Rock cover weight consolidation grouting evaluation method for easy-to-relax rock mass

Abstract

The invention provides a rock cover weight consolidation grouting evaluation method for easy-to-relax rock mass. The rock cover weight consolidation grouting evaluation method comprises the following steps: S1, quality detection before dam foundation rock mass reinforcement; s2, formulating consolidation grouting quality evaluation indexes and individual inspection hole acceptance standards of each subarea; s3, rock mass quality evaluation after rock cover weight consolidation grouting; s4, rock mass quality evaluation after excavation of the protective layer; and S5, evaluating the quality of the rock mass after the guide pipe consolidation grouting. According to the method, the average value of the small values of the sound wave velocities of the rock mass before grouting is adopted as the standard of grouting quality evaluation, rock mass data of a high-wave-velocity section with unobvious change are abandoned, and sound wave improvement of the rock mass of a low-wave-velocity section is more targeted; through multi-stage detection and evaluation, the reinforcement quality of the easy-to-relax rock mass is ensured, and the reliability and effectiveness of consolidation grouting are improved.

Description

Technical Field

[0001] The invention belongs to the field of foundation treatment of civil engineering and water conservancy projects, and in particular relates to a rock cover consolidation grouting evaluation method for loose rock masses. Background Art

[0002] Consolidation grouting is a commonly used reinforcement method for rock masses, which enhances their quality by injecting grouting materials into the rock mass. The quality of consolidation grouting can generally be evaluated by measuring the improvement in the rock mass's acoustic wave velocity. Due to the significant differences between rock mass quality and lithology, the standard does not provide a quantitative calculation method for the design wave velocity for grouting quality evaluation. Conventional methods use the average wave velocity of the rock mass as an evaluation indicator. For rock masses with numerous joints and fissures, the increase in average wave velocity before and after grouting is small, and the sensitivity to the increase in rock mass acoustic waves in the low-velocity range is low, making it an ineffective indicator of the quality of grouting reinforcement. Summary of the Invention

[0003] The main purpose of the present invention is to provide a rock cover consolidation grouting evaluation method for loose rock masses in response to the above-mentioned problems.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for evaluating rock cover consolidation grouting of loose rock mass comprises the following steps:

[0006] S1. Quality inspection of dam foundation rock mass before reinforcement: When excavating to the reserved rock protection layer, select holes no less than the total number of grouting holes as pre-grouting test holes, and conduct rock mass acoustic wave testing through the pre-grouting test holes;

[0007] S2. Divide the rock mass into zones according to its lithology and rock mass quality classification, determine the minimum average value of the acoustic wave velocity of the rock mass before grouting in each zone as the index velocity, and formulate the consolidation grouting quality evaluation index and individual inspection hole acceptance criteria for each zone;

[0008] S3. Rock mass quality evaluation after consolidation grouting of rock cover: Arrange post-grouting inspection holes no less than the total number of grouting holes according to geological conditions and consolidation grouting construction conditions, collect acoustic wave measurements of the post-grouting inspection holes within the consolidation grouting quality evaluation unit, and evaluate using the consolidation grouting quality control indicators;

[0009] S4. Rock mass quality evaluation after excavation of the protective layer: After excavation of the protective layer rock mass, inspection holes are arranged with a number not less than the total number of grouting holes to evaluate the impact of rock protective layer excavation blasting and rock mass unloading on the quality of the dam foundation rock mass;

[0010] S5. Evaluation of rock mass quality after consolidation grouting with conduit: The evaluation is mainly based on controlling the grouting construction process and analyzing the grouting construction record data, supplemented by acoustic wave detection of long-term observation holes in the dam foundation.

[0011] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0012] As a preferred technical solution of the present invention: in step S1, the consolidation grouting quality evaluation index is: the acoustic wave velocity of more than 90% of the measuring points is greater than or equal to the minimum average value of the acoustic wave velocity of the rock mass before grouting, and the proportion of measuring points with an acoustic wave velocity less than 0.9 times the minimum average value of the acoustic wave velocity of the rock mass before grouting does not exceed 5% of the total number of measuring points.

[0013] As a preferred technical solution of the present invention: in step S1, the acceptance criteria for individual inspection holes are: the acoustic wave velocity of more than 85% of the measuring points is greater than or equal to the minimum average value of the acoustic wave velocity of the rock mass before filling, and the proportion of measuring points with an acoustic wave velocity less than 0.9 times the minimum average value of the acoustic wave velocity of the rock mass before filling does not exceed 5% of the total number of measuring points.

[0014] As a preferred technical solution of the present invention: in step S1, the number of test holes before grouting is no less than 5% of the total number of grouting holes.

[0015] As a preferred technical solution of the present invention: in step S2, the post-pouring quality inspection is mainly aimed at the rock mass below the dam base surface, and the rock protection layer is not within the evaluation scope.

[0016] As a preferred technical solution of the present invention: in step S3, the inspection hole is mainly used to check the unloading relaxation of the surface rock mass.

[0017] As a preferred technical solution of the present invention: in step S3, the number of inspection holes arranged is no less than 5% of the total number of grouting holes.

