A high-precision prediction method for the degree of surrounding rock fracture in deep tunnels

Abstract

A high-precision prediction method for the degree of surrounding rock rupture in deep tunnels. The method establishes a comprehensive geological investigation for the environment of deep high-stress fractured rock masses, combines image methods to conduct detailed observation and research on deep high-stress fractured rock masses, and preliminarily determines various states such as the existence status of surrounding rock fractures, the diversity of rupture modes, the directionality of progressive rupture, and the timeliness of rupture. Then, ultrasonic technology and disturbed stress testing methods are used to cross-verify the results of previous pinhole photography to construct a high-precision prediction system for visual deep high-stress fractured rock masses; the method is used to predict and study the developed fractures, and a safety factor is proposed to warn of the development of fractures; finally, the response surface method is used to optimize the proposed safety factor. The method of the present invention has clear thinking, clear goals, and is simple and convenient to operate, enabling engineering technicians to easily solve the problem of high-precision prediction of the degree of surrounding rock rupture in deep tunnels.

Description

Technical Field

[0001] The present invention relates to a method for accurately predicting the degree of surrounding rock rupture in deep tunnels. Background Art

[0002] The commonly used methods for predicting the degree of surrounding rock rupture in deep tunnels in engineering mainly include topographic and geologic analysis method, AE method (acoustic emission method), drill cuttings method (rock core discing method), and geothermal method.

[0003] The topographic and geologic analysis method obtains a general understanding of the terrain of the area by carefully observing its topography. In alpine and canyon areas, the valleys are areas with highly concentrated stress. In addition, according to the geological report data, the sections with stress concentration and relatively large ground stress that may be encountered during the construction of the auxiliary tunnel are preliminarily determined. However, the topographic and geologic analysis method is mainly applicable to engineering geological environments such as alpine and canyon areas that are easy to observe, and cannot accurately predict the degree of surrounding rock rupture in deep tunnels, and cannot solve the problem of high-precision prediction under various conditions such as the diversity of deep rock rupture modes, the directionality of progressive rupture, and the timeliness of rupture under the excavation disturbance of deep high-stress fractured rock masses.

[0004] The AE method (acoustic emission method) utilizes the result that there is an acoustic emission phenomenon before the rock approaches failure, and detects the internal situation of the rock through an acoustic wave detector. The basic parameters of this method are the energy rate E and the frequency N of large events, which reflect the degree of internal rock rupture and the stress growth rate to a certain extent. This prediction method is the most direct and effective. However, due to the complexity of the internal environment of deep surrounding rock tunnels, the prediction result of the AE method (acoustic emission method) is affected by the internal environment and cannot be accurately predicted, and cannot solve the problem of high-precision prediction under multiple states of excavation disturbance of deep high-stress fractured rock masses.

[0005] The drill cuttings method (rock core discing method) is carried out by drilling the rock. While conducting the advanced prediction drilling, the drill cuttings and the taken rock cores can be analyzed; for rocks with relatively low strength, the rock burst trend is judged according to the ratio of the volume of the drilled cuttings to the theoretical volume of the drilled hole. However, the sampling of the drill cuttings method (rock core discing method) is relatively single, and it cannot accurately predict the internal situation of deep tunnels in complex environments, and cannot solve the problem of high-precision prediction under various conditions such as the diversity of deep rock rupture modes, the directionality of progressive rupture, and the timeliness of rupture under the excavation disturbance of deep high-stress fractured rock masses.

[0006] The geothermal method uses an infrared thermometer. If the geothermal temperature is close to the geothermal temperature at normal burial depth, it indicates weak groundwater seepage and dry and water-free surrounding rock, and the possibility of rockburst is relatively high. However, predicting rock mass fractures through groundwater seepage cannot quantify the indicators and is not accurate enough for predicting the degree of surrounding rock rupture in deep tunnels under complex engineering backgrounds, and cannot solve the problem of high-precision prediction under complex excavation disturbance environmental conditions of deep high-stress fractured rock masses.

