Improved RMR rock mass evaluation method based on high and cold underground water environment

Abstract

The invention belongs to the technical field of rock engineering, and particularly discloses an improved RMR rock mass evaluation method based on a high and cold underground water environment. The method comprises the following steps: carrying out hydraulic ring investigation, investigating weather, determining a sampling interval and a drilling scheme, and carrying out a water pumping test; obtaining rock mechanical properties and parameters, finding out main water-containing rock groups in a mining area, and obtaining hydrogeological parameters; carrying out uniaxial compression test on the rock sample and calculating an elastic modulus; carrying out XRD component analysis on the rock sample, and preparing a corresponding chemical solution to carry out a chemical erosion test on the rock sample; performing a freeze thawing test on the rock sample according to the standard, weighing the mass of the rock sample after the test, and adding a chemical erosion damage parameter Ds in a constitutive equation; performing a mechanical test on the rock sample subjected to the freeze-thaw test, and calculating a total damage parameter Dm of the rock sample; and modifying the rock mass score R5 according to the Dm and optimizing the rock mass score RMR improvement, and predicting the future change trend of the rock mass according to the RMR improvement. The method has the characteristics of low cost, scientific and reasonable process and practical result.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rock engineering, and particularly relates to an improved RMR rock mass evaluation method based on high-cold groundwater environment, which is low in cost, reasonable in process and practical in result. BACKGROUND

[0002] Among many mines in high-cold regions of China, the seasonal temperature difference of some mines is large, so the mine body will be affected by the freeze-thaw effect caused by the change of water phase. According to the research, the freeze-thaw effect has a great influence on the performance of the mine body, which is directly related to the mining and safety performance of the mine slope.

[0003] In addition to the periodic freeze-thaw effect, the mine in the high-cold region may also be affected by the complex water environment erosion. As a key dynamic factor in the rock mass environment, groundwater can significantly aggravate the plastic deformation and progressive failure of rock structure, so the key factor affecting the safety performance of rock mass engineering is the mixing effect between water and rock. Groundwater seems to be a single water body, but in essence it is a complex liquid chemical substance formed by the joint action of multiple chemical parameters. Essentially, it constitutes a diversified water chemical system due to the presence of various dissolved ions, pH value and other indicators. The ore body below the water level will be eroded by groundwater and affected by ion migration reaction, which is a long process. It changes the mineral composition and structural characteristics of the rock mass from the micro level by dissolving the cementing material of the rock mass and expanding the pore structure, and ultimately causes the deterioration of the mechanical properties of the rock mass, leading to the occurrence of collapse geological disasters.

[0004] At present, in the relatively representative engineering rock mass classification method RMR classification system, although the influence of groundwater environment on rock mass evaluation is considered, but only the gushing state of groundwater is considered, without considering the interaction between water and rock and the freeze-thaw effect of water phase change, and there are problems of difficult rock mass sampling and high cost in some engineering projects, which leads to a large deviation between the RMR rock mass evaluation results under high-cold groundwater environment and the actual situation, and it is difficult to effectively guide the engineering application.

[0005] Therefore, how to consider the gushing state of groundwater in the RMR rock mass evaluation process, and also consider the interaction between water and rock and the freeze-thaw effect of water phase change, so that the RMR rock mass evaluation results under high-cold groundwater environment are more practical, and the future trend of rock mass in geological engineering application under high-cold groundwater environment can be scientifically predicted, so as to take necessary engineering measures to avoid adverse effects, is one of the technical problems to be solved in geological engineering under high-cold groundwater environment. SUMMARY

[0006] In order to solve the problems in the prior art, the application provides an improved RMR rock mass evaluation method based on a high-cold groundwater environment, which is low in cost, reasonable in process and practical in result.

