A method for rapid determination of mechanical strength of tunnel rock mass during excavation

Abstract

The present invention discloses a method for rapidly determining the mechanical strength of a tunnel rock mass during excavation, comprising the following steps: 1. obtaining the uniaxial compressive strength data of a core sample, the excavation pressure data of a drill when collecting cores, and a drill feed rate data set; 2. establishing a linear observation equation for the uniaxial compressive strength of a rock mass; 3. using a linear fitting method to solve the linear correlation coefficient in the linear observation equation for the uniaxial compressive strength of a rock mass; 4. calculating the correlation coefficient during the drilling process; 5. obtaining the excavation pressure data of a drill when excavating a tunnel and a drill feed rate data set; 6. calculating the uniaxial compressive strength of a rock mass according to the linear observation equation for the uniaxial compressive strength of a rock mass. The present invention can rapidly determine the mechanical strength changes of a rock mass along a tunnel through the excavation data of a drill, and provides a reliable and rapid in-situ determination method for fine detection of rock mass strength determination at a construction site, which is helpful for the optimization design of a surrounding rock reinforcement scheme and the optimization of grouting parameters in the later stage.

Description

Technical Field

[0001] The invention belongs to the technical field of rock mass mechanical strength determination, and in particular relates to a method for quickly determining the mechanical strength of a tunnel rock mass during excavation. Background Art

[0002] In underground space engineering, geotechnical engineering and water conservancy engineering, drilling grouting is widely used in tunnel surrounding rock reinforcement and anti-seepage treatment. How to finely identify the strength of the rock mass along the tunnel is the key to surrounding rock reinforcement and anti-seepage treatment. However, in the actual grouting process, due to the fuzzy mechanical strength of the rock mass along the tunnel and the unclear location of the adverse geological structure, the surrounding rock support parameters and grouting parameters are unreasonable, resulting in surrounding rock collapse, repeated grouting and even grouting failure. Therefore, in many engineering construction projects, how to quickly determine the mechanical strength distribution of the rock mass along the tunnel is the key to determining the surrounding rock support parameters and grouting parameters, and it is also a key factor in controlling the progress and investment of the project.

[0003] In many engineering construction projects, the mechanical strength of rock mass along the tunnel is usually obtained through hydraulic fracturing, point load test and conventional indoor rock mass compression and crushing test. The above methods have many disadvantages such as high test cost, long test time, large error and delay of construction process. At present, there is no mature solution to the disadvantages of the above methods. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for quickly determining the mechanical strength of tunnel rock mass during excavation in response to the deficiencies in the above-mentioned prior art. Based on the nature of rock-machine interaction during tunnel excavation, a relationship expression between drilling rig excavation data and rock mass mechanical strength is constructed, thereby realizing rapid determination of the mechanical strength of tunnel rock mass during excavation. This provides a reliable and rapid in-situ determination method for fine-grained detection of rock mass strength at the construction site without affecting the construction period, which is helpful for optimizing the construction design during excavation, optimizing the design of the surrounding rock reinforcement scheme in the later stage, and optimizing the grouting parameters, making the overall tunnel construction process safer and more reliable.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for quickly determining the mechanical strength of tunnel rock mass during excavation, characterized in that the method comprises the following steps:

[0006] Step 1: Obtain the uniaxial compressive strength data of the core sample, the pressure data of the drill while collecting the core, and the drill feed rate data set: Use the drill to sample the core at the construction site and make I core sample; obtain the uniaxial compressive strength data of I core sample, the pressure data of the drill while collecting the core, and the drill feed rate data set, that is, {(UCS 1 ,F n1 ,δ1 ),(UCS 2 ,F n2 ,δ 2 ),...,(UCS i ,F ni ,δ i ),...,(UCS I ,F nI ,δ I )}, where UCS i is the uniaxial compressive strength of the i-th core sample; F ni is the drilling pressure of the drilling rig when collecting the i-th core sample; δ i is the drill feed rate when the drill collects the i-th core sample, in m / rev; i is the number of the core sample and i=1,2,...,I;