[0007] Based on the existing prediction methods and technologies for the degree of surrounding rock rupture in deep tunnels, it is difficult to accurately predict the degree of surrounding rock rupture under various conditions such as the diversity of deep rock mass rupture modes, the directionality of progressive rupture, and the timeliness of rupture under the excavation disturbance conditions of deep high-stress fractured rock masses. The main problems are as follows:

[0008] (1) The topographic and geologic analysis method is mainly applicable to engineering geological environments such as high mountain and canyon areas that are easy to observe, and cannot accurately predict the degree of surrounding rock rupture in deep tunnels, and cannot solve the problem of high-precision prediction under various conditions such as the diversity of deep rock mass rupture modes, the directionality of progressive rupture, and the timeliness of rupture under the excavation disturbance conditions of deep high-stress fractured rock masses;

[0009] (2) The prediction results of the AE method (acoustic emission method) are affected by the complexity of the internal environment of deep surrounding rock tunnels and cannot be accurately predicted, and cannot solve the problem of high-precision prediction under multiple states of excavation disturbance of deep high-stress fractured rock masses;

[0010] (3) The sampling of the drill cuttings method (core disking method) is relatively single, and cannot accurately predict the internal situation of deep tunnels under complex environments, and cannot solve the problem of high-precision prediction under various conditions such as the diversity of deep rock mass rupture modes, the directionality of progressive rupture, and the timeliness of rupture under the excavation disturbance conditions of deep high-stress fractured rock masses;

[0011] (4) The geothermal method cannot quantify the indicators for predicting rock mass fractures through groundwater seepage and is not accurate enough for predicting the degree of surrounding rock rupture in deep tunnels under complex engineering backgrounds, and cannot solve the problem of high-precision prediction under complex excavation disturbance environmental conditions of deep high-stress fractured rock masses. Summary of the Invention

[0012] Based on this, the present invention proposes a high-precision prediction method for the degree of surrounding rock rupture in deep tunnels, which can accurately predict the degree of surrounding rock rupture under various conditions such as the diversity of deep rock mass rupture modes, the directionality of progressive rupture, and the timeliness of rupture under the excavation disturbance conditions of deep high-stress rock mass fractures.

[0013] The present invention provides a high-precision prediction method for the degree of surrounding rock rupture in deep tunnels, including the following steps:

[0014] (1) First, conduct a comprehensive geological survey to gain a preliminary understanding of the basic geological conditions of the surrounding rock of the deep tunnel and provide an environmental basis for in-situ observation;

[0015] (2) Through in-situ observation, the branch detects the surrounding rock of deep tunnels. Combined with the geological survey, borehole photography is carried out in areas prone to surrounding rock fracture. The real-time images of surrounding rock fractures transmitted back by borehole photography can accurately grasp the development of cracks inside the surrounding rock;

[0016] (3) Analyze and judge the images sent back by the borehole camera, use ultrasonic detection technology to conduct secondary detection for the parts of the deep tunnel surrounding rock where cracks are prone to occur or where large cracks have already occurred, and use the borehole camera technology to secondary determine the accurate situation inside the deep tunnel surrounding rock, predict and prevent excavation for large cracks that have already occurred, and conduct disturbance stress testing for surrounding rock cracks that are still developing;

[0017] (4) Based on the borehole camera technology and ultrasonic detection technology, the disturbance stress test is used to detect the surrounding rock cracks that are still developing. The borehole camera technology and ultrasonic detection technology are combined to detect and analyze the cracks in the surrounding rock of the deep tunnel in stages, ensuring the accuracy of the prediction of the surrounding rock cracks.

