An improved RMR rock mass evaluation method based on alpine groundwater environment
By introducing a multi-field coupled damage model and a modified RMR evaluation index, the problem of water-rock interaction and freeze-thaw effects not being considered in the groundwater environment of high-altitude and cold regions was solved, achieving more accurate rock mass evaluation and safety prediction, and reducing costs and workload.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- KUNMING PROSPECTING DESIGN INSTITUTE OF CHINA NONFERROUS METALS INDUSTRY CO LTD
- Filing Date
- 2025-09-01
- Publication Date
- 2026-07-21
AI Technical Summary
Existing RMR rock mass evaluation methods fail to effectively consider the water-rock interaction and freeze-thaw effects of groundwater in high-altitude and cold regions, resulting in evaluation results that do not match reality and are difficult to scientifically guide engineering applications.
A multi-field coupled damage model was introduced, and the total damage parameter Dm was obtained through chemical erosion test and freeze-thaw test. R5, R1 and R2 in the RMR evaluation index were corrected, and the rock mass score RMR was optimized by combining hydrogeological parameters, taking into account water-rock interaction and freeze-thaw effect.
It improves the scientific rigor and practicality of RMR assessment, enabling the prediction of future changes in rock masses in cold groundwater environments, reducing sampling and monitoring costs, and ensuring the safety of mines and slope engineering.
Smart Images
Figure CN120801683B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of rock engineering technology, specifically relating to an improved RMR rock mass evaluation method based on a cold-climate groundwater environment that is low-cost, scientifically sound, and yields practical results. Background Technology
[0002] In many mines in high-altitude and cold regions of my country, some mines experience significant seasonal temperature variations, resulting in freeze-thaw effects on the ore body caused by changes in the water phase. Research indicates that freeze-thaw effects have a substantial impact on the properties of the ore body, directly affecting mining operations and the safety of mine slopes.
[0003] In addition to the periodic freeze-thaw effect, mines in high-altitude and cold regions may also be subject to erosion from complex aquatic environments. Groundwater, as a key dynamic factor in the rock mass environment, can significantly exacerbate the plastic deformation and progressive damage of rock structures. Therefore, a crucial factor affecting the safety performance of rock mass engineering is the mixing of water and rock. Groundwater, seemingly a single body of water, is in fact a complex liquid chemical substance formed by the combined effects of multiple chemical parameters. Essentially, it contains various dissolved ions, pH values, and other indicators, constituting a diverse hydrochemical system. Minerals that have been below the water table for a long period will be subject to erosion and ion migration reactions by groundwater. This is a lengthy process that alters the mineral composition and structural characteristics of the rock mass at the microscopic level by dissolving the cementing materials and expanding the pore structure, ultimately leading to the deterioration of the rock's mechanical properties and causing geological disasters such as landslides.
[0004] Currently, in the relatively representative engineering rock mass classification method, the RMR grading system, although the influence of the groundwater environment on rock mass evaluation is taken into account, it only considers the groundwater inflow state and does not consider the water-rock interaction and the freeze-thaw effect of water phase change. In addition, some engineering projects also have problems such as difficulty and high cost of rock mass sampling. As a result, the RMR rock mass evaluation results in high-altitude groundwater environment are significantly different from the actual situation, making it difficult to provide effective guidance for engineering applications.
[0005] Therefore, how to consider both the groundwater inflow state and the water-rock interaction and freeze-thaw effects of water phase changes during the RMR rock mass evaluation process, so that the RMR rock mass evaluation results in high-altitude groundwater environments are more in line with reality, and thus scientifically predict the future change trend of rock masses in geological engineering applications in high-altitude groundwater environments, so as to take necessary engineering measures to avoid adverse effects, is one of the technical problems that urgently need to be solved in geological engineering in high-altitude groundwater environments. Summary of the Invention
[0006] To address the shortcomings of existing technologies, this invention provides an improved RMR rock mass evaluation method based on high-altitude cold groundwater environments, which is low-cost, scientifically sound, and yields practical results.