[0007] Step 2: Establish the linear observation equation of uniaxial compressive strength of rock mass: According to the uniaxial compressive strength data of a core sample, the drilling pressure data of the drill bit when collecting the core, the linear observation equation of uniaxial compressive strength of rock mass is established. Where K is the linear correlation coefficient of the linear observation equation of the uniaxial compressive strength of rock mass;

[0008] Step 3: Use the linear fitting method to solve the linear correlation coefficient K in the linear observation equation of the uniaxial compressive strength of the rock mass;

[0009] Step 4: Calculate the correlation coefficient of the drilling process: According to the formula Calculate the correlation coefficient f of the drilling process; where k is the correlation coefficient between the drill bit torque and the drilling pressure, k is 2.0-10.0; μ is the rock friction coefficient; w is the drill bit tooth width; b is the drill bit size coefficient; M is the total number of drill teeth on the drill bit, r m is the diameter of the mth drill tooth, m=1,2,...,M;

[0010] Step 5: Obtain the pressure data and drill feed rate data set of the drilling rig during tunnel excavation: Use the drilling rig to carry out tunnel excavation construction, and obtain the pressure data and drill feed rate data set of the drilling rig during tunnel excavation, that is, {(F n1 ,δ 1 ),(F n2 ,δ 2 ),...,(F nj ,δ j ),...,(F nJ ,δ J )}, where F nj is the drilling pressure at the jth sampling point during tunnel excavation, δ jis the drill feed rate at the jth sampling point when the drilling rig is excavating the tunnel; j is the sampling point number along the tunnel excavation time and j=1,2,...,J;

[0011] Step 6: Calculate the uniaxial compressive strength of the rock mass according to the linear observation equation of the uniaxial compressive strength of the rock mass: According to the formula Calculate the uniaxial compressive strength UCS of the rock mass in the construction area where the jth sampling point is located j .

[0012] The above-mentioned method for quickly determining the mechanical strength of tunnel rock mass during excavation is characterized in that: in step 1, the drill feed rate δ of the drill when collecting the i-th core sample is obtained. i The specific steps are:

[0013] S1, obtain the drill bit feed speed V when the drill rig collects the i-th core sample i and the drill pipe rotation speed N when the drill rig collects the i-th core sample i ;

[0014] S2, according to the formula Calculate the drill bit feed rate δ when the drill collects the i-th core sample i .

[0015] The above-mentioned method for quickly determining the mechanical strength of tunnel rock mass during excavation is characterized in that: in step 1, the excavation pressure F of the drilling rig when collecting the i-th core sample is obtained. ni The specific steps are: install an oil pressure sensor on the main oil line of the drilling rig, and the measured value of the oil pressure sensor when the drilling rig collects the i-th core sample is F ni .

[0016] The above-mentioned method for quickly determining the mechanical strength of tunnel rock mass during excavation is characterized in that: in step 1, before constructing the uniaxial compressive strength data of a core sample, the excavation pressure data of the drill rig when collecting the core, and the drill feed rate data set, it is also necessary to pre-process the excavation pressure data and the drill feed rate data of the drill rig when collecting the core, and the specific steps are:

[0017] s1. Eliminate the pressure data of the drilling rig during core collection. ni Invalid data ≤0;

[0018] s2, remove the drill feed data δ i Invalid data ≤0;

[0019] s3, using wavelet analysis algorithm to analyze F ni and δ i Perform noise reduction processing separately.

[0020] The above-mentioned method for quickly determining the mechanical strength of tunnel rock mass during tunneling is characterized in that: in step 5, the sampling time interval of the sampling points along the tunneling depth when the drilling rig is excavating the tunnel is not greater than 5s.

[0021] The beneficial effects of the present invention are as follows: based on the nature of rock-machine interaction during tunnel excavation, the present invention constructs a relationship expression between the drilling rig excavation data and the mechanical strength of the rock mass, thereby realizing the rapid determination of the mechanical strength of the tunnel rock mass during excavation, and providing a reliable and rapid in-situ determination method for the refined detection of rock strength determination at the construction site without affecting the construction period, which is helpful for the optimization of construction design during excavation and the optimization design of the subsequent surrounding rock reinforcement plan and the optimization of grouting parameters, making the overall tunnel construction process safer and more reliable.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flowchart of the method of the present invention.

