Rock mass quality crmr classification method

Abstract

The present application belongs to the technical field of geological engineering, and discloses a rock mass quality CRMR classification method, which comprises the following steps: determining rock block and structural plane data according to field geological survey and indoor rock mechanics test; scoring five indexes based on fitting continuous function, namely uniaxial compressive strength sigma, core quality index RQD, structural plane spacing JS, structural plane opening filling condition Jc and structural plane groundwater condition G; obtaining CRMR score by accumulating the scores of the five indexes; and classifying rock mass quality and estimating rock mass mechanics indexes according to the total CRMR score. The rock mass quality CRMR classification method provided by the present application is an improvement on the traditional rock mass quality RMR classification method, and can greatly improve the accuracy and efficiency of rock mass quality classification and equivalent rock mass mechanics parameter estimation.

Description

Technical Field

[0001] This invention relates to the field of geological engineering technology, and in particular to a CRMR classification method for rock mass quality. Background Technology

[0002] The traditional Rock Mass Quality RMR (Resolution Mapping) classification method, proposed by Bieniawski in 1973, mainly classifies rock mass quality based on the total score of five indicators: rock strength, core quality indices, spacing between structural planes, openness and filling of structural planes, and hydrogeological conditions. This method has the following drawbacks:

[0003] (1) Scoring based on piecewise function is not accurate enough. For example, when the uniaxial compressive strength of rock is about 100 MPa, its score can be either 12 or 7, which is too obvious. However, the scores for the uniaxial compressive strength of rock from 100 MPa to 250 MPa are exactly the same, which cannot reasonably reflect the contribution of the changes in sub-items to the classification of rock mass quality.

[0004] (2) The method of determining the index score based on table lookup is not fast enough. In complex situations with a large amount of exploration data, the redundant table lookup scoring process reduces the scoring accuracy and seriously restricts the statistical efficiency. There is an urgent need for a computerized method that can directly obtain accurate sub-index scores, total scores, rock mass quality classification results and mechanical parameter recommendations based on the input data. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a rock mass quality GRMR classification method. Without changing the accumulated experience in RMR engineering applications, the rock mass quality RMR classification method is improved based on continuous function relationships. This can improve the accuracy of rock mass quality RMR classification and optimize the scoring process to improve the efficiency of rock mass quality classification and equivalent rock mass mechanical parameter estimation. It is suitable for efficient analysis of large-scale engineering complex geological environments and large amounts of geological exploration data.

[0006] The technical solution adopted in this invention is as follows: A CRMR classification method for rock mass quality, comprising the following steps:

[0007] Based on on-site geological surveys and indoor rock mechanics tests, data on rock blocks and structural surfaces were obtained, including uniaxial compressive strength σ, core quality index RQD, and structural surface spacing J. S Structural surface opening and filling condition J C The structural surface groundwater condition G consists of 5 indicators;

[0008] Scoring of five indicators is based on a fitted continuous function;

[0009] The total CRMR score is obtained by summing the scores of the five indicators;

[0010] Rock mass quality classification and rock mass mechanical parameters estimation are performed based on the GRMR total score.

[0011] Furthermore, the data for rock blocks and structural planes were determined according to the following steps:

[0012] The compressive strength of intact rock was determined by uniaxial compressive strength test, and the uniaxial compressive strength σ was obtained, in MPa.

[0013] Based on the borehole logging data, the percentage of core lengths longer than 10cm in the total core length was determined, and the core quality index RQD value was obtained.

[0014] Based on the on-site structural surface survey, the structural surface spacing J was determined. S The unit is cm;

[0015] Based on the on-site structural surface investigation, the opening or filling thickness of the structural surface is determined, and the opening and filling conditions of the structural surface are obtained. C The unit is mm;

[0016] Based on the on-site structural surface investigation, the ratio of fissure water pressure to maximum principal stress was determined, and the groundwater condition G of the structural surface was obtained.

[0017] Furthermore, the fitted continuous function relationship for the scoring of the five indicators is:

[0018]

[0019] in:

[0020] r σ This refers to the score value of the uniaxial compressive strength σ;

[0021] r RQD This refers to the score of the rock core quality index, RQD.

[0022] r Js This refers to the structural surface spacing J. S The rating value;

[0023] r Jc This refers to the structural surface opening and filling condition J. c The rating value;

[0024] r G This refers to the score of the groundwater condition G on the structural surface.

[0025] Furthermore, the calculation method for the CRMR total score is as follows:

[0026] CRMR = r σ +r RQD +r Js +r Jc +r G .

[0027] Furthermore, the standard for classifying rock mass quality based on the CRMR total score is as follows:

[0028] 0 < GRMR ≤ 20, belonging to Class V rock mass; 20 < GRMR ≤ 40, belonging to Class IV rock mass; 40 < GRMR ≤ 60, belonging to Class III rock mass; 60 < GRMR ≤ 80, belonging to Class II rock mass; 80 < GRMR < 100, belonging to Class I rock mass.