[0007] The improved RMR rock mass evaluation method based on the high-cold groundwater environment is realized by comprising the steps of surveying and testing, data acquisition, rock sample testing, subsequent processing and score improvement, and the specific contents of each step are as follows. A, surveying and testing: for the geological engineering needing rock mass quality evaluation, water conservancy ring surveying work is carried out and the weather conditions in the region are investigated, the sampling interval and drilling scheme are determined according to the census report and the pre-feasibility study report, and the related pumping test is completed; B, data acquisition: the rock mechanics properties and parameters are acquired, the main water-bearing rock group and the groundwater composition in the mining area are found out through hydrogeological investigation, hydrogeological drilling, geophysical prospecting and field test work, and the hydrogeological parameters of each water-bearing layer are acquired; C, rock sample testing: the rock sample taken from the field is subjected to uniaxial compression test and the elastic modulus is calculated; the rock sample is subjected to XRD component analysis to determine the reaction components, and the corresponding chemical solution is configured according to the reaction components and the groundwater composition to carry out different period chemical erosion test on the rock sample in the simulated groundwater environment; the rock sample is subjected to freeze-thaw test according to the test standard; D, subsequent processing: the mass of the rock sample after chemical erosion test is weighed, 15d is taken as a period, the mass change law is studied with the period number as the variable, the mass of the rock sample after different soaking periods is weighed and data processing is carried out, and the time-mass curve is summarized, and then the chemical erosion damage parameter is added in the constitutive equation D s for characterizing the water chemical erosion damage; the rock sample after freeze-thaw test is subjected to mechanical test, and then the total damage parameter of the rock sample after hydration-freeze-thaw is calculated D m ; E, score improvement: according to the total damage parameter D m , the rock mass score value R5 depending on the groundwater state in the rock RMR evaluation index and the rock mass score value R1 and the rock core quality index rock mass score value R2 which are affected by the rock strength are corrected, and the rock mass score index value changing with time under the conditions of freeze-thaw and chemical erosion is optimized RMR 改进后 , the rock mass score index value RMR 改进后 changes with time according to the law formula, and the future change trend of the rock mass is predicted.

[0008] Further, in the A step, the water conservancy ring surveying includes geological surveying, geophysical prospecting, remote sensing, drilling and rock and mineral mechanics test.

[0009] Further, in the B step, the rock mechanics properties and parameters are obtained based on the engineering geological drilling work, geophysical testing and rock and mineral mechanics test results of the A step; the hydrogeological parameters of the aquifer include determining the boundary of the hydrogeological unit in the mining area, the lithological characteristics and water-rich conditions of the aquifer, the hydrochemical characteristics of the groundwater, and the hydrogeological conditions of groundwater recharge, runoff and discharge; the hydrogeological investigation is to find out the pH value and ionic properties of the groundwater and the hydrochemical characteristics of the groundwater; the composition of the groundwater is determined by the pumping test of the A step.

[0010] Further, in the C step, the rock sample is a Φ50mmx h 100mm standard sample made of the rock mass taken on site; the XRD composition analysis of the rock sample is to analyze the main chemical reaction equation of the rock mass and the groundwater to determine the reaction composition; the rock sample in the chemical erosion test and the freeze-thaw test and the treatment of the rock sample including drying and saturation should meet the requirements of the rock test piece in GB / T 50266-2013 "Engineering Rock Mass Test Method Standard" 2.3.2, and the freeze-thaw test of the test sample should be carried out according to the test method in GB / T 50266-2013 "Engineering Rock Mass Test Method Standard" 2.8.6; the chemical erosion test is to configure the solution according to the pH of the groundwater and the main reaction components, and the chemical solution is fully immersed by referring to the pumping saturation in the forced saturation method, and the prepared solution is used instead of water for immersion.

[0011] Further, in the chemical erosion test and the freeze-thaw test of the D step, the water-rock reaction will cause mineral dissolution, leading to an increase in porosity, a decrease in effective bearing area, and a grain dissociation and cement destruction in the microstructure, while the macroscopic performance is mass loss and mechanical property degradation, the chemical alteration of the soluble phase is the main controlling factor of damage accumulation, and the degradation of the rock is the process of converting from solid phase to liquid phase, which can be directly reflected in mass, so the chemical erosion damage parameter D s related to mass change is used to represent the chemical erosion damage effect, and the constitutive equation of chemical erosion is: In the formula: m 0、 m t are the mass of the initial state of the rock sample, the mass of the rock sample after chemical erosion t and the mass of the rock sample after chemical erosion and freeze-thaw, respectively.

