Acoustic emission micro-seismic monitoring analysis method suitable for hard rock

Abstract

The invention discloses an acoustic emission micro-seismic monitoring and analyzing method suitable for hard rocks, and relates to the field of high-level radioactive waste dispose.The method comprises the steps that firstly, a hole is drilled in the direction from an excavated roadway to a TBM roadway / drilling and blasting roadway to be excavated, an acoustic emission sensor and a micro-seismic sensor are arranged in the drilled hole, and a TBM section / drilling and blasting section acoustic emission micro-seismic monitoring system is formed; in the TBM method / drilling and blasting method excavation process, a TBM section / drilling and blasting section acoustic emission microseismic monitoring system is adopted for monitoring to obtain TBM section / drilling and blasting section acoustic emission microseismic monitoring data, the surrounding rock response process of a TBM roadway / drilling and blasting roadway is analyzed according to the TBM section / drilling and blasting section acoustic emission microseismic monitoring data, and the accuracy of surrounding rock response characterization in the TBM method and drilling and blasting method excavation process can be improved; according to the analysis result of the surrounding rock response process of the TBM roadway and the drilling and blasting roadway, the excavation process of the TBM method and the drilling and blasting method is guided, and scientific construction of the TBM method and the drilling and blasting method can be achieved.

Description

Technical Field

[0001] The present application relates to the technical field of high-level radioactive waste disposal, and in particular to an acoustic emission microseismic monitoring and analysis method applicable to hard rock. Background Art

[0002] High-level radioactive waste (abbreviated as HLW) is characterized by strong radioactivity, high toxicity and long half-life, making it extremely difficult to dispose of it safely and facing a series of scientific, technological and engineering challenges. Whether high-level radioactive waste can be safely disposed of is a strategic issue related to the sustainable development of the nuclear industry and environmental protection. The geological disposal repository for high-level radioactive waste has the characteristics of complex construction conditions, high safety level and long service life (tens of thousands of years), which makes research and development very difficult. To this end, based on previous research experience, it is necessary to first build an underground laboratory for high-level radioactive waste disposal at the depth of the repository, conduct site characteristic evaluation, and conduct on-site testing and verification of disposal technology, so as to provide the necessary scientific research foundation and practical experience for the construction of the repository.

[0003] TBM (Tunnel Boring Machine) and drilling and blasting are two commonly used methods in the construction of underground projects (underground laboratories and disposal repositories). They have their own characteristics and are suitable for different geological conditions and engineering requirements. In the excavation process of underground laboratories and disposal repositories, TBM and drilling and blasting are often used in combination. However, there is a lack of comparative analysis methods for the surrounding rock response during the excavation process of the two methods in this field, making it difficult to guide the actual excavation process of TBM and drilling and blasting. Summary of the invention

[0004] The purpose of this application is to provide an acoustic emission microseismic monitoring and analysis method suitable for hard rock, so as to accurately characterize the surrounding rock response during the TBM and drilling and blasting excavation process, and guide the scientific excavation of the TBM and drilling and blasting methods.

[0005] To achieve the above objectives, this application provides the following solutions.

[0006] The present application provides an acoustic emission microseismic monitoring and analysis method applicable to hard rock, comprising:

[0007] Drill holes from the excavated tunnel to the direction of the TBM tunnel to be excavated, and place acoustic emission sensors and microseismic sensors in the holes to form an acoustic emission microseismic monitoring system for the TBM section;

[0008] During the TBM excavation process, the TBM section acoustic emission microseismic monitoring system is used to obtain the TBM section acoustic emission microseismic monitoring data;

[0009] The surrounding rock response process of TBM tunnel excavation was analyzed based on the acoustic emission microseismic monitoring data of the TBM section;

[0010] Drill holes from the excavated tunnel to the direction of the drilling and blasting tunnel to be excavated, and place acoustic emission sensors and microseismic sensors in the holes to form an acoustic emission and microseismic monitoring system for the drilling and blasting section;

[0011] During the drilling and blasting excavation process, the drilling and blasting section acoustic emission microseismic monitoring system is used to obtain the drilling and blasting section acoustic emission microseismic monitoring data;

[0012] The surrounding rock response process of drilling and blasting tunnel excavation was analyzed based on the acoustic emission microseismic monitoring data of the drilling and blasting section;

[0013] The surrounding rock response process analysis results of TBM tunnels and drill-and-blast tunnels are used to guide the TBM and drill-and-blast excavation processes.

[0014] Optionally, drilling a hole from the excavated tunnel toward the TBM tunnel to be excavated, and placing an acoustic emission sensor and a microseismic sensor in the borehole to form a TBM section acoustic emission microseismic monitoring system, specifically includes:

[0015] Drill holes from the excavated tunnel toward the TBM tunnel to be excavated, both in the up-dip and down-dip directions;

[0016] An acoustic emission sensor is installed at a preset position in a preset borehole, and multiple acoustic emission sensors form an array structure around half of the wall of the TBM tunnel;

[0017] Microseismic sensors are installed at preset positions in the preset boreholes, and at least four microseismic sensors are arranged on each side of the TBM tunnel in the horizontal direction.

[0018] Optionally, during the TBM excavation process, the TBM segment acoustic emission microseismic monitoring system is used to monitor and obtain TBM segment acoustic emission microseismic monitoring data, specifically including:

[0019] During the TBM excavation process, the acoustic emission sensors deployed in the TBM section are used to monitor the number of acoustic emission impacts at different locations and times;

[0020] Microseismic sensors deployed in the TBM section are used to monitor microseismic events caused by rock damage or rock fracture.

