for processing.

6. The test method for shear creep characteristics of rock mass structural surfaces near the dam area as described in claim 5, characterized in that, Step S5 includes: S51: Place the saturated specimen in the shear box of the seepage shear box and its sealing unit (2) and apply the side sealing capsule pressure seal; S52: First apply normal stress. After the normal stress reaches the set value, apply initial seepage water pressure, and then apply shear load to the set value and keep it unchanged. S53: Gradually increase the permeation water pressure to the set value and carry out the creep test, recording the creep deformation of the sample; S54: After the shear creep deformation rate of the specimen meets the convergence requirement, first unload the permeation water pressure to 0, then unload the normal stress to 0, and finally unload the shear stress to 0. Remove the specimen and export the test data for processing.

7. The test method for shear creep characteristics of rock mass structural planes near the dam area as described in claim 6, characterized in that, Step S6 includes: S61: Place the saturated specimen in a shear box and apply side-sealing capsule pressure to seal it; S62: First apply normal stress. After the normal stress reaches the set value, apply initial seepage water pressure, and then apply shear load to the set value and keep it unchanged. S63: Apply cyclic osmotic pressure step by step, conduct creep tests at the maximum and minimum osmotic pressure points, and record the creep deformation of the sample. S64: After the test, first unload the permeation water pressure to 0, then unload the normal stress to 0, and finally unload the shear stress to 0. Remove the specimen and export the test data for processing.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store instructions that, when executed, cause the method as described in any one of claims 1 to 7 to be implemented.

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