CN105651668A - Determination method of permeability rule of crack surrounding rock bolting and grouting in underground engineering - Google Patents

Abstract

The invention discloses a method for measuring the law of anchoring and grouting seepage in surrounding rocks of fissures in underground engineering. According to a large number of experiments, the data are comprehensive and reliable, and the density of rock fissures is a variable. A set of variables, controlling the degree of rock fissures unchanged, conducting multi-factor and multi-level comprehensive experiments on significant factors, and determining the optimal level of each significant factor corresponding to rocks with different fracture densities based on the principle of minimum permeability coefficient The present invention obtains the relational expression of many factors to surrounding rock fissure density through regression analysis after comprehensive test, and according to the optimal principle of experimental result, organizes into the experience table corresponding by surrounding rock fissure density and each significant factor, to In the future, it will be of guiding significance for seepage treatment in underground engineering and support design and implementation under seepage environment.

Description

Method for Measuring Seepage Law of Anchor Grouting in Crack Surrounding Rock in Underground Engineering

technical field

The invention belongs to the technical field of safety in underground engineering, and in particular relates to a method for measuring the law of anchoring and grouting seepage in cracked surrounding rocks in underground engineering.

Background technique

The degree of fracture development in rock mass in underground engineering is not the same. Underground excavation will increase the degree of rock mass fissures, and underground engineering will pass through natural rock mass fissure zones, which will pose a great threat to the safety of underground engineering. Excessive cracks in the rock mass may lead to rock shedding, resulting in insufficient strength of the surrounding rock itself, thus affecting the stability of the underground project. Through the grouting reinforcement of the surrounding rock of the underground engineering fissure, the strength of the surrounding rock can be changed, so as to give full play to the self-bearing capacity of the surrounding rock. The rock mass reinforced by grouting has huge differences in its mechanical parameters and seepage laws. Similarly, grouting anchorage is the most commonly used support method in underground engineering today, and it is also one of the hot spots in rock mechanics research today.

For grouting reinforcement of fractured rock mass, although many scholars have studied its seepage law, there is still no relatively complete experimental program and evaluation mechanism. Every time a different geological environment is encountered, it is necessary to conduct experiments to explore its permeability. The lack of data and data references leads to a large waste of resources in the experimental process.

Contents of the invention

The purpose of the invention is to provide a method for measuring the law of anchoring and grouting seepage in cracked surrounding rocks in underground engineering. Through the orthogonal test of various factors affecting the seepage law of anchoring and grouting in the surrounding rock through the fracture, the factors that have a significant impact on the seepage law of the anchoring and grouting in the surrounding rock through the fracture are analyzed, and a comprehensive experiment is carried out on the significant factors and their different levels, and it is concluded that After a large amount of data, the method of regression analysis is used to analyze the regression relationship between the significant factors and the degree of cracks in the surrounding rock.

In order to achieve the above object, the present invention adopts the following technical solutions:

The method for determining the law of anchoring and grouting seepage in fractured surrounding rock in underground engineering, the specific steps are as follows:

1) Simulate the rock mass environment in the underground engineering based on the rocks and stones collected at the underground engineering site, and measure the crack degree of the rock;

2) drilling and grouting the rocks in step 1), and controlling the corresponding influencing factors in drilling and grouting;

3) The rock is placed in the seepage test system, and the permeability coefficient of the rock is measured;

4) Find the main factors that have a significant impact on the infiltration system, and eliminate the secondary factors;

5) Carry out a multi-level comprehensive test on the main factors;

6) According to the results of the comprehensive experiment, the regression relationship between the main factors and the crack degree of the surrounding rock is found, that is, the seepage law of anchoring and grouting in the surrounding rock of the crack is obtained.

Further, the measured amount of crack degree in the surrounding rock in the step 1) and step 6) is the crack density.

Further, the influencing factors controlled in the drilling in the step 2) are the length, diameter, inclination angle of the drill rod and the distance between adjacent drill holes.

