Underground tunnel altered rock mass quality classification method
By modifying the Q value in the Q-system classification method and taking into account the degree of alteration, location relationship, and groundwater exposure, the problem of inaccurate classification of altered rock masses in the existing technology is solved, and a more accurate quality assessment of altered rock masses is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA HYDROELECTRIC ENGINEERING CONSULTING GROUP CHENGDU RESEARCH HYDROELECTRIC INVESTIGATION DESIGN AND INSTITUTE
- Filing Date
- 2026-03-06
- Publication Date
- 2026-06-05
AI Technical Summary
The existing Q-system classification method has biases when classifying altered rock masses, failing to fully consider factors such as the integrity, water sensitivity, and rock mass strength of the altered rock mass, resulting in inaccurate classification.
By defining indicators corresponding to the degree of alteration, the positional relationship between the altered rock mass and the tunnel, and the groundwater exposure, the Q value in the Q-system classification method is corrected, and the corrected Q value is calculated for the quality classification of the altered rock mass.
This improves the accuracy of altered rock mass classification by comprehensively considering the degree of alteration, location relationship, and the influence of groundwater on altered rock masses, thus ensuring the accuracy of the classification results.
Smart Images
Figure CN122151245A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of rock mass classification technology, and in particular to a method for classifying the quality of altered rock mass in underground tunnels. Background Technology
[0002] Underground engineering construction often encounters rock masses with unique geological conditions. However, most existing rock mass quality classification methods are based on shallow rock engineering and are not applicable to deep rock masses. Therefore, it is necessary to establish a rock mass quality classification method adapted to special underground rock masses. Accurate rock mass quality assessment is the foundation for the stability analysis of surrounding rock and the subsequent support design of underground engineering projects.
[0003] Alteration occurs when the original rock is altered by changes in the external environment, resulting in changes to its chemical composition, mineral composition, and structure. The resulting rock is called altered rock. Alteration changes the internal structure and composition of the original rock, leading to changes in the physical and mechanical properties of the rock mass. This reduces the quality of the rock mass and adversely affects the stability of the surrounding rock and the quality of engineering projects.
[0004] The widely accepted method for rock mass quality classification in the industry is the Q-system classification method, and the formula for the Q-system classification method is: ,in, Indicates rock mass quality indicators. Indicates rock quality indicators, Indicates the number of joint groups. Indicates joint roughness, Indicates the degree of joint alteration. This represents the water reduction factor for water treatment. Indicates the stress reduction factor. It reflects the integrity of the rock mass (the proportional relationship between rock blocks and joints). Describe the shear strength of the joint surface (comparison of roughness and degree of alteration). It reflects environmental stress conditions (the interaction between water pressure and ground stress).
[0005] However, the Q-system classification method only considers the influence of alteration on the mechanical properties of joints. In actual engineering, the integrity, water sensitivity, rock strength, and altered minerals of altered rock masses are different from those of the original rock. It is insufficient to classify altered rock masses by only considering the changes in the mechanical properties of joints, which will lead to deviations in the classification of altered rock masses. Summary of the Invention
[0006] The technical problem solved by this invention: This invention provides a method for classifying the quality of altered rock mass in underground tunnels, which solves the problem of deviation in the classification of altered rock mass by the existing Q system classification method.
[0007] The technical solution adopted by this invention to solve the above-mentioned technical problems is: a method for quality classification of altered rock mass in underground tunnels, which obtains the Q value of the rock mass through the Q-system classification method, and the method further includes:
[0008] S1. Define the first indicator corresponding to the degree of alteration, the second indicator corresponding to the positional relationship between the altered rock mass and the tunnel, and the third indicator corresponding to the groundwater outburst.
[0009] S2. Calculate the product of the first indicator, the second indicator, the third indicator, and the Q value to obtain the corrected Q value;
[0010] S3. The quality of the altered rock mass is classified using the corrected Q value.
[0011] Furthermore, the degree of alteration includes slight alteration, weak alteration, moderate alteration, and strong alteration; the first index value corresponding to slight alteration ranges from 0.95 to 1, the first index value corresponding to weak alteration ranges from 0.9 to 0.95, the first index value corresponding to moderate alteration ranges from 0.85 to 0.9, and the first index value corresponding to strong alteration ranges from 0.8 to 0.85; slight alteration is defined as alteration mineral content between 0 and 5%, weak alteration as alteration mineral content between 5% and 10%, moderate alteration as alteration mineral content between 10% and 20%, and strong alteration as alteration mineral content exceeding 20%.