[0012] Further, in the freeze-thaw test, the strain equivalence principle is introduced, and the damage stress-strain relationship of the rock sample is: In the formula: εis the strain, σ and σ' are the nominal stress and the effective stress respectively, E is the elastic modulus of the material in the reference state; E’ is the elastic modulus of the material in the damaged state, D is the freeze-thaw damage parameter; wherein the first freeze-thaw damage parameter n is the first freeze-thaw damage parameter D n is: wherein: E n is the elastic modulus after n freeze-thaw cycles, n is the elastic modulus after n freeze-thaw cycles, E 0 is the elastic modulus before freeze-thaw cycles; After the rock sample undergoes hydration-freezing action, the damage state of the rock sample is divided into two kinds: the first damage state is the damage of the rock sample after freeze-thaw chemical erosion, and the second damage state is the damage caused by loading under the action of freeze-thaw cycles; therefore, the total damage parameter of the rock sample D m is: .

[0013] Further, in the E step, first, the rock mass score value R5 depending on the state of groundwater and the rock mass score value R1 and the rock mass score value R2 of the core quality index which affect the rock strength in the rock RMR evaluation index are corrected according to the total damage parameter D m . Table 1 rock mass score value R5 depending on the state of groundwater

[0014] Then, the improved rock mass score value R is obtained by optimization RMR 改进后 is: wherein: R1 is the rock mass score value of rock strength, R2 is the rock mass score value of the core quality index, R3 is the rock mass score value of the most influential joint group spacing, R4 is the rock mass score value of the joint state, R5 is the rock mass score value depending on the state of groundwater, and R6 is the correction value of the joint orientation to RMR.

[0015] The present application has the following beneficial effects: 1. The present application innovatively introduces a multi-field coupling damage model: by adding a chemical erosion test, and correspondingly introducing a chemical erosion damage parameter DsQuantify the microscopic damage of water-rock interaction to rock mass (such as cement dissolution, pore expansion); through the standard freeze-thaw test, and combined with the strain equivalence principle to calculate the freeze-thaw damage parameter Dn ; then the total damage parameter of hydration-freezing is obtained Dm , and then based on the total damage parameter Dm , the score value R5 in the RMR system which depends on the state of groundwater and the rock mass score value R1 and the rock mass score value R2 of the rock core quality index which affect the rock strength are corrected, and finally the rock mass score value based on freeze-thaw and groundwater chemical erosion is obtained RMR 改进后 Multi-field coupling damage model, so for the first time, the "water-rock interaction + freeze-thaw effect" system is integrated into the RMR evaluation system, which can systematically evaluate the influence of groundwater and rock mass chemical action (such as ion migration, cement dissolution) and freeze-thaw cycle (microstructure damage caused by phase change) on rock mass, make up for the omission of key factors in high-cold groundwater environment in traditional methods, and make the evaluation results more in line with the actual deterioration state of rock mass in high-cold groundwater environment, and provide reusable technical paradigm for similar projects.

[0016] 2、The mass-time change curve is used to fit the mass loss law of rock mass under chemical erosion in the application, and the chemical erosion damage parameter Ds is introduced into the constitutive equation Dm , and then the freeze-thaw damage is calculated combined with the change of elastic modulus, and finally the total damage parameter Dm quantifies the correlation between microscopic deterioration (grain dissociation, porosity rise) and macroscopic mechanical property deterioration of rock mass, so as to convert the microscopic pore expansion-macroscopic mechanical decay into measurable damage value, so that the improved RMR score can not only reflect the current rock mass quality, but also can reflect the future change trend (such as mechanical property degradation, collapse risk) of rock mass in high-cold groundwater environment through the damage parameters Ds .

[0017] 3、The application is aimed at the problems of difficult sampling and high cost of rock mass in high-cold regions, and a small amount of field sampling and indoor rapid chemical erosion-freezing combined test is used to replace large-scale long-term field monitoring, combined with hydrogeological parameters (pH value, ion properties, etc.) and previous water conservancy and geological survey data, which can not only avoid excessive drilling and sampling, thereby significantly reducing material consumption and labor cost, but also deduce the correlation between mass and time through fitting curve in chemical erosion, without the need to extend the test period indefinitely, thereby reducing the test energy consumption and time cost, and finally realizing efficient evaluation of rock mass damage effect.

