Rapid evaluation method for shear strength of rock structural plane under normal disturbance effect

Abstract

The invention provides a rapid evaluation method for shear strength of a rock structural plane under normal disturbance, and belongs to the technical field of geotechnical engineering and rock mechanics, the method comprises the following steps: S1, sample preparation and initial parameter acquisition; s2, normal disturbance direct shear test; s3, fitting test data and establishing an empirical model; and S4, rapidly evaluating the shear strength. According to the method, by introducing a normal disturbance stress parameter, an empirical calculation formula capable of rapidly predicting the shear strength after disturbance is established, and key parameters are provided for engineering design and stability analysis.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geotechnical engineering and rock mechanics, and in particular to a method for rapidly evaluating the shear strength of rock structural plane under normal disturbance. BACKGROUND

[0002] In the field of geotechnical engineering, such as slope, tunnel and underground cavern engineering, the shear strength of rock mass structural plane is a key factor affecting the stability of the engineering. Controlled by the structural plane, the rock mass often exhibits complex mechanical behavior, especially when subjected to normal disturbance load caused by blasting, mechanical vibration or adjacent engineering activities, the shear strength of the structural plane often deteriorates significantly, which seriously threatens the safety of the engineering.

[0003] Currently, the determination of the shear strength of rock structural plane mainly relies on indoor and outdoor direct shear tests and empirical estimation methods based on Barton's standard. However, the outdoor direct shear test is long in period and high in cost, and it is difficult to effectively simulate the dynamic load condition of normal disturbance. Although the JRC-JCS model proposed by Barton is widely used, it is mainly suitable for static load conditions and does not fully consider the cumulative effect of normal cyclic loading or other dynamic disturbances on the mechanical behavior of the structural plane, resulting in a large error in evaluating the strength of the structural plane after disturbance.

[0004] Traditional direct shear tests are usually carried out under constant normal stress, which cannot reflect the cumulative deterioration process of the structural plane morphology damage and mechanical properties caused by the repeated fluctuation of normal stress in actual engineering. In addition, existing research on the influence of shear velocity on shear strength mainly focuses on constant normal load conditions, ignoring the coupling effect of disturbance and shear. The parameters (such as JRC) in the commonly used empirical formula (such as Barton formula) are not constant before and after disturbance, and the existing models cannot quantitatively describe the variation of such parameters, resulting in insufficient reliability of the prediction results. In order to obtain the peak strength of the structural plane after disturbance, multiple samples with similar topography need to be prepared and different working conditions need to be tested, which is time-consuming and inefficient, and cannot meet the demand of rapid evaluation on site.

[0005] Although existing research has shown that dynamic load can reduce the shear strength of rock structural plane, quantitative research on the influence of disturbance frequency and amplitude on shear strength is still lacking. Therefore, it is urgent to establish a new method that can quickly and accurately evaluate the shear strength of rock structural plane after disturbance by considering the influence of normal disturbance and shear rate. SUMMARY

[0006] The present application provides a method for rapidly evaluating the shear strength of rock structural plane under normal disturbance, which introduces the parameter of "normal disturbance stress" to establish an empirical calculation formula that can quickly predict the shear strength after disturbance, providing key parameters for engineering design and stability analysis.

[0007] To achieve the above object, the application adopts the following technical solutions: A method for rapidly evaluating the shear strength of a rock structural plane under normal disturbance, comprising: S1. Sample preparation and initial parameter acquisition: prepare a standard sample containing a rock structural plane, scan the surface topography of the structural plane and calculate the initial roughness coefficient, and test the uniaxial compressive strength and basic friction angle of the rock through a rock mechanics test; S2. Normal disturbance direct shear test: install the standard sample in a rock direct shear test system capable of applying a normal cyclic load, first apply an initial normal stress, then superimpose a normal cyclic disturbance stress with a set amplitude and frequency on the basis of the initial normal stress, and perform a direct shear test at a fixed shear rate until the sample is sheared and destroyed, and record the peak shear strength; change the values of the initial normal stress, disturbance stress amplitude, disturbance frequency and shear rate, and repeat the above test to obtain multiple sets of test data; S3. Test data fitting and empirical model establishment: normalize the peak shear strength in the multiple sets of test data, and based on the Barton strength theory, obtain a modified shear strength empirical model containing a shear rate function through multi-parameter data fitting; S4. Rapid evaluation of shear strength: substitute the test data into the modified shear strength empirical model, verify the model accuracy by comparing the predicted peak shear strength of the model with the true peak shear strength measured by the test; for a rock structural plane in an actual engineering project, obtain its initial roughness coefficient, uniaxial compressive strength and basic friction angle, determine the corresponding initial normal stress, disturbance stress amplitude, disturbance frequency and shear rate in combination with the engineering environment, and substitute them into the verified modified shear strength empirical model to calculate the peak shear strength of the structural plane after normal disturbance.

