An acoustic emission microseismic monitoring and analysis method suitable for hard rock

Abstract

The present application discloses an acoustic emission and microseismic monitoring and analysis method applicable to hard rock, which relates to the field of high-level radioactive waste disposal. The method firstly drills a hole from an excavated roadway toward a TBM roadway / drill-blast roadway to be excavated, and arranges an acoustic emission sensor and a microseismic sensor in the borehole to form an acoustic emission and microseismic monitoring system for the TBM section / drill-blast section. During the TBM / drill-blast excavation process, the acoustic emission and microseismic monitoring system for the TBM section / drill-blast section is used to monitor and obtain acoustic emission and microseismic monitoring data for the TBM section / drill-blast section. The surrounding rock response process of the TBM roadway / drill-blast roadway is analyzed based on the acoustic emission and microseismic monitoring data of the TBM section / drill-blast section, thereby improving the accuracy of the surrounding rock response characterization during the TBM and drill-blast excavation processes. The TBM and drill-blast excavation processes are guided by the analysis results of the surrounding rock response process of the TBM roadway and drill-blast roadway, thereby achieving scientific construction of the TBM and drill-blast excavation processes.

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 (HLW) is characterized by strong radioactivity, high toxicity, and a long half-life, making its final safe disposal extremely difficult and facing a series of scientific, technological, and engineering challenges. Whether HLW can be ultimately and safely disposed of is a strategic issue related to the sustainable development of the nuclear industry and environmental protection. High-level radioactive waste geological disposal repositories are characterized by complex construction conditions, high safety levels, and a long service life (tens of thousands of years), making research and development very difficult. To this end, based on previous research experience, it is necessary to first build a high-level radioactive waste disposal underground laboratory deep within the repository to conduct site characterization assessments, field trials, and verification of disposal technologies, providing the necessary scientific research foundation and practical experience for repository construction.

[0003] TBM (Tunnel Boring Machine) and drill-and-blast are two commonly used construction methods for underground projects, including underground laboratories and repositories. Each has its own unique characteristics and is suitable for different geological conditions and engineering requirements. During the excavation of underground laboratories and repositories, TBM and drill-and-blast are often combined. However, a lack of comparative analysis of the surrounding rock response during the excavation process of these two methods has hindered guidance for actual TBM and drill-and-blast excavation. 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 drill-and-blast excavation processes, and to guide the scientific excavation of the TBM and drill-and-blast methods.

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

[0006] This application provides an acoustic emission microseismic monitoring and analysis method applicable to hard rock, including:

[0007] Drill holes from the excavated roadway toward the TBM roadway to be excavated, and deploy acoustic emission sensors and microseismic sensors in the holes to form an acoustic emission and microseismic monitoring system for the TBM section.

[0008] During the TBM excavation process, the TBM section acoustic emission microseismic monitoring system was 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 toward the 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 and microseismic monitoring system was used to obtain the drilling and blasting section acoustic emission and microseismic monitoring data;

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

[0013] The TBM and drilling and blasting excavation processes are guided by the surrounding rock response process analysis results of TBM tunnels and drilling and blasting tunnels.

[0014] Optionally, 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 a TBM section acoustic emission and microseismic monitoring system, specifically includes:

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

[0016] Acoustic emission sensors are installed at preset positions in the preset boreholes, with multiple acoustic emission sensors forming an array structure around half of the TBM tunnel wall;

[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 section acoustic emission microseismic monitoring system is used to monitor and obtain TBM section acoustic emission microseismic monitoring data, specifically including:

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

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

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

[0022] According to the variation pattern 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. A negative exponential function is used to fit the relationship between the acoustic emission impact number per unit time and time.

[0023] Optionally, analyzing the surrounding rock response process of the TBM tunnel based on 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 a precursor to 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 a magnitude greater than or equal to M1 during the monitoring period T; M2 represents the number of earthquake events with a 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 the microseismic events and their energy, and the surrounding rock fracture damage mechanism is analyzed based on the Es / Ep indicator.