[0012] Furthermore, the values of the second index corresponding to the positional relationship between the altered rock mass and the tunnel include: if the angle between the dip of the altered rock mass and the tunnel excavation direction is 0 to 20 degrees, the second index is 0.9; if the angle between the dip of the altered rock mass and the tunnel excavation direction is 20 to 45 degrees, the second index is 0.95; if the angle between the dip of the altered rock mass and the tunnel excavation direction is 45 to 90 degrees, the second index is 1; if the angle between the dip of the altered rock mass and the reverse direction of tunnel excavation is 0 to... If the angle between the altered rock mass and the tunnel excavation direction is 20 degrees, the second index is 0.8; if the angle between the altered rock mass and the tunnel excavation direction is 45 degrees to 90 degrees, the second index is 0.9; or, if the angle between the altered rock mass and the tunnel axis is 0 degrees to 45 degrees, the second index is 0.9; if the angle between the altered rock mass and the tunnel axis is 45 degrees to 90 degrees, the second index is 0.85.
[0013] Furthermore, if the dip of the altered rock mass forms an angle with the tunnel excavation direction or the reverse direction of tunnel excavation, and the dip of the altered rock mass forms an angle with the tunnel axis, then the second index is the minimum value corresponding to the angle.
[0014] Furthermore, in S1, the groundwater exposure conditions include dry, damp but without seepage, localized minor seepage, significant seepage, and abnormally large seepage; the value range of the second indicator corresponding to dry is 1.0 to 0.9, the value range of the second indicator corresponding to damp but without seepage is 0.9 to 0.8, the value range of the second indicator corresponding to localized minor seepage is 0.8 to 0.5, the value range of the second indicator corresponding to significant seepage is 0.5 to 0.3, and the value range of the second indicator corresponding to abnormally large seepage is 0.3 to 0.1; localized minor seepage is defined as a seepage rate of less than 0.5 m² / h per unit area, significant seepage is defined as a seepage rate of 0.5 m² / h to 2 m² / h per unit area, and abnormally large seepage is defined as a seepage rate of greater than 2 m² / h per unit area.
[0015] Furthermore, in S3, if the corrected Q value is greater than 40, the altered rock mass quality is level one; if the corrected Q value is between 10 and 40, the altered rock mass quality is level two; if the corrected Q value is between 1 and 10, the altered rock mass quality is level three; if the corrected Q value is between 0.1 and 1, the altered rock mass quality is level four; and if the corrected Q value is less than 0.1, the altered rock mass quality is level five.
[0016] Furthermore, in S3, if the corrected Q value is greater than 1000, the altered rock mass quality is exceptionally good; if the corrected Q value is between 400 and 1000, the altered rock mass quality is excellent; if the corrected Q value is between 100 and 400, the altered rock mass quality is very good; if the corrected Q value is between 40 and 100, the altered rock mass quality is good; if the corrected Q value is between 10 and 40, the altered rock mass quality is average; if the corrected Q value is between 4 and 10, the altered rock mass quality is poor; if the corrected Q value is between 1 and 4, the altered rock mass quality is very poor; if the corrected Q value is between 0.1 and 1, the altered rock mass quality is extremely poor; and if the corrected Q value is less than 0.1, the altered rock mass quality is exceptionally poor.
[0017] The beneficial effects of this invention are as follows: This invention provides a method for quality classification of altered rock masses in underground tunnels. The Q-value of the rock mass is obtained through the Q-system classification method. A first index corresponding to the degree of alteration, a second index corresponding to the positional relationship between the altered rock mass and the tunnel, and a third index corresponding to groundwater exposure are defined. The product of the first, second, and third indices and the Q-value is calculated to obtain a corrected Q-value. The altered rock mass is then classified using the corrected Q-value. This method incorporates the degree of alteration, the positional relationship between the altered rock mass and the tunnel, and the influence of groundwater on the altered rock mass, making the classification of altered rock masses according to the corrected Q-value more accurate and solving the problem of deviations in the classification of altered rock masses in existing Q-system classification methods. Attached Figure Description
[0018] Figure 1 This is a flowchart illustrating a method for classifying the quality of altered rock masses in underground tunnels, as provided by this invention. Detailed Implementation
[0019] This invention addresses the problem of inaccuracies in the existing Q-system classification method for altered rock masses by providing a quality classification method for altered rock masses in underground tunnels. Based on engineering examples and numerous experiments, it has been confirmed that altered rocks developed in tunnels resemble a weak zone, with reduced rock mass strength, similar to the impact of faults on the overall stability of tunnels. Three factors influencing the quality of altered rock masses in underground tunnels have been identified: the degree of alteration, the positional relationship between the altered rock mass and the tunnel, and the groundwater exposure. Therefore, based on the Q-system classification method, the Q-value obtained by the Q-system classification method is corrected using the indicators corresponding to these three factors. The corrected Q-value is then used to classify the quality of the altered rock mass, improving the accuracy of the classification.