[0018] 4、The rock mass score value RMR 改进后Only the groundwater term R5, the related terms R1 and R2 of freeze-thaw and groundwater chemical erosion in RMR are modified, and the remaining three terms are kept unchanged, so as to realize seamless connection of new and old systems, effectively reduce variables to reduce the workload in the early stage, and facilitate design, construction, monitoring and other continuous use stages.

[0019] In summary, the application successfully unifies the three core deterioration mechanisms of physical action of water, chemical erosion and freeze-thaw caused by temperature phase change into the classic RMR evaluation system in the high-cold groundwater environment, significantly improves the scientificity and practicality of the evaluation result, and has important guiding significance for ensuring the long-term safety of mine and slope engineering in high-cold regions. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the improved RMR rock mass evaluation method flowchart based on high-cold groundwater environment of the application; In the figure: S100-survey and test, S200-data acquisition, S300-rock sample test, S400-subsequent processing, S500-score improvement. DETAILED DESCRIPTION

[0021] The application will be further described below in combination with the drawings and examples, but the application is not limited in any way by the description, and any change or improvement based on the teaching of the application belongs to the protection scope of the application.

[0022] As shown in Figure 1 The improved RMR rock mass evaluation method based on high-cold groundwater environment of the application includes the steps of survey and test, data acquisition, rock sample test, subsequent processing and score improvement, and the specific contents of each step are as follows: A, survey and test: for the geological engineering that needs to be evaluated, carry out hydrological survey and investigate the weather conditions in the area, determine the sampling interval and drilling scheme according to the survey report and pre-feasibility study report, and complete the related pumping test; B, data acquisition: obtain rock mechanics properties and parameters, find out the main water-bearing rock group and groundwater composition in the mining area through hydrogeological investigation, hydrogeological drilling, geophysical prospecting and field test work, and obtain the hydrogeological parameters of each aquifer; C, rock sample test: perform uniaxial compression test on the rock sample taken from the field and calculate the elastic modulus; perform XRD component analysis on the rock sample to determine the reaction components, configure the corresponding chemical solution according to the reaction components and groundwater components to perform different period chemical erosion test on the rock sample in the simulated groundwater environment; perform freeze-thaw test on the rock sample according to the test standard; D, subsequent processing: weighing the mass of the rock sample after chemical erosion test, taking 15d as a cycle, taking the number of cycles as the variable, studying the mass change law, weighing the mass of the rock sample in different soaking cycles and processing the data, summarizing the time-mass curve, and then adding the chemical erosion damage parameter in the constitutive equation D s For characterizing water chemical erosion damage; after the freeze-thaw test, the rock sample is subjected to mechanical test, and then the total damage parameter of the rock sample after hydration-freezing and thawing is calculated D m ; E, score value improvement: according to the total damage parameter D m , the rock mass score value R5 which depends on the state of groundwater and the rock mass score value R1 and the rock core quality index of the rock mass score value R2 which affect the rock strength are corrected, and the rock mass score index value changing with time under the conditions of freeze-thaw and chemical erosion is optimized RMR 改进后 , according to the improved rock mass score index value RMR 改进后 The formula of the change rule with time is used to predict the future trend of the rock mass.

[0023] In the A step, the hydraulic ring survey includes geological survey, geophysical prospecting, remote sensing, drilling and rock and mineral mechanics test.

[0024] In the B step, the rock mechanics properties and parameters are obtained based on the engineering geological drilling work, geophysical prospecting test and rock and mineral mechanics test results of the A step; the hydrogeological parameters of the aquifer include determining the boundary of the mine hydrogeological unit, the lithological characteristics and water-rich conditions of the aquifer, the groundwater chemical characteristics, and the hydrogeological conditions of groundwater recharge, runoff and discharge; the hydrogeological survey is to find out the pH value and ionic properties of groundwater and the chemical characteristics of groundwater; the composition of groundwater is determined by the groundwater obtained by the pumping test in the A step.