[0007] The improved RMR rock mass evaluation method based on high-altitude groundwater environment of this invention is implemented as follows: it includes exploration and testing, data acquisition, rock sample testing, post-processing, and score improvement steps, the specific contents of each step are as follows: A. Exploration and Testing: For geological engineering projects that require rock mass quality assessment, conduct hydrogeological and environmental exploration and investigate the past weather conditions of the area. Based on the general survey report and pre-feasibility study report, determine the sampling area and drilling plan, and complete the relevant pumping tests. B. Data Acquisition: Obtain rock mechanical properties and parameters; through hydrogeological surveys, hydrogeological drilling, geophysical exploration and field tests, identify the main water-bearing rock groups and groundwater composition in the mining area, and obtain the hydrogeological parameters of each aquifer; C. Rock Sample Testing: Uniaxial compression tests were conducted on the rock samples taken from the field, and the elastic modulus was calculated; XRD composition analysis was performed on the rock samples to determine the reactive components; corresponding chemical solutions were prepared according to the reactive components and groundwater composition to conduct chemical erosion tests on the rock samples in simulated groundwater environment at different cycles; freeze-thaw tests were conducted on the rock samples according to the test standards. D. Subsequent processing: Weigh the rock samples after the chemical erosion test. Using 15 days as a cycle, study the mass change pattern with the cycle number as the variable. Weigh the rock samples at different immersion cycles and process the data. Summarize the time-mass curves, and then add the chemical erosion damage parameter to the constitutive equation. D s Used to characterize water-chemical erosion damage; rock samples after freeze-thaw tests are subjected to mechanical tests, and then the total damage parameters of the rock samples after hydration-freeze-thaw interaction are calculated. D m ; E. Improvement of scoring values: Based on total damage parameters D m The rock mass score R5, which depends on the groundwater condition, and the rock mass score R1, which is related to rock strength, and the rock mass score R2, which is related to core quality, in the rock RMR evaluation index are modified. The rock mass score index values that change over time under freeze-thaw and chemical erosion conditions are also optimized. RMR 改进后 Based on the improved rock mass scoring index values RMR 改进后 Formulas that predict the future trend of rock mass changes over time.
[0008] Furthermore, in step A, the hydrogeological and environmental survey includes geological surveying, geophysical exploration, remote sensing, drilling, and rock and mineral mechanics testing.
[0009] Furthermore, in step B, the rock mechanical properties and parameters are obtained based on the results of engineering geological drilling, geophysical testing, and rock and mineral mechanics tests in step A; the hydrogeological parameters of the aquifer include determining the boundaries of the hydrogeological units in the mining area, the lithological characteristics and water-bearing conditions of the aquifer, the hydrochemical characteristics of the groundwater, and the hydrogeological conditions of groundwater recharge, flow, and discharge; the hydrogeological survey is to ascertain the pH value and ionic properties of the groundwater and the hydrochemical characteristics of the groundwater; the groundwater composition is determined by the groundwater obtained from the pumping test in step A.
[0010] Furthermore, in step C, the rock sample is prepared from the rock mass extracted on-site and sized to Φ50mm × h A standard 100mm specimen is required. XRD analysis of the rock sample is used to analyze the main chemical reaction equations between the rock mass and groundwater to determine the reaction components. The rock samples used in chemical erosion tests and freeze-thaw tests, as well as the treatments for the rock samples including drying and saturation, should meet the requirements for rock specimens in GB / T50266-2013 "Standard for Test Methods of Engineering Rock Mass" 2.3.2. Freeze-thaw tests should be conducted according to the test methods in GB / T50266-2013 "Standard for Test Methods of Engineering Rock Mass" 2.8.6. For chemical erosion tests, the solution is prepared according to the pH of the groundwater and the main reaction components. The test is conducted by full immersion in the chemical solution using the prepared solution instead of water, referring to the forced saturation method.
[0011] Furthermore, in the chemical erosion test and freeze-thaw test of step D, the water-rock reaction triggers mineral dissolution, leading to increased porosity, decreased effective bearing area, grain dissociation and cement destruction in the microstructure, which macroscopically manifests as mass loss and deterioration of mechanical properties. Chemical alteration of the soluble phase is the main controlling factor for damage accumulation. Rock deterioration is a process of solid-phase transformation into liquid-phase, which can be directly reflected in the quality of the rock. Therefore, the chemical erosion damage parameter is crucial in the constitutive equation of chemical erosion. D s Related to changes in mass, it is used to characterize the damage effect of water chemical erosion. The constitutive equation for chemical erosion is: In the formula: m 0、 m t These represent the initial mass of the rock sample and the chemical erosion of the rock sample, respectively. t The quality of a diva.