[0018] As a preferred technical solution of the present invention: in step S4, the number of inspection holes arranged is no less than 5% of the total number of grouting holes.

[0019] As a preferred technical solution of the present invention: in step S5, under maximum pressure, when the injection rate is ≤0.4 L / min, the perfusion is continued for more than 20 minutes.

[0020] The present invention provides a rock cover consolidation grouting evaluation method for easily loose rock mass, which has the following beneficial effects: the present invention adopts the minimum average value of the acoustic wave velocity of the rock mass before grouting as the benchmark for grouting quality evaluation, discards the high-velocity section rock mass data with insignificant changes, and is more targeted at reflecting the acoustic wave improvement of the low-velocity section rock mass; the acoustic wave velocity distribution of the rock mass before grouting basically conforms to the normal distribution law, and the proportion of the part greater than the minimum average value is generally between 72% and 80%. In order to reflect the improvement of the rock mass acoustic wave in the low-velocity section after consolidation grouting, a secondary control index for quality evaluation is established, and the acoustic wave velocity of 90% of the measuring points after grouting reaches the minimum average value of the acoustic wave velocity of the rock mass before grouting, and the cumulative frequency of the measuring points whose acoustic wave velocity is less than 0.9 times the minimum average value is no more than 5%; the present invention ensures the reinforcement quality of easily loose rock mass through multi-stage detection and evaluation, and improves the reliability and effectiveness of consolidation grouting. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of the rock cover consolidation grouting evaluation method for easily loosened rock mass provided by the present invention. DETAILED DESCRIPTION

[0022] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

[0023] like Figure 1 As shown, a rock cover consolidation grouting evaluation method for a loose rock mass includes the following steps:

[0024] S1. Quality inspection of dam foundation rock mass before reinforcement: When excavating to the reserved rock protection layer, select no less than 5% of the total number of grouting holes as pre-grouting test holes, and conduct rock mass acoustic wave testing through the pre-grouting test holes;

[0025] S2. Divide the rock mass into zones according to its lithology and rock mass quality classification, determine the minimum average value of the acoustic wave velocity of the rock mass before grouting in each zone as the index velocity, and formulate the consolidation grouting quality evaluation index and individual inspection hole acceptance criteria for each zone;

[0026] The evaluation index of consolidation grouting quality is: the acoustic wave velocity of more than 90% of the measuring points is greater than or equal to the minimum average value of the acoustic wave velocity of the rock mass before grouting, and the proportion of measuring points with an acoustic wave velocity less than 0.9 times the minimum average value of the acoustic wave velocity of the rock mass before grouting does not exceed 5% of the total number of measuring points.

[0027] The acceptance criteria for individual inspection holes are: the acoustic wave velocity at more than 85% of the measuring points is greater than or equal to the minimum average value of the acoustic wave velocity of the rock mass before filling, and the proportion of measuring points with an acoustic wave velocity less than 0.9 times the minimum average value of the acoustic wave velocity of the rock mass before filling does not exceed 5% of the total number of measuring points.

[0028] S3. Rock mass quality evaluation after consolidation grouting of rock cover: Arrange post-grouting inspection holes of no less than 5% of the total number of grouting holes according to geological conditions and consolidation grouting construction conditions. Count the acoustic wave values ​​of the post-grouting inspection holes within the consolidation grouting quality evaluation unit, evaluate with the consolidation grouting quality control index, and conduct supplementary grouting for unqualified areas.

[0029] The post-pouring quality inspection is mainly aimed at the rock mass below the dam base surface, and the rock protection layer is not within the evaluation scope.

[0030] The number of inspection holes shall not be less than 5% of the total number of grouting holes.

[0031] S4. Rock mass quality evaluation after protective layer excavation: After the protective layer rock mass is excavated, inspection holes are arranged at a rate of no less than 5% of the total number of grouting holes to evaluate the impact of rock protective layer excavation blasting and rock mass unloading on the quality of the dam foundation rock mass. For areas that do not meet the secondary control indicators of consolidation grouting, concrete cover and heavy lead pipe consolidation grouting are carried out;

[0032] Inspection holes are mainly used to check the unloading and relaxation of surface rock masses.

[0033] The number of inspection holes shall not be less than 5% of the total number of grouting holes.

[0034] S5. Evaluation of rock mass quality after consolidation grouting with conduit: The evaluation is mainly based on controlling the grouting construction process and analyzing the grouting construction record data, supplemented by acoustic wave detection of long-term observation holes in the dam foundation.

[0035] At maximum pressure, when the injection rate is ≤0.4L / min, the perfusion should be continued for more than 20 minutes.

[0036] Specifically, the rock cover consolidation grouting evaluation method for the loose rock mass is implemented as follows:

[0037] S1. The foundation rock of a dam has easily loose jointed rock layers. The rock mass in different areas has different characteristics of acoustic wave velocity distribution before grouting due to the influence of ground stress and structural surface distribution. The consolidation grouting evaluation method process is as follows: Figure 1 shown.