[0024] Figure 2 This is a curve diagram showing the relationship between the tunnel excavation depth and the uniaxial compressive strength of this embodiment. DETAILED DESCRIPTION

[0025] like Figure 1 As shown, a method for quickly determining the mechanical strength of a tunnel rock mass during excavation of the present invention comprises the following steps:

[0026] Step 1: Obtain the uniaxial compressive strength data of the core sample, the pressure data of the drill while collecting the core, and the drill feed rate data set: Use the drill to sample the core at the construction site and make I core sample; obtain the uniaxial compressive strength data of I core sample, the pressure data of the drill while collecting the core, and the drill feed rate data set, that is, {(UCS 1 ,F n1 ,δ 1 ),(UCS 2 ,F n2 ,δ 2 ),...,(UCS i ,F ni ,δ i ),...,(UCS I ,F nI ,δ I )}, where UCS i is the uniaxial compressive strength of the i-th core sample; F ni is the drilling pressure of the drilling rig when collecting the i-th core sample; δ iis the drill feed rate when the drill collects the i-th core sample, in m / rev; i is the number of the core sample and i=1,2,...,I;

[0027] Step 2: Establish the linear observation equation of uniaxial compressive strength of rock mass: According to the uniaxial compressive strength data of a core sample, the drilling pressure data of the drill bit when collecting the core, the linear observation equation of uniaxial compressive strength of rock mass is established. Where K is the linear correlation coefficient of the linear observation equation of the uniaxial compressive strength of rock mass;

[0028] Step 3: Use the linear fitting method to solve the linear correlation coefficient K in the linear observation equation of the uniaxial compressive strength of the rock mass;

[0029] Step 4: Calculate the correlation coefficient of the drilling process: According to the formula Calculate the correlation coefficient f of the drilling process; where k is the correlation coefficient between the drill bit torque and the drilling pressure, k is 2.0-10.0; μ is the rock friction coefficient; w is the drill bit tooth width; b is the drill bit size coefficient; M is the total number of drill teeth on the drill bit, r m is the diameter of the mth drill tooth, m=1,2,...,M;

[0030] Step 5: Obtain the pressure data and drill feed rate data set of the drilling rig during tunnel excavation: Use the drilling rig to carry out tunnel excavation construction, and obtain the pressure data and drill feed rate data set of the drilling rig during tunnel excavation, that is, {(F n1 ,δ 1 ),(F n2 ,δ 2 ),...,(F nj ,δ j ),...,(F nJ ,δ J )}, where F nj is the drilling pressure at the jth sampling point during tunnel excavation, δ j is the drill feed rate at the jth sampling point when the drilling rig is excavating the tunnel; j is the sampling point number along the tunnel excavation time and j=1,2,...,J;

[0031] Step 6: Calculate the uniaxial compressive strength of the rock mass according to the linear observation equation of the uniaxial compressive strength of the rock mass: According to the formula Calculate the uniaxial compressive strength UCS of the rock mass in the construction area where the jth sampling point is located j .

[0032] In this embodiment, I is a positive integer not less than 10, J is a positive integer, and the value of J is proportional to the total depth of the tunnel; this method uses a top-driven fully hydraulic tunnel drilling rig for tunnel excavation. For this type of drilling rig, according to experience, k=2.54.

[0033] It should be noted that the mechanical strength of rock mass is generally expressed by the uniaxial compressive strength of rock mass. The uniaxial compressive strength of rock mass can be measured by a uniaxial compressive strength test. The test steps are simple and the test results are reliable.

[0034] Since core samples must be collected for testing before tunnel excavation construction, there is no need to add additional construction steps in actual construction. It is only necessary to install sensors for obtaining corresponding data on the drilling rig, and then go through the steps of the method to achieve rapid determination of the mechanical strength of the tunnel rock mass during excavation, effectively saving construction costs.

[0035] It should be noted that the formula in step six takes into account the influence of drill bit size and drill tooth distribution on the machine-rock interaction during excavation. Compared with the traditional empirical formula, it greatly improves the accuracy of rock strength measurement and has a good effect.