[0008] In this specification, the topography of the rock structural plane in step S1 is determined by simulating the characteristics of the rock structural plane in an actual engineering site, or is preformed according to common structural plane types in engineering.

[0009] In this specification, the normal cyclic disturbance stress in step S2 fluctuates periodically, and the fluctuation rule is consistent with the stress change rule generated by disturbances such as blasting and mechanical vibration in actual engineering.

[0010] In this specification, the purpose of the normalization processing in step S3 is to eliminate the interference of the normal load-related effective value, the normal dynamic load-related effective value and the dynamic load frequency-related effective value on the peak shear strength, so that the processed data only focuses on the correlation between the shear rate and the peak shear strength.

[0011] In this specification, the shear rate function described in step S3 can couple the combined effects of initial normal stress, disturbance stress amplitude, disturbance frequency and shear rate, and quantify the synergistic effect of each factor on the shear strength of the rock structural surface.

[0012] In this specification, when establishing the modified empirical model for shear strength in step S3, the shear rate function can be simplified to a form that is only related to the single factor and the shear rate for a single factor among the initial normal stress, disturbance stress amplitude, and disturbance frequency, thereby obtaining a simplified calculation model for shear strength under the influence of the corresponding single factor.

[0013] In this manual, the core basis for verifying the model accuracy in step S4 is that the deviation between the peak shear strength predicted by the model and the actual peak shear strength measured by the experiment is within a preset reasonable range, ensuring the reliability of the model for actual engineering evaluation.

[0014] In this specification, in step S1, the surface morphology of the structural surface is scanned by a three-dimensional laser scanner, and the initial roughness coefficient is calculated based on the morphology data obtained from the scan; the rock mechanics test is a uniaxial compressive strength test and a basic friction angle test that conform to the geotechnical engineering testing standards.

[0015] In this specification, the engineering environment described in step S4 includes the types and intensity levels of activities that may generate normal disturbances, such as blasting operations, mechanical vibrations, and construction of adjacent projects in the area where the project is located.

[0016] In this specification, the loading process of the direct shear test in step S2 is as follows: first, apply an initial normal stress and keep it stable, then superimpose normal cyclic disturbance stress until the fluctuation stabilizes, and then start shear loading at a fixed shear rate until the specimen fails under shear.

[0017] In summary, the present invention has at least the following beneficial effects: It innovatively introduces the concept of "normal perturbation stress": the perturbation amplitude σ a ,frequency f and shear rate v The influence is coupled to a synthetic function f ( v In this study, the intensity of the normal disturbance load was scientifically quantified.

[0018] A quantitative normal disturbance degradation model was established: In the shear strength formula, a modified shear strength model was established to characterize the normal disturbance, such as the law of shear strength attenuation with the increase of shear rate, such as the amplitude and frequency. The physical meaning is clear and can accurately reflect the structural surface wear and strength degradation caused by the normal disturbance and the change of shear rate.

[0019] Fast and efficient: only through a limited number of indoor direct shear test to establish the model and a plurality of factors related function , can be used to establish the correction of shear strength formula for a large number of different disturbance conditions of the structure surface strength of fast prediction, without one by one to carry out complex direct shear test, greatly improve the efficiency, reduce the test cost.

[0020] Strong practicality: the method of the application closely combines with engineering practice, considering the real normal disturbance conditions, the prediction result is closer to the actual situation, provides more reliable theoretical basis for the stability analysis and design of rock mass engineering in disturbance environment. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description, obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings.