[0021] Optionally, the process of analyzing the surrounding rock response of the TBM tunnel according to the acoustic emission microseismic monitoring data of the TBM section specifically includes:

[0022] According to the variation law of acoustic emission impact number over time, the rock fracture process during TBM excavation is divided into damage stage, progressive damage stage and stable stage, and a negative exponential function is used to fit the relationship between the acoustic emission impact number per unit time and time.

[0023] Optionally, the process of analyzing the surrounding rock response of the TBM tunnel according to the acoustic emission microseismic monitoring data of the TBM section specifically includes:

[0024] According to the microseismic events and their energy, the formula Calculate the microseismic b value as the precursor information of the increased surrounding rock damage; b represents the microseismic b value; T is the monitoring time period; N M1 N represents the number of earthquake events with magnitude greater than or equal to M1 during the monitoring period T; M2 It represents the number of earthquake events with magnitude greater than or equal to M2 during the monitoring period T; M1 and M2 are both positive integers and M2>M1;

[0025] The ratio of shear wave to longitudinal wave energy, Es / Ep, is calculated based on microseismic events and their energy, and the surrounding rock fracture damage mechanism is analyzed based on the Es / Ep index.

[0026] The moment tensor theory is introduced to solve the inversion parameters of the moment tensor of microseismic events, and the moment tensor is decomposed to reveal the micro-fracture mechanism of the surrounding rock.

[0027] Optionally, drilling a hole from the excavated tunnel toward the drilling and blasting tunnel to be excavated, and arranging an acoustic emission sensor and a microseismic sensor in the borehole to form an acoustic emission and microseismic monitoring system for the drilling and blasting section specifically includes:

[0028] Drill holes from the excavated tunnel to the drill-blast tunnel to be excavated. The drilling directions include up-dipping, nearly horizontal, and down-dipping.

[0029] Acoustic emission sensors are installed at preset positions in preset boreholes in three directions: up-dipping, nearly horizontal, and down-dipping. Multiple acoustic emission sensors are located on one side of the drill and blast tunnel close to the excavated tunnel.

[0030] Microseismic sensors are installed at preset positions in preset boreholes in both up-dip and down-dip directions, and at least four microseismic sensors are arranged on each side of the drill and blast tunnel in the horizontal direction.

[0031] Optionally, during the drilling and blasting excavation process, the drilling and blasting section acoustic emission microseismic monitoring system is used to monitor and obtain the drilling and blasting section acoustic emission microseismic monitoring data, specifically including:

[0032] During the drilling and blasting excavation process, the acoustic emission sensors deployed in the drilling and blasting section are used to monitor the number of acoustic emission impacts at different locations and times;

[0033] Microseismic sensors placed in the drilling and blasting section are used to monitor microseismic events caused by rock destruction or rock fracture.

[0034] Optionally, the process of analyzing the surrounding rock response of the drilling and blasting tunnel according to the acoustic emission microseismic monitoring data of the drilling and blasting section specifically includes:

[0035] According to the variation law of acoustic emission impact number over time, the rock fracture process after blasting is divided into blasting damage stage, progressive damage stage and stable stage, and the function N(t) = N0 + β(1-e αt ) is used to fit the relationship between the number of acoustic emission impacts and time; where N(t) represents the number of acoustic emission impacts at time t; N0 represents the constant of the initial acoustic emission activity; α is the time factor; and β is the basic constant affected by the acoustic emission activity.

[0036] Optionally, the process of analyzing the surrounding rock response of the drilling and blasting tunnel according to the acoustic emission microseismic monitoring data of the drilling and blasting section specifically includes:

[0037] According to the temporal and spatial evolution law, amplitude-frequency distribution and mechanism of microseismic events, the progressive damage process of surrounding rock and its controlling factors are analyzed.

[0038] Optionally, guiding the TBM method and drilling and blasting method excavation process according to the surrounding rock response process analysis results of the TBM tunnel and the drilling and blasting tunnel specifically includes:

[0039] According to the analysis results of the surrounding rock response process of TBM tunnels and drill-blast tunnels, the blasting plan and construction plan are reasonably designed, the tunnel shape and direction are reasonably designed, the tunnel excavation sequence is guided, the support plan design is guided, and geological disaster risk warnings are carried out.

[0040] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0041] The present application provides an acoustic emission microseismic monitoring and analysis method suitable for hard rock, which can accurately characterize the internal damage evolution process of the surrounding rock by deploying an acoustic emission microseismic monitoring system in the TBM section and the drilling and blasting section, and analyzing the surrounding rock response process based on the acoustic emission microseismic monitoring data obtained during the TBM / drilling and blasting excavation process. Furthermore, guiding the TBM and drilling and blasting excavation process based on the surrounding rock response process analysis results of the TBM tunnel and the drilling and blasting tunnel can not only improve the safety of the project, optimize the construction plan, and improve the construction efficiency, but also realize scientific and intelligent management, providing important guarantees for the smooth implementation of underground projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 A schematic diagram of a flow chart of an acoustic emission microseismic monitoring and analysis method applicable to hard rock in this application;

[0044] Figure 2 Schematic diagram of the layout of drilling and acoustic emission sensors in the TBM section and the drilling and blasting section;

[0045] Figure 3 Schematic diagram of the layout of drilling holes and microseismic sensors in the TBM section and the drilling and blasting section;

[0046] Figure 4 This is a schematic diagram of the structure of the acoustic emission sensor monitoring equipment;

[0047] Figure 5 This is a schematic diagram of the acoustic emission response results monitored by two acoustic emission sensors;

[0048] Figure 6 This is a schematic diagram of the acoustic emission response results monitored by the A12 sensor;

[0049] Figure 7 Schematic diagram of the relationship between the spatial distribution of microseismicity and TBM construction conditions;

[0050] Figure 8 The diagram is a schematic diagram of the triggering of microseismic events and the working status of the on-site TBM;

[0051] Fig. 9 This is a schematic diagram of the change of the microseismic b value of a microseismic event monitored by a microseismic sensor over time;