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

[0027] Optionally, drilling holes from the excavated tunnel toward the drill-and-blast tunnel to be excavated, and placing acoustic emission sensors and microseismic sensors in the holes to form an acoustic emission and microseismic monitoring system for the drilling and blasting section, specifically includes:

[0028] Drill holes from the excavated roadway toward the drill-and-blast roadway to be excavated. The drilling directions include up-dip, near-horizontal, and down-dip.

[0029] Acoustic emission sensors are installed at preset locations in the preset boreholes in three directions: up-dip, near-horizontal, and down-dip. Multiple acoustic emission sensors are located on the 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 the 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 and microseismic monitoring system is used to monitor and obtain drilling and blasting section acoustic emission and microseismic monitoring data, specifically including:

[0032] During the drilling and blasting excavation process, acoustic emission sensors placed 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 damage or rock fracture.

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

[0035] According to the variation 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, analyzing the surrounding rock response process of the drilling and blasting tunnel based on the acoustic emission microseismic monitoring data of the drilling and blasting section specifically includes:

[0037] Based on the spatiotemporal 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 and drill-and-blast excavation processes based on the surrounding rock response process analysis results of the TBM tunnel and the drill-and-blast tunnel specifically includes:

[0039] Based on the analysis results of the surrounding rock response process of TBM tunnels and drill-and-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] This application provides an acoustic emission microseismic monitoring and analysis method suitable for hard 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, it is possible to accurately characterize the internal damage evolution process of the surrounding rock. Furthermore, the TBM and drilling and blasting excavation processes are guided by the analysis results of the surrounding rock response process of the TBM tunnel and the drilling and blasting tunnel. This can not only improve the safety of the project, optimize the construction plan, and improve 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 following briefly introduces the drawings required for use in the embodiments. 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 creative work.

[0043] Figure 1 This is 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 drilling and acoustic emission sensor layout in the TBM section and the drilling and blasting section;

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

[0046] Figure 4 This is a structural diagram 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 microseismic events and TBM construction conditions;

[0050] Figure 8 Schematic diagram of the triggering of microseismic events and the working status of the on-site TBM;

[0051] Figure 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] Figure 10 This is a schematic diagram of the evolution of rupture types in slightly larger energy microseismic events;

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

[0054] Figure 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 this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0056] Acoustic emission and microseismic monitoring technologies are important monitoring methods in geotechnical engineering. By acquiring and processing monitoring signals, they can infer the time, location, intensity, and form of internal rock fractures, thereby characterizing the evolution of internal rock damage. Based on this, this application provides an acoustic emission and microseismic monitoring and analysis method for hard rock to accurately characterize the surrounding rock response during TBM and drill-and-blast excavation, guiding scientific excavation using these methods.

[0057] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to 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 this 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 deploy acoustic emission (AE) sensors and microseismic sensors in the holes to form an AE microseismic monitoring system for the TBM section.

[0060] like Figure 2 As shown in the left half, a hole is drilled from the excavated roadway to the direction of the TBM roadway (also known as a 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 acoustic emission sensors focus on monitoring the spandrels, arch corners, and the middle of the tunnel sidewall, monitoring the acoustic emission response of the surrounding rock at different distances from the middle of the tunnel sidewall. Acoustic emission signal monitoring utilizes a minimum of four-point positioning, preferably six-point positioning.

[0061] exist Figure 2In the illustrated embodiment, the TBM tunnel has a circular cross-section. Within this cross-section, multiple acoustic emission sensors can be seen forming an array structure around half of the TBM tunnel wall. This means that the monitoring range of the multiple acoustic emission sensors encompasses half of the TBM tunnel, and the multiple acoustic emission sensors are arranged in an array structure as much as possible. This arrangement offers the advantage of wide coverage, allowing the symmetric algorithm to directly recover the acoustic emission signal for the entire circular cross-section. However, a disadvantage is that when performing six-point positioning of the acoustic emission signal, or at least four-point positioning, the lines connecting two sensors may pass through voids formed by the TBM tunnel excavation. This void area can affect subsequent analysis of the acoustic emission signal, and the calculation process needs to account for the influence of the void area, making the algorithm complex and affecting computational efficiency.

