Roadway roof stability evaluation method based on while-drilling parameter response characteristics

Abstract

The invention relates to a roadway roof stability evaluation method based on while-drilling parameter response characteristics. The method comprises the steps that any roof is selected in a roadway, and while-drilling parameters of a drilling machine in the roadway roof drilling process are continuously collected through a sensor; noise reduction is conducted on the while-drilling parameters through a singular value decomposition method, a while-drilling data set after noise reduction is obtained, unit volume rock drilling energy consumption is analyzed, and the rock uniaxial compressive strength is obtained based on unit volume rock drilling energy consumption inversion; according to the drilling energy consumption or drilling images of different drilling depths, the thickness of a complete rock stratum of the roadway roof, the number of fractures and the width of the fractures are analyzed; according to the thickness of the complete rock stratum, the accumulated complete rock stratum proportion of the roadway roof is analyzed, and according to the rock uniaxial compressive strength of the roadway roof, the thickness of the complete rock stratum, the number of fractures, the width of the fractures and the accumulated complete rock stratum proportion, the stability evaluation result of the roadway roof is determined. Therefore, effective grading evaluation can be performed on the top plate stability simply and quickly.

Description

Technical Field

[0001] The present application relates to the technical field of underground engineering tunnel analysis, and in particular to a tunnel roof stability evaluation method based on drilling parameter response characteristics. Background Art

[0002] At the excavation site of shallow and deep tunnel projects (such as subways, tunnels, and coal mines), if reinforcement measures are not taken in time for the exposed tunnel roof, the tunnel surrounding rock is very likely to fall off and spall in a short period of time, causing large deformation or even instability and damage to the tunnel. Real-time and rapid reliable evaluation of the stability of the tunnel roof not only helps to reasonably select support parameters, but also avoids excessive or insufficient support, thereby improving the economy and safety of the tunnel project. The traditional method of evaluating the stability of the tunnel roof requires the calculation of rock quality indicators through drilling and coring. At the same time, relatively complete cores need to be taken and sent to the laboratory for processing into standard specimens and mechanical experiments. It is also necessary to combine drilling and peeping to conduct statistical analysis on the development of cracks in the roof rock layer. This method is relatively complex to operate, has a long experimental cycle, and has a certain lag. Summary of the invention

[0003] Based on this, it is necessary to provide a tunnel roof stability evaluation method based on the drilling parameter response characteristics, which can simply and quickly evaluate the stability of the tunnel roof effectively in order to address the above technical problems.

[0004] A method for evaluating the stability of a tunnel roof based on a while-drilling parameter response characteristic, the method comprising:

[0005] Step S1: Select any roof in the tunnel, and continuously collect the drilling parameters of the drilling rig during the drilling of the tunnel roof through the sensor, wherein the drilling parameters include drilling torque M, drill bit speed N, thrust F, drilling speed V, drilling depth h and drilling time t;

[0006] Step S2: using singular value decomposition method to perform noise reduction processing on the while drilling parameters to obtain a noise-reduced while drilling data set X(B);

[0007] Step S3: Analyze the energy consumption E per unit volume of rock drilling according to the de-noised while drilling data set X(B), and invert the uniaxial compressive strength UCS of rock based on the energy consumption E per unit volume of rock drilling;

[0008] Step S4: analyzing the thickness l of the complete rock layer of the tunnel roof, the number n of cracks, and the width b of the cracks according to the drilling energy consumption or drilling images at different drilling depths;

[0009] Step S5, analyzing the cumulative intact rock formation ratio RQD of the tunnel roof according to the thickness l of the intact rock formation;

[0010] Step S6: Determine the stability evaluation result of the tunnel roof according to the rock uniaxial compressive strength UCS of the tunnel roof, the thickness l of the intact rock layer, the number of cracks n, the width b of the cracks and the cumulative intact rock layer ratio RQD.