[0052] Fig.10 This is a schematic diagram of the evolution of rupture types of slightly larger energy microseismic events;

[0053] Fig.11 This is the numerical simulation displacement cloud map of the TBM section;

[0054] Fig.12 This is the numerical simulation shear stress cloud diagram of the TBM section. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0056] Acoustic emission and microseismic monitoring technologies are important monitoring methods in the field of geotechnical engineering. By acquiring and processing monitoring signals, they can invert the time, location, intensity and form of internal fractures in the surrounding rock, and characterize the internal damage evolution process of the rock mass. Based on this, the present application provides an acoustic emission microseismic monitoring and analysis method suitable for hard rock, so as to accurately characterize the surrounding rock response during the TBM and drilling and blasting excavation process, and guide the scientific excavation of the TBM and drilling and blasting methods.

[0057] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0058] See also Figure 1 , the present application provides an acoustic emission microseismic monitoring and analysis method suitable for hard rock, including the following steps 1 to 7. The method of the present application is mainly used in the excavation process of underground laboratories. In the embodiment of the present application, the rock mass condition in the excavation area is high-integrity, high-strength granite; the core with RQD>90 accounts for 86% of the total length; the average uniaxial compressive strength of the rock is above 170MPa, and the highest uniaxial compressive strength is 235MPa or higher. The ground stress is low, and the maximum principal stress of the -280m platform is less than 12MPa. At this time, there is σ H >σ V >σ h ; where σ H is the maximum horizontal principal stress, σ V is the vertical stress, σ h is the minimum horizontal principal stress. Therefore, the method of the present application can also be applied to other hard rock areas.

[0059] Step 1: Drill holes from the excavated tunnel toward the TBM tunnel to be excavated, and place acoustic emission (AE) sensors and microseismic sensors in the holes to form a TBM section AE microseismic monitoring system.

[0060] like Figure 2 As shown in the left half, a hole is drilled from the excavated tunnel to the direction of the TBM tunnel (also called tunnel) to be excavated. The drilling (represented by a straight line in the figure) includes both up-dip and down-dip directions. An acoustic emission sensor ( Figure 2 The key monitoring areas of the acoustic emission sensor are the spandrel, arch corner and the middle of the tunnel side wall, monitoring the acoustic emission response of the surrounding rock at different distances from the middle of the tunnel side wall. The acoustic emission signal monitoring adopts a minimum four-point positioning method, preferably a six-point positioning method.

[0061] exist Figure 2In the embodiment shown, the cross section of the TBM tunnel is circular. In the same cross section, it can be seen that multiple acoustic emission sensors form an array structure around half of the wall of the TBM tunnel. In other words, the monitoring range of multiple acoustic emission sensors covers half of the TBM tunnel, and multiple acoustic emission sensors try to form an array structure. The advantage of such a layout is that the coverage is wide, and the acoustic emission signal of the entire circular cross-section area can be directly restored through a symmetric algorithm. The disadvantage is that when performing six-point positioning of the acoustic emission signal, at least four-point positioning, the connection between two sensors may pass through the empty area formed by the excavation of the TBM tunnel. The empty area will affect the subsequent analysis of the acoustic emission signal. The calculation process needs to consider the influence of the empty area. The algorithm is relatively complex, which affects the calculation efficiency.

[0062] Therefore, in other embodiments, multiple acoustic emission sensors may also be arranged only on one side of the TBM tunnel close to the excavated tunnel, similar to Figure 2 The advantage of this arrangement is that there is no empty area, which is convenient for data analysis. The disadvantage is that the connection between the two sensors should avoid passing through the tunnel section (i.e., the empty area), so it can only cover a part of the area. Therefore, when arranging the acoustic emission sensors, the distance between the sensor closest to the tunnel side wall in each borehole and the tunnel side wall is set to 0.3m-1m, which can ensure that the sensor is arranged as close as possible to the maximum stress point obtained by numerical simulation, and avoid being damaged by excavation.

[0063] Furthermore, if Figure 2 As shown in the left half, the sensor located on the central axis of the TBM tunnel is 0.1-1m away from the TBM tunnel wall. The distance between two adjacent acoustic emission sensors in the same borehole is 1.5-2.5m. Multiple sensors are arranged in an array structure as much as possible to facilitate four-point or six-point positioning. In the two middle boreholes, the height of the sensor closest to the tunnel wall relative to the central axis of the tunnel is 1 / 3 to 1 / 5 of the tunnel diameter, preferably corresponding to 1 / 4 and 3 / 4 of the tunnel diameter respectively.

[0064] The structure of the acoustic emission sensor monitoring equipment used is as follows: Figure 4 As shown, it includes an AE sensor and preamplifier in a protective cover and a signal acquisition and processing system. The acoustic emission host used is SH-III type, and the acoustic emission sensor uses R.45I-LP-AST signal with a frequency range of 5kHz to 30kHz. The gain of the low-power amplifier is 26dB. The AE sensor and preamplifier are in a waterproof integrated package.

[0065] like Figure 3 As shown in the left half, a borehole is drilled from the excavated tunnel to the TBM tunnel to be excavated. The boreholes (represented by straight lines in the figure) include both up-inclined and down-inclined directions. A microseismic sensor ( Figure 3 The key monitoring areas of microseismic monitoring are the spandrels, arch corners and the middle of the tunnel sidewall, and the microseismic response of the surrounding rock at different distances from the middle of the tunnel sidewall is monitored. Therefore, at least four microseismic sensors are arranged on each side of the TBM tunnel in the horizontal direction.