[0025] In the C step, the rock sample is Φ50mmx h100 mm of standard sample; XRD composition analysis of rock samples is the main chemical reaction equation to analyze the chemical reaction of rock mass and groundwater to determine the reaction composition; the rock samples in the chemical erosion test and freeze-thaw test and the treatment of the rock samples including drying and saturation shall meet the requirements of GB / T 50266-2013 "Standard for Test Methods of Engineering Rock Mass" 2.3.2 for rock test pieces, and the sample for freeze-thaw test shall be tested according to the test method in GB / T 50266-2013 "Standard for Test Methods of Engineering Rock Mass" 2.8.6; the chemical erosion test is configured according to the pH of the groundwater and the main components of the reaction solution, and the test refers to the forced saturation method for chemical solution immersion, and the prepared solution is used instead of water for immersion.

[0026] The water-rock reaction in the chemical erosion test and freeze-thaw test of the D step will cause mineral dissolution, leading to an increase in porosity, a decrease in effective bearing area, and a grain dissociation and cement destruction in the microstructure, and the macroscopic performance is mass loss and mechanical property degradation. The chemical alteration of the soluble phase is the main controlling factor of damage accumulation, and the degradation of the rock is the process of converting from solid phase to liquid phase, which can be directly reflected in mass, so the chemical erosion damage parameter D s related to mass change, used to represent the chemical erosion damage effect of water, and the constitutive equation of chemical erosion is: In the formula: m 0、 m t M0, M and M(t) are the initial state mass of the rock sample, the chemical erosion mass of the rock sample and the mass of the rock sample after a certain period of time, respectively. t

[0027] Among them, different soaking periods are designed to obtain the mass of the rock sample m with time data, and the time-mass curve of the rock sample mass m is summarized, the fitting equation conforming to the curve shape is selected, and the parameters in the fitting equation are determined through the mass of the rock sample m with time data, and finally the residual between the fitting value and the actual data value is calculated to calculate the correlation degree R 2 of the fitting equation:

[0028] In the formula: y i M(t) is the actual data value, M is the mean value of the actual data, M(t) is the predicted value of the fitting equation.

[0029] The fitting equation with the highest correlation degree is selected to obtain the mass of the rock sample m ​The fitting relationship curve of the relationship with time change is combined to obtain the rock sample quality m and time t The change relationship m t , and thus the erosion damage D s The relationship between the change and time t.

[0030] The freeze-thaw damage in the freeze-thaw test introduces the strain equivalence principle, and the damage stress-strain relationship of the rock sample is: Where: ε For strain, σ and σ' are the nominal stress and effective stress, respectively, E is the elastic modulus of the material in the reference state; E’ is the elastic modulus of the material in a damaged state, D is the freeze-thaw damage parameter; Among them, n freeze-thaw damage parameters D n for: Where: E n For experience n Elastic modulus after freeze-thaw cycles, E 0 is the elastic modulus before freeze-thaw cycles; After the rock sample undergoes hydration-freeze-thaw action, the rock sample damage state is divided into two types: the first damage state is the damage caused by the rock sample undergoing freeze-thaw chemical erosion, and the second damage state is the damage caused by loading after the rock sample undergoes freeze-thaw cycles; therefore, the total damage parameter of the rock sample is D m for: .

[0031] In the E step, first, based on the total damage parameter D m , in the rock RMR evaluation index, the rock mass score value R5, which depends on the groundwater status, as well as the rock mass score value R1 of the rock strength and the rock mass score value R2 of the core quality index, which are affected by it, are corrected; Table 1 Rock mass score R5 depending on groundwater status

[0032] Then, the improved rock mass score is obtained by optimization RMR 改进后 for: In the formula, R1 is the rock mass score value of rock strength, R2 is the rock mass score value of core quality index, R3 is the rock mass score value of the most influential joint group spacing, R4 is the rock mass score value of joint state, R5 is the rock mass score value depending on the groundwater state, and R6 is the correction value of joint orientation to RMR.

[0033] It should be noted that the improved rock mass score value RMR in the improved formula of E step is (R1+R2+R5)(1-D m ), that is, the aforementioned correction of R5, R1 and R2, R1 in the formula is taken according to Table 1, and R2, R3, R4, R5 and R6 are respectively taken according to the normal RMR score index.