[0012] Furthermore, the freeze-thaw test incorporates the principle of strain equivalence in addressing freeze-thaw damage, resulting in the following stress-strain relationship for the rock sample: In the formula: eIn response, s and in These are the nominal stress and the effective stress, respectively. E The elastic modulus of the material under reference conditions; E’ This refers to the elastic modulus of the material when it is in a damaged state. D For freeze-thaw damage parameters; Among them, the n Secondary freeze-thaw damage parameters D n for: In the formula: E n For experience n Elastic modulus after one freeze-thaw cycle E 0 The elastic modulus before freeze-thaw cycles; After hydration-freeze-thaw cycles, the damage state of rock samples can be divided into two types: the first type is damage caused by freeze-thaw chemical erosion, and the second type is damage caused by loading after freeze-thaw cycles. Therefore, the total damage parameter of the rock sample... D m for: .
[0013] Furthermore, in step E, the total damage parameter mentioned above is first determined... D m The rock mass score R5, which depends on the groundwater state, the rock mass score R1, which is related to the rock strength, and the rock mass score R2, which is related to the core quality index, are corrected in the rock RMR evaluation index. Table 1. Rock mass score R5 depending on groundwater condition
[0014] Then, the improved rock mass score value is obtained through optimization. RMR 改进后 for: In the formula: R1 is the rock mass score of rock strength, R2 is the rock mass score of core quality index, R3 is the rock mass score of the spacing of the most influential joint group, R4 is the rock mass score of joint state, R5 is the rock mass score that depends on the groundwater state, and R6 is the correction value of joint orientation to RMR.
[0015] The present invention has the following beneficial effects: 1. This invention innovatively introduces a multi-field coupled damage model: by adding a chemical erosion test and correspondingly introducing chemical erosion damage parameters. DsQuantify the microscopic damage of rock masses caused by water-rock interactions (such as cement dissolution and pore expansion); calculate freeze-thaw damage parameters through standardized freeze-thaw tests and the principle of strain equivalence. Dn Then, the hydration-freeze-thaw total damage parameter was obtained by integration. Dm Then based on the total damage parameter Dm The RMR system's score R5, which depends on groundwater conditions, and the rock mass score R1, which is related to rock strength, and the rock mass score R2, which is based on core quality indicators, are corrected to obtain the final rock mass score based on freeze-thaw cycles and groundwater chemical erosion. RMR 改进后 The multi-field coupled damage model integrates "water-rock interaction + freeze-thaw effect" into the RMR evaluation system for the first time. It can systematically evaluate the impact of chemical interactions between groundwater and rock mass (such as ion migration and cement dissolution) and freeze-thaw cycles (microstructural damage caused by phase change) on rock mass. It makes up for the omission of key factors in high-altitude groundwater environment by traditional methods, and makes the evaluation results more consistent with the actual deterioration state of rock mass in high-altitude groundwater environment, providing a reusable technical paradigm for similar projects.
[0016] 2. This invention fits the mass loss law of rock mass under chemical erosion by mass-time variation curves, and introduces chemical erosion damage parameters into the constitutive equation. Ds Then, the freeze-thaw damage is calculated by combining the change in elastic modulus, and finally the total damage parameter is used. Dm This study quantifies the correlation between microscopic deterioration (grain dissociation, increased porosity) and macroscopic mechanical property degradation in rock masses, thereby transforming the microscopic porosity expansion-macroscopic mechanical attenuation into measurable damage values. This allows the improved RMR score to not only reflect the current rock mass quality but also to provide a more comprehensive picture through damage parameters. Dm and Ds This study reveals the deterioration patterns of rock masses under water-rock interaction and freeze-thaw cycles, providing a scientific basis for predicting future trends of rock masses (such as mechanical property degradation and collapse risk) in cold groundwater environments.
[0017] 3. This invention addresses the challenges of difficult and costly rock mass sampling in high-altitude and cold regions by replacing large-scale, long-term field monitoring with small-scale on-site sampling and rapid indoor chemical erosion-freeze-thaw combined tests. By combining hydrogeological parameters (pH value, ionic properties, etc.) and previous hydrogeological and environmental survey data, it not only avoids excessive drilling and sampling, thus significantly reducing material consumption and labor costs, but also allows for the derivation of the correlation between quality and time through curve fitting in chemical erosion, eliminating the need for indefinitely extended test cycles, reducing test energy consumption and time costs, and ultimately achieving efficient assessment of rock mass damage effects.