[0062] Therefore, in other embodiments, multiple acoustic emission sensors can also be arranged only on one side of the TBM tunnel close to the excavated tunnel, similar to Figure 2 The right half of the diagram is shown in the figure. The advantage of this placement is that there are no dead zones, facilitating data analysis. However, its disadvantage is that the lines connecting each sensor must avoid crossing the tunnel cross-section (i.e., the dead zones), thus only covering a limited area. Therefore, when placing the acoustic emission sensors, the distance between the sensor closest to the tunnel sidewall in each borehole and the tunnel sidewall is set at 0.3m-1m. This ensures that the sensors are placed as close as possible to the maximum stress points obtained from numerical simulations while preventing damage from excavation.

[0063] Further, if Figure 2 As shown in the left half, the sensor located on the TBM tunnel's central axis is 0.1-1m from the tunnel wall. The distance between adjacent acoustic emission sensors in the same borehole is 1.5-2.5m. Multiple sensors are arranged in an array configuration to facilitate four- or six-point positioning. In the two center boreholes, the sensor closest to the tunnel wall is positioned at a height of 1 / 3 to 1 / 5 of the tunnel's central axis, preferably at 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, the system includes an AE sensor and preamplifier housed in a protective housing, along with a signal acquisition and processing system. The AE sensor uses an SH-III acoustic emission host, and the sensor utilizes an R.45I-LP-AST signal with a frequency range of 5kHz to 30kHz. The low-power amplifier has a gain of 26dB. The AE sensor and preamplifier are housed in a waterproof, integrated package.

[0065] like Figure 3 As shown in the left half, a borehole is drilled from the excavated tunnel toward the TBM tunnel to be excavated. The boreholes (represented by straight lines in the figure) include both up-dip and down-dip directions. A microseismic sensor ( Figure 3 Microseismic monitoring focuses on spandrels, arch corners, and the middle of the tunnel sidewalls. 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 deployed on each horizontal side of the TBM tunnel.

[0066] contrast Figure 2 and Figure 3 As can be seen in the left half, the difference between the placement of microseismic sensors and acoustic emission sensors is that the microseismic sensors are only placed on the side of the TBM tunnel closest to the excavated tunnel, while the microseismic sensors are placed on both sides of the TBM tunnel, with at least four sensors on each side to facilitate four-point positioning. This is because acoustic emission sensors generally have a narrow monitoring range, and the excavation cross-section of a TBM tunnel is usually circular. Simply monitoring the acoustic emission response on one side of the tunnel can symmetrically determine the acoustic emission response on the other side, with an acceptable error. Microseismic sensors, on the other hand, have a wider monitoring range. By placing at least four microseismic sensors on both sides of the tunnel, accurate response data can be measured for the entire area surrounding the tunnel.

[0067] The microseismic sensor can be a uniaxial microseismic sensor (model A1-30-1.0) or a triaxial microseismic sensor (model A3-1.0-1.25). The uniaxial microseismic sensor provides 360° monitoring, has a damping sensitivity of 30V / g, a response frequency of 50Hz to 5kHz, a dynamic response of 100dB, a diameter of 25.4mm, and operates in an ambient temperature range of -20°C to +85°C. The triaxial microseismic sensor has a damping sensitivity of 1V / g.

[0068] In such Figure 2 and Figure 3 In the illustrated embodiment, 16 acoustic emission sensors are deployed in eight different boreholes, and 22 microseismic sensors are deployed in eight different boreholes. Table 1 shows the locations of some boreholes and sensors in the TBM section. In Table 1, each borehole is numbered ZKC, the acoustic emission sensors are numbered A, and the microseismic sensors are numbered M. Sensor location refers to the distance (in meters) between the sensor and the borehole opening.

[0069] Table 1. Locations 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 TBM excavation, acoustic emission sensors placed along the TBM section monitor the number of acoustic emission impacts at different locations and times. Microseismic sensors placed along the TBM section also monitor microseismic events caused by rock failure or rock fracture.