[0029] Furthermore, the method for estimating rock mechanics parameters based on the GRMR total score is to convert the range of rock mechanics parameters for various types of engineering rock masses using empirical formulas.

[0030] The beneficial effects of this invention are as follows: This invention provides a rock mass quality CRMR (Continuous Rock Mass Rating) classification method. This method fits the piecewise function of the traditional rock mass quality RMR classification and then carries out rock mass quality classification based on the continuous function relationship. It not only makes full use of the long-standing engineering application experience of RMR, but also improves the problem of reduced scoring accuracy and limited statistical efficiency in the table lookup process. It is suitable for efficient analysis of a large amount of geological exploration data in complex geological environments of large-scale engineering projects. Attached Figure Description

[0031] Figure 1 A flowchart of the CRMR classification method for rock mass quality provided in this embodiment of the invention;

[0032] Figure 2 r provided for embodiments of the present invention σ Piecewise function fitting curve of weights;

[0033] Figure 3 r provided for embodiments of the present invention RQD Piecewise function fitting curve of weights;

[0034] Figure 4 r provided for embodiments of the present invention Js Piecewise function fitting curve of weights;

[0035] Figure 5 r provided for embodiments of the present invention Jc Piecewise function fitting curve of weights;

[0036] Figure 6 r provided for embodiments of the present invention G Piecewise function fitting curve of weights;

[0037] Figure 7 This is a diagram illustrating the rock mass deformation modulus analysis based on a continuous function relationship, provided as an embodiment of the present invention. Detailed Implementation

[0038] This application provides a rock mass quality CRMR classification method. By fitting the piecewise function of the traditional rock mass quality RMR classification, rock mass quality classification is carried out based on the continuous function relationship, thereby improving the traditional rock mass quality RMR classification method and significantly improving the accuracy and efficiency of rock mass quality classification and equivalent rock mass mechanical parameter estimation.

[0039] To better understand the above technical solutions, the following will describe the above technical solutions in detail with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solutions of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0040] See Figure 1 The present invention provides a CRMR classification method for rock mass quality, comprising the following steps:

[0041] Based on on-site geological surveys and laboratory rock mechanics tests, data on rock blocks and structural surfaces were determined. Specifically, the compressive strength of intact rock was measured using uniaxial compressive strength tests, yielding the uniaxial compressive strength σ (in MPa). Based on borehole logging data, the percentage of core lengths longer than 10 cm was determined, resulting in the core quality index RQD value. The spacing J between structural surfaces was determined based on on-site structural surface surveys. S The unit is cm; based on the on-site structural surface investigation, the opening or filling thickness of the structural surface is determined, and the opening and filling condition of the structural surface is obtained J. C The unit is mm; based on the on-site structural surface investigation, the ratio of fissure water pressure to the maximum principal stress is determined, and the groundwater condition G of the structural surface is obtained.

[0042] Furthermore, based on the fitted continuous function, the uniaxial compressive strength σ, core quality index RQD, and structural plane spacing J were calculated. S Structural surface opening and filling condition J C The scoring is based on five indicators: structural surface groundwater conditions (G), etc. Specifically, piecewise functions are derived for each of the five indicators using the traditional RMR classification method. (See [link to relevant documentation]). Figures 2-6 The middle step-shaped dashed line segment is used to fit the continuous function curves of the five indicator scores and the following relationship:

[0043]

[0044] in:

[0045] r σ This refers to the score value of the uniaxial compressive strength σ;

[0046] r RQD This refers to the score of the rock core quality index, RQD.

[0047] r Js This refers to the structural surface spacing J. S The rating value;

[0048] r Jc This refers to the structural surface opening and filling condition J. c The rating value;

[0049] r G This refers to the score of the groundwater condition G on the structural surface.

[0050] Furthermore, the total CRMR score is obtained by summing the scores of the five indicators; the formula for calculating the total CRMR score is:

[0051] CRMR = r σ +r RQD +r Js +r Jc +r G

[0052] Furthermore, referring to Table 1, rock mass quality is classified according to the total CRMR score. The classification criteria are consistent with the traditional RMR classification method, and rock mass quality is classified according to 5 intervals. If 0 < CRMR ≤ 20, it belongs to Class V rock mass with very poor quality; if 20 < CRMR ≤ 40, it belongs to Class IV rock mass with poor quality; if 40 < CRMR ≤ 60, it belongs to Class III rock mass with average quality; if 60 < CRMR ≤ 80, it belongs to Class II rock mass with good quality; if 80 < CRMR < 100, it belongs to Class I rock mass with very good quality.