[0018] 4. Rock mass scoring value of the present invention RMR 改进后Only the groundwater item R5, the freeze-thaw and groundwater chemical erosion related items R1 and R2 in the RMR are modified, while the other three items remain unchanged. This achieves a seamless connection between the old and new systems, effectively reduces variables to lower the workload in the early stages, and facilitates continuous use in multiple stages such as design, construction, and monitoring.
[0019] In summary, this invention, targeting high-altitude and cold groundwater environments, successfully integrates the three core degradation mechanisms of water—physical action, chemical erosion, and freeze-thaw action caused by temperature phase changes—into the classic RMR evaluation system. This significantly improves the scientific validity and practicality of the evaluation results and has important guiding significance for ensuring the long-term safety of mines and slope engineering in high-altitude and cold regions. Attached Figure Description
[0020] Figure 1 This is a flowchart of the improved RMR rock mass evaluation method based on high-altitude groundwater environment according to the present invention; In the diagram: S100 - Exploration and testing, S200 - Data acquisition, S300 - Rock sample testing, S400 - Post-processing, S500 - Score improvement. Detailed Implementation
[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this does not limit the present invention in any way. Any changes or improvements made based on the teachings of the present invention shall fall within the protection scope of the present invention.
[0022] like Figure 1 As shown, the improved RMR rock mass evaluation method based on high-altitude groundwater environment of this invention includes the following steps: exploration and testing, data acquisition, rock sample testing, post-processing, and score improvement. The specific contents of each step are as follows: A. Exploration and Testing: For geological engineering projects that require rock mass quality assessment, conduct hydrogeological and environmental exploration and investigate the past weather conditions of the area. Based on the general survey report and pre-feasibility study report, determine the sampling area and drilling plan, and complete the relevant pumping tests. B. Data Acquisition: Obtain rock mechanical properties and parameters; through hydrogeological surveys, hydrogeological drilling, geophysical exploration and field tests, identify the main water-bearing rock groups and groundwater composition in the mining area, and obtain the hydrogeological parameters of each aquifer; C. Rock Sample Testing: Uniaxial compression tests were conducted on the rock samples taken from the field, and the elastic modulus was calculated; XRD composition analysis was performed on the rock samples to determine the reactive components; corresponding chemical solutions were prepared according to the reactive components and groundwater composition to conduct chemical erosion tests on the rock samples in simulated groundwater environment at different cycles; freeze-thaw tests were conducted on the rock samples according to the test standards. D. Subsequent processing: Weigh the rock samples after the chemical erosion test. Using 15 days as a cycle, study the mass change pattern with the cycle number as the variable. Weigh the rock samples at different immersion cycles and process the data. Summarize the time-mass curves, and then add the chemical erosion damage parameter to the constitutive equation. D s Used to characterize water-chemical erosion damage; rock samples after freeze-thaw tests are subjected to mechanical tests, and then the total damage parameters of the rock samples after hydration-freeze-thaw interaction are calculated. D m ; E. Improvement of scoring values: Based on total damage parameters D m The rock mass score R5, which depends on the groundwater condition, and the rock mass score R1, which is related to rock strength, and the rock mass score R2, which is related to core quality, in the rock RMR evaluation index are modified. The rock mass score index values that change over time under freeze-thaw and chemical erosion conditions are also optimized. RMR 改进后 Based on the improved rock mass scoring index values RMR 改进后 Formulas that predict the future trend of rock mass changes over time.
[0023] In step A, the hydrogeological and environmental exploration includes geological surveying, geophysical exploration, remote sensing, drilling, and rock and mineral mechanics testing.
[0024] In step B, the rock mechanical properties and parameters are obtained based on the results of engineering geological drilling, geophysical testing, and rock and mineral mechanics tests in step A; the hydrogeological parameters of the aquifer include determining the boundaries of the hydrogeological units in the mining area, the lithological characteristics and water-bearing conditions of the aquifer, the hydrochemical characteristics of the groundwater, and the hydrogeological conditions of groundwater recharge, flow, and discharge; the hydrogeological survey is to ascertain the pH value and ionic properties of the groundwater and the hydrochemical characteristics of the groundwater; the groundwater composition is determined by the groundwater obtained from the pumping test in step A.