[0034] Embodiment

[0035] 100: For the geological engineering that needs to be evaluated for rock mass quality, carry out geological survey, geophysical prospecting, remote sensing, drilling and rock and mineral mechanics test, and investigate the weather conditions in the area, determine the sampling interval and drilling scheme according to the general survey report and pre-feasibility study report, and complete the related pumping test.

[0036] S200: Obtain the rock mechanics properties and parameters according to the results of the aforementioned engineering geological drilling work, geophysical prospecting test and rock and mineral mechanics test, find out the main water-bearing rock group and the composition of groundwater through hydrogeological investigation, hydrogeological drilling, geophysical prospecting and field test work, and obtain the hydrogeological parameters of each aquifer, including determining the hydrogeological unit boundary of the mining area, the lithological characteristics and water-rich conditions of the aquifer, the hydrochemical characteristics of groundwater, and the hydrogeological conditions of groundwater recharge, runoff and discharge; wherein, the hydrogeological investigation is to find out the pH value and ionic properties of groundwater and the hydrochemical characteristics of groundwater.

[0037] S300: Make the rock mass taken from the site into Φ50mm× h100mm of standard sample and uniaxial compression test and calculate the elastic modulus; XRD composition analysis of rock sample to analyze the main chemical reaction equation of rock mass and groundwater interaction, determine the reaction composition, so as to configure the corresponding chemical solution to simulate the chemical erosion test of rock sample in different periods of groundwater environment; According to the test standard, the freeze-thaw test of rock sample is carried out; Among them, the rock sample in chemical erosion test and freeze-thaw test and the treatment of rock sample including drying and saturation shall meet the requirements of rock sample in GB / T50266-2013 "engineering rock mass test method standard" 2.3.2, and the sample shall be subjected to freeze-thaw test according to the test method in GB / T50266-2013 "engineering rock mass test method standard" 2.8.6; The chemical erosion test is carried out according to the pH value of groundwater and the main components of the reaction solution, and the chemical solution is immersed in the whole immersion according to the forced saturation method, and the prepared solution is used instead of water for immersion.

[0038] S400: weigh the mass of the rock sample after chemical erosion test, take 15d as a period, take the number of periods as a variable, study the mass change rule, weigh the mass of the rock sample in different immersion periods and carry out data processing, summarize the time-mass curve, and then increase the chemical erosion damage parameter in the constitutive equation D s Characterize the water chemical erosion damage; the rock sample after freeze-thaw test is subjected to mechanical test, and then the total damage parameter of the rock sample after hydration-freezing is calculated D m .

[0039] Among them, the water-rock reaction in the chemical erosion test and freeze-thaw test of the D step will cause mineral dissolution, leading to the increase of porosity, the decrease of effective bearing area, the grain dissociation and the destruction of cementation in microstructure, and the macroscopic performance of mass loss and mechanical property deterioration, the chemical alteration of soluble phase is the main controlling factor of damage accumulation, and the deterioration of rock is the process of solid phase to liquid phase, which can be directly reflected in mass, so the chemical erosion damage parameter D s Related to mass change, used to characterize the water chemical erosion damage effect, the constitutive equation of chemical erosion is: In the formula: m 0、 m t The mass of the rock sample in the initial state, the mass of the rock sample after chemical erosion t And the mass of the rock sample after chemical erosion Among them, different immersion periods are designed, the mass of the rock sample is obtained m With time, and the mass of the rock sample is summarized mThe time-quality curve is selected, the fitting equation is selected according to the curve shape, and the quality of the rock sample is determined by the fitting equation m The parameters in the fitting equation are determined according to the change data over time, and finally the correlation R of the fitting equation is calculated by calculating the residual between the fitting value and the actual data value 2 :

[0040] In the formula: y i is the actual data value, is the mean value of the actual data, is the predicted value of the fitting equation.

[0041] The fitting equation with the highest correlation is selected, and the fitting relationship curve of the quality of the rock sample m and the change of time is obtained, and the change relationship m m of the quality of the rock sample and the change of time t is obtained t . t Thus, the change relationship of the erosion damage D s and the change of time t is obtained [for example, the initial quality of the rock sample is 125g, after 15 days of immersion, it becomes 123g, and after 30 days of immersion, it becomes 121g, at this time, the relationship between the quality and the time is m t =125-0.13t (the actual situation is more complex than the case described, and the corresponding curve relationship will be more complex, and the selected curve relationship will be more complex); then m t is brought into the chemical erosion damage parameter formula, and the relationship between the erosion damage and the time is obtained as Ds =[1-(125-0.13t) / 125]^2 / 3].