[0018] (5) After comprehensive evaluation of the development of cracks in the surrounding rock of deep tunnels using borehole photography technology, ultrasonic detection technology and disturbance stress testing, a mathematical formula is used to predict the development of cracks in the surrounding rock of deep tunnels. Based on a large amount of practical data, the prediction formula for the development of cracks in the surrounding rock of deep tunnels is finally obtained as follows:

[0019] ;

[0020] Where: Indicates the development of cracks in the surrounding rock of deep tunnels; Indicates the surrounding rock cracks measured by borehole camera technology; Indicates the surrounding rock crack conditions measured by ultrasonic detection technology; It indicates the surrounding rock crack conditions measured by the disturbance stress test; are the safety factors of the three methods respectively;

[0021] (6) For the determination of the safety factor, the practical experience of borehole imaging technology, ultrasonic detection technology and disturbance stress test is integrated, and the response surface method is used to optimize and determine the three safety factors. The safety factor can be appropriately adjusted according to different geological conditions, but the coefficient must be optimized through the response surface method.

[0022] (7) By comprehensively using geological investigation, in-situ observation, mathematical fitting methods, and the response surface method to optimize the safety factor, a high-precision prediction method for the degree of surrounding rock rupture in deep tunnels applicable to different geological conditions can be finally obtained.

[0023] Compared with the prior art, the advantages of the present invention are as follows:

[0024] The high-precision prediction method for the degree of surrounding rock rupture in deep tunnels of the present invention has the following advantages compared with the prior art. On the one hand, it is particularly suitable for high-precision prediction of various states such as the diversity of deep rock mass rupture modes, the directionality of progressive rupture, and the timeliness of rupture under the condition of excavation disturbance of deep high-stress rock mass fissures. On the other hand, through the establishment of comprehensive geological investigation on the rock mass fissures in the deep high-stress environment, combined with methods such as imaging to conduct detailed observation and research on the deep high-stress rock mass fissures, initially determine the existence status of surrounding rock fissures and various states such as the diversity of rupture modes, the directionality of progressive rupture, and the timeliness of rupture. Then, through ultrasonic technology and disturbance stress test methods, cross-verify the results of the previous borehole imaging, and construct a high-precision prediction system for visual deep high-stress rock mass fissures. Use the method to predict and study the developed fissures, and propose a safety factor to warn of the development of fissures. Finally, through the response surface method, optimize the proposed safety factor, form an integrated high-precision prediction system for the degree of surrounding rock rupture in deep tunnels with observation - prediction - optimization, and propose a high-precision prediction method for the degree of surrounding rock rupture in deep tunnels based on the combination of in-situ observation and mathematical methods. This method has clear thinking, clear goals, and is simple and convenient to operate, enabling engineering and technical personnel to easily solve the problem of high-precision prediction of the degree of surrounding rock rupture in deep tunnels. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a flow chart of the high-precision prediction method for the degree of surrounding rock rupture in deep tunnels of the present invention;

[0026] Figure 2 is the digital borehole imaging test method and results;

[0027] Figure 3 is a schematic diagram of acoustic wave detection of surrounding rock fissures in deep tunnels;

[0028] Figure 4 is a schematic diagram of the prediction of surrounding rock fissures in deep tunnels. EMBODIMENTS

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0030] See also Figures 1-4 The present invention provides a high-precision prediction method for the degree of surrounding rock fracture in a deep tunnel, comprising the following steps:

[0031] (1) First, conduct a comprehensive geological survey to gain a preliminary understanding of the basic geological conditions of the surrounding rock of the deep tunnel and provide an environmental basis for in-situ observation;

[0032] (2) Through in-situ observation, the branch detects the surrounding rock of deep tunnels. Combined with the geological survey, borehole photography is carried out in areas prone to surrounding rock fracture. The real-time images of surrounding rock fractures transmitted back by borehole photography can accurately grasp the development of cracks inside the surrounding rock;

[0033] (3) Analyze and judge the images sent back by the borehole camera, use ultrasonic detection technology to conduct secondary detection for the parts of the deep tunnel surrounding rock where cracks are prone to occur or where large cracks have already occurred, and use the borehole camera technology to secondary determine the accurate situation inside the deep tunnel surrounding rock, predict and prevent excavation for large cracks that have already occurred, and conduct disturbance stress testing for surrounding rock cracks that are still developing;

[0034] (4) Based on the borehole camera technology and ultrasonic detection technology, the disturbance stress test is used to detect the surrounding rock cracks that are still developing. The borehole camera technology and ultrasonic detection technology are combined to detect and analyze the cracks in the surrounding rock of the deep tunnel in stages, ensuring the accuracy of the prediction of the surrounding rock cracks.

[0035] (5) After comprehensive evaluation of the development of cracks in the surrounding rock of deep tunnels using borehole photography technology, ultrasonic detection technology and disturbance stress testing, a mathematical formula is used to predict the development of cracks in the surrounding rock of deep tunnels. Based on a large amount of practical data, the prediction formula for the development of cracks in the surrounding rock of deep tunnels is finally obtained as follows:

[0036] ;

[0037] Where: Indicates the development of cracks in the surrounding rock of deep tunnels; Indicates the surrounding rock cracks measured by borehole camera technology; Indicates the surrounding rock crack conditions measured by ultrasonic detection technology; It indicates the surrounding rock crack conditions measured by the disturbance stress test; are the safety factors of the three methods respectively;

[0038] (6) For the determination of the safety factor, based on the practical experience of borehole camera technology, ultrasonic detection technology and disturbed stress testing, combined with the response surface method, optimization experiments are carried out for the three safety factors. For different geological conditions, the safety factor can be appropriately adjusted, but the coefficient must be optimized through the response surface method;

[0039] (7) By comprehensively considering geological investigation, in-situ observation, mathematical fitting method and response surface method to optimize the safety factor, a high-precision prediction method for the rupture degree of deep tunnel surrounding rock applicable to different geological conditions can be finally obtained.

[0040] The high-precision prediction method for the rupture degree of deep tunnel surrounding rock of the present invention first conducts comprehensive geological investigation to provide an environmental basis for in-situ observation, adopts a trinity in-situ observation method to conduct high-precision observation and excavation warning for the rupture degree of deep tunnel surrounding rock, and constructs a high-precision prediction system for the visualization of deep high-stress rock mass fissures; then, through mathematical fitting combined with the response surface method for optimization, an integrated high-precision prediction system for the rupture degree of deep tunnel surrounding rock of observation-prediction-optimization is formed, and a high-precision prediction method for the rupture degree of deep tunnel surrounding rock based on the combination of in-situ observation and mathematical methods is obtained; further, the in-situ observation includes three testing methods, namely, the trinity of borehole camera technology, ultrasonic detection technology and disturbed stress testing technology, which verify each other and jointly ensure the accuracy of the prediction of the rupture degree of deep tunnel surrounding rock; on the basis of in-situ observation, the development prediction of the rupture degree of deep tunnel surrounding rock by various testing technologies is fitted by mathematical methods; in the mathematical fitting, a safety factor is innovatively proposed for the testing accuracy of the three in-situ observation methods to ensure the accuracy of mathematical fitting; on the basis of mathematical fitting, the response surface method is used to optimize the proposed safety factor, and the optimal safety factor is obtained in combination with engineering practice, which ensures the accuracy of the prediction of the rupture degree of deep tunnel surrounding rock and solves the problem of high-precision prediction under various conditions such as the diversity of the rupture mode of deep rock mass, the directionality of progressive rupture and the timeliness of rupture under the excavation disturbance conditions of deep high-stress rock mass fissures.