[0066] contrast Figure 2 and Figure 3 As can be seen from the left half, the difference between the microseismic sensors and the acoustic emission sensors is that the microseismic sensors are only arranged on the side of the TBM tunnel close to the excavated tunnel, while the microseismic sensors are arranged on both sides of the TBM tunnel, and at least four microseismic sensors are arranged on each side to facilitate four-point positioning. This is because the acoustic emission sensor usually has a narrow monitoring range, and the excavation section of the TBM tunnel is usually circular. It is only necessary to monitor the acoustic emission response on one side of the tunnel to symmetrically obtain the acoustic emission response on the other side of the tunnel, and the error is within an acceptable range. The microseismic sensor has a wider monitoring range. By arranging at least four microseismic sensors on both sides of the tunnel, accurate response data surrounding the entire area of ​​the tunnel can be measured.

[0067] Among them, the microseismic sensor can be a uniaxial microseismic sensor with model specification A1-30-1.0 or a triaxial microseismic sensor with model specification A3-1.0-1.25. The uniaxial microseismic sensor can achieve 360° monitoring in all directions, with a damping sensitivity of 30V / g, a sound frequency of 50Hz to 5KHz, a dynamic response of 100dB, a diameter of 25.4mm, and an ambient temperature of -20℃ to +85℃. The triaxial microseismic sensor has a damping sensitivity of 1V / g.

[0068] In such Figure 2 and Figure 3 In the embodiment shown, there are 16 acoustic emission sensors, which are distributed in 8 different boreholes; and 22 microseismic sensors, which are distributed in 8 different boreholes. Some boreholes and sensor layout positions of the TBM section are shown in Table 1 below. In Table 1, each borehole is numbered with ZKC, the acoustic emission sensor is numbered with the letter A, the microseismic sensor is numbered with the letter M, and the sensor position refers to the distance between the sensor and the borehole opening / m.

[0069] Table 1 Location of drilling holes and acoustic emission microseismic sensors in some TBM sections

[0070]

[0071]

[0072] Step 2: During the TBM excavation process, the TBM section acoustic emission microseismic monitoring system is used to obtain the TBM section acoustic emission microseismic monitoring data.

[0073] During the TBM excavation process, the acoustic emission sensors deployed in the TBM section are used to monitor the number of acoustic emission impacts at different locations and times. The microseismic sensors deployed in the TBM section are used to monitor the microseismic events caused by rock mass damage or rock fracture.

[0074] Step 3: Analyze the surrounding rock response process of TBM tunnel excavation based on the acoustic emission microseismic monitoring data of the TBM section.

[0075] Figure 5 The figure shows the acoustic emission response results monitored by the A11 sensor and the A12 sensor after the TBM section stopped excavation. The horizontal axis is time and the vertical axis is the number of acoustic emission impacts. Figure 5 The results show that, under the same threshold, the closer to the TBM wall, the more acoustic emission impacts per unit time; after the TBM stops excavating for 0.6 hours, the number of acoustic emission impacts per unit time tends to zero; the relationship between the number of acoustic emission impacts per unit time and time can be fitted by a negative exponential function. Figure 5 In the embodiment shown, a negative exponential function y=a may be used. 11 +b 11 *exp(-k 11 *x) to fit the acoustic emission response curve monitored by the A11 sensor, where parameter a 11 =-20.25746±2.4842; b 11 =1269.07488±10.40; k 11 =5.57924±0.0757. Using the function y=A 12 *exp(-x / t 12 )+y0 to fit the acoustic emission response curve monitored by A12 sensor, where parameter y0=4±0.9456; A 12 =328.62852±4.62628; t 12 =0.1281±0.00286.

[0076] Figure 6 The acoustic emission response results monitored by the A12 sensor are specifically shown. It can be seen that at the moment the TBM stops excavating, the number of acoustic emissions per unit time is consistent with that during the TBM excavation, followed by rapid decay, and then the decay gradually slows down; sporadic impacts after the number of acoustic emission impacts per unit time tends to zero can be identified as noise; it is preliminarily determined that the rock fracture process during TBM excavation can be divided into a damage stage, a progressive damage stage and a stable stage (noise stage).

[0077] Figure 7 The relationship between the spatial distribution of microseismicity and TBM construction conditions is shown. Figure 7Each ball in the figure represents a microseismic event, and the color represents the energy E, which is lgE. Taking February 8 as an example, the triggering of microseismic events is related to the working status of the TBM on site. Figure 8 As shown in the figure, from 0 to 3, the TBM excavated at a speed of 1 m / h, and the number of microseismic events triggered was generally large. It was shut down from 05:20 to 11:35, and almost no microseismic events were generated. From 13 to 23, the TBM excavated at a speed of 0.6 m / h, and microseismic events were generated during the process, but the number of microseismic events triggered was generally less than that at 0 to 3.

[0078] The microseismic b value represents the proportion of earthquake events in different magnitude ranges. A larger b value indicates that small-magnitude events dominate during this period, while a smaller b value indicates that large-magnitude events dominate during this period. The calculation of microseismic b values ​​is usually based on statistical analysis of magnitude distribution. This application considers the introduction of time factors and the spatial distribution of earthquake events to obtain the following calculation formula:

[0079]

[0080] Where b is the microseismic b value, which indicates the slope of the magnitude distribution and reflects the ratio of small magnitude to large magnitude events. T is the monitoring time period, which can be in years, months or days, reflecting the temporal distribution of earthquake events. M1 It represents the number of earthquake events with magnitude greater than or equal to M1 during the monitoring period T. M2 It represents the number of earthquake events with magnitude greater than or equal to M2 within the monitoring time period T. M1 and M2 are both positive integers and M2>M1. By introducing the monitoring time period T, the time dimension of the earthquake event is taken into account, making the calculation of the b value more dynamic and able to reflect the changes in seismic activity in different time periods. Allowing users to customize the magnitude ranges M1 and M2 makes the calculation of the b value more flexible and able to adapt to different research needs and seismic activity characteristics. Formula (1) can help researchers better understand and analyze the characteristics of microseismic activity, especially the changes in different time periods and magnitude ranges.