[0022] Figure 1 The schematic diagram of the method for fast evaluation of rock structure surface shear strength under normal disturbance in the present application.

[0023] Figure 2 The schematic diagram of the normalized statistical relationship between normal stress and shear rate in the present application.

[0024] Figure 3 The schematic diagram of the normalized statistical relationship between amplitude and shear rate in the present application.

[0025] Figure 4 The schematic diagram of the normalized statistical relationship between frequency and shear rate in the present application DETAILED DESCRIPTION

[0026] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the embodiments of the present application. Therefore, the drawings and the description are considered to be essentially exemplary rather than limiting.

[0027] The following disclosure provides many different embodiments, or examples, for implementing different structures of embodiments of the application. For the purpose of simplifying the disclosure of embodiments of the application, the components and arrangements of specific examples are described below. Of course, they are only examples and are not intended to limit the embodiments of the application. In addition, the embodiments of the application can refer to reference numerals and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, which does not indicate the relationship between the various embodiments and / or arrangements discussed.

[0028] The embodiments of the application will be described in detail below with reference to the accompanying drawings.

[0029] As Figure 1 shown, the embodiments provide a method for rapid evaluation of the shear strength of rock structural plane under normal disturbance, comprising: S1. Sample preparation and initial parameter acquisition: prepare a standard sample containing a rock structural plane, scan the surface topography of the structural plane and calculate the initial roughness coefficient, and test the uniaxial compressive strength and basic friction angle of the rock through rock mechanics test; S2. Normal disturbance direct shear test: install the standard sample in a rock direct shear test system capable of applying normal cyclic load, first apply the initial normal stress, then superimpose the normal cyclic disturbance stress with a set amplitude and frequency on the basis of the initial normal stress, and perform the direct shear test with a fixed shear rate until the sample is sheared and destroyed, and record the peak shear strength; change the values of the initial normal stress, disturbance stress amplitude, disturbance frequency and shear rate, and repeat the above test to obtain multiple sets of test data; S3. Test data fitting and empirical model establishment: normalize the peak shear strength in the multiple sets of test data, and based on the Barton strength theory, obtain a modified shear strength empirical model containing a shear rate function through multi-parameter data fitting; S4. Rapid evaluation of shear strength: substitute the test data into the modified shear strength empirical model, verify the model accuracy by comparing the predicted peak shear strength of the model with the true peak shear strength measured by the test; for the rock structural plane in actual engineering, obtain its initial roughness coefficient, uniaxial compressive strength and basic friction angle, determine the corresponding initial normal stress, disturbance stress amplitude, disturbance frequency and shear rate in combination with the engineering environment, and substitute them into the verified modified shear strength empirical model to calculate the peak shear strength of the structural plane after normal disturbance.

[0030] In this specification, the topography of the rock structural plane in step S1 is determined by simulating the characteristics of the rock structural plane in actual engineering site, or is preformed according to common structural plane types in engineering.

[0031] In the specification, the normal cyclic disturbance stress in step S2 fluctuates periodically, and the fluctuation rule is consistent with the stress change rule generated by disturbance such as blasting and mechanical vibration in actual engineering.

[0032] In the specification, the purpose of the normalization processing in step S3 is to eliminate the interference of the normal load related effective value, the normal dynamic load related effective value and the dynamic load frequency related effective value on the peak shear strength, so that the processed data only focuses on the correlation between the shear rate and the peak shear strength.

[0033] In the specification, the shear rate function in step S3 can couple the comprehensive influence of the initial normal stress, the disturbance stress amplitude, the disturbance frequency and the shear rate, and quantify the synergistic effect of each factor on the shear strength of the rock structural surface.

[0034] In the specification, when establishing the modified shear strength empirical model in step S3, the shear rate function can be simplified to a form related only to the single factor and the shear rate for the single factor among the initial normal stress, the disturbance stress amplitude and the disturbance frequency, to obtain a simplified calculation model of the shear strength under the influence of the corresponding single factor.

[0035] In the specification, the core basis for verifying the model accuracy in step S4 is that the deviation between the peak shear strength predicted by the model and the true peak shear strength measured by the test is within a preset reasonable range, so as to ensure the reliability of the model for actual engineering evaluation.