[0041] Compared with the prior art, the advantages of the present invention are as follows:

[0042] The advantages of the high-precision prediction method for the degree of surrounding rock fracture in deep tunnels of the present invention compared with the prior art are as follows. On the one hand, it is particularly suitable for the high-precision prediction of various states of deep rock mass fractures under excavation disturbance conditions, such as the diversity of deep rock mass fracture modes, the directionality of progressive fractures, and the timeliness of fractures. On the other hand, by establishing a comprehensive geological investigation of the deep high-stress rock mass fracture environment and combining the method of borehole camera imaging to conduct a detailed observation and study of the deep high-stress rock mass fractures, the existence status of surrounding rock fractures and various states such as the diversity of fracture modes, the directionality of progressive fractures, and the timeliness of fractures are initially determined. Then, through ultrasonic technology and disturbance stress testing methods, cross-verification is carried out on the results of the previous borehole camera imaging to construct a visualized high-precision prediction system for deep high-stress rock mass fractures. The method is used to predict and study the developed fractures, and a safety factor is proposed to warn of the development of fractures. Finally, through the response surface method, the proposed safety factor is optimized to form an integrated high-precision prediction system for the degree of surrounding rock fracture in deep tunnels, namely observation - prediction - optimization. A high-precision prediction method for the degree of surrounding rock fracture in deep tunnels based on the combination of in-situ observation and mathematical methods is proposed. This method has clear ideas, clear goals, and is simple and convenient to operate, enabling engineering and technical personnel to easily solve the problem of high-precision prediction of the degree of surrounding rock fracture in deep tunnels.

[0043] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not limited to the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high-precision prediction method for the degree of surrounding rock rupture in deep tunnels, characterized in that, The following steps are involved: (1) First, conduct a comprehensive geological survey to gain a preliminary understanding of the basic geological conditions of the surrounding rock of the deep tunnel and provide an environmental basis for in-situ observation; (2) Through in-situ observation, the branch detects the surrounding rock of deep tunnels. Combined with the geological survey, pinhole photography is used in areas prone to surrounding rock fractures. The real-time images of surrounding rock fractures transmitted back by pinhole photography can accurately grasp the development of cracks inside the surrounding rock; (3) Analyze and judge the images sent back by the pinhole camera, use ultrasonic detection technology to conduct secondary detection for the parts of the deep tunnel surrounding rock where cracks are prone to occur or where large cracks have already occurred, and use the pinhole camera technology to secondary determine the accurate situation inside the deep tunnel surrounding rock, predict and prevent excavation for large cracks that have already occurred, and conduct disturbance stress testing for surrounding rock cracks that are still developing; (4) Based on the pinhole camera technology and ultrasonic detection technology, the disturbance stress test is used to detect the surrounding rock cracks that are still developing. The pinhole camera technology and ultrasonic detection technology are combined to detect and analyze the cracks in the surrounding rock of the deep tunnel in stages, ensuring the accuracy of the prediction of the surrounding rock cracks. (5) After comprehensive analysis of the crack development in the surrounding rock of deep tunnels using pinhole photography technology, ultrasonic detection technology and disturbance stress testing, a mathematical formula is used to predict the crack development in the surrounding rock of deep tunnels. Based on a large amount of practical data, the prediction formula for the crack development in the surrounding rock of deep tunnels is finally obtained as follows: ； Wherein: represents the crack development of the surrounding rock of the deep tunnel; represents the crack condition of the surrounding rock measured by the pinhole camera technology; represents the crack condition of the surrounding rock measured by the ultrasonic detection technology; represents the crack condition of the surrounding rock measured by the disturbed stress test; are the safety factor coefficients of the three methods respectively; (6) For the determination of the safety factor, the practical experience of video technology, ultrasonic detection technology and disturbance stress test is integrated, and the three safety factors are optimized and determined by the response surface method. The safety factor can be appropriately adjusted according to different geological conditions, but the coefficient must be optimized by the response surface method. (7) By integrating geological surveys, in-situ observations, mathematical fitting methods, and response surface methodology to optimize the safety factor, a high-precision prediction method for the degree of surrounding rock fracture in deep tunnels under different geological conditions can be developed.

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