Further, the influencing factors controlled in the grouting in the step 2) are the water-cement ratio in the cement slurry, the strength grade of the cement and the grouting pressure.

Further, the experimental data of the influencing factors in the step 2) are processed by an orthogonal experiment method.

Further, in the step 4, according to the principle of the minimum permeability coefficient, find out the main factors that have a significant impact on the seepage system.

Further, in the step 6), the method of regression analysis is used to find out the regression relationship between the main factors and the degree of cracks in the surrounding rock.

Further, the specific process of using the orthogonal experiment method is as follows: the length of the borehole is l, the diameter of the borehole is d, the inclination angle is α, the gradation of the filler is ε, the cement strength grade is ω, and the water-cement ratio is n, The grouting pressure is s, etc. As the relevant factors affecting the seepage law of anchoring and grouting in the surrounding rock of the filled through cracks, the approximate range of the levels of each factor is determined according to the engineering experience and published related results, and the factors used in the test plan are determined from them Levels, the experimental program was designed by combining the levels of the corresponding factors.

Furthermore, the method of orthogonal experiment includes range R analysis, variance analysis and contribution rate M analysis. Range R analysis considers the influence of errors. If the extreme value R' of the blank column is greater than the extreme value R _i of the factor, it is possible that the Factors have no significant effect on the seepage law of anchoring and grouting in surrounding rocks filled through fractures;

The contribution rate M analysis is the ratio of the sum of squares of K factors to the total sum of squares, that is, M=S _K /S. The greater the contribution rate, the stronger the factor’s ability to influence the evaluation index.

Furthermore, according to the regression relationship between the main factors and the degree of cracks in the surrounding rock, an empirical table corresponding to the degree of cracks in the surrounding rock and each main factor is sorted out to guide engineering practice.

The working principle of the present invention is: through the orthogonal test on various factors affecting the seepage law of anchoring and grouting in the surrounding rock of the through-fissure, the factors that significantly affect the law of anchoring and grouting in the surrounding rock of the through-fissure are analyzed, and the significant factors and their differences are obtained. A comprehensive experiment was carried out horizontally, and after obtaining a large amount of data, the regression analysis method was used to analyze the regression relationship between the significant influencing factors and the degree of cracks in the surrounding rock, so as to obtain the law of seepage.

Compared with the prior art, the present invention has the following advantages:

1) The experimental materials of the present invention are taken from large rocks and stones at the engineering site, which can better simulate the real situation of underground engineering, and can effectively explore the laws of anchoring and grouting seepage in surrounding rocks filling and penetrating cracks.

2) The present invention is based on a large number of experiments, and the data are comprehensive and reliable. The crack density of the rock is a variable, and the significant factors that affect the seepage law of anchoring and grouting in the surrounding rocks that fill through the cracks are a group of variables. According to the principle of the minimum permeability coefficient, the optimal level of each significant factor corresponding to the different fracture densities of the rock is determined by carrying out a comprehensive experiment of multiple factors and levels.

3) the present invention obtains the relational expression of many factors to surrounding rock fissure density through regression analysis after comprehensive test, and according to the optimal principle of experimental result, organizes into the experience table corresponding by surrounding rock fissure density and each significant factor, It has guiding significance for seepage treatment in underground engineering and support design and implementation under seepage environment.