[0020] This invention provides a method for quality classification of altered rock masses in underground tunnels, which obtains the Q value of the rock mass through the Q-system classification method. The method also includes, for example, Figure 1 The following steps are shown:
[0021] S1. Define the first indicator corresponding to the degree of alteration, the second indicator corresponding to the positional relationship between the altered rock mass and the tunnel, and the third indicator corresponding to the groundwater outburst.
[0022] S2. Calculate the product of the first indicator, the second indicator, the third indicator and the Q value to obtain the corrected Q value.
[0023] S3. The quality of the altered rock mass is classified using the corrected Q value.
[0024] Specifically, the formula for obtaining the Q value of rock mass using the Q-system classification method is as follows: ,in, Indicates rock mass quality indicators. Indicates rock quality indicators, Indicates the number of joint groups. Indicates joint roughness, Indicates the degree of joint alteration. This represents the water reduction factor for water treatment. Indicates the stress reduction factor. It reflects the integrity of the rock mass (the proportional relationship between rock blocks and joints). Describe the shear strength of the joint surface (comparison of roughness and degree of alteration). It reflects environmental stress conditions (the interaction between water pressure and ground stress).
[0025] Rock quality indicators can be obtained through precise measurements along the adit route combined with borehole data, or through formulas: ,in, This indicates the number of joints per unit rock mass.
[0026] Joint group number The criteria for the values are shown in Table 1.
[0027] Table 1 Standard for determining the number of joint groups
[0028]
[0029] If the altered rock mass is located at the tunnel intersection, the number of joint groups is increased by 3 times; if the altered rock mass is located at the tunnel entrance or exit, the number of joint groups is increased by 2 times.
[0030] Joint roughness The criteria for the values are shown in Table 2.
[0031] Table 2 Standard for Joint Roughness Values
[0032]
[0033] Joint alteration degree The value criteria are shown in Table 3.
[0034] Table 3. Standards for Determining the Degree of Joint Alteration
[0035]
[0036] Jointed water reduction factor The value criteria are shown in Table 4.
[0037] Table 4. Standards for Determining the Value of Joint Water Reduction Factor
[0038]
[0039] Stress reduction factor The value criteria are shown in Table 5.
[0040] Table 5. Standards for Determining Stress Reduction Factors
[0041]
[0042] The criteria for the first indicator corresponding to the degree of alteration include: the degree of alteration includes slight alteration, weak alteration, moderate alteration, and strong alteration. The proportion of alteration minerals is obtained by X-ray powder diffraction test. The higher the proportion of alteration minerals, the stronger the degree of alteration. Slight alteration is defined as an alteration mineral content between 0% and 5%, weak alteration as an alteration mineral content between 5% and 10%, moderate alteration as an alteration mineral content between 10% and 20%, and strong alteration as an alteration mineral content exceeding 20%.
[0043] Triaxial strength tests were conducted on altered rock masses of different alteration degrees. The strength of the rock mass was compared with that of the altered rock, and the strength reduction corresponding to the alteration degree was calculated. The results showed that the first index value for slight alteration ranged from 0.95 to 1, the first index value for weak alteration ranged from 0.9 to 0.95, the first index value for moderate alteration ranged from 0.85 to 0.9, and the first index value for strong alteration ranged from 0.8 to 0.85, as shown in Table 6.
[0044] Table 6. Value standards for the first index corresponding to the degree of alteration.