[0025] In step C, the rock sample is prepared from the rock mass taken from the site and made into a Φ50mm × hA standard 100mm specimen is required. XRD analysis of the rock sample is used to analyze the main chemical reaction equations between the rock mass and groundwater to determine the reaction components. The rock samples used in chemical erosion tests and freeze-thaw tests, as well as the treatments for the rock samples including drying and saturation, should meet the requirements for rock specimens in GB / T50266-2013 "Standard for Test Methods of Engineering Rock Mass" 2.3.2. Freeze-thaw tests should be conducted according to the test methods in GB / T50266-2013 "Standard for Test Methods of Engineering Rock Mass" 2.8.6. For chemical erosion tests, the solution is prepared according to the pH of the groundwater and the main reaction components. The test is conducted by full immersion in the chemical solution using the prepared solution instead of water, referring to the forced saturation method.
[0026] In the chemical erosion and freeze-thaw tests of step D, the water-rock reaction triggers mineral dissolution, leading to increased porosity, decreased effective bearing area, and microstructural changes including grain dissociation and cement destruction. Macroscopically, this manifests as mass loss and deterioration of mechanical properties. Chemical alteration of the soluble phase is the primary controlling factor for damage accumulation. Rock degradation is a process of solid-liquid phase transformation, which is directly reflected in its quality. Therefore, the chemical erosion damage parameter is crucial in the constitutive equation of chemical erosion. D s Related to changes in mass, it is used to characterize the damage effect of water chemical erosion. The constitutive equation for chemical erosion is: In the formula: m 0、 m t These represent the initial mass of the rock sample and the chemical erosion of the rock sample, respectively. t The quality of a diva.
[0027] Among these methods, different soaking cycles were designed to obtain rock sample quality. m Data on changes over time, and a summary of rock sample quality. m The time-mass curve was used to select a fitting equation that conformed to the aforementioned curve shape, and the rock sample quality was used as the basis for the calculation. m The parameters in the fitted equation are determined by the data changing over time. Finally, the correlation R of the fitted equation is calculated by taking the residual between the fitted value and the actual data value. 2 :
[0028] In the formula: y i These are actual data values. The mean of the actual data. These are the predicted values from the fitted equation.
[0029] The rock sample quality was obtained by selecting the fitting equation with the highest correlation. mThe fitted curve of the relationship between the rock sample and time variation is used to determine the rock sample quality. m With time t The relationship of change m t Thus, the erosion damage D is obtained. s The relationship between the time t and the change.
[0030] In the freeze-thaw test, the principle of strain equivalence is introduced to address freeze-thaw damage. The stress-strain relationship of the rock sample is as follows: In the formula: e In response, s and in These are the nominal stress and the effective stress, respectively. E The elastic modulus of the material under reference conditions; E’ This refers to the elastic modulus of the material when it is in a damaged state. D For freeze-thaw damage parameters; Among them, the n Secondary freeze-thaw damage parameters D n for: In the formula: E n For experience n Elastic modulus after one freeze-thaw cycle E 0 The elastic modulus before freeze-thaw cycles; After hydration-freeze-thaw cycles, the damage state of rock samples can be divided into two types: the first type is damage caused by freeze-thaw chemical erosion, and the second type is damage caused by loading after freeze-thaw cycles. Therefore, the total damage parameter of the rock sample... D m for: .
[0031] In step E, firstly based on the aforementioned total damage parameter... D m The rock mass score R5, which depends on the groundwater state, the rock mass score R1, which is related to the rock strength, and the rock mass score R2, which is related to the core quality index, are corrected in the rock RMR evaluation index. Table 1. Rock mass score R5 depending on groundwater condition
[0032] Then, the improved rock mass score value is obtained through optimization. RMR 改进后 for: In the formula: R1 is the rock mass score of rock strength, R2 is the rock mass score of core quality index, R3 is the rock mass score of the spacing of the most influential joint group, R4 is the rock mass score of joint state, R5 is the rock mass score that depends on the groundwater state, and R6 is the correction value of joint orientation to RMR.
[0033] It should be noted that in the improved formula for the rock mass score RMR after step E, (R1+R2+R5)(1-D m This refers to the aforementioned corrections to R5, R1, and R2. R1 in the formula is taken according to Table 1, while R2, R3, R4, R5, and R6 are taken according to the normal RMR scoring indicators.