Description of drawings

Fig. 1 is a schematic diagram of anchor grouting in surrounding rock for filling through fissures;

Wherein, 1. rock stone, 2. bolt.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

The method for measuring the seepage law of bolting and grouting in the surrounding rock of the crack in the underground engineering comprises the following steps:

Step 1: Collect large-scale rocks and rocks at the underground engineering site, use this as the research object to simulate the rock mass environment in the underground engineering, measure the degree of cracks in the large rocks, and obtain the crack density;

Step 2: Design an orthogonal test scheme for anchoring and grouting seepage in the surrounding rock for filling through fractures;

Orthogonal test scheme for anchoring and grouting seepage in surrounding rock filled through cracks, the process is as follows: borehole length l, borehole diameter d, inclination angle α, filler gradation ε, cement strength grade ω, water-cement ratio as n, grouting pressure as s, etc. as related factors affecting the law of anchoring and grouting seepage in the surrounding rock for filling through fractures, according to engineering experience and published related results, determine the approximate range of each factor level, and determine the test plan adopted The level of each factor of the corresponding factor is combined to design the test plan, for example, l _i d _j α _k ε _l ω _m n _n s _o represents the i level of factor l, the j level of factor d, the k level of factor α, The experimental scheme of the combination of the ε factor at the first level and so on

Step 3: Drill and grout large rocks according to construction experience and corresponding specifications, and control the length, diameter, inclination, hole distance, water-cement ratio in cement slurry, and cement strength grade of the drill hole according to the orthogonal experiment plan , grouting pressure and other factors;

The method of grouting for large rocks is the general method used in engineering, and it is consistent with the engineering site as much as possible.

Step 4: Put the large rock in the corresponding seepage experimental system, and measure its permeability coefficient;

The seepage test system is a large-scale electro-hydraulic servo rock test system with a permeation device, and the permeability coefficient is an evaluation index for the seepage law of anchoring and grouting in surrounding rocks filling and penetrating cracks.

Step 5: Process the data of the orthogonal experiment, find out the significant factors of grouting and anchor rod according to the principle of the minimum permeability coefficient, and eliminate the secondary factors;

Orthogonal test processing method, based on the comprehensive analysis and judgment of the data processing results, determines the more significant factors affecting the seepage law of anchoring and grouting in the surrounding rock of the filling through fissures.

The orthogonal test processing methods include range R analysis, variance analysis and contribution rate M analysis.

The analysis of the range R needs to consider the influence of errors (blank columns). If the extreme value R' of the blank column is greater than the extreme value R _i of the factor, it is possible that this factor has no significant effect on the seepage law of anchoring and grouting in the surrounding rock filling through fractures.

The contribution rate M analysis is the ratio of the sum of squares of K factors to the total sum of squares, that is, M=S _K /S. The greater the contribution rate, the stronger the factor's ability to influence the evaluation index.

Step 6: Carry out multi-factor and multi-level comprehensive experiments on the anisotropic factors of grouting and anchor;

A multi-factor and multi-level comprehensive experiment was carried out on the significant factors affecting the penetration law. If the drilling inclination angle is α, the cement strength grade is ω, and the grouting pressure is s, they are significant influencing factors, which have k, m, and o levels respectively. Then the test scheme is α _k ω _m s _o , and a total of k×m×o tests are to be carried out.

Step 7: According to the law of comprehensive experimental data, use the method of regression analysis to find the regression relationship between the significant factors of grouting and anchor bolts and the crack density of surrounding rock;

The method of regression analysis, using multivariate quadratic polynomial linear regression model, using the principle of least square method and comprehensive test data, finds the regression relationship between the significant factors of grouting and anchor bolts and the crack density of surrounding rock.

Step 8: According to the optimal principle of the experimental results, that is, the minimum permeability coefficient, sort out an empirical table corresponding to the density of cracks in the surrounding rock and the significant factors of grouting and bolting;

Step 9: The research results guide the engineering practice of seepage control and support stability in underground engineering.

specifically,

Step 1: Collect large rocks and stones at the underground engineering site, use this as the research object to simulate the rock mass environment in the underground engineering, measure the crack degree of large rocks, and obtain the crack density as the evaluation index of the crack degree;