[0042] At the same time, in the freeze-thaw test, the freeze-thaw damage introduces the strain equivalence principle, and the damage stress-strain relationship of the rock sample is: In the formula: ε is the strain, σ and σ' are the nominal stress and the effective stress, respectively, E is the elastic modulus of the material in the reference state; E’ is the elastic modulus of the material in the damaged state, D is the freeze-thaw damage parameter; wherein the first freeze-thaw damage parameter n D n is: In the formula: E n is the first freeze-thaw damage parameter n ​Elastic modulus after freeze-thaw cycles, E 0 is the elastic modulus before freeze-thaw cycles; After the rock sample undergoes hydration-freeze-thaw action, the rock sample damage state is divided into two types: the first damage state is the damage caused by the rock sample undergoing freeze-thaw chemical erosion, and the second damage state is the damage caused by loading after the rock sample undergoes freeze-thaw cycles; therefore, the total damage parameter of the rock sample is D m for: .

[0043] S500: Based on the above total damage parameters D m , in the rock RMR evaluation index, the rock mass score value R5, which depends on the groundwater status, as well as the rock mass score value R1 of the rock strength and the rock mass score value R2 of the core quality index, which are affected by it, are corrected; Table 1 Rock mass score R5 depending on groundwater status

[0044] Then, the improved rock mass score is obtained by optimization RMR 改进后 for: Where: R1 is the rock mass score value of rock strength, R2 is the rock mass score value of core quality index, R3 is the rock mass score value of the most influential joint group spacing, R4 is the rock mass score value of joint state, R5 depends on the rock mass score value of 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 ) is the aforementioned correction to R5, R1 and R2. The value of R1 in the formula is taken according to Table 1, and the values ​​of 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 changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope 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 based on the scope of protection of the claims.

Claims

1. An improved RMR rock mass evaluation method based on alpine groundwater environment, characterized by: It includes the steps of investigation and testing, data acquisition, rock sample testing, subsequent processing, and score value improvement. The specific contents of each step are as follows: A. Investigation and Testing: For geological projects requiring rock mass quality assessment, we conduct hydraulic and environmental investigations and investigate the area's past weather conditions. Based on the survey report and pre-feasibility study report, we determine the sampling interval and drilling plan, and complete relevant pumping tests. B. Data acquisition: Obtain rock mechanical properties and parameters. Through hydrogeological surveys, hydrogeological drilling, geophysical prospecting and field tests, identify the main water-bearing rock formations and groundwater composition in the mining area, and obtain the hydrogeological parameters of each aquifer. C. Rock Sample Test: Perform uniaxial compression tests on rock samples taken from the site and calculate the elastic modulus; perform XRD composition analysis on the rock samples to determine the reaction components; prepare corresponding chemical solutions based on the reaction components and groundwater composition to simulate the groundwater environment and conduct chemical erosion tests on the rock samples at different cycles; and perform freeze-thaw tests on the rock samples according to the test standards; D. Subsequent processing: Weigh the rock sample after the chemical erosion test, take 15 days as a cycle, use the number of cycles as a variable, study the law of mass change, weigh the rock sample mass at different immersion cycles and perform data processing, summarize the time-mass curve, and then add the chemical erosion damage parameter to the constitutive equation. D s Used to characterize water chemical erosion damage; the rock samples after freeze-thaw test are subjected to mechanical tests, and then the total damage parameters of the rock samples after hydration-freeze-thaw are calculated D m ; E. Improvement of scoring value: Based on the total damage parameter D m The rock mass score R5, which depends on the groundwater status, and the rock mass score R1 of the rock strength and the rock mass score R2 of the core quality index in the rock RMR evaluation index are corrected, and the rock mass score index values ​​that change with time under freeze-thaw and chemical erosion conditions are optimized. RMR 改进后 , based on the improved rock mass scoring index value RMR 改进后 The regular formula of change over time is used to predict the future change trend of the rock mass.