[0011] In one embodiment, the step S2 comprises:

[0012] Step 1.1: Mark the zero-value points and significant mutation points of the drilling data caused by human factors during the drilling process, filter and delete the drilling data corresponding to the zero-value points and significant mutation points of the drilling data, and obtain the filtered drilling data set X(A), wherein when the abnormal data evaluation index T at a certain moment is 0 or the fluctuation amplitude of the adjacent data of the drilling torque is ≥25%, the drilling data corresponding to the moment needs to be deleted, and the expression of the abnormal data evaluation index is:

[0013]

[0014] In the formula, T represents the abnormal data evaluation index; XM, XN, XF, and XV represent the drilling torque, drill bit speed, propulsion force, and drilling speed of the drilling rig at a certain moment, respectively;

[0015] Step 1.2: Use the singular value decomposition method to decompose and reconstruct the filtered while drilling data set X(A)={a1, a2, a3, ..., aA} and convert it into a singular value matrix H. The conversion process is:

[0016]

[0017] Wherein, D is the effective molecular space of the noisy while drilling signal, W is the noise molecular space, i is the number of the while drilling parameters, and j is the number of sampling points;

[0018] Step 1.3: Determine the singular values ​​of the singular value matrix H, separate the effective while-drilling signal components from the noise components, and obtain the denoised while-drilling data set X(B) through inverse transformation.

[0019] In one embodiment, the analytical formula for the energy consumption E per unit volume of rock drilling is:

[0020]

[0021] Among them, N is the drill bit speed; M is the drilling torque; F is the thrust; μ is the friction coefficient between the drill bit and the rock contact surface; Rs represents the radius of the drill bit; L is the length of the cutting edge; and V is the drilling speed.

[0022] In one embodiment, the analytical formula for the uniaxial compressive strength UCS of rock is:

[0023] UCS=0.2938E+9.718

[0024] Among them, UCS is the uniaxial compressive strength of rock.

[0025] In one embodiment, the step S4 comprises:

[0026] Establishing a curve of the relationship between the energy consumption E per unit volume of rock drilling and the drilling depth h, and determining a stable drilling section and a data abnormality stage of the curve;

[0027] Determine the thickness l of the complete rock layer of the tunnel roof, the number n of cracks, and the width b of the cracks according to the stable drilling section and the data abnormal stage;

[0028] Alternatively, in the borehole formed after drilling is completed, a borehole peep instrument is used to obtain borehole images corresponding to different depths of the inner wall of the borehole, and the thickness l of the complete rock layer inside the borehole, the number n of cracks and the width b of the cracks are analyzed by image processing software.

[0029] In one embodiment, the analysis formula of the cumulative intact rock formation proportion RQD is:

[0030]

[0031] Wherein, lq represents the thickness of the qth section of complete rock formation; L represents the total length of the borehole, and Q is the total number of complete rock formations in the roof of the tunnel.

[0032] In one embodiment, determining the thickness l of the complete rock formation of the tunnel roof, the number n of cracks, and the width b of the cracks according to the stable drilling section and the data abnormal stage includes:

[0033] Each steady drilling section corresponds to a complete rock formation, and the difference between the drilling depth at the starting point and the drilling depth at the end point of the steady drilling section is the thickness l of the corresponding complete rock formation;

[0034] Each data abnormality stage corresponds to a crack, the difference between the drilling depth at the start point and the drilling depth at the end point of the data abnormality stage corresponds to the width b of the crack, and the number of data abnormality stages is determined as the number of cracks n.

[0035] In one embodiment, the step S6 comprises:

[0036] Determine whether the tunnel roof meets the Class I roof stability classification standard. If the tunnel roof meets the Class I roof stability classification standard, determine that the stability evaluation result of the tunnel roof is Class I roof. The Class I roof stability classification standard is: rock uniaxial compressive strength UCS ≥ 90MPa, cumulative intact rock layer proportion RQD ≥ 0.95, thickness of each intact rock layer l> 100cm, number of cracks n ≤ 1 and width of each crack b < 1cm;

[0037] If the tunnel roof does not meet the Class I roof stability classification standard, determine whether the tunnel roof meets the Class II roof stability classification standard. If the tunnel roof meets the Class II roof stability classification standard, determine that the stability evaluation result of the tunnel roof is Class II roof. The Class II roof stability classification standard is: rock uniaxial compressive strength UCS ≥ 60MPa, cumulative intact rock layer proportion RQD ≥ 0.85, thickness of each intact rock layer l> 50cm, number of cracks n ≤ 2 and width of each crack b < 2cm;

[0038] If the tunnel roof does not meet the Class II roof stability classification standard, determine whether the tunnel roof meets the Class III roof stability classification standard. If the tunnel roof meets the Class III roof stability classification standard, determine that the stability evaluation result of the tunnel roof is Class III roof. The Class III roof stability classification standard is: rock uniaxial compressive strength UCS ≥ 30MPa, cumulative intact rock layer proportion RQD ≥ 0.75, thickness of each intact rock layer l> 30cm, number of cracks n ≤ 3 and width of each crack b < 5cm;

[0039] If the tunnel roof does not meet the Class III roof stability classification standard, determine whether the tunnel roof meets the Class IV roof stability classification standard. If the tunnel roof meets the Class IV roof stability classification standard, determine that the stability evaluation result of the tunnel roof is Class IV roof. The Class IV roof stability classification standard is: rock uniaxial compressive strength UCS ≥ 5MPa, cumulative intact rock layer proportion RQD ≥ 0.65, thickness of each intact rock layer l> 10cm, number of cracks n ≤ 5 and width of each crack b < 10cm;

[0040] If the tunnel roof does not meet the IV-level roof stability classification standard, the stability evaluation result of the tunnel roof is determined to be a V-level roof.

[0041] The above-mentioned tunnel roof stability evaluation method based on the response characteristics of drilling parameters selects any roof in the tunnel, and continuously collects the drilling parameters of the drilling rig during the drilling of the tunnel roof through sensors, wherein the drilling parameters include drilling torque, drill bit speed, thrust, drilling speed, drilling depth and drilling time; the drilling parameters are denoised by singular value decomposition method to obtain a denoised drilling data set; the drilling energy consumption per unit volume of rock is analyzed based on the denoised drilling data set, and the drilling energy consumption per unit volume of rock is inverted to obtain the drilling energy consumption per unit volume of rock. The uniaxial compressive strength of rock is obtained; according to the drilling energy consumption or drilling images at different drilling depths, the thickness of the complete rock layer, the number of cracks and the width of the cracks of the tunnel roof are analyzed; according to the thickness of the complete rock layer, the cumulative proportion of complete rock layers in the tunnel roof is analyzed; according to the uniaxial compressive strength of the rock of the tunnel roof, the thickness of the complete rock layer, the number of cracks, the width of the cracks and the cumulative proportion of complete rock layers, the stability evaluation result of the tunnel roof is determined, thereby the stability of the roof can be effectively graded and evaluated simply and quickly. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic flow chart of a method for evaluating the stability of a tunnel roof based on the response characteristics of drilling parameters in one embodiment;

[0043] Figure 2 Schematic diagram of a curve showing the relationship between the energy consumption E per unit volume of rock drilling and the drilling depth h in one embodiment. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0045] In one embodiment, Figure 1 As shown, a method for evaluating the stability of a tunnel roof based on the response characteristics of drilling parameters is provided, comprising the following steps:

[0046] Step S1: Select any roof in the tunnel, and continuously collect the drilling parameters of the drilling rig during the drilling process of the tunnel roof through the sensor, the drilling parameters including drilling torque M, drill bit speed N, thrust F, drilling speed V, drilling depth h and drilling time t;

[0047] Step S2: Using singular value decomposition method to perform noise reduction on the while drilling parameters to obtain a noise-reduced while drilling data set X(B);

[0048] Step S3: Analyze the energy consumption per unit volume of rock drilling E according to the de-noised while drilling data set X(B), and invert the uniaxial compressive strength UCS of rock based on the energy consumption per unit volume of rock drilling E;

[0049] Step S4: Analyze the thickness l of the complete rock layer of the tunnel roof, the number n of cracks, and the width b of the cracks according to the drilling energy consumption or drilling images at different drilling depths;

[0050] Step S5, analyzing the cumulative intact rock formation proportion RQD of the tunnel roof according to the thickness l of the intact rock formation;

[0051] Step S6: Determine the stability evaluation result of the tunnel roof according to the rock uniaxial compressive strength UCS of the tunnel roof, the thickness l of the intact rock layer, the number of cracks n, the width b of the cracks and the cumulative intact rock layer ratio RQD.

[0052] The above-mentioned tunnel roof stability evaluation method based on the response characteristics of drilling parameters selects any roof in the tunnel, and continuously collects the drilling parameters of the drilling rig during the drilling process of the tunnel roof through sensors. The drilling parameters include drilling torque, drill bit speed, thrust, drilling speed, drilling depth and drilling time; the singular value decomposition method is used to reduce the noise of the drilling parameters to obtain the reduced-noise drilling data set; according to the reduced-noise drilling data set X(B), the drilling energy consumption per unit volume of rock is analyzed, and based on the unit volume of rock The uniaxial compressive strength of rock is obtained by inversion of drilling energy consumption. The thickness of the intact rock layer, the number of cracks and the width of the cracks of the tunnel roof are analyzed according to the drilling energy consumption or borehole images at different drilling depths. The cumulative proportion of intact rock layers in the tunnel roof is analyzed according to the thickness of the intact rock layers. The stability evaluation result of the tunnel roof is determined according to the uniaxial compressive strength of rock on the tunnel roof, the thickness of the intact rock layer, the number of cracks, the width of the cracks and the cumulative proportion of intact rock layers. This can effectively grade and evaluate the stability of the roof simply and quickly.

[0053] In one embodiment, step S2 includes:

[0054] Step 1.1: Mark the zero-value points and significant mutation points of the drilling data caused by human factors during the drilling process, filter and delete the drilling data corresponding to the zero-value points and significant mutation points of the drilling data, and obtain the filtered drilling data set X(A). Among them, when the abnormal data evaluation index T at a certain moment is 0 or the fluctuation amplitude of the adjacent data of the drilling torque is ≥25%, the drilling data corresponding to the moment needs to be deleted. The expression of the abnormal data evaluation index is:

[0055]

[0056] In the formula, T represents the abnormal data evaluation index; XM, XN, XF, and XV represent the drilling torque, drill bit speed, propulsion force, and drilling speed of the drilling rig at a certain moment, respectively;

[0057] Step 1.2: Use the singular value decomposition method to decompose and reconstruct the filtered while drilling data set X(A) = {a1, a2, a3, ..., aA} and convert it into a singular value matrix H. The conversion process is:

[0058]

[0059] Where D is the effective molecular space of the noisy while drilling signal, W is the noise molecular space, i is the number of while drilling parameters, and j is the number of sampling points;

[0060] Step 1.3: Determine the singular values ​​of the singular value matrix H, separate the effective while-drilling signal components from the noise components, and obtain the denoised while-drilling data set X(B) through inverse transformation.

[0061] Among them, the human factors that cause zero-value points and significant mutation points in the drilling data may include the operating environment, stuck drill pipe, and replacement of drill pipes.

[0062] In one embodiment, the analytical formula for the energy consumption E per unit volume of rock drilling is:

[0063]

[0064] Among them, N is the drill bit speed, in r / min; M is the drilling torque, in N·m; F is the thrust, in N·m; μ is the friction coefficient between the drill bit and the rock contact surface; Rs is the radius of the drill bit, in mm; L is the length of the cutting edge, in mm; V is the drilling speed, in mm / s.

[0065] In one embodiment, the analytical formula for the uniaxial compressive strength of rock UCS is:

[0066] UCS=0.2938E+9.718

[0067] Among them, UCS is the uniaxial compressive strength of rock.

[0068] In one embodiment, step S4 includes:

[0069] Establish the relationship curve between the energy consumption E per unit volume of rock drilling and the drilling depth h, and determine the stable drilling section and data abnormal stage of the relationship curve;

[0070] According to the stable drilling section and the data abnormal stage, the thickness l of the intact rock layer of the tunnel roof, the number n of cracks and the width b of the cracks are determined;

[0071] Alternatively, in the borehole formed after drilling is completed, a borehole peep instrument is used to obtain borehole images corresponding to different depths of the borehole inner wall, and the thickness l of the complete rock layer inside the borehole, the number n of cracks, and the width b of the cracks are analyzed by image processing software.

[0072] When analyzing the width of the crack by image processing software, the maximum width value in the crack can be used as the width of the crack.

[0073] Among them, the relationship curve between the energy consumption E per unit volume of rock drilling and the drilling depth h includes the initial steep rise section, the stable drilling section and the data abnormal stage.

[0074] Among them, the initial steep rise stage is shown in the curve of the relationship between the energy consumption E per unit volume of rock drilling and the drilling depth h as a sharp increase in slope starting from the drilling depth of 0. This is because the drill bit changes from the initial idling state to the rotary cutting and breaking of the rock on the rock surface and penetrating into the rock mass. This stage is generally completed within a drilling depth of 2-3mm.

[0075] Among them, in the stable drilling stage, the curve of the relationship between the energy consumption E per unit volume of rock drilling and the drilling depth h is shown as a curve that maintains stability and maintains small fluctuations. This curve is approximately a straight line parallel to the horizontal axis. When the drill bit speed N and the drilling speed V remain unchanged, the change relationship curve will be relatively stable and maintain small fluctuations after the drill bit completely enters the rock formation. The difference between the maximum drilling energy consumption Emax and the minimum drilling energy consumption Emin in this interval is ≤5%.

[0076] Among them, the data abnormal stage is manifested in the curve of the relationship between the energy consumption E per unit volume of rock drilling and the drilling depth h. After a period of stable drilling, the energy consumption E per unit volume of rock drilling suddenly drops to 0 and then increases rapidly. This is because after the drill bit enters the original cracks in the top rock layer, it is first in an idling state, and then part of the drill bit cuts into the rock mass. At this time, the data fluctuation of the energy consumption E per unit volume of rock drilling is relatively large.

[0077] In one embodiment, the analysis formula for the cumulative intact rock formation ratio RQD is:

[0078]

[0079] Where lq represents the thickness of the qth section of complete rock formation; L represents the total length of the borehole, and Q represents the total number of complete rock formations in the tunnel roof.

[0080] In one embodiment, according to the stable drilling section and the data abnormal stage, the thickness l of the complete rock formation of the tunnel roof, the number n of cracks and the width b of the cracks are determined, including:

[0081] Each steady drilling section corresponds to a complete rock formation, and the difference between the drilling depth at the starting point and the drilling depth at the end point of the steady drilling section is the thickness l of the corresponding complete rock formation;

[0082] Each data abnormal stage corresponds to a crack, and the difference between the drilling depth at the starting point and the drilling depth at the end point of the data abnormal stage corresponds to the width b of the crack. The number of data abnormal stages is determined as the number of cracks n.

[0083] In one embodiment, step S6 includes:

[0084] Determine whether the tunnel roof meets the Class I roof stability classification standard. If the tunnel roof meets the Class I roof stability classification standard, the tunnel roof stability evaluation result is determined to be Class I roof. The Class I roof stability classification standard is: rock uniaxial compressive strength UCS ≥ 90MPa, cumulative intact rock layer proportion RQD ≥ 0.95, thickness of each intact rock layer l> 100cm, number of cracks n ≤ 1 and width of each crack b < 1cm;

[0085] If the tunnel roof does not meet the Class I roof stability classification standard, determine whether the tunnel roof meets the Class II roof stability classification standard. If the tunnel roof meets the Class II roof stability classification standard, determine that the tunnel roof stability evaluation result is Class II roof. Class II roof stability classification standards are: rock uniaxial compressive strength UCS ≥ 60MPa, cumulative intact rock layer proportion RQD ≥ 0.85, thickness of each intact rock layer l> 50cm, number of cracks n ≤ 2 and width of each crack b < 2cm;

[0086] If the tunnel roof does not meet the Class II roof stability classification standard, determine whether the tunnel roof meets the Class III roof stability classification standard. If the tunnel roof meets the Class III roof stability classification standard, determine that the tunnel roof stability evaluation result is Class III roof. The Class III roof stability classification standard is: rock uniaxial compressive strength UCS ≥ 30MPa, cumulative intact rock layer proportion RQD ≥ 0.75, thickness of each intact rock layer l> 30cm, number of cracks n ≤ 3 and width of each crack b < 5cm;