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

[0075] Figure 5 The following figure shows the acoustic emission response results of the A11 and A12 sensors after the TBM section stops excavating. The horizontal axis is time and the vertical axis is the number of acoustic emission impacts. Figure 5 The results show that, at 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 acoustic emission number per unit time tends to zero; the relationship between the number of acoustic emission impacts per unit time and time can be fitted with 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 the 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 the 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 a rapid decay, and then the decay gradually slows down; sporadic impacts after the number of acoustic emission impacts per unit time approaches 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 microseismic events and TBM construction conditions is shown. Figure 7Each ball represents a microseismic event, and the color represents the magnitude of 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 time 0 to 3, the TBM was advancing at a speed of 1 m / h, and the number of microseismic events it triggered was generally high. From 05:20 to 11:35, the machine was shut down, and almost no microseismic events were generated. From 13:23 to 23, the TBM was advancing at a speed of 0.6 m / h, and microseismic events were generated throughout the process, but the number of microseismic events triggered was generally lower than that from time 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 the period, while a smaller b-value indicates that large-magnitude events dominate the 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 represents 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 N represents the number of earthquake events with a magnitude greater than or equal to M1 during the monitoring period T. M2 It represents the number of earthquake events with a 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 can 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 Figure 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 during this period are mainly relatively large-magnitude events, and the decrease in the b-value also occurs before the sharp increase in the apparent volume. Therefore, the b-value can also be used as a precursor information for 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. Figure 10 As shown. When analyzing the fracture 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 a high Es / Ep value means that the elastic properties of the surrounding rock are stronger and it is more likely to undergo shear slip under stress. 2) Mixed failure: When the Es / Ep value is moderate, the surrounding rock may undergo 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 a 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 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. The introduction of moment tensor inversion methods aims to address the limitations of traditional microseismic data interpretation. Traditional microseismic data interpretation mainly relies on the spatial distribution of microseismic events, combining seismic and geological data for qualitative interpretation, but it is difficult to quantitatively analyze the rock failure properties. Through moment tensor inversion, the rupture properties of microseismic events, such as strike angle, dip angle, and slip angle, can be quantitatively analyzed, thereby more accurately describing the rock failure process and mechanism. Various methods have been proposed and applied to solve the moment tensor inversion parameters of microseismic events. Decomposing the moment tensor is a key step in understanding the nature of microseismic events. Through moment tensor decomposition, the rupture type and stress state of microseismic events can be further analyzed. This helps to better understand the geological structure and physical properties of rocks, which is of great significance for geotechnical engineering and geological hazard early 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 as dev Decomposed into contributions from 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 Represent the moment tensors of the tensile mode, shear mode, and compression mode respectively; M shear-tensile The moment tensor representing the shear-stretch mixed mode; M shear-compressiv Moment tensor representing the shear-compression blending mode.

[0099] By using 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; is the theoretical data given by the model. min means the minimum value.

[0102] The above formulas and theoretical framework can provide a deeper understanding of the microfracture mechanisms of surrounding rock after microseismic events. However, further adjustments and optimization of these formulas may be necessary in practical applications, depending on the specific microseismic event monitoring data and geological conditions.

[0103] During the on-site investigation, it was discovered that a weak structural surface was indeed exposed near the gathering point of tension microseismic events. Although this was a weak structural surface that passed 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 closer to the excavated tunnel.

[0104] Furthermore, a comparative analysis of microseismic numerical simulation can be performed, taking the excavated water tank tunnel (represented as water tank in the figure) as an example of the excavated tunnel. Figure 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. Figure 12 As shown in Figure 2, numerical simulation shows that shear stress concentrates 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 drill-and-blast 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 is done from the excavated tunnel to the tunnel to be excavated. The drilling directions include upward, nearly horizontal, and downward. An acoustic emission sensor is installed at a preset position in each preset drill hole. Figure 2 In the embodiment shown in the right half, multiple acoustic emission sensors are only arranged on one side of the drill and blast tunnel close to the excavated tunnel. The advantage of this layout is that there are no empty areas, which facilitates data analysis. The disadvantage is that the connection between each sensor 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 a TBM tunnel. Therefore, in actual applications, multiple 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. The drilling includes both up-dip and down-dip directions. A microseismic sensor ( Figure 3 (Indicated by the green dots in the center). Microseismic monitoring focuses on spandrels, arch corners, and the middle of the tunnel sidewalls, monitoring the microseismic response of the surrounding rock at various distances from the middle of the tunnel sidewall. Similar to the TBM section, at least four microseismic sensors are deployed on each horizontal side of the drill-and-blast tunnel to facilitate four- 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 ZBC.