[0081] The embodiment of the present application calculates the microseismic b-value of the microseismic events monitored by a microseismic sensor from February 1 to February 12, 2024 on a daily basis, such as Fig. 9 As shown in the figure, the b value is at a low level on February 2, February 4, February 5, and February 10, indicating that the microseismic events in this period are mainly relatively large-magnitude events, and the decrease in the b value also occurs before the apparent volume increases sharply. Therefore, the b value can also be used as a precursor information of the intensification of surrounding rock damage.

[0082] Furthermore, seismological theory believes that the ratio of shear wave to longitudinal wave energy Es / Ep is an important indicator for studying rock fracture types. In microseismic monitoring, Es / Ep is often used to analyze the fracture damage mechanism of surrounding rocks. The Es / Ep indicator is mainly used to analyze the fracture damage of surrounding rocks under different stress conditions, including shear failure, mixed failure and tensile failure. Fig.10 As shown. When analyzing the rupture damage of surrounding rock, the role of the Es / Ep index is mainly reflected in the following aspects: 1) Shear failure: When the Es / Ep value is high, the surrounding rock is more prone to shear failure; this is because the high Es / Ep value means that the elastic properties of the surrounding rock are stronger and it is more likely to shear slip under stress. 2) Mixed failure: When the Es / Ep value is moderate, the surrounding rock may suffer mixed failure, that is, shear and tensile failure exist at the same time. In this case, the elastic and plastic properties of the surrounding rock are relatively balanced, and it is easy to fail under multiple stresses. 3) Tensile failure: When the Es / Ep value is low, the surrounding rock is more prone to tensile failure; this is because the low Es / Ep value means that the plastic properties of the surrounding rock are stronger and it is easy to break under tensile stress.

[0083] Furthermore, by introducing the moment tensor theory, the moment tensor inversion parameters of microseismic events can be solved, and the moment tensor can be decomposed to more accurately reveal the microfracture mechanism of the surrounding rock. First, the introduction of the moment tensor inversion method is to solve the limitations of traditional microseismic data interpretation. Traditional microseismic data interpretation is mainly based on the spatial distribution of microseismic events, combined with seismic and geological data for qualitative interpretation, but it is difficult to quantitatively analyze the rock fracture properties. Through moment tensor inversion, the fracture properties of microseismic events, such as strike angle, dip angle and slip angle, can be quantitatively analyzed, so as to more accurately describe the process and mechanism of rock fracture. In the process of solving the moment tensor inversion parameters of microseismic events, many methods have been proposed and applied. Decomposing the moment tensor is a key step in understanding the nature of microseismic events. Through moment tensor decomposition, the fracture type and stress state of microseismic events can be further analyzed. This helps to better understand the geological structure and the physical properties of rocks, which is of great significance for geotechnical engineering and geological disaster warning.

[0084] Introducing moment tensor theory to perform moment tensor inversion and decomposition of microseismic events is a complex process. The most basic moment tensor (MT) is usually defined as:

[0085] M=∫ρu(r)dV (2)

[0086] Where M is the moment tensor; ρ is the density at each point; u(r) is the displacement vector at point r; and dV is the volume element.

[0087] In microseismic events, the moment tensor can be decomposed into the following form:

[0088] M=M iso +M dev (3)

[0089] Among them, M iso represents the volume moment tensor (volume expansion or contraction); M dev It represents the deviation moment tensor and can be used to analyze the plasticity and fracture behavior of surrounding rock.

[0090] The volume moment tensor is usually:

[0091]

[0092] where tr(M) is the trace of the moment tensor (i.e., the sum of the diagonal elements); I is the identity tensor.

[0093] By combining the moment tensor with the stress relationship, the stress distribution can be solved. The stress tensor σ can be expressed as:

[0094]

[0095] in is the unit vector pointing to the observation point; r is the distance between the observation point and the source point.

[0096] By analyzing the deviation moment tensor M dev , can further reveal the micro-fracture mechanism of the surrounding rock. For example, M can be expressed by the following relationship dev Decomposed into contributions of different fracture modes:

[0097] M dev =M tensile +M shear-tensile +M shear +M shear-compressiv +M compressiv (6)

[0098] Among them, M tensile 、M shear 、M compressiv Respectively represent the moment tensor of the tension mode, shear mode, and compression mode; M shear-tensile The moment tensor representing the shear-stretch mixed mode; M shear-compressiv Moment tensor representing the shear-compression mixed mode.

[0099] Through optimization techniques such as the least squares method, the moment tensor inversion parameters can be solved using the following formula:

[0100]

[0101] where di is the monitoring data; N is the number of monitoring data; It is the theoretical data given by the model. Min means taking the minimum value.

[0102] The above formulas and theoretical context can help us deeply understand the microfracture mechanism of surrounding rocks after microseismic events. According to the specific microseismic event monitoring data and geological conditions, these formulas may need to be further adjusted and optimized in practical applications.

[0103] During the on-site investigation, it was discovered that a weak structural surface was indeed exposed near the point where the tension microseismic events were concentrated. Although this was a weak structural surface that ran through the TBM, the on-site investigation showed that the weak structural surface away from the side of the excavated tunnel was obviously more broken than the side close to the excavated tunnel.

[0104] Furthermore, a comparative analysis of microseismic numerical simulation can be performed, taking the excavated water tank tunnel (represented as a water tank in the figure) as an example of the excavated tunnel. Fig.11 As shown in the figure, numerical simulation shows that the deformation on both sides of the TBM excavation is large, and the same microseismic events (represented by spheres in the figure) are also concentrated on both sides of the TBM tunnel. Fig.12 As shown in the figure, numerical simulation shows that shear stress is concentrated at the top and bottom arches of the tunnel after TBM excavation. Microseismic monitoring shows that the rupture mechanism of the top and bottom arches is mainly shear failure, accompanied by a small amount of tensile failure.