[0036] In the specification, in step S1, the surface topography of the structural surface is scanned by a three-dimensional laser scanner, and the initial roughness coefficient is calculated based on the topography data obtained by scanning; the rock mechanics test is a uniaxial compressive strength test and a basic friction angle test in accordance with the geotechnical engineering test standard.

[0037] In the specification, the engineering environment in step S4 includes the activity type and intensity level of the normal disturbance that may be generated by blasting, mechanical vibration and adjacent engineering construction in the region where the engineering is located.

[0038] In the specification, the loading process of the direct shear test in step S2 is as follows: first, apply the initial normal stress and keep it stable, then superimpose the normal cyclic disturbance stress until it is stable, then start the shear loading with a fixed shear rate until the sample is sheared and destroyed.

[0039] The technical concept of the application is as follows: Step S1: sample preparation and initial parameter acquisition Prepare a standard sample of a rock structural surface, and the sample size is 100mmx100mm; use a three-dimensional laser scanner to obtain the surface topography of the structural surface, and calculate the initial roughness coefficient JRC; test the uniaxial compressive strength of the rock σ c .

[0040] Step S2: Normal Disturbance Direct Shear Test The prepared specimens were installed in a rock direct shear test system capable of applying normal cyclic loading; first, initial normal stress was applied. σ n Then, based on the initial normal stress, an amplitude of Δ is applied. σ n , frequency is f Normal cyclic perturbation stress, fixed shear rate v Perform cyclic perturbation direct shear tests until the specimen fails under shear stress, and record the peak shear strength. τ p .

[0041] Similarly, different shear rates were applied using the method described above. v Conduct a direct shear test.

[0042] Step S3: Fitting Experimental Data and Establishing an Empirical Model Changing test conditions, including different initial normal stresses σ 0. Different disturbance stress amplitudes σ a Different perturbation frequencies f and different shear rates v Repeat step S2 to obtain multiple sets of experimental data. Based on the strength formula (1) of Barton and Choubey (1977): (1) In the formula: τ This represents the peak shear strength. σ n is the normal stress; JRC is the surface roughness coefficient; JCS is the strength of the surface rock, and for unweathered surface rock, JCS is taken as the uniaxial compressive strength value; φ b This is the basic friction angle.

[0043] Based on experimental data, a method is proposed that considers the amplitude of disturbance stress. σ a ,frequency f and shear rate v The corrected shear strength formula for the effect: (2) (3) (4) In the formula, σ ′ T This represents the effective value of the total stress under normal disturbance.σ ′ n This is the effective value of the normal load. σ′ a This is the effective value of the normal dynamic load. f ′ RMS value of dynamic load frequency f ( v K is a function related to multiple influencing factors, where K = JCS / σ n , t This represents the moment when the peak shear stress was reached during the experiment.

[0044] When only normal load is considered σ n The effect of different shear rates on shear strength. f ( v s It can be simplified to f ( v s ) σ n , σ′ n and f ( v s ) σ n The variable is a constant and the other parameters are constants. The structural surface strength is shown in formula (4): (4) When only dynamic load amplitude is considered σ a The effect of different shear rates on shear strength. f It can be simplified to f ( v s ) σ a ; σ′ a and f ( v s ) σ n The variable is a constant and the other parameters are constants. The structural surface strength is shown in formula (5): (5) When only the effect of dynamic load frequency f on shear strength at different shear rates is considered, f ( v s It can be simplified to f ( v s ) f ;f ′ and f ( v s ) f The variable is a constant and the other parameters are constants. The structural surface strength is shown in formula (6): (6) In obtaining f ( v s ) σ n , f ( v s ) σ a and f ( v s ) f When determining the relationship between peak shear strength and shear rate, in order to eliminate... σ ′ n , σ′ a and f ′ To mitigate the impact of the experiment, the shear strength obtained in the experiment was normalized beforehand.

[0045] By transforming and altering the three formulas (4) to (6), σ′ n , σ′ a and f ′ It can be calculated using the following formulas (8) to (10): (8) (9) (10) Substituting formulas (8) to (10) into formula (2), calculate... f ( v s The specific approach is to introduce dimensionless analysis as a basis. σ′ n , σ′ a and f ′ right σ n , σ a Dimensionless processing of f and multi-parameter data fitting yield the shear rate function. f ( v ).