[0034] Example
[0035] 100: For geological engineering projects that require rock mass quality assessment, conduct geological surveys, geophysical exploration, remote sensing, drilling, rock and mineral mechanics tests, and hydrogeological and environmental exploration work, investigate the past weather conditions of the area, determine the sampling area and drilling plan based on the general survey report and pre-feasibility study report, and complete relevant pumping tests.
[0036] S200: Based on the aforementioned engineering geological drilling work, geophysical testing, and rock and mineral mechanics test results, obtain the rock mechanical properties and parameters. Through hydrogeological surveys, hydrogeological drilling, geophysical exploration, and field tests, identify the main water-bearing rock groups and groundwater composition in the mining area, and obtain the hydrogeological parameters of each aquifer, including determining the boundaries of hydrogeological units in the mining area, the lithological characteristics and water-bearing conditions of the aquifer, the hydrochemical characteristics of groundwater, and the hydrogeological conditions of groundwater recharge, flow, and discharge. Among these, the hydrogeological survey is to identify the pH value and ionic properties of groundwater, as well as the hydrochemical characteristics of groundwater.
[0037] S300: The rock mass extracted from the site will be processed into Φ50mm× hA standard 100mm specimen was used, and a uniaxial compression test was conducted to calculate the elastic modulus. XRD analysis was performed on the rock sample to determine the main chemical reaction equations between the rock mass and groundwater, identify the reaction components, and prepare appropriate chemical solutions to simulate groundwater environments for chemical erosion tests on the rock sample at different cycles. Freeze-thaw tests were conducted on the rock sample according to the test standards. The rock sample used in the chemical erosion and freeze-thaw tests, as well as the treatments including drying and saturation, should meet the requirements for rock specimens in GB / T50266-2013 "Standard for Test Methods of Engineering Rock Mass" 2.3.2. Freeze-thaw tests should be conducted according to the test methods in GB / T50266-2013 "Standard for Test Methods of Engineering Rock Mass" 2.8.6. For the chemical erosion test, the solution was prepared according to the pH of the groundwater and the main reaction components. The test involved full immersion in the chemical solution using the prepared solution instead of water, referring to the forced saturation method.
[0038] S400: Weigh the rock samples after the chemical erosion test, taking 15 days as a cycle, and using the number of cycles as a variable to study the mass change pattern. Weigh the rock samples with different immersion cycles and perform data processing to summarize the time-mass curve. Then, add the chemical erosion damage parameter to the constitutive equation. D s Characterizing hydrochemical erosion damage; mechanical tests were conducted on rock samples after freeze-thaw cycles, and then the total damage parameters of the rock samples after hydration-freeze-thaw interaction were calculated. D m .
[0039] In the chemical erosion test and freeze-thaw test of step D, the water-rock reaction triggers mineral dissolution, leading to increased porosity, decreased effective bearing area, grain dissociation and cement destruction in the microstructure. Macroscopically, this manifests as mass loss and deterioration of mechanical properties. Chemical alteration of the soluble phase is the primary controlling factor for damage accumulation. Rock deterioration is a process of solid-to-liquid transformation, which is directly reflected in the quality of the rock. Therefore, the chemical erosion damage parameter is crucial in the constitutive equation of chemical erosion. D s Related to changes in mass, it is used to characterize the damage effect of water chemical erosion. The constitutive equation for chemical erosion is: In the formula: m 0、 m t These represent the initial mass of the rock sample and the chemical erosion of the rock sample, respectively. t The quality of a queen; Among these methods, different soaking cycles were designed to obtain rock sample quality. m Data on changes over time, and a summary of rock sample quality. mThe time-mass curve was used to select a fitting equation that conformed to the aforementioned curve shape, and the rock sample quality was used as the basis for the calculation. m The parameters in the fitted equation are determined by the data changing over time. Finally, the correlation R of the fitted equation is calculated by taking the residual between the fitted value and the actual data value. 2 :
[0040] In the formula: y i These are actual data values. The mean of the actual data. These are the predicted values from the fitted equation.
[0041] The rock sample quality was obtained by selecting the fitting equation with the highest correlation. m The fitted curve of the relationship between the rock sample and time variation is used to determine the rock sample quality. m With time t The relationship of change m t Thus, the erosion damage D is obtained. s The relationship between mass and time t [e.g., if the initial mass of the rock sample is 125g, it becomes 123g after 15 days of soaking, and 121g after 30 days of soaking; the relationship between mass and time at this point is m]. t =125-0.13t (The actual situation is more complex than the listed situation, and the corresponding curve relationships will also be more complex, and the selected curve relationships will also be more complex); then m t Substituting these parameters into the chemical erosion damage formula, the relationship between erosion damage and time is obtained as follows: Ds =[1-(125-0.13t) / 125]^2 / 3].