[0036] In this embodiment, in step 1, the drill feed rate δ of the drill when collecting the i-th core sample is obtained. i The specific steps are:

[0037] S1, obtain the drill bit feed speed V when the drill rig collects the i-th core sample i and the drill pipe rotation speed N when the drill rig collects the i-th core sample i ;

[0038] S2, according to the formula Calculate the drill bit feed rate δ when the drill collects the i-th core sample i .

[0039] In this embodiment, the drill feed speed V i The displacement detected by the drilling displacement sensor is divided by the drilling time, and the unit is m / min; the drill rod rotation speed N i It is measured by the drill pipe rotation speed sensor installed on the drill pipe of the drilling rig, and the unit is rev / min.

[0040] In this embodiment, in step 1, the drilling pressure F of the drilling rig when collecting the i-th core sample is obtained. ni The specific steps are: install an oil pressure sensor on the main oil line of the drilling rig, and the measured value of the oil pressure sensor when the drilling rig collects the i-th core sample is F ni .

[0041] In this embodiment, the tunnel is a horizontal tunnel, and the excavation pressure F niIt is the downward pressure exerted by the drill bit on the rock during excavation.

[0042] In this embodiment, in step 1, before constructing the uniaxial compressive strength data of one core sample, the drilling pressure data of the drill rig when collecting the core, and the drill feed rate data set, it is also necessary to pre-process the drilling pressure data and the drill feed rate data of the drill rig when collecting the core. The specific steps are:

[0043] s1. Eliminate the pressure data of the drilling rig during core collection. ni Invalid data ≤0;

[0044] s2, remove the drill feed data δ i Invalid data ≤0;

[0045] s3, using wavelet analysis algorithm to analyze F ni and δ i Perform noise reduction processing separately.

[0046] It should be noted that due to δ i It is the drill feed speed V detected by the relevant sensor. i and the drill pipe rotation speed N i The calculated excavation pressure F ni It is measured by the oil pressure sensor, and invalid detection values, that is, null values, will appear during sensor detection. Therefore, when eliminating invalid data, the null values ​​detected by the sensor also need to be eliminated to ensure the standardization and validity of the data in the data set, which is convenient for subsequent calculations.

[0047] It should be noted that the data set of along-dig pressure data and drill feed rate obtained by the drilling rig during tunnel excavation in step five is also a data set after invalid data is eliminated and the data is denoised. The elimination process is the same as the invalid data elimination process in step one, and the denoising process is also the same.

[0048] It should be noted that by performing noise reduction processing on the data collected by the sensor, the accuracy of the measurement results can be greatly improved, thereby ensuring the reasonable safety of subsequent support or grouting construction.

[0049] In this embodiment, in step five, the sampling time interval of the sampling points along the tunnel excavation depth when the drilling rig is excavating the tunnel is not greater than 5s.

[0050] In this embodiment, preferably, the sampling time interval of the sampling points along the tunnel excavation depth when the drill is excavating the tunnel is 1s, which can be approximately regarded as continuous sampling, so the continuous uniaxial compressive strength of the rock mass in the construction area along the tunnel excavation time can be obtained. After adding the excavation depth sensor, the continuous uniaxial compressive strength along the tunnel excavation time can be converted into the continuous uniaxial compressive strength along the tunnel excavation depth. In actual on-site construction, it can also be as follows Figure 2 As shown, the relationship curve between excavation depth and uniaxial compressive strength is drawn by software, making the result more intuitive, which is helpful for construction design optimization, surrounding rock reinforcement scheme design and intelligent optimization of grouting parameters during excavation.