[0046] Finally, by combining formulas (2) and (8)~(10), the shear strength of the structural surface under various influencing factors can be calculated (11): (11) Step S4: Rapid evaluation of shear strength The proposed shear strength formula was verified using experimental data from structural surfaces under different shear conditions. The predicted strength values ​​of the formula were compared with the actual strength obtained from the experiments to verify the predictive effect of the strength formula.

[0047] For rock structural surfaces in actual engineering, their roughness JRC and uniaxial compressive strength are obtained through step S1. σ c Determine the initial normal stress it may withstand based on the engineering environment. σ 0. Disturbance stress amplitude σ a and frequency f and shear rate v Substituting the above parameters into the empirical model established in step S3, the peak shear strength of the structural surface after experiencing normal disturbance can be quickly calculated. τ .

[0048] In one specific embodiment: Taking the sawtooth-shaped structural surface in a sandstone slope project as an example, the shear strength after normal disturbance is evaluated using the method of this invention.

[0049] Step S1: Sample preparation and initial parameter acquisition Complete sandstone blocks were obtained from the site and processed into standard direct shear specimens measuring 100mm × 100mm × 50mm (including the structural surface) in the laboratory. Regular serrated structural surfaces with a pre-fabricated serration angle of 15° were created. The structural surfaces were scanned using a 3D laser scanner, and the initial roughness coefficient JRC = 22.5° was calculated. The uniaxial compressive strength of the sandstone was measured through rock mechanics tests. σ c =20.3MPa, basic friction angle φ b =15.6°.

[0050] Step S2: Normal Disturbance Direct Shear Test Nine sets of tests were designed under different working conditions, with six different shear rates designed for each set. Specific parameters are shown in the table below. The prepared specimens were installed in a rock direct shear test system capable of applying normal cyclic loading; first, initial normal stress was applied. σ n Then, based on the initial normal stress, an amplitude of Δ is applied. σn , frequency is f Normal cyclic perturbation stress, fixed shear rate v Perform cyclic perturbation direct shear tests until the specimen fails under shear stress, and record the peak shear strength. τ p .

[0051] Similarly, different shear rates were applied using the method described above. v A direct shear test was conducted. The test protocol is shown in Table 1.

[0052] Table 1. Test Protocol ; Taking working condition A2 as an example: the sample is installed in the servo-controlled direct shear apparatus, and an initial normal stress of 2 MPa is applied first. σ n Then, normal cyclic loading was initiated, causing the normal stress to fluctuate sinusoidally between 1.5 MPa and 2.5 MPa at a frequency of 1 Hz to simulate mid-frequency disturbances.

[0053] After the normal cyclic perturbation begins, a direct shear test is simultaneously conducted at a constant shear rate. Shear rates of 0.3, 0.6, 3, 6, 30, and 60 mm / min are applied sequentially to specimens with the same morphology but different shapes. The shear stress-displacement curves are recorded, and the peak strength is read. τ .

[0054] Step S3: Fitting Experimental Data and Establishing an Empirical Model The test data ( σ n Δ σ n , τ ) and the known JRC, σ c , φ b Organize. After obtaining... f ( v s ) σ n , f ( v s ) σ a and f ( v s ) f When determining the relationship between peak shear strength and shear rate, in order to eliminate... σ′ n , σ′ a and f ′To mitigate the impact of the experiment, the shear strength obtained was normalized beforehand, as shown in Table 2.

[0055] Table 2. Normalized shear strength values ; Nonlinear regression analysis was performed using mathematical software (such as Origin) to analyze the relationship between normalized shear strength and shear rate. Figure 2 , Figure 3 , Figure 4 As shown in the image. f ( v s ) σ n , f ( v s ) Fa and f ( v s ) f This can be expressed as the following formulas (12) to (14): (12) (13) (14) By fitting the model, the parameters are obtained: f ( v s ) σ n , f ( v s ) Fa and f ( v s ) f The goodness of fit R of the model 2 A value above 0.959 indicates that the model closely matches the experimental data.