[0109] Table 2 Some boreholes 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 with microseismic sensors.

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

[0114] During the drilling and blasting excavation process, acoustic emission sensors deployed in the drilling and blasting section monitor the number of acoustic emission impacts at different locations and times. Microseismic sensors deployed in the drilling and blasting section monitor microseismic events caused by rock failure or rock fracture.

[0115] Step 6: Analyze the surrounding rock response process during the 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 the blasting damage stage, the progressive damage stage and the stable stage. 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] 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, which represents the rate at which the number of AE impacts increases rapidly with increasing time t; β is the basic constant of the acoustic emission activity influence, which represents the basic level of AE activity under a certain acoustic emission activity influence.

[0119] The spatial and temporal evolution patterns, amplitude-frequency distribution, and mechanism of microseismic events during the drilling and blasting phase can be used to further analyze the progressive damage process and controlling factors of the surrounding rock. The spatial distribution, temporal evolution, and amplitude-frequency distribution characteristics of microseismic events are important indicators for assessing the stability of the surrounding rock. Monitoring these characteristics can predict the progressive failure process of the surrounding rock. First, the spatial and temporal evolution patterns of microseismic events are key to analyzing progressive failure of the surrounding rock. Research has shown that the spatial and temporal distribution of microseismic events exhibits certain regularities. By comparing actual field conditions with microseismic monitoring results, the relationship between the spatial and temporal evolution of microseismic events and rockbursts can be revealed. For example, in deep rock tunnels, the temporal, spatial, and intensity distributions of rockbursts exhibit significant regularity, and microseismic activity generally exhibits temporal priority and spatial consistency with rockbursts. Second, the amplitude-frequency distribution is also a crucial parameter for analyzing progressive failure of the surrounding rock. The amplitude-frequency distribution reflects the energy release of microseismic events, and by analyzing the amplitude-frequency distribution of microseismic events, the stability and failure trends of the surrounding rock can be determined. Studies have shown that with the increase in the depth of the chamber, the b value tends to decrease, indicating that the damage to 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 of microseismic events in the drilling and blasting section, the amplitude-frequency distribution and the mechanism of microseismic events, 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 drill-and-blast excavation processes based on the surrounding rock response process analysis results of the TBM and drill-and-blast roadways.

[0121] Based on the analysis results of the surrounding rock response process of TBM tunnels and drill-and-blast tunnels, it is possible to rationally design blasting plans and construction plans, rationally 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 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 the blasting parameters and support measures when necessary. 4) Emergency plan: Develop 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 and drill-and-blast tunnels, either the TBM or drill-and-blast method can be selected for construction in different application scenarios. The TBM method performs better in hard rock, maintaining high construction speed and stability, but requires special attention to support and groundwater treatment when encountering weak surrounding rock or adverse geological conditions. The 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. However, in weak surrounding rock, special attention must be paid to surrounding rock stability and safety.

[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 design. By analyzing the deformation characteristics and stress distribution of the surrounding rock, we can understand the differentiated response characteristics of the tunnel under different stress conditions. 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 the two sides of the tunnel. In addition, the surrounding rock control of deep underground projects needs to take into account the changes in the physical and mechanical properties of the rock mass and its self-repairing ability, and adopt the pressure-yielding 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 drill-and-blast are two common methods for excavating surrounding rock. Both methods may encounter geological hazards such as rockbursts during implementation. These hazards not only threaten the safety of construction workers but can also lead to project delays and increased costs. Therefore, analyzing the response of surrounding rock excavation is crucial. This application analyzes the response of surrounding rock excavation using TBM and drill-and-blast methods based on an acoustic emission microseismic monitoring system, which can improve project safety and efficiency, as well as effectively predict and prevent geological hazards such as rockbursts.

[0126] The core of geological disaster risk warning based on the results of surrounding rock response process analysis lies in real-time monitoring and analysis of small changes in surrounding rocks, 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 a rapid response mechanