Excavation compensation control method for soft surrounding rock of underground engineering

Abstract

The present application belongs to the field of underground engineering surrounding rock control, and particularly relates to a kind of underground engineering soft surrounding rock excavation compensation control method. The soft surrounding rock is drilled in advance and classified by softness through a digital in-situ drilling test system, and corresponding control methods are adopted in combination with the detection results. Whether to adopt grouting reinforcement compensation control mode is judged through critical grouting conditions, and the control of soft surrounding rock of underground engineering is realized in combination with high pre-stress compensation. After field application, various application effects are monitored and evaluated in time, and the control method is further optimized through monitoring data and evaluation results.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of surrounding rock control of underground engineering, and particularly relates to a soft surrounding rock excavation compensation control method for underground engineering. BACKGROUND

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] Soft surrounding rock is a common problem in underground engineering. It is relatively difficult to control the stability of soft surrounding rock, and thus often leads to engineering accidents. Therefore, it is extremely important to control the stability of soft surrounding rock in underground engineering.

[0004] At present, the following problems exist in the control of soft surrounding rock:

[0005] (1) Passive control: The support time is mainly after the initial support. Since the initial support is insufficient, it cannot meet the support requirements of soft surrounding rock, and thus reinforcement is needed after the initial support. This passive control results in insufficient active bearing capacity of surrounding rock, failure of support components, and inability to meet the requirements of surrounding rock stability control.

[0006] (2) Single mode: The control mode of soft surrounding rock is single, and the soft surrounding rock cannot be classified and controlled. The control effect cannot be fed back in time.

[0007] (3) Lack of advance determination: The soft surrounding rock condition cannot be determined in advance, and the targeted control mode cannot be adjusted. SUMMARY

[0008] In view of the deficiencies in the prior art, the present application aims to provide a soft surrounding rock excavation compensation control method for underground engineering.

[0009] In order to achieve the above-mentioned purpose, the present application realizes the technical scheme as follows:

[0010] The embodiment of the present application provides a soft surrounding rock excavation compensation control method for underground engineering, as follows:

[0011] An intelligent in-situ drilling test system is used to obtain multi-element while-drilling parameters of the advanced working face surrounding rock;

[0012] Based on a multi-element while-drilling parameter comprehensive evaluation method, the surrounding rock conditions are divided into extremely soft surrounding rock, general soft surrounding rock, and hard surrounding rock.

[0013] For very weak surrounding rock, pre-grouting reinforcement is carried out before excavation, and high pre-stress compensation control is carried out after excavation by using constant resistance energy absorption material; for general weak surrounding rock, whether grouting reinforcement is carried out is determined by critical grouting value after excavation, and then high pre-stress compensation control is carried out by using constant resistance energy absorption material; for hard surrounding rock, high pre-stress compensation control is directly carried out by using constant resistance energy absorption material after excavation;

[0014] Carrying out multi-element real-time wisdom monitoring of surrounding rock stability of underground engineering, and feeding back and optimizing the excavation compensation control scheme.

[0015] The beneficial effects of the above embodiments of the present application are as follows:

[0016] 1. By adopting digital in-situ drilling, the softness degree of surrounding rock is classified, the control mode is selected according to the softness of surrounding rock, the softness of surrounding rock in the field can be more comprehensively, quickly and quantitatively reflected, and the control mode can be more targetedly selected.