[0056] Therefore, the empirical shear strength calculation formula (11) applicable to this sandstone structural plane is established as follows: (11) Step S4: Rapid evaluation of shear strength Assume that during the blasting process of this slope, the initial normal stress at the location of a key structural surface is... σ n =2MPa, estimated normal disturbance stress amplitude Δ generated by the blast. σ n=±0.5MPa, frequency f=1Hz, different shear rate conditions were set, and the test parameters were substituted into formula (11) and compared with the measured values ​​to obtain an error ≤6.241%, which proves that the evaluation method has good accuracy. The comparison between the predicted and calculated peak shear strength values ​​is shown in Table 3.

[0057] Therefore, this shear strength evaluation method can quickly predict the shear strength of the structural surface after this blasting disturbance. Engineers can use this result to verify slope stability and develop corresponding reinforcement or controlled blasting plans.

[0058] Table 3. Comparison of predicted and calculated peak shear strength values ; The embodiments described above are for illustrative purposes only and are not intended to limit the invention. Therefore, any changes in numerical values ​​or substitutions of equivalent elements should still fall within the scope of this invention.

[0059] The above detailed description will enable those skilled in the art to understand that the present invention can indeed achieve the aforementioned objectives and has complied with the provisions of the Patent Law.

[0060] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention. The above descriptions are merely preferred embodiments of the invention and are not intended to limit the invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

[0061] It should be noted that the above description of the process is for illustrative purposes only and does not limit the scope of this specification. Those skilled in the art can make various modifications and changes to the process under the guidance of this specification. However, these modifications and changes remain within the scope of this specification.

[0062] The basic concepts have been described above. Obviously, for those skilled in the art who have read this application, the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore, such modifications, improvements, and corrections still fall within the spirit and scope of the exemplary embodiments of this application.

[0063] Furthermore, this application uses specific terms to describe its embodiments. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different positions in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0064] Furthermore, those skilled in the art will understand that aspects of this application can be described and illustrated through several patentable types or situations, including any new and useful combination of processes, machines, products, or substances, or any new and useful improvements thereof. Therefore, aspects of this application can be implemented entirely in hardware, entirely in software (including firmware, resident software, microcode, etc.), or a combination of hardware and software. All of the above hardware or software can be referred to as a “unit,” “module,” or “system.” Furthermore, aspects of this application can take the form of a computer program product embodied in one or more computer-readable media, wherein computer-readable program code is contained therein.

[0065] The computer program code required for the operation of each part of this application can be written in any one or more programming languages, including object-oriented programming languages ​​such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, and Python; general programming languages ​​such as C; Visual Basic, Fortran2103, Perl, COBOL2102, PHP, and ABAP; dynamic programming languages ​​such as Python, Ruby, and Groovy; or other programming languages. This program code can run entirely on the user's computer, or as a standalone software package on the user's computer, or partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer can be connected to the user's computer via any network, such as a local area network (LAN) or wide area network (WAN), or connected to an external computer (e.g., via the Internet), or in a cloud computing environment, or used as a service such as Software as a Service (SaaS).

[0066] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this application are not intended to limit the order of the processes and methods of this application. Although some currently considered useful embodiments of the invention have been discussed in the foregoing disclosure by way of various examples, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments; rather, the claims are intended to cover all modifications and equivalent combinations that conform to the substance and scope of the embodiments of this application. For example, although the implementation of the various components described above can be embodied in a hardware device, it can also be implemented as a purely software solution, such as an installation on an existing server or mobile device.

[0067] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this approach of the present application should not be construed as reflecting an intention that the claimed subject matter requires more features than expressly recited in each claim. Rather, the subject of the invention should possess fewer features than in any single embodiment described above.