[0087] If the tunnel roof does not meet the Class III roof stability classification standard, determine whether the tunnel roof meets the Class IV roof stability classification standard. If the tunnel roof meets the Class IV roof stability classification standard, determine that the tunnel roof stability evaluation result is Class IV roof. The Class IV roof stability classification standard is: rock uniaxial compressive strength UCS ≥ 5MPa, cumulative intact rock layer proportion RQD ≥ 0.65, thickness of each intact rock layer l> 10cm, number of cracks n ≤ 5 and width of each crack b < 10cm;

[0088] If the tunnel roof does not meet the IV level roof stability classification standard, the stability evaluation result of the tunnel roof is determined to be a V level roof.

[0089] The above-mentioned tunnel roof stability evaluation method based on the response characteristics of drilling parameters can overcome the shortcomings of traditional tunnel stability evaluation methods, which are time-consuming, cumbersome and lagging behind the site. Through real-time drilling parameter inversion, the stability of the roof can be quickly evaluated quantitatively and graded, which is conducive to the reasonable selection of support parameters on site, and can also avoid excessive or insufficient support, thereby improving the economy and safety of tunnel engineering. In addition, by continuously collecting the drilling parameters during the roof anchor drilling process, the uniaxial compressive strength of the roof rock, the thickness of the intact rock layer, the development of cracks, etc. are inverted and predicted based on the response characteristics of the drilling parameters, thereby realizing an accurate evaluation of the stability of the roof. This method is highly operational and the evaluation indicators are comprehensive and reliable.

[0090] In one embodiment, a coal mine tunnel is used as an application scenario to carry out a quantitative evaluation of the tunnel roof stability based on the response characteristics of the drilling parameters. First, a high-precision sensor is used to continuously collect different types of drilling parameters during the drilling process, and the drilling torque M, drill speed N, thrust F, drilling speed V, drilling depth h and drilling time t are de-noised in turn using the singular value decomposition denoising method. The process is as follows:

[0091] First, mark the zero-value points and significant mutation points of the drilling data caused by human factors such as the operating environment, stuck drill pipe, and replacement of drill pipe during the drilling process, and filter and delete the corresponding drilling data. The filtering rules are as follows:

[0092]

[0093] Where XM, XN, XF, and XV represent the drilling torque, drill bit speed, thrust, and drilling speed of the drilling rig at a certain moment, respectively; if T = 0 or the fluctuation amplitude of adjacent data of the drilling torque is ≥ 25%, the drilling data corresponding to this moment needs to be deleted.

[0094] Secondly, taking the drilling torque M in the drilling parameters as an example, for the drilling data set X(MA)={a1,a2,a3,……,ai} after deleting zero values ​​and significant outliers, a 600×400-order singular value matrix H is constructed, and the demarcation singular value is determined to be 0.1534, and then the reconstructed drilling data set X(MB)={a1,a2,a3,……,ai} is obtained through inverse transformation. In order to quantitatively evaluate the denoising effect, the mean square error is used to compare the discrete degree of the torque data set before and after denoising, which are 47.25% and 9.17% respectively. It can be seen that the singular value denoising method has a significant denoising effect on the drilling data.

[0095] For the remaining types of drilling parameters, such as drill bit speed N, thrust F, and drilling speed V, the singular value denoising method is used for data preprocessing.