[0045]
[0046] The positional relationship between the altered rock mass and the tunnel affects the overall stability of the underground tunnel. The altered rock mass is analogous to a structural plane, and the value of the second index is determined by the positional relationship between the altered rock mass and the tunnel. Specifically: if the angle between the dip of the altered rock mass and the tunnel excavation direction is 0 to 20 degrees, the second index is 0.9; if the angle is 20 to 45 degrees, the second index is 0.95; if the angle is 45 to 90 degrees, the second index is 1; if the angle is... If the angle between the altered rock mass and the tunnel axis is 0 to 20 degrees, the second index is 0.8; if the angle between the altered rock mass and the tunnel axis is 20 to 45 degrees, the second index is 0.85; if the angle between the altered rock mass and the tunnel axis is 45 to 90 degrees, the second index is 0.9; or, if the angle between the altered rock mass and the tunnel axis is 0 to 45 degrees, the second index is 0.9; if the angle between the altered rock mass and the tunnel axis is 45 to 90 degrees, the second index is 0.85. See Table 7.
[0047] Table 7. Value standards for the second index corresponding to the locational relationship between altered rock mass and tunnel.
[0048]
[0049] Specifically, if the dip of the altered rock mass forms an angle with the tunnel excavation direction or the reverse direction of tunnel excavation, and the dip of the altered rock mass forms an angle with the tunnel axis, then the second index is the minimum value corresponding to the angle.
[0050] Hydrological tests will be conducted on the altered rock mass. The results show that the higher the alteration intensity, the stronger the water absorption and the stronger the swelling. At the same time, the more abundant the groundwater in the tunnel, the stronger the influence of groundwater on the altered rock. When the water content reaches a certain level, the altered rock will disintegrate, which will seriously affect the stability of the tunnel.
[0051] The value standards for the third indicator corresponding to groundwater exposure include: groundwater exposure conditions include dry, damp but no seepage, localized minor seepage, significant seepage, and abnormally large seepage; the value range of the second indicator corresponding to dry is 1.0 to 0.9, the value range of the second indicator corresponding to damp but no seepage is 0.9 to 0.8, the value range of the second indicator corresponding to localized minor seepage is 0.8 to 0.5, the value range of the second indicator corresponding to significant seepage is 0.5 to 0.3, and the value range of the second indicator corresponding to abnormally large seepage is 0.3 to 0.1; localized minor seepage is defined as a seepage rate of less than 0.5 m² / h per unit area, significant seepage is defined as a seepage rate of 0.5 m² / h to 2 m² / h per unit area, and abnormally large seepage is defined as a seepage rate of greater than 2 m² / h per unit area. See Table 8.
[0052] Table 8. Value standards for the third indicator corresponding to groundwater exposure.
[0053]
[0054] In S3, the quality of altered rock mass is classified by the corrected Q value, specifically as follows: if the corrected Q value is greater than 40, the quality of altered rock mass is grade 1; if the corrected Q value is between 10 and 40, the quality of altered rock mass is grade 2; if the corrected Q value is between 1 and 10, the quality of altered rock mass is grade 3; if the corrected Q value is between 0.1 and 1, the quality of altered rock mass is grade 4; and if the corrected Q value is less than 0.1, the quality of altered rock mass is grade 5.
[0055] The classification can be further refined. For example, if the corrected Q value is greater than 1000, the altered rock mass is of exceptionally good quality; if the corrected Q value is between 400 and 1000, the altered rock mass is of very good quality; if the corrected Q value is between 100 and 400, the altered rock mass is of very good quality; if the corrected Q value is between 40 and 100, the altered rock mass is of good quality; if the corrected Q value is between 10 and 40, the altered rock mass is of average quality; if the corrected Q value is between 4 and 10, the altered rock mass is of poor quality; if the corrected Q value is between 1 and 4, the altered rock mass is of very poor quality; if the corrected Q value is between 0.1 and 1, the altered rock mass is of extremely poor quality; and if the corrected Q value is less than 0.1, the altered rock mass is of exceptionally poor quality.
Claims
1. A method for quality classification of altered rock mass in underground tunnels, wherein the Q value of the rock mass is obtained through the Q-system classification method, characterized in that, The method further includes: S1. Define the first indicator corresponding to the degree of alteration, the second indicator corresponding to the positional relationship between the altered rock mass and the tunnel, and the third indicator corresponding to the groundwater outburst. S2. Calculate the product of the first indicator, the second indicator, the third indicator, and the Q value to obtain the corrected Q value; S3. The quality of the altered rock mass is classified using the corrected Q value.