[0017] 2. The soft surrounding rock is controlled by the method of surrounding rock grouting compensation and high pre-stress compensation, and the control method is optimized by carrying out field application and monitoring evaluation, which can effectively mobilize the surrounding rock to form an active bearing structure, improve the mechanical properties of the surrounding rock, and ensure the stability of the surrounding rock of the underground engineering. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the method flow chart of the embodiment 1 of the present application. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed description is all exemplary, and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0020] It should be noted that the terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless otherwise explicitly indicated by the present application, the singular form is also intended to include the plural form, and in addition, it should be understood that when the terms "comprise" and / or "include" are used in the specification, it means that there is a feature, step, operation, device, component and / or combination thereof;

[0021] As introduced in the background, there are deficiencies in the prior art, in order to solve the above technical problems

[0022] The present application proposes a kind of underground engineering soft surrounding rock excavation compensation control method, as follows:

[0023] Intelligent in-situ drilling test system is used to obtain multi-element drilling parameters of surrounding rock in advance working face;

[0024] Based on the comprehensive evaluation method of multiple parameters while drilling, the surrounding rock conditions are divided into extremely weak surrounding rock, general weak surrounding rock and hard surrounding rock.

[0025] For the extremely weak surrounding rock, pre-grouting reinforcement is carried out before excavation, and high pre-stress compensation control is carried out by using constant resistance energy absorption material after excavation; for the general weak surrounding rock, whether grouting reinforcement is carried out is determined by the critical grouting value after excavation, and then high pre-stress compensation control is carried out by using constant resistance energy absorption material; for the hard surrounding rock, high pre-stress compensation control is directly carried out by using constant resistance energy absorption material after excavation.

[0026] Carry out multi-element real-time wisdom monitoring of the stability of the surrounding rock of the underground engineering, and feed back and optimize the excavation compensation control scheme.

[0027] In a typical embodiment of the application, as shown in Figure 1 The underground engineering soft surrounding rock excavation compensation control method proposed in the embodiment is as follows:

[0028] The intelligent in-situ drilling test system is used to obtain the multi-element parameters while drilling of the surrounding rock of the advanced working face in real time, and in order to update the control method in a timely manner according to different surrounding rock properties and ensure the accuracy and effectiveness of the control method, the intelligent in-situ drilling test system needs to be carried out in close proximity to the working face. The intelligent in-situ drilling test system has a drilling test range of not less than 3 times the excavation radius, and is carried out synchronously with the excavation of the tunneling working face.

[0029] The geological conditions of underground engineering are complex. The conventional surrounding rock classification method is to take samples on site, process the sampled rock mass into standard test pieces in the laboratory, determine the mechanical parameters, and use the mechanical parameters determined by the indoor test as the standard for surrounding rock classification. However, the test pieces tested by this classification method are obtained by sampling complete rock mass, and the sampling position often has great limitations. When sampling on site, soft and weak rock mass that cannot be sampled is automatically omitted, resulting in that the test results are generally better than the actual rock mass conditions, but it cannot be completely ruled out that the prepared test pieces have original fissures. The intelligent in-situ drilling test system can directly test the mechanical parameters at any position of the underground engineering, avoiding the difficulties of sampling and the errors caused by indoor test, and can more truly reflect the properties of the surrounding rock of the underground engineering, and has more guiding significance for surrounding rock classification. In order to ensure the authenticity of the test results and further eliminate accidental errors, the in-situ digital drilling is carried out at the same time, and the indoor test is also carried out, and the worst value of all test results is used as the standard for the weak grade of the surrounding rock, which can further ensure the strength reserve in the support design.

[0030] The mechanical parameters include equivalent compressive strength UCS of surrounding rock, ground stress SD, fissure development degree CD and fissure water content WD.

[0031] The method comprises on-site advanced detection and indoor drilling test, and comprehensively considers influences of the equivalent compressive strength UCS, the ground stress SD, the fissure development degree CD and the fissure water content WD, and determines a comprehensive evaluation index Q through the parameters.

[0032] The UCS parameter is the equivalent compressive strength of rock mass obtained through inversion of broken drilling parameters, and the equivalent compressive strength of rock mass is inverted through the drilling bit rotating speed, the drilling speed, the drilling torque, the drilling pressure, the drilling bit radius and the length of each cutting edge.

[0033] The equivalent compressive strength obtained through on-site drilling test is denoted as UCS1,..., UCS n The equivalent compressive strength obtained through indoor drilling test is denoted as UCS n+1 ,..., UCS n+i .