[0096] Then, the noise-reduced drilling data is substituted into the following formula to calculate the energy consumption E per unit volume of rock drilling:

[0097]

[0098] Where, N is the drill bit speed, r / min; M is the drilling torque, N·m; F is the thrust, kN; μ is the friction coefficient between the drill bit and the rock, and the friction coefficient between the metal drill bit and the rock is 0.15; Rs is the radius of the drill bit, mm, here it is 14 mm; L is the length of the cutting edge, mm, here it is 2 mm; V is the drilling speed, mm / s;

[0099] The uniaxial compressive strength of rock UCS is calculated by the following formula:

[0100] UCS=0.2938E+9.718

[0101] According to the above calculation results, the relationship curve between the energy consumption E per unit volume of rock drilling and the drilling depth h is drawn, as shown in the attached figure. Figure 2 As shown in the figure, statistical analysis shows that there are 3 mutation points in the roof with a depth of 10m, forming 3 data abnormal stages, corresponding to 3 cracks; the widths of the cracks b1, b2 and b3 are 7.31cm, 2.04cm and 9.65cm respectively; from the variation curve of the energy consumption of unit volume rock drilling along the drilling depth h, it can be seen that there are 4 stable drilling sections (l1, l2, l3, l4), and the corresponding thicknesses of the complete rock formations are 0.95m, 2.79m, 2.93m and 3.08m, respectively, and the RQD value is 0.87; in addition, the uniaxial compressive strength of the rock is 57.35MPa through calculation; by comparing the roof stability classification standard of the roof rock formation, it can be seen that the roof here is Grade IV.

[0102] It can be seen from the above embodiments that by adopting the method proposed in this application, multiple evaluation indicators in the roof stability evaluation standard can be predicted and inverted according to the drilling parameter response characteristics. The roof stability evaluation results obtained by this method are scientific and accurate, and the evaluation process is convenient and highly operational.

[0103] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0104] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0105] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for evaluating the stability of a tunnel roof based on the response characteristics of drilling parameters, characterized in that: The method comprises: Step S1: Select any roof in the tunnel, and continuously collect the drilling parameters of the drilling rig during the drilling of the tunnel roof through the sensor, wherein the drilling parameters include drilling torque M, drill bit speed N, thrust F, drilling speed V, drilling depth h and drilling time t; Step S2: using singular value decomposition method to perform noise reduction processing on the while drilling parameters to obtain a noise-reduced while drilling data set X(B); Step S3: Analyze the energy consumption E per unit volume of rock drilling according to the de-noised while drilling data set X(B), and invert the uniaxial compressive strength UCS of rock based on the energy consumption E per unit volume of rock drilling; Step S4: analyzing the thickness l of the complete rock layer of the tunnel roof, the number n of cracks, and the width b of the cracks according to the drilling energy consumption or drilling images at different drilling depths; Step S5, analyzing the cumulative intact rock formation ratio RQD of the tunnel roof according to the thickness l of the intact rock formation; Step S6: Determine the stability evaluation result of the tunnel roof according to the rock uniaxial compressive strength UCS of the tunnel roof, the thickness l of the intact rock layer, the number of cracks n, the width b of the cracks and the cumulative intact rock layer ratio RQD.

2. The method according to claim 1, characterized in that The step S2 comprises: Step 1.1: Mark the zero-value points and significant mutation points of the drilling data caused by human factors during the drilling process, filter and delete the drilling data corresponding to the zero-value points and significant mutation points of the drilling data, and obtain the filtered drilling data set X(A), wherein when the abnormal data evaluation index T at a certain moment is 0 or the fluctuation amplitude of the adjacent data of the drilling torque is ≥25%, the drilling data corresponding to the moment needs to be deleted, and the expression of the abnormal data evaluation index is: In the formula, T represents the abnormal data evaluation index; X M , X N , X F , X V They represent the drilling torque, drill bit speed, propulsion force and drilling speed of the drilling rig at a certain moment respectively; Step 1.2: Use singular value decomposition method to analyze the filtered while drilling data set X(A) = {a1, a2, a3, ..., a A } is decomposed and reconstructed into a singular value matrix H. The transformation process is: Wherein, D is the effective molecular space of the noisy while drilling signal, W is the noise molecular space, i is the number of the while drilling parameters, and j is the number of sampling points; Step 1.3: Determine the singular values ​​of the singular value matrix H, separate the effective while-drilling signal components from the noise components, and obtain the denoised while-drilling data set X(B) through inverse transformation.

3. The method according to claim 1, characterized in that The analytical formula for the energy consumption E per unit volume of rock drilling is: Where N is the drill bit speed; M is the drilling torque; F is the thrust; μ is the friction coefficient between the drill bit and the rock; R s It represents the radius of the drill bit; L is the length of the cutting edge; V is the drilling speed.