[0105] Step 4: Drill holes from the excavated tunnel toward the drilling and blasting tunnel to be excavated, and place acoustic emission sensors and microseismic sensors in the holes to form an acoustic emission and microseismic monitoring system for the drilling and blasting section.

[0106] like Figure 2 As shown in the right half, drilling holes is done from the excavated tunnel to the tunnel to be excavated. The drilling directions include up-dipping, nearly horizontal, and down-dipping. An acoustic emission sensor is installed at a preset position in each preset borehole. Figure 2 In the embodiment shown in the right half, a plurality of acoustic emission sensors are arranged only on one side of the drill and blast tunnel close to the excavated tunnel. The advantage of this arrangement is that there is no empty area, which is convenient for data analysis. The disadvantage is that the connection between the two sensors must avoid passing through the tunnel section (i.e., the empty area), so only a part of the area can be covered. Of course, in the actual excavation process, the excavation section of the drill and blast tunnel is not limited to the rectangular straight wall + three-center arch vault structure shown in the figure, but can also be a rectangular straight wall + horseshoe or semicircular vault structure, or a near-circular structure similar to the excavation section of the TBM tunnel. Therefore, in actual applications, a plurality of acoustic emission sensors can also form an array structure around half of the wall of the drill and blast tunnel.

[0107] like Figure 3As shown in the right half, drilling is done from the excavated tunnel to the tunnel to be excavated, and the drilling includes both up-dip and down-dip directions. Microseismic sensors ( Figure 3 The key monitoring areas of microseismic monitoring are the spandrels, arch corners and the middle of the tunnel sidewalls, and the microseismic responses of the surrounding rock at different distances from the middle of the tunnel sidewalls are monitored. Similar to the TBM section, at least four microseismic sensors are deployed on each side of the drill-blast tunnel in the horizontal direction to facilitate four-point or six-point positioning.

[0108] In such Figure 2 and Figure 3 In the embodiment shown, the locations of some boreholes and acoustic emission microseismic sensors in the drilling and blasting section are shown in Table 2 below, and each borehole is numbered with ZBC.

[0109] Table 2 Some drilling holes and sensor layout locations in the drilling and blasting section

[0110]

[0111]

[0112] As shown in Table 2, there are 5 boreholes for acoustic emission sensors, 4 of which are shared with microseismic sensors. There are 8 boreholes for microseismic sensors, 4 of which are shared.

[0113] Step 5: During the drilling and blasting excavation process, the drilling and blasting section acoustic emission microseismic monitoring system is used to obtain the drilling and blasting section acoustic emission microseismic monitoring data.

[0114] During the drilling and blasting excavation process, the acoustic emission sensors deployed in the drilling and blasting section are used to monitor the number of acoustic emission impacts at different positions and times. The microseismic sensors deployed in the drilling and blasting section are used to monitor the microseismic events caused by rock mass damage or rock fracture.

[0115] Step 6: Analyze the surrounding rock response process of drilling and blasting tunnel excavation based on the acoustic emission microseismic monitoring data of the drilling and blasting section.

[0116] According to the variation law of the number of acoustic emission impacts in the drilling and blasting stage over time, the rock fracture process after blasting can be divided into blasting damage stage, progressive damage stage and stable stage, and the following formula is used to fit the relationship between the number of acoustic emission impacts and time:

[0117] N(t)=N0+β(1-e αt )(8)

[0118] Among them, N(t) represents the number of acoustic emission impacts at time t; N0 represents the constant of the initial acoustic emission activity; α is the time factor, which represents the rate at which the number of AE impacts increases rapidly with the increase of time t; β is the basic constant of the influence of acoustic emission activity, which represents the basic level of AE activity under the influence of a certain acoustic emission activity.

[0119] According to the temporal and spatial evolution law, amplitude-frequency distribution and mechanism of microseismic events in the drilling and blasting section, the progressive damage process and control factors of the surrounding rock can be further analyzed. The spatial distribution, temporal evolution and amplitude-frequency distribution characteristics of microseismic events are important bases for judging the stability of the surrounding rock. By monitoring these characteristics, the progressive destruction process of the surrounding rock can be predicted. First, the temporal and spatial evolution law of microseismic events is the key to analyzing the progressive destruction of the surrounding rock. Studies have shown that the temporal and spatial distribution of microseismic events has certain regularity, and the relationship between the temporal and spatial evolution of microseismic events and rockburst can be revealed by comparing the actual situation on site with the microseismic monitoring results. For example, in deep rock tunnels, the distribution of rockburst in time, space, intensity, etc. has obvious regularity, and microseismic activities generally have time priority and spatial consistency for rockburst events. Secondly, the amplitude-frequency distribution is also an important parameter for analyzing the progressive destruction of the surrounding rock. The amplitude-frequency distribution can reflect the energy release of microseismic events. By analyzing the amplitude-frequency distribution of microseismic events, the stability and destruction trend of the surrounding rock can be judged. Studies have shown that with the increase of the depth of the chamber, the b value tends to decrease, which indicates that the damage of the surrounding rock is mainly shear failure, with local tensile failure. Finally, the analysis of the mechanism of microseismic events can help understand the progressive failure process of the surrounding rock. By analyzing the number, intensity and distribution of microseismic events, the stress state and failure mode of the surrounding rock can be inferred. For example, the development of high-frequency sound acquisition technology has made it possible to better predict the possibility of rock bursts through sound propagation and microseismic monitoring methods. By monitoring and analyzing the spatiotemporal evolution laws, amplitude-frequency distribution and mechanism of microseismic events in the drilling and blasting section, the progressive failure process of the surrounding rock can be effectively analyzed, providing an important basis for engineering safety and stability assessment.