[0042] Meanwhile, in the freeze-thaw test, the principle of strain equivalence is introduced to address freeze-thaw damage, and the stress-strain relationship of the rock sample is as follows: In the formula: e In response, s and in These are the nominal stress and the effective stress, respectively. E The elastic modulus of the material under reference conditions; E’ This refers to the elastic modulus of the material when it is in a damaged state. D For freeze-thaw damage parameters; Among them, the n Secondary freeze-thaw damage parameters D n for: In the formula: E n For experience nElastic modulus after one freeze-thaw cycle E 0 The elastic modulus before freeze-thaw cycles; After hydration-freeze-thaw cycles, the damage state of rock samples can be divided into two types: the first type is damage caused by freeze-thaw chemical erosion, and the second type is damage caused by loading after freeze-thaw cycles. Therefore, the total damage parameter of the rock sample... D m for: .
[0043] S500: Based on the aforementioned total damage parameters D m The rock mass score R5, which depends on the groundwater state, the rock mass score R1, which is related to the rock strength, and the rock mass score R2, which is related to the core quality index, are corrected in the rock RMR evaluation index. Table 1. Rock mass score R5 depending on groundwater condition
[0044] Then, the improved rock mass score value is obtained through optimization. RMR 改进后 for: In the formula: R1 is the rock mass score of rock strength, R2 is the rock mass score of core quality index, R3 is the rock mass score of the spacing of the most influential joint group, R4 is the rock mass score of joint state, R5 is the rock mass score that depends on the groundwater state, and R6 is the correction value of joint orientation to RMR.
[0045] Improved rock mass score RMR 改进后 In the formula, (R1+R2+R5)(1-D m This refers to the aforementioned corrections to R5, R1, and R2. R1 in the formula is taken according to Table 1, while R2, R3, R4, R5, and R6 are taken according to the normal RMR scoring indicators.
[0046] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. An improved RMR rock mass evaluation method based on high-altitude cold groundwater environment, characterized in that: The process includes exploration and testing, data acquisition, rock sample testing, post-processing, and score improvement. The specific details of each step are as follows: A. Exploration and Testing: For geological engineering projects that require rock mass quality assessment, conduct hydrogeological and environmental exploration and investigate past weather conditions in the area. Based on the general survey report and pre-feasibility study report, determine the sampling area and drilling plan, and complete relevant pumping tests. B. Data Acquisition: Obtain rock mechanical properties and parameters; through hydrogeological surveys, hydrogeological drilling, geophysical exploration and field tests, identify the main water-bearing rock groups and groundwater composition in the mining area, and obtain the hydrogeological parameters of each aquifer; C. Rock Sample Testing: Uniaxial compression tests were conducted on the rock samples taken from the field, and the elastic modulus was calculated; XRD composition analysis was performed on the rock samples to determine the reactive components; corresponding chemical solutions were prepared according to the reactive components and groundwater composition to conduct chemical erosion tests on the rock samples in simulated groundwater environment at different cycles; freeze-thaw tests were conducted on the rock samples according to the test standards. D. Subsequent processing: Weigh the rock samples after the chemical erosion test. Using 15 days as a cycle, study the mass change pattern with the cycle number as the variable. Weigh the rock samples at different immersion cycles and process the data. Summarize the time-mass curves, and then add the chemical erosion damage parameter to the constitutive equation. D s Used to characterize water-chemical erosion damage; rock samples after freeze-thaw tests are subjected to mechanical tests, and then the total damage parameters of the rock samples after hydration-freeze-thaw interaction are calculated. D m ; E. Improvement of scoring values: Based on total damage parameters D m The rock mass score R5, which depends on the groundwater condition, and the rock mass score R1, which is related to rock strength, and the rock mass score R2, which is related to core quality, in the rock RMR evaluation index are modified. The rock mass score index values that change over time under freeze-thaw and chemical erosion conditions are also optimized. RMR 改进后 Based on the improved rock mass scoring index values RMR 改进后 Formulas that predict the future trend of rock mass changes over time; In the chemical erosion and freeze-thaw tests of step D, the water-rock reaction triggers mineral dissolution, leading to increased porosity, decreased effective bearing area, and microstructural changes including grain dissociation and