4. The method according to claim 1, characterized in that: The analytical formula for the uniaxial compressive strength UCS of rock is: UCS=0.2938E+9.718 Among them, UCS is the uniaxial compressive strength of rock.

5. The method according to claim 1, characterized in that The step S4 comprises: Establishing a curve of the relationship between the energy consumption E per unit volume of rock drilling and the drilling depth h, and determining a stable drilling section and a data abnormality stage of the curve; Determine the thickness l of the complete rock layer of the tunnel roof, the number n of cracks, and the width b of the cracks according to the stable drilling section and the data abnormal stage; Alternatively, in the borehole formed after drilling is completed, a borehole peep instrument is used to obtain borehole images corresponding to different depths of the inner wall of the borehole, and the thickness l of the complete rock layer inside the borehole, the number n of cracks and the width b of the cracks are analyzed by image processing software.

6. The method according to claim 5, characterized in that The analytical formula for the cumulative intact rock formation proportion RQD is: In the formula, l q represents the thickness of the qth section of complete rock formation; L represents the total length of the borehole, and Q is the total number of complete rock formations in the roof of the tunnel.

7. The method according to claim 5, characterized in that Determining the thickness l of the complete rock layer of the tunnel roof, the number n of cracks and the width b of the cracks according to the stable drilling section and the data abnormal stage includes: Each steady drilling section corresponds to a complete rock formation, and the difference between the drilling depth at the starting point and the drilling depth at the end point of the steady drilling section is the thickness l of the corresponding complete rock formation; Each data abnormal stage corresponds to a crack, the difference between the drilling depth at the start point and the drilling depth at the end point of the data abnormal stage corresponds to the width b of the crack, and the number of data abnormal stages is determined as the number of cracks n.

8. The method according to claim 1, characterized in that The step S6 comprises: Determine whether the tunnel roof meets the Class I roof stability classification standard. If the tunnel roof meets the Class I roof stability classification standard, determine that the stability evaluation result of the tunnel roof is Class I roof. The Class I roof stability classification standard is: rock uniaxial compressive strength UCS ≥ 90MPa, cumulative intact rock layer proportion RQD ≥ 0.95, thickness of each intact rock layer l> 100cm, number of cracks n ≤ 1 and width of each crack b < 1cm; If the tunnel roof does not meet the Class I roof stability classification standard, determine whether the tunnel roof meets the Class II roof stability classification standard. If the tunnel roof meets the Class II roof stability classification standard, determine that the stability evaluation result of the tunnel roof is Class II roof. The Class II roof stability classification standard is: rock uniaxial compressive strength UCS ≥ 60MPa, cumulative intact rock layer proportion RQD ≥ 0.85, thickness of each intact rock layer l> 50cm, number of cracks n ≤ 2 and width of each crack b < 2cm; If the tunnel roof does not meet the Class II roof stability classification standard, determine whether the tunnel roof meets the Class III roof stability classification standard. If the tunnel roof meets the Class III roof stability classification standard, determine that the stability evaluation result of the tunnel roof is Class III roof. The Class III roof stability classification standard is: rock uniaxial compressive strength UCS ≥ 30MPa, cumulative intact rock layer proportion RQD ≥ 0.75, thickness of each intact rock layer l> 30cm, number of cracks n ≤ 3 and width of each crack b < 5cm; If the tunnel roof does not meet the Class III roof stability classification standard, determine whether the tunnel roof meets the Class IV roof stability classification standard. If the tunnel roof meets the Class IV roof stability classification standard, determine that the stability evaluation result of the tunnel roof is Class IV roof. The Class IV roof stability classification standard is: rock uniaxial compressive strength UCS ≥ 5MPa, cumulative intact rock layer proportion RQD ≥ 0.65, thickness of each intact rock layer l> 10cm, number of cracks n ≤ 5 and width of each crack b < 10cm; If the tunnel roof does not meet the IV-level roof stability classification standard, the stability evaluation result of the tunnel roof is determined to be a V-level roof.

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