[0034] The fissure development degree obtained through on-site drilling test is denoted as CD1,..., CD n The fissure development degree obtained through indoor drilling test is denoted as CD n+1 ,..., CD n+i .

[0035] The fissure water content obtained through on-site drilling test is denoted as WD1,..., WD n The equivalent compressive strength obtained through indoor drilling test is denoted as WD n+1 ,..., WD n+i .

[0036] The above n , i are natural numbers greater than 1.

[0037] The worst parameter UCS n+i is taken from UCS1,..., UCS min , the worst parameter CDmax is taken from CD1,..., CD n+i , the worst parameter WD n+i is taken from WD1,..., WD max , and the ground stress SD is taken to calculate the comprehensive evaluation index Q.

[0038]

[0039] is the UCS correction coefficient, is the CD correction coefficient, The coefficient for the WD is, The coefficient for the SD is.

[0040] Based on the comprehensive evaluation method of multiple parameters while drilling, the index interval of Q is determined. When Q is less than 30, the surrounding rock is defined as extremely weak surrounding rock. When Q is between 30 and 60 (including 30 and 60), the surrounding rock is defined as general weak surrounding rock. When Q is greater than 60, the surrounding rock is defined as hard surrounding rock.

[0041] Specifically, for extremely weak surrounding rock, it is more susceptible to excavation disturbance and prone to large deformation and other damages. Therefore, for extremely weak surrounding rock, pre-grouting reinforcement is performed before excavation to ensure the stability and smoothness of the excavation process. After completing a section of excavation, high pre-stress compensation control is performed in a timely manner using high pre-stress constant resistance energy-absorbing anchor rods and high pre-stress constant resistance energy-absorbing anchor cables to ensure that the surrounding rock can form an effective active bearing structure. The "high pre-stress" mentioned above refers to a pre-stress value greater than 20t.

[0042] For general weak surrounding rock, due to the existence of numerous primary and secondary fissures in the surrounding rock, the bearing capacity and integrity of the surrounding rock are affected. Therefore, after excavation, it is necessary to determine whether to perform surrounding rock grouting reinforcement through critical grouting conditions.

[0043] Whether to perform grouting reinforcement is determined by the comprehensive evaluation index δ of grouting conditions. δ is a function of the average depth of surrounding rock fissures, the distribution law of surrounding rock fissures, the mechanical parameters of surrounding rock, the stress value of the drill hole, and the deformation amount of the surrounding rock after the excavation of the roadway. The critical value of the comprehensive evaluation index δ under the critical grouting condition is measured through on-site grouting tests.

[0044] δ is a function of the average depth of surrounding rock fissures h, the distribution rate of surrounding rock fissures χ , the mechanical parameters of surrounding rock σ 1 , the stress value of the drill hole σ 2 , and the deformation amount s of the surrounding rock after the excavation of the roadway:

[0045]

[0046] wherein x1, x2, x3, x4, and x5 are correction coefficients.

[0047] The critical grouting condition is related to the average depth of surrounding rock fissures, the distribution rate of surrounding rock fissures, the mechanical parameters of surrounding rock, the stress value of the drill hole, and the deformation amount of the surrounding rock. The greater the average depth of surrounding rock fissures and the distribution rate of surrounding rock fissures, the higher the requirement for grouting pressure. According to the mechanical parameters of surrounding rock, the proportioning and material of the grout can be selected. The stress value of the drill hole and the deformation amount of the surrounding rock are used to evaluate the state of the surrounding rock.