[0051] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for quickly determining the mechanical strength of tunnel rock mass during excavation, characterized in that: The method comprises the following steps: Step 1: Obtain the uniaxial compressive strength data of the core sample, the pressure data of the drill while collecting the core, and the drill feed rate data set: Use a drill to sample the core at the construction site and make I core samples; obtain the uniaxial compressive strength data of I core samples, the pressure data of the drill while collecting the core, and the drill feed rate data set, that is, {(UCS1,Fn1,δ1),(UCS2,Fn2,δ2),...,(UCSi,Fni,δi),...,(UCS I ,Fn I ,δ I )}, where UCSi is the uniaxial compressive strength of the i-th core sample; F ni is the drilling pressure of the drilling rig when collecting the i-th core sample; δ i is the drill feed rate when the drill rig collects the i-th core sample, in m / rev; i is the number of the core sample and i=1,2,...,I; Step 2: Establish the linear observation equation of uniaxial compressive strength of rock mass: According to the uniaxial compressive strength data of a core sample, the drilling pressure data of the drill bit when collecting the core, the linear observation equation of uniaxial compressive strength of rock mass is established. Where K is the linear correlation coefficient of the linear observation equation of the uniaxial compressive strength of rock mass; Step 3: Use the linear fitting method to solve the linear correlation coefficient K in the linear observation equation of the uniaxial compressive strength of the rock mass; Step 4: Calculate the correlation coefficient of the drilling process: According to the formula Calculate the correlation coefficient f of the drilling process; where k is the correlation coefficient between the drill bit torque and the drilling pressure, k is 2.0-10.0; μ is the rock friction coefficient; w is the drill bit tooth width; b is the drill bit size coefficient; M is the total number of drill teeth on the drill bit, r m is the diameter of the mth drill tooth, m=1,2,...,M; Step 5: Obtain the pressure data and drill feed rate data set of the drilling rig during tunnel excavation: Use the drilling rig to carry out tunnel excavation construction, and obtain the pressure data and drill feed rate data set of the drilling rig during tunnel excavation, that is, {(Fn1,δ1),(Fn2,δ2),...,(Fnj,δj),...,(Fn J ,δ J )}, where Fnj is the drilling pressure at the jth sampling point during tunnel excavation, δ j is the drill feed rate at the jth sampling point when the drilling rig is excavating the tunnel; j is the sampling point number along the tunnel excavation time and j=1,2,...,J; Step 6: Calculate the uniaxial compressive strength of the rock mass according to the linear observation equation of the uniaxial compressive strength of the rock mass: According to the formula Calculate the uniaxial compressive strength UCS of the rock mass in the construction area where the jth sampling point is located j ; In step 1, the drill feed rate δ of the drill when collecting the i-th core sample is obtained i The specific steps are: S1, obtain the drill bit feed speed V when the drill rig collects the i-th core sample i and the drill pipe rotation speed N when the drill rig collects the i-th core sample i ; S2, according to the formula Calculate the drill bit feed rate δ when the drill collects the i-th core sample i ; Drill feed speed V i The displacement detected by the drilling displacement sensor is divided by the drilling time, and the unit is m / min; the drill rod rotation speed N i It is measured by the drill pipe rotation speed sensor installed on the drill pipe of the drilling rig, and the unit is rev / min.

2. A method for rapidly determining the mechanical strength of a tunnel rock mass during excavation according to claim 1, characterized in that: In step 1, the drilling pressure F of the drilling rig when collecting the i-th core sample is obtained. ni The specific steps are: install an oil pressure sensor on the main oil line of the drilling rig, and the measured value of the oil pressure sensor when the drilling rig collects the i-th core sample is F ni .

3. A method for rapidly determining the mechanical strength of a tunnel rock mass during excavation according to claim 1, characterized in that: In step 1, before constructing the uniaxial compressive strength data of a core sample, the drilling pressure data of the drill rig when collecting the core, and the drill feed rate data set, it is also necessary to pre-process the drilling pressure data and the drill feed rate data of the drill rig when collecting the core. The specific steps are: s1. Eliminate the pressure data of the drilling rig during core collection. ni Invalid data ≤0; s2, remove the drill feed data δ i Invalid data ≤0; s3, using wavelet analysis algorithm to analyze F ni and δ i Perform noise reduction processing separately.

4. A method for rapidly determining the mechanical strength of a tunnel rock mass during excavation according to claim 1, characterized in that: In step five, the sampling time interval of the sampling points along the tunnel excavation depth when the drilling rig is excavating the tunnel shall not exceed 5s.

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