[0038] S2, the consolidation grouting quality evaluation index determined based on the sonic wave results of the pre-grouting test hole is shown in Table 1. The brackets in the table are the acceptance criteria for a single inspection hole;

[0039] Table 1 Consolidation grouting quality evaluation indicators

[0040]

[0041] The pre-filling acoustic wave test results showed that the rate was ≥4700m / s in 81.4% of cases and that was less than 4230m / s in 6.4%.

[0042] S3, after consolidation grouting of the rock protective layer, the proportion of rock mass wave velocity ≥ 4700 m / s increased to 93.6%, and the proportion of less than 4230 m / s decreased to 1.2%;

[0043] S4: After blasting and excavation of the protective layer, the proportion of rock mass with a wave velocity of ≥4700 m / s in the surface 5 m layer decreased to 85.6%, and the proportion with a wave velocity of less than 4230 m / s increased to 9.3%, requiring consolidation grouting with pipe guide;

[0044] S5, the consolidation grouting process of the guide pipe was carried out strictly in accordance with the requirements. After grouting, acoustic wave inspection was carried out through the long-term rock mass quality observation holes arranged in the 24 dam sections. The proportion of rock mass wave velocity ≥4700m / s recovered to 90.1%, and the proportion less than 4230m / s decreased to 4.0%, meeting the design standards.

[0045] The above-mentioned specific implementation methods are used to illustrate the present invention and are only preferred embodiments of the present invention, rather than limiting the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit of the present invention and the scope of protection of the claims shall fall within the scope of protection of the present invention.

Claims

1. A method for evaluating rock cover consolidation grouting of loose rock mass, characterized by: The steps include: S1. Quality inspection of dam foundation rock mass before reinforcement: When excavating to the reserved rock protection layer, select holes no less than the total number of grouting holes as pre-grouting test holes, and conduct rock mass acoustic wave testing through the pre-grouting test holes; S2. Divide the rock mass into zones according to its lithology and rock mass quality classification, determine the minimum average value of the acoustic wave velocity of the rock mass before grouting in each zone as the index velocity, and formulate the consolidation grouting quality evaluation index and individual inspection hole acceptance criteria for each zone; S3. Rock mass quality evaluation after consolidation grouting of rock cover: Arrange post-grouting inspection holes no less than the total number of grouting holes according to geological conditions and consolidation grouting construction conditions, collect acoustic wave measurements of the post-grouting inspection holes within the consolidation grouting quality evaluation unit, and evaluate using the consolidation grouting quality control indicators; S4. Rock mass quality evaluation after excavation of the protective layer: After excavation of the protective layer rock mass, inspection holes are arranged with a number not less than the total number of grouting holes to evaluate the impact of rock protective layer excavation blasting and rock mass unloading on the quality of the dam foundation rock mass; S5. Evaluation of rock mass quality after consolidation grouting with conduit: The evaluation is mainly based on controlling the grouting construction process and analyzing the grouting construction record data, supplemented by acoustic wave detection of long-term observation holes in the dam foundation.

2. The rock cover consolidation grouting evaluation method for loose rock mass according to claim 1, characterized in that: In step S1, the consolidation grouting quality evaluation index is: more than 90% of the measuring points have an acoustic wave velocity greater than or equal to the minimum average value of the rock mass acoustic wave velocity before grouting, and the proportion of measuring points with an acoustic wave velocity less than 0.9 times the minimum average value of the rock mass acoustic wave velocity before grouting does not exceed 5% of the total number of measuring points.

3. The rock cover consolidation grouting evaluation method for loose rock mass according to claim 1, characterized in that: In step S1, the acceptance criteria for individual inspection holes are: more than 85% of the measuring points have an acoustic velocity greater than or equal to the minimum average value of the rock mass acoustic velocity before filling, and the proportion of measuring points with an acoustic velocity less than 0.9 times the minimum average value of the rock mass acoustic velocity before filling does not exceed 5% of the total number of measuring points.

4. The rock cover consolidation grouting evaluation method for loose rock mass according to claim 1, characterized in that: In step S1, the number of test holes before grouting is no less than 5% of the total number of grouting holes.

5. The rock cover consolidation grouting evaluation method for loose rock mass according to claim 1, characterized in that: In step S2, the post-pouring quality inspection is mainly aimed at the rock mass below the dam foundation surface, and the rock protection layer is not within the evaluation scope.

6. The rock cover consolidation grouting evaluation method for loose rock mass according to claim 1, characterized in that: In step S3, the inspection hole is mainly used to check the unloading relaxation of the surface rock mass.

7. The rock cover consolidation grouting evaluation method for loose rock mass according to claim 1, characterized in that: In step S3, the number of inspection holes arranged is no less than 5% of the total number of grouting holes.

8. The rock cover consolidation grouting evaluation method for loose rock mass according to claim 1, characterized in that: In step S4, the number of inspection holes arranged is no less than 5% of the total number of grouting holes.

9. The rock cover consolidation grouting evaluation method for loose rock mass according to claim 1, characterized in that: In step S5, at the maximum pressure, the perfusion is continued for more than 20 minutes when the injection rate is ≤ 0.4 L / min.

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