cement destruction. Macroscopically, this manifests as mass loss and deterioration of mechanical properties. Chemical alteration of the soluble phase is the primary controlling factor for damage accumulation. Rock degradation is a process of solid-liquid phase transformation, which is directly reflected in its quality. Therefore, the chemical erosion damage parameter is crucial in the constitutive equation of chemical erosion. D s Related to changes in mass, it is used to characterize the damage effect of water chemical erosion. The constitutive equation for chemical erosion is: In the formula: m 0、 m t These represent the initial mass of the rock sample and the chemical erosion of the rock sample, respectively. t The quality of a queen; In the freeze-thaw test, the principle of strain equivalence is introduced to address freeze-thaw damage. The stress-strain relationship of the rock sample is as follows: In the formula: ε In response, σ and σ' These are the nominal stress and the effective stress, respectively. E The elastic modulus of the material under reference conditions; E’ This refers to the elastic modulus of the material when it is in a damaged state. D For freeze-thaw damage parameters; Among them, the n Secondary freeze-thaw damage parameters D n for: In the formula: E n For experience n Elastic modulus after one freeze-thaw cycle E 0 The elastic modulus before freeze-thaw cycles; After hydration-freeze-thaw cycles, the damage state of rock samples can be divided into two types: the first type is damage caused by freeze-thaw chemical erosion, and the second type is damage caused by loading after freeze-thaw cycles. Therefore, the total damage parameter of the rock sample... D m for: 。 2. The improved RMR rock mass evaluation method based on high-altitude cold groundwater environment according to claim 1, characterized in that: In step A, the hydrogeological and environmental exploration includes geological surveying, geophysical exploration, remote sensing, drilling, and rock and mineral mechanics testing.
3. The improved RMR rock mass evaluation method based on high-altitude cold groundwater environment according to claim 1, characterized in that: In step B, the rock mechanical properties and parameters are obtained based on the results of engineering geological drilling, geophysical testing, and rock and mineral mechanics tests in step A; the hydrogeological parameters of the aquifer include determining the boundaries of the hydrogeological units in the mining area, the lithological characteristics and water-bearing conditions of the aquifer, the hydrochemical characteristics of the groundwater, and the hydrogeological conditions of groundwater recharge, flow, and discharge; the hydrogeological survey is to ascertain the pH value and ionic properties of the groundwater and the hydrochemical characteristics of the groundwater; the groundwater composition is determined by the groundwater obtained from the pumping test in step A.
4. The improved RMR rock mass evaluation method based on high-altitude cold groundwater environment according to claim 1, characterized in that: In step C, the rock sample is prepared from the rock mass taken from the site and made into a Φ50mm × h A standard 100mm specimen is required. XRD analysis of the rock sample is used to analyze the main chemical reaction equations between the rock mass and groundwater to determine the reaction components. The rock samples used in chemical erosion tests and freeze-thaw tests, as well as the treatments for the rock samples including drying and saturation, should meet the requirements for rock specimens in GB / T50266-2013 "Standard for Test Methods of Engineering Rock Mass" 2.3.
2. Freeze-thaw tests should be conducted according to the test methods in GB / T50266-2013 "Standard for Test Methods of Engineering Rock Mass" 2.8.
6. For chemical erosion tests, the solution is prepared according to the pH of the groundwater and the main reaction components. The test is conducted by full immersion in the chemical solution using the prepared solution instead of water, referring to the forced saturation method.
5. The improved RMR rock mass evaluation method based on high-altitude cold groundwater environment according to claim 1, characterized in that: In step E, firstly based on the aforementioned total damage parameter... D m The rock mass score R5, which depends on the groundwater state, the rock mass score R1, which is related to the rock strength, and the rock mass score R2, which is related to the core quality index, are corrected in the rock RMR evaluation index. Table 1. Rock mass score R5 depending on groundwater condition Then, the improved rock mass score value is obtained through optimization. RMR 改进后 for: In the formula: R1 is the rock mass score of rock strength, R2 is the rock mass score of core quality index, R3 is the rock mass score of the spacing of the most influential joint group, R4 is the rock mass score of joint state, R5 is the rock mass score that depends on the groundwater state, and R6 is the correction value of joint orientation to RMR.