[0048] When the comprehensive evaluation index of grouting condition is less than the critical value of δ, directly proceed to the high pre-stress compensation reinforcement link;

[0049] When the comprehensive evaluation index of grouting condition is greater than or equal to the critical value of δ, adopt the filling grouting reinforcement; after the filling grouting reinforcement construction is completed, carry out the comprehensive evaluation of grouting condition again, if the comprehensive evaluation index of δ is less than or equal to the critical value of δ, it proves that only the filling reinforcement method can meet the requirements of grouting reinforcement, and the high pre-stress compensation reinforcement link can be entered; if the comprehensive evaluation index of δ is still greater than the critical value of δ after the filling grouting reinforcement, it indicates that the filling grouting reinforcement cannot meet the requirements of grouting reinforcement, and the grouting pressure should be increased; if the comprehensive evaluation index of δ is still greater than or equal to the critical value of δ after the filling reinforcement, increase the grouting pressure, carry out grouting again, until the comprehensive evaluation index of δ is less than the critical value of δ.

[0050] The grouting reinforcement needs to determine the grouting parameters, including determining the grouting material, determining the different slurry ratio, and determining the grouting pressure; the effect of grouting reinforcement is closely related to the grouting material, the slurry ratio, and the grouting pressure; in order to ensure the effect of grouting reinforcement and make the grouting reinforcement meet the reinforcement requirements as much as possible, the appropriate grouting material, slurry ratio, and grouting pressure should be determined. The grouting material is determined by the crack opening degree and whether the crack contains water; the slurry ratio is determined by preparing test pieces with different slurry ratios, carrying out indoor mechanical tests to obtain mechanical parameters, and comparing the mechanical parameters; the grouting pressure is determined by carrying out on-site grouting pressure pre-test; when selecting the grouting material, if the crack opening degree is large, the grouting material with good expansibility or a certain amount of expansive agent should be added to the conventional cement of the same grade. If the crack opening degree is small, ordinary Portland cement should be selected. If the crack contains water, the material with good water condensation and water plugging effect should be selected. Different slurry ratios affect the mechanical properties of the slurry after setting, so test pieces with different ratios are prepared, and the mechanical parameters of the slurry after setting under different ratio conditions are obtained through indoor tests to select the appropriate slurry ratio. Because the crack morphology and crack distribution in the rock mass cannot be simulated through tests, the test section is selected on the engineering site to carry out the grouting pressure pre-test, and the grouting pressure suitable for the engineering site is obtained.

[0051] For hard surrounding rock, the surrounding rock itself has good properties and good stability, the surrounding rock is complete, and the cracks are not developed, which is more likely to form an effective surrounding rock self-stabilizing structure under support. Therefore, after the hard surrounding rock is excavated, high pre-stress constant resistance energy-absorbing anchor rods or high pre-stress constant resistance energy-absorbing anchor cables are directly used for high pre-stress compensation support after excavation. (The high pre-stress of the high pre-stress constant resistance energy-absorbing anchor rod refers to the pre-stress greater than 10t, and the high pre-stress of the high pre-stress constant resistance energy-absorbing anchor cable refers to the pre-stress greater than 20t).

[0052] The high pre-stress compensation control design includes support member interval design and high pre-stress compensation value design.

[0053] The support member interval and the high pre-stress compensation value are adjusted and designed based on the support interval (commonly 800*800, 1000*1000) and the high pre-stress compensation value (commonly 10t for anchor rod and 20t for anchor cable) under similar geological conditions; and the numerical model is modeled according to the engineering geological parameters to simulate the support effect of the support member design interval and the compensation value. For example, under a certain geological condition, the anchor rod and cable interval of a roadway is 800*850, the anchor rod pre-stress compensation value is 10t, and the anchor cable pre-stress is 20t. If the surrounding rock condition of another roadway is slightly worse than that of this roadway, the anchor rod and cable interval of this roadway is preset to 800*800 according to engineering experience, the anchor rod pre-stress compensation value is 12t, and the anchor cable pre-stress compensation value is 22t. The numerical model is modeled with these parameters to simulate the support effect.

[0054] The multi-element real-time support monitoring includes multi-element real-time monitoring platform construction and intelligent comprehensive analysis model establishment.

[0055] The multi-element real-time monitoring platform includes displacement monitoring, support body stress monitoring and surrounding rock stress monitoring. The real-time monitoring data are transmitted to the ground monitoring platform, and the intelligent comprehensive analysis model can couple and analyze the data transmitted to the platform in real time to comprehensively determine the stability of the underground engineering.

[0056] The displacement monitoring includes surrounding rock loosening monitoring and surrounding rock deformation monitoring. The surrounding rock loosening monitoring adopts high-definition borehole peeping equipment to borehole peep the surrounding rock to determine whether the surrounding rock loosening state meets the stability requirement. Specifically, borehole peeping holes are arranged equidistantly in the surrounding rock, and after hole cleaning, the high-definition borehole peeping equipment is used to borehole peep the surrounding rock. The borehole peeping images are processed to determine the softness of the surrounding rock at different distances from the roadway to determine the surrounding rock loosening circle range. If the surrounding rock loosening circle range is greater than one-third of the hole diameter, the stability requirement is not met. If the surrounding rock loosening circle range is less than one-third of the hole diameter, the stability requirement is met. The surrounding rock deformation monitoring includes roof and floor deformation measurement, two-side deformation measurement and roof separation measurement. The roof and floor deformation measurement and the two-side deformation measurement are measured by using the cross-point method in the monitoring section, and the roof separation measurement is measured by installing an infrared roof separation instrument. When the roof and floor approach amount and the two-side deformation amount are less than 100mm, and the total roof separation amount is less than 50mm or the single-day separation amount is less than 2mm, the stability requirement is met. Otherwise, the stability requirement is not met.

[0057] The surrounding rock stress monitoring includes borehole stress meter and mine pressure and microseismic monitoring data to analyze the stress in the surrounding rock. The borehole stress meter is installed in the surrounding rock. When the borehole stress meter stress continuously rises or the microseismic monitoring data shows that the energy exceeds 105 J, then the stability requirement is not met. When the borehole stress gauge stress has no significant change, the microseismic monitoring data shows that the energy is not more than 10 5 J, then it is considered that the stability requirement is met.

[0058] The stress monitoring of the support member includes monitoring of the pre-tightening force value of the anchor rod (cable), monitoring of the pre-tightening force loss value, monitoring of the stress condition of the anchor rod (cable), and monitoring of the strength reserve of the combined support member. After the excavation compensation control method is used for support design and application, the surrounding rock condition after control is evaluated by monitoring and evaluation effect, so as to feedback and optimize the control scheme. Taking a deep mine as an example: if the deformation of the surrounding rock of the roadway is less than 100 mm, and the stress value of the anchor rod (cable) is less than 60% of the limit breaking force, then it is considered to be stable, and if it is greater than the value, then the support interval distance should be shortened, the length of the anchor rod (cable) should be increased, and the pre-tightening force value should be increased.

[0059] The above method can effectively support control design in underground engineering with large burial depth, high stress, poor surrounding rock condition, and complex geological structure.