[0120] Step 7: Guide the TBM and drilling and blasting excavation processes based on the surrounding rock response process analysis results of the TBM tunnel and drilling and blasting tunnel.

[0121] Based on the analysis results of the surrounding rock response process of TBM tunnels and drill-and-blast tunnels, we can reasonably design blasting plans and construction plans, reasonably design tunnel shapes and directions, guide tunnel excavation sequences, guide support scheme design, and conduct geological disaster risk warnings.

[0122] Specifically, the design of the blasting plan needs to comprehensively consider the following aspects: 1) Geological conditions: According to the geological overview, understand the rock properties, crack direction, groundwater conditions, etc., and select appropriate blasting parameters. 2) Support measures: Provide support in time before and after the blasting to ensure the stability of the surrounding rock and prevent collapse. 3) Construction monitoring: Use the acoustic emission microseismic monitoring system of this application to monitor blasting vibrations, evaluate the blasting effect and the safety of the surrounding environment, and adjust blasting parameters and support measures when necessary. 4) Emergency plan: Formulate detailed emergency plans and disposal measures for possible geological disasters (such as rock bursts, water gushing, etc.).

[0123] Based on the analysis results of the surrounding rock response process of TBM tunnels and drill-and-blast tunnels, TBM method or drill-and-blast method can be selected for construction in different applicable scenarios. TBM method performs better in hard rock and can maintain a high construction speed and stability, but special attention should be paid to support and groundwater treatment when encountering soft surrounding rock or poor geological conditions. Drill-and-blast method is more flexible in dealing with complex geological conditions and can adapt to different geological conditions by adjusting blasting parameters and support measures, but special attention should be paid to the stability and safety of the surrounding rock in soft surrounding rock.

[0124] It is also possible to select appropriate tunnel shapes and directions based on the deformation characteristics and stress distribution of the surrounding rock to ensure the stability and safety of the tunnel. First of all, the analysis of the surrounding rock response process is the basis of the design. By analyzing the deformation characteristics and stress distribution of the surrounding rock, the differentiated response characteristics of the tunnel under different stress conditions can be understood. For example, when the lateral stress coefficient k>1, attention should be paid to the support of the tunnel top (bottom) plate; when k<1, attention should be paid to the support of both sides of the tunnel. In addition, the surrounding rock control of deep underground projects needs to consider the changes in the physical and mechanical properties of the rock mass and its self-repairing ability, and adopt the yield design technology to give full play to the vitality of the surrounding rock and achieve the purpose of optimized design.

[0125] In underground engineering, TBM and drilling and blasting are two common methods of surrounding rock excavation. Both methods may encounter geological disasters such as rock bursts during implementation. These disasters not only threaten the safety of construction workers, but may also lead to delays in project progress and increased costs. Therefore, the analysis of surrounding rock excavation response is crucial. This application analyzes the surrounding rock excavation response of TBM and drilling and blasting methods based on an acoustic emission microseismic monitoring system, which can improve project safety and efficiency, as well as achieve effective prediction and prevention of geological disasters such as rock bursts.

[0126] The core of geological disaster risk warning based on the results of surrounding rock response process analysis is to monitor and analyze small changes in surrounding rocks in real time, so as to provide early warning. Surrounding rock response process analysis is the basis of geological disaster warning. This application deploys an acoustic emission microseismic monitoring system in the TBM section and the drilling and blasting section, and analyzes the surrounding rock response process based on the acoustic emission microseismic monitoring data obtained during the TBM / drilling and blasting excavation process. It can detect geological disaster risks in advance, and effectively reduce casualties and property losses caused by geological disasters through a widely covered monitoring network and rapid response mechanism.

[0127] The acoustic emission microseismic monitoring system of this application evaluates the damage and safety conditions of the surrounding rock of the tunnel by monitoring the vibrations generated by the surrounding rock fracture, thereby providing a basis for predicting and controlling disasters. By real-time monitoring of rock mass stability, potential safety hazards can be discovered and dealt with in a timely manner, geological disasters such as rock bursts can be avoided, and the safety of construction personnel and equipment can be guaranteed. According to the monitoring data, the construction plan can be adjusted, such as changing the excavation speed, support method, etc., to adapt to different geological conditions and reduce the occurrence of safety accidents. By accurately predicting geological disasters such as rock bursts, the construction schedule can be reasonably arranged to avoid project delays caused by emergencies, thereby improving construction efficiency. Combined with modern information technology, real-time transmission and processing of data can be realized, providing intelligent support for engineering management, and further improving the efficiency and accuracy of engineering management. This application conducts TBM method and drilling and blasting method surrounding rock excavation response analysis based on the acoustic emission microseismic monitoring system, which can not only improve the safety of the project, optimize the construction plan, and improve the construction efficiency, but also realize intelligent management, providing important guarantees for the smooth implementation of underground projects.

[0128] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. An acoustic emission microseismic monitoring and analysis method suitable for hard rock, characterized in that: include: Drill holes from the excavated tunnel to the direction of the TBM tunnel to be excavated, and place acoustic emission sensors and microseismic sensors in the holes to form an acoustic emission microseismic monitoring system for the TBM section; During the TBM excavation process, the TBM section acoustic emission microseismic monitoring system is used to obtain the TBM section acoustic emission microseismic monitoring data; The surrounding rock response process of TBM tunnel excavation was analyzed based on the acoustic emission microseismic monitoring data of the TBM section; Drill holes from the excavated tunnel to the direction of the drilling and blasting tunnel to be excavated, and place acoustic emission sensors and microseismic sensors in the holes to form an acoustic emission and microseismic monitoring system for the drilling and blasting section; During the drilling and blasting excavation process, the drilling and blasting section acoustic emission microseismic monitoring system is used to obtain the drilling and blasting section acoustic emission microseismic monitoring data; The surrounding rock response process of drilling and blasting tunnel excavation was analyzed based on the acoustic emission microseismic monitoring data of the drilling and blasting section; The surrounding rock response process analysis results of TBM tunnels and drill-and-blast tunnels are used to guide the TBM and drill-and-blast excavation processes.

2. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 1 is characterized in that: The method of drilling holes from the excavated tunnel toward the TBM tunnel to be excavated and placing acoustic emission sensors and microseismic sensors in the holes to form an acoustic emission microseismic monitoring system for the TBM section specifically includes: Drill holes from the excavated tunnel toward the TBM tunnel to be excavated, both in the up-dip and down-dip directions; An acoustic emission sensor is installed at a preset position in a preset borehole, and multiple acoustic emission sensors form an array structure around half of the wall of the TBM tunnel; Microseismic sensors are installed at preset positions in the preset boreholes, and at least four microseismic sensors are arranged on each side of the TBM tunnel in the horizontal direction.

3. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 2 is characterized in that: During the TBM excavation process, the TBM section acoustic emission microseismic monitoring system is used to monitor and obtain TBM section acoustic emission microseismic monitoring data, which specifically includes: During the TBM excavation process, the acoustic emission sensors deployed in the TBM section are used to monitor the number of acoustic emission impacts at different locations and times; Microseismic sensors deployed in the TBM section are used to monitor microseismic events caused by rock damage or rock fracture.

4. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 3 is characterized in that: The process of analyzing the surrounding rock response of the TBM tunnel based on the acoustic emission microseismic monitoring data of the TBM section specifically includes: According to the variation law of acoustic emission impact number over time, the rock fracture process during TBM excavation is divided into damage stage, progressive damage stage and stable stage, and a negative exponential function is used to fit the relationship between the acoustic emission impact number per unit time and time.

5. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 3 is characterized in that: The process of analyzing the surrounding rock response of the TBM tunnel based on the acoustic emission microseismic monitoring data of the TBM section specifically includes: According to the microseismic events and their energy, the formula Calculate the microseismic b value as the precursor information of the increased surrounding rock damage; b represents the microseismic b value; T is the monitoring time period; N M1 N represents the number of earthquake events with magnitude greater than or equal to M1 during the monitoring period T; M2 It represents the number of earthquake events with magnitude greater than or equal to M2 during the monitoring period T; M1 and M2 are both positive integers and M2>M1; The ratio of shear wave to longitudinal wave energy, Es / Ep, is calculated based on microseismic events and their energy, and the surrounding rock fracture damage mechanism is analyzed based on the Es / Ep index. The moment tensor theory is introduced to solve the inversion parameters of the moment tensor of microseismic events, and the moment tensor is decomposed to reveal the micro-fracture mechanism of the surrounding rock.

6. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 1, characterized in that: The drilling and blasting section acoustic emission and microseismic monitoring system is formed by drilling holes from the excavated tunnel to the direction of the drilling and blasting tunnel to be excavated, and arranging acoustic emission sensors and microseismic sensors in the holes. Specifically, it includes: Drill holes from the excavated tunnel to the drill-blast tunnel to be excavated. The drilling directions include up-dipping, nearly horizontal, and down-dipping. Acoustic emission sensors are installed at preset positions in preset boreholes in three directions: up-dipping, nearly horizontal, and down-dipping. Multiple acoustic emission sensors are located on one side of the drill and blast tunnel close to the excavated tunnel. Microseismic sensors are installed at preset positions in preset boreholes in both up-dip and down-dip directions, and at least four microseismic sensors are arranged on each side of the drill and blast tunnel in the horizontal direction.

7. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 6, characterized in that: In the process of drilling and blasting excavation, the drilling and blasting section acoustic emission microseismic monitoring system is used to monitor and obtain the drilling and blasting section acoustic emission microseismic monitoring data, which specifically includes: During the drilling and blasting excavation process, the acoustic emission sensors deployed in the drilling and blasting section are used to monitor the number of acoustic emission impacts at different locations and times; Microseismic sensors placed in the drilling and blasting section are used to monitor microseismic events caused by rock destruction or rock fracture.

8. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 7, characterized in that: The process of analyzing the surrounding rock response of the drilling and blasting tunnel according to the acoustic emission microseismic monitoring data of the drilling and blasting section specifically includes: According to the variation law of acoustic emission impact number over time, the rock fracture process after blasting is divided into blasting damage stage, progressive damage stage and stable stage, and the function N(t) = N0 + β(1-e αt ) is used to fit the relationship between the number of acoustic emission impacts and time; where N(t) represents the number of acoustic emission impacts at time t; N0 represents the constant of the initial acoustic emission activity; α is the time factor; and β is the basic constant affected by the acoustic emission activity.

9. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 7, characterized in that: The process of analyzing the surrounding rock response of the drilling and blasting tunnel according to the acoustic emission microseismic monitoring data of the drilling and blasting section specifically includes: According to the temporal and spatial evolution law, amplitude-frequency distribution and mechanism of microseismic events, the progressive damage process of surrounding rock and its controlling factors are analyzed.

10. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 1, characterized in that: The method of guiding the excavation process of the TBM method and the drilling and blasting method according to the surrounding rock response process analysis results of the TBM tunnel and the drilling and blasting tunnel specifically includes: According to the analysis results of the surrounding rock response process of TBM tunnels and drill-blast tunnels, the blasting plan and construction plan are reasonably designed, the tunnel shape and direction are reasonably designed, the tunnel excavation sequence is guided, the support plan design is guided, and geological disaster risk warnings are carried out.

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