2. The improved RMR rock mass evaluation method based on alpine groundwater environment according to claim 1 is characterized by: In step A, the hydraulic and environmental survey includes geological survey, geophysical prospecting, remote sensing, drilling and rock and mineral mechanics testing.

3. The improved RMR rock mass evaluation method based on alpine groundwater environment according to claim 1 is characterized by: In step B, the rock mechanical properties and parameters are obtained based on the engineering geological drilling work, geophysical testing and rock and mineral mechanics test results of 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-richness of the aquifer, the hydrochemical characteristics of the groundwater, and the hydrogeological conditions of groundwater recharge, flow and discharge; the hydrogeological survey is to determine 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 by the pumping test in step A.

4. The improved RMR rock mass evaluation method based on alpine groundwater environment according to claim 1 is characterized in that: In step C, the rock sample is made of Φ50mm× h 100mm standard specimen; XRD composition analysis of rock samples is to analyze the main chemical reaction equations of the interaction between rock and groundwater to determine the reaction components; rock samples in chemical erosion test and freeze-thaw test, as well as the treatment of rock samples including drying and saturation, should meet the requirements of rock specimens in GB / T50266-2013 "Engineering Rock Test Method Standard" 2.3.2, and the freeze-thaw test of samples should be carried out in accordance with the test method in GB / T50266-2013 "Engineering Rock Test Method Standard" 2.8.6; chemical erosion test solution is prepared according to the pH of groundwater and the main components of the reaction. The test is fully immersed in the chemical solution with reference to the forced saturation method of pumping saturation, and the prepared solution is used instead of water for immersion.

5. The improved RMR rock mass evaluation method based on alpine groundwater environment according to claim 4 is characterized in that: The water-rock reaction in the chemical erosion test and freeze-thaw test in step D will induce mineral dissolution, resulting in increased porosity, decreased effective bearing area, grain dissociation and cement destruction in the microstructure, and macroscopic manifestations such as mass loss and deterioration of mechanical properties. The chemical alteration of the soluble phase is the main controlling factor for damage accumulation. The degradation of rock is a process of transformation from solid phase to liquid phase, which can be intuitively reflected in quality. Therefore, the chemical erosion damage parameter is used in the constitutive equation of chemical erosion. D s It is related to mass change and is used to characterize the damage effect of water chemical erosion. The constitutive equation of chemical erosion is: Where: m 0. m t They are the mass of the initial state of the rock sample, the chemical erosion of the rock sample t The quality of the diva.

6. The improved RMR rock mass evaluation method based on alpine groundwater environment according to claim 5 is characterized by: The freeze-thaw damage in the freeze-thaw test introduces the strain equivalence principle, and the damage stress-strain relationship of the rock sample is: Where: ε For strain, σ and σ' are the nominal stress and effective stress, respectively, E is the elastic modulus of the material in the reference state; E’ is the elastic modulus of the material in a damaged state, D is the freeze-thaw damage parameter; Among them, n freeze-thaw damage parameters D n for: Where: E n For experience n Elastic modulus after freeze-thaw cycles, E 0 is the elastic modulus before freeze-thaw cycles; After the rock sample undergoes hydration-freeze-thaw action, the rock sample damage state is divided into two types: the first damage state is the damage caused by the rock sample undergoing freeze-thaw chemical erosion, and the second damage state is the damage caused by loading after the rock sample undergoes freeze-thaw cycles; therefore, the total damage parameter of the rock sample is D m for: 。 7. The improved RMR rock mass evaluation method based on alpine groundwater environment according to claim 6 is characterized by: In the E step, first, based on the total damage parameter D m , in the rock RMR evaluation index, the rock mass score value R5, which depends on the groundwater status, as well as the rock mass score value R1 of the rock strength and the rock mass score value R2 of the core quality index, which are affected by it, are corrected; Table 1 Rock mass score R5 depending on groundwater status Then, the improved rock mass score is obtained by optimization RMR 改进后 for: Where: R1 is the rock mass score value of rock strength, R2 is the rock mass score value of core quality index, R3 is the rock mass score value of the most influential joint group spacing, R4 is the rock mass score value of joint state, R5 depends on the rock mass score value of groundwater state, and R6 is the correction value of joint orientation to RMR.

Images