[0060] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for excavation compensation control of soft surrounding rock of underground works, The characteristics are as follows: The intelligent in-situ drilling test system is used to obtain the multi-element while-drilling parameters of the surrounding rock of the advanced working face; Based on the multi-element while-drilling parameter comprehensive evaluation method, the surrounding rock conditions are divided into extremely weak surrounding rock, general weak surrounding rock and hard surrounding rock; The intelligent in-situ drilling test system obtains the equivalent compressive strength UCS of the surrounding rock of the advanced working face, the ground stress SD, the fissure development degree CD and the fissure water content WD in real time; The multi-element while-drilling parameter comprehensive evaluation method includes field advanced detection and indoor drilling test, and based on the test results, the comprehensive evaluation method is used to divide the weak grade of the advanced surrounding rock conditions; The multi-element while-drilling parameter comprehensive evaluation method is established, which comprehensively considers the influences of the equivalent compressive strength UCS, the ground stress SD, the fissure development degree CD and the fissure water content WD, and determines the comprehensive evaluation index Q through the above parameters; UCS correction factor, CD correction factor, WD correction factor, SD correction factor; For the extremely weak surrounding rock, the advanced grouting reinforcement is carried out before excavation, and the high pre-stress compensation control is carried out by using the constant resistance energy-absorbing material after excavation; for the general weak surrounding rock, whether to carry out the surrounding rock grouting reinforcement is determined by the critical grouting value after excavation, and then the high pre-stress compensation control is carried out by using the constant resistance energy-absorbing material; for the hard surrounding rock, the high pre-stress compensation control is directly carried out by using the constant resistance energy-absorbing material after excavation; The multi-element real-time wisdom monitoring of the stability of the surrounding rock of the underground engineering is carried out, and the excavation compensation control scheme is fed back and optimized; Whether to carry out the grouting reinforcement is determined by the grouting condition comprehensive evaluation index δ; The δ is a function of the average depth h of the surrounding rock fissure, the distribution rate χ of the surrounding rock fissure, the mechanical parameter σ1 of the surrounding rock, the drilling stress value σ2 and the deformation amount s of the surrounding rock after the excavation of the roadway: Wherein, x1, x2, x3, x4 and x5 are correction coefficients; When the comprehensive evaluation index δ is greater than or equal to the critical value of δ, the filling grouting reinforcement is adopted; after the filling grouting reinforcement construction is completed, if the comprehensive evaluation index δ is less than the critical value of δ, the high pre-stress compensation reinforcement is carried out; if the comprehensive evaluation index δ is still greater than the critical value of δ after the filling grouting reinforcement is adopted, the grouting pressure is increased, the grouting is carried out again, and until the comprehensive evaluation index δ is less than the critical value of δ; The constant resistance energy-absorbing material includes the high pre-stress constant resistance energy-absorbing anchor rod and the high pre-stress constant resistance energy-absorbing anchor cable.

2. The underground engineering soft surrounding rock excavation compensation control method according to claim 1, characterized in that, The intelligent in-situ drilling test system has an advanced drilling test range of not less than 3 times of the excavation radius, and carries out the test closely following the working face.

3. The underground engineering soft surrounding rock excavation compensation control method according to claim 1, characterized in that, For the general weak surrounding rock, the grouting condition comprehensive evaluation index δ is established, the δ is a function of the average depth of the surrounding rock fissure, the distribution rate of the surrounding rock fissure, the mechanical parameter of the surrounding rock, the drilling stress value and the deformation amount of the surrounding rock after the excavation of the roadway; at the same time, the critical value of the comprehensive evaluation index δ under the critical grouting condition is determined through the field grouting test.

4. The underground engineering soft surrounding rock excavation compensation control method according to claim 1, characterized in that, The high pre-stress compensation control includes the design of the row spacing between the supporting members and the design of the high pre-stress compensation value.

5. The underground engineering soft surrounding rock excavation compensation control method according to claim 4, characterized in that, The row spacing between the supporting members and the high pre-stress compensation value are designed by adjusting the row spacing between the supporting members under the similar geological conditions; the numerical model is established, the supporting effect of different row spacings between the supporting members and the compensation stress values is simulated, and thus the optimal parameters meeting the allowable value of the surrounding rock deformation are determined.

6. The underground engineering soft surrounding rock excavation compensation control method according to claim 1, characterized in that, The multi-element real-time wisdom monitoring comprises multi-element real-time monitoring platform construction and wisdom comprehensive analysis model establishment.

7. The underground engineering soft surrounding rock excavation compensation control method according to claim 6, characterized in that, The multi-element real-time monitoring platform comprises displacement monitoring, support body stress monitoring and surrounding rock stress monitoring, and the data of each monitoring part is transmitted to the ground monitoring platform in real time; the wisdom comprehensive analysis model performs coupling analysis on the data transmitted to the platform in real time, and comprehensively judges the stability of the underground engineering.

Images