2. The method for quality classification of altered rock mass in underground tunnels according to claim 1, characterized in that, In S1, the degree of alteration includes slight alteration, weak alteration, moderate alteration, and strong alteration; the first index value corresponding to slight alteration ranges from 0.95 to 1, the first index value corresponding to weak alteration ranges from 0.9 to 0.95, the first index value corresponding to moderate alteration ranges from 0.85 to 0.9, and the first index value corresponding to strong alteration ranges from 0.8 to 0.85; slight alteration means that the content of altered minerals is between 0 and 5%, weak alteration means that the content of altered minerals is between 5% and 10%, moderate alteration means that the content of altered minerals is between 10% and 20%, and strong alteration means that the content of altered minerals exceeds 20%.
3. The method for quality classification of altered rock mass in underground tunnels according to claim 1, characterized in that, In S1, the values of the second index corresponding to the positional relationship between the altered rock mass and the tunnel include: if the angle between the dip of the altered rock mass and the tunnel excavation direction is 0 to 20 degrees, the second index is 0.9; if the angle between the dip of the altered rock mass and the tunnel excavation direction is 20 to 45 degrees, the second index is 0.95; if the angle between the dip of the altered rock mass and the tunnel excavation direction is 45 to 90 degrees, the second index is 1; if the angle between the dip of the altered rock mass and the reverse direction of tunnel excavation is 0 to 2 degrees... If the angle between the altered rock mass and the tunnel excavation direction is 0 degrees, the second index is 0.8; if the angle between the altered rock mass and the tunnel excavation direction is 20 to 45 degrees, the second index is 0.85; if the angle between the altered rock mass and the tunnel excavation direction is 45 to 90 degrees, the second index is 0.9; or, if the angle between the altered rock mass and the tunnel axis is 0 to 45 degrees, the second index is 0.9; if the angle between the altered rock mass and the tunnel axis is 45 to 90 degrees, the second index is 0.
85.
4. The method for quality classification of altered rock mass in underground tunnels according to claim 3, characterized in that, If the dip of the altered rock mass forms an angle with the tunnel excavation direction or the reverse direction of tunnel excavation, and the dip of the altered rock mass forms an angle with the tunnel axis, then the second index is the minimum value corresponding to the angle.
5. The method for quality classification of altered rock mass in underground tunnels according to claim 1, characterized in that, In S1, the groundwater exposure conditions include dry, damp but no seepage, localized minor seepage, significant seepage, and abnormally large seepage. The value range of the second indicator corresponding to dry is 1.0 to 0.9, the value range of the second indicator corresponding to damp but no seepage is 0.9 to 0.8, the value range of the second indicator corresponding to localized minor seepage is 0.8 to 0.5, the value range of the second indicator corresponding to significant seepage is 0.5 to 0.3, and the value range of the second indicator corresponding to abnormally large seepage is 0.3 to 0.
1. Localized minor seepage is defined as a seepage rate of less than 0.5 m² / h per unit area, significant seepage is defined as a seepage rate of 0.5 m² / h to 2 m² / h per unit area, and abnormally large seepage is defined as a seepage rate of greater than 2 m² / h per unit area.
6. The method for quality classification of altered rock mass in underground tunnels according to claim 1, characterized in that, In S3, if the corrected Q value is greater than 40, the altered rock mass quality is level 1; if the corrected Q value is between 10 and 40, the altered rock mass quality is level 2; if the corrected Q value is between 1 and 10, the altered rock mass quality is level 3; if the corrected Q value is between 0.1 and 1, the altered rock mass quality is level 4; and if the corrected Q value is less than 0.1, the altered rock mass quality is level 5.
7. The method for quality classification of altered rock mass in underground tunnels according to claim 1, characterized in that, In S3, if the corrected Q value is greater than 1000, the altered rock mass quality is exceptionally good; if the corrected Q value is between 400 and 1000, the altered rock mass quality is excellent; if the corrected Q value is between 100 and 400, the altered rock mass quality is very good; if the corrected Q value is between 40 and 100, the altered rock mass quality is good; if the corrected Q value is between 10 and 40, the altered rock mass quality is average; if the corrected Q value is between 4 and 10, the altered rock mass quality is poor; if the corrected Q value is between 1 and 4, the altered rock mass quality is very poor; if the corrected Q value is between 0.1 and 1, the altered rock mass quality is extremely poor; and if the corrected Q value is less than 0.1, the altered rock mass quality is exceptionally poor.