[0053] Table 1. Rock mass quality classification based on CRMR total score:

[0054] Rating value 0～20 20～40 40～60 60～80 80～100 Quality Classification V IV Ⅲ Ⅱ I Quality Description Very poor rock mass Poor rock mass General rock mass good rock mass Very good rocks Deformation modulus (GPa) ＜1.8 1.8～5.6 5.6～20 20～60 ＞60 Cohesion (kPa) ＜100 100～200 200～300 300～400 ＞400 Angle of friction (°) ＜15 15～25 25～35 35～45 ＞45

[0055] Optionally, rock mass quality subclasses can be determined based on the total CRMR score. For example, if 40 < CRMR ≤ 50, it belongs to Class III2 rock mass of average quality; if 50 < CRMR ≤ 60, it belongs to Class III1 rock mass of average quality.

[0056] Furthermore, rock mass mechanical parameters can be estimated based on the CRMR total score; existing empirical formulas can be used to convert the range of rock mechanical parameters (deformation modulus, cohesion, and friction angle, etc.) for various types of rock masses; and based on the accumulated experience in CRMR classification of rock mass quality, suggested values ​​for various rock mass mechanical parameters can be proposed and optimized. For example, the deformation modulus of rock mass can be estimated using the empirical formula proposed by Serafim and Pereira (1983), and the relationship between the deformation modulus and rock mass integrity (structural plane spacing J) can be examined. S For the variation characteristics of (and RQD value), see Figure 7 The empirical formula is:

[0057]

[0058] Where: E m This refers to the deformation modulus of the rock mass.

[0059] Similarly, based on the Hoek-Brown empirical strength criterion, and using CRMR values ​​instead of GSI or RMR values, the equivalent cohesion c′ and friction angle of the rock mass can be estimated using the following formula.

[0060]

[0061]

[0062] In the formula:

[0063]

[0064]

[0065]

[0066] σ' 3n =σ' 3max / σ ci

[0067] Where: σ ci The uniaxial compressive strength of intact rock, m i The rock material constant, σ' 3max The upper limit of the lateral confined stress in the rock mass is referred to as the D-value, which is the rock mass excavation disturbance factor.

[0068] Furthermore, referring to Table 2, scores for five indicators were derived from the fitted continuous function formula for the four groups of measured rock mass data. These scores were then summed to obtain the total CRMR score, which can be used to classify the rock mass quality according to Table 1. Additionally, different confining pressure levels (such as σ') can be calculated using the Hoek-Brown empirical formula. 3maxDeformation and strength parameters of rock masses with a strength of 10 MPa. In particular, if the traditional RMR method is used for rock masses in groups 1 and 2, and groups 3 and 4, their scores are exactly the same; however, the CRMR method can reasonably reflect the differences in rock mass quality, just like the geological strength index GSI, thereby improving the accuracy of the estimation of equivalent rock mass mechanical parameters.

[0069] Table 2. Examples of rock mass quality classification based on the CRMR method:

[0070]

[0071] The above description is merely a preferred embodiment of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rock mass quality CRMR classification method, characterized in that, Includes the following steps: Based on on-site geological surveys and indoor rock mechanics tests, data on rock blocks and structural surfaces were determined, including five indicators: uniaxial compressive strength σ, core quality index RQD, structural surface spacing Js, structural surface opening and filling Jc, and structural surface groundwater conditions G. Scoring of five indicators is based on a fitted continuous function; The total CRMR score is obtained by summing the scores of the five indicators; Rock mass quality classification and rock mass mechanical parameters estimation are performed based on the CRMR total score; Determine data for rock blocks and structural surfaces using the following steps: The compressive strength of intact rock was determined by uniaxial compressive strength test, and the uniaxial compressive strength σ was obtained, in MPa. Based on the borehole logging data, the percentage of core lengths longer than 10cm in the total core length was determined, and the core quality index RQD value was obtained. Based on the on-site structural surface survey, the spacing between structural surfaces Js is determined, in cm; Based on the on-site structural surface survey, determine the opening or filling thickness of the structural surface, and obtain the structural surface opening and filling condition Jc, in mm; Based on the on-site structural surface investigation, the ratio of fissure water pressure to maximum principal stress was determined, and the groundwater condition G of the structural surface was obtained; The fitted continuous function relationship for the five indicators is: ,in: r σ This refers to the score value of the uniaxial compressive strength σ; r RQD This refers to the score of the rock core quality index, RQD. r Js This refers to the score value of the structural surface spacing Js; r Jc This refers to the score value of the structural surface opening and filling condition Jc; r G This refers to the score value of the groundwater condition G on the structural surface; The method for calculating the CRMR total score is as follows: ； The standard for classifying rock mass quality based on the CRMR total score is: It belongs to Class V rock mass; It belongs to Class IV rock mass; It belongs to Class III rock mass It belongs to Class II rock mass; It belongs to Class I rock mass; The method for estimating rock mass mechanical parameters based on the CRMR total score is as follows: based on the Serafim and Pereira empirical formulas and the Hoek-Brown empirical strength criterion, the range of rock mechanical parameters for various types of engineering rock masses is converted.

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