Claims

1. A method for rapid evaluation of the shear strength of rock structural surfaces under normal disturbance, characterized in that, include: S1. Sample preparation and initial parameter acquisition: Prepare standard samples containing rock structural surfaces, scan the surface morphology of the structural surfaces and calculate the initial roughness coefficient, and test the uniaxial compressive strength and basic friction angle of the rock through rock mechanics tests; S2. Normal Disturbance Direct Shear Test: A standard specimen is installed in a rock direct shear test system capable of applying normal cyclic loads. An initial normal stress is applied first, and then a normal cyclic disturbance stress with a set amplitude and frequency is superimposed on the initial normal stress. The direct shear test is carried out at a fixed shear rate until the specimen fails in shear, and the peak shear strength is recorded. The values ​​of the initial normal stress, disturbance stress amplitude, disturbance frequency, and shear rate are changed, and the above test is repeated to obtain multiple sets of test data. S3. Experimental data fitting and empirical model establishment: The peak shear strength in multiple sets of experimental data is normalized. Based on Barton strength theory, a modified shear strength empirical model containing the shear rate function is obtained through multi-parameter data fitting. S4. Rapid evaluation of shear strength: Substitute the experimental data into the modified empirical shear strength model, and verify the accuracy of the model by comparing the peak shear strength predicted by the model with the actual peak shear strength measured by the experiment; for rock structural surfaces in actual engineering, obtain their initial roughness coefficient, uniaxial compressive strength and basic friction angle, and determine the corresponding initial normal stress, disturbance stress amplitude, disturbance frequency and shear rate in combination with the engineering environment, and substitute them into the verified modified empirical shear strength model to calculate the peak shear strength of the structural surface after normal disturbance.

2. The method for rapid evaluation of the shear strength of rock structural surfaces under normal disturbance as described in claim 1, characterized in that, The morphology of the rock structure surface mentioned in step S1 is determined by simulating the characteristics of the rock structure surface in the actual engineering site, or it is prefabricated according to the common structural surface types in engineering.

3. The method for rapid evaluation of the shear strength of rock structural surfaces under normal disturbance as described in claim 1, characterized in that, The normal cyclic disturbance stress described in step S2 exhibits periodic fluctuations, and the fluctuation pattern is consistent with the stress change pattern generated by disturbances in actual engineering.

4. The method for rapid evaluation of the shear strength of rock structural surfaces under normal disturbance as described in claim 1, characterized in that, In step S3, normalization is performed to eliminate the interference of the effective values ​​related to normal load, effective values ​​related to normal dynamic load, and effective values ​​related to dynamic load frequency on the peak shear strength.

5. The method for rapid evaluation of the shear strength of rock structural surfaces under normal disturbance as described in claim 1, characterized in that, The shear rate function described in step S3 is used to couple the combined effects of initial normal stress, disturbance stress amplitude, disturbance frequency and shear rate, and to quantify the synergistic effect of each factor on the shear strength of the rock structural surface.

6. The method for rapid evaluation of the shear strength of rock structural surfaces under normal disturbance as described in claim 1, characterized in that, In step S3, when establishing the modified empirical model for shear strength, the shear rate function is simplified to a form that is only related to the single factor and the shear rate for a single factor among the initial normal stress, disturbance stress amplitude, and disturbance frequency, thus obtaining a simplified calculation model for shear strength under the influence of the corresponding single factor.

7. The method for rapid evaluation of the shear strength of rock structural surfaces under normal disturbance as described in claim 1, characterized in that, The basis for verifying the model accuracy in step S4 is that the deviation between the peak shear strength predicted by the model and the actual peak shear strength measured by the experiment is within a preset reasonable range.

8. The method for rapid evaluation of the shear strength of rock structural surfaces under normal disturbance as described in claim 1, characterized in that, In step S1, the surface morphology of the structure is scanned by a three-dimensional laser scanner, and the initial roughness coefficient is calculated based on the morphology data obtained from the scan. The rock mechanics test is a uniaxial compressive strength test and a basic friction angle test that conform to the geotechnical engineering testing standards.

9. The method for rapid evaluation of the shear strength of rock structural surfaces under normal disturbance as described in claim 1, characterized in that, The engineering environment mentioned in step S4 includes the types and intensity levels of activities that cause normal disturbances in the area where the project is located.

10. The method for rapid evaluation of the shear strength of rock structural surfaces under normal disturbance as described in claim 1, characterized in that, The loading process for the direct shear test in step S2 is as follows: first, apply an initial normal stress and keep it stable, then superimpose normal cyclic disturbance stress until the fluctuation stabilizes, and then start shear loading at a fixed shear rate until the specimen fails under shear conditions.

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