Step 2: Design an orthogonal test plan for anchoring and grouting seepage in the surrounding rock that fills through the cracks. According to the construction experience and corresponding specifications, use hollow grouting bolts to drill and grout large rocks, and control the drilling according to the orthogonal test plan. Length l, diameter d, inclination angle α, hole distance, water-cement ratio in cement slurry, cement strength grade, grouting pressure and other factors, l _i d _j α _k ε _l ω _m n _n s _o represents the i-th level of factor l , d factor jth level, α factor kth level, ε factor l level and other combinations of experimental schemes;

Step 3: Large rocks are placed in the corresponding seepage experimental system, and the permeability coefficient is measured;

Step 4: Process the orthogonal experimental data, find out the significant factors affecting the penetration law, eliminate the secondary factors, and then conduct a multi-factor and multi-level comprehensive experiment on the significant factors affecting the penetration law;

Step 5: According to the law of the comprehensive experimental data, use the method of regression analysis to find the regression relationship between the significant factors and the crack density of the surrounding rock, and according to the principle of optimal experimental results, organize it into Empirical tables corresponding to factors.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or changes that can be made are still within the protection scope of the present invention.

Claims (10)

1. measure the method for crack country rock anchor note percolation law in underground engineering, it is characterised in that specifically comprise the following steps that

1) under base area, the large-scale rock stone of engineering site collection simulates the rock mass environment in underground engineering, measures the crack degree of rock;

2) to step 1) in rock stone hole, slip casting, and corresponding influence factor in keyhole and slip casting;

3) rock is placed in seepage flow experiment system, records the infiltration coefficient of rock;

4) find and infiltration coefficient is affected significant principal element, rejecting secondary cause;

5) principal element is carried out multilevel comprehensive test;

6) find out the regression relation of principal element and wall-rock crack degree according to the result of experiment comprehensively, namely obtain crack country rock anchor note percolation law.

2. the method for claim 1, it is characterised in that described step 1) and step 6) in the measured quantity of wall-rock crack degree be fracture density.

3. method as claimed in claim 1 or 2, it is characterised in that described step 2) in the influence factor that controls in boring be the pitch-row of the length of drilling rod, diameter, inclination angle and adjacent boring.

4. method as claimed in claim 3, it is characterised in that described step 2) in the influence factor that controls in slip casting be the ratio of mud in cement mortar, the strength grade of cement and grouting pressure.

5. the method as described in claim 1 or 4, it is characterised in that to described step 2) in influence factor processed the experimental data of major influence factors by the method for orthogonal experiment.

6. method as claimed in claim 5, it is characterised in that according to the principle that infiltration coefficient is minimum in described step 4, find out and osmosis system is affected significant principal element.

7. the method as described in claim 1 or 6, it is characterised in that described step 6) in utilize the method for regression analysis to find out the regression relation of principal element and wall-rock crack degree.

8. method as claimed in claim 5, it is characterized in that, the detailed process of the method for employing orthogonal experiment is: drillable length l, bore diameter is d, angle of inclination is ��, the grating of implant is ��, strength of cement grade is ��, the ratio of mud is n, grouting pressure is that s etc. fills the correlative factor of through crack country rock anchor note percolation law as impact, according to engineering experience and the related ends delivered, it is determined that the approximate range of each factor level, and therefrom determine each factor level adopted in testing program, by incompatible for each for corresponding factor horizontal group design experiment scheme.

9. the method as described in claim 5 or 8, it is characterised in that adopting the method for orthogonal experiment to include extreme difference R analysis, variance analysis and contribution rate M and analyze, extreme difference R analyzes the impact considering error, and the extreme value R ' of blank column is if more than factor extreme value R_i, then this factor it is likely to not notable on filling the country rock anchor note percolation law impact of through crack;

Contribution rate M analyzes the ratio for K factor quadratic sum with total sum of squares, i.e. M=S_K/ S, contribution rate is bigger, then it represents that this factor is stronger to the capability of influence of this evaluation index.

10. the method for claim 1, it is characterised in that the regression relation according to principal element Yu wall-rock crack degree, sorts out the empirical table that wall-rock crack degree is corresponding with each principal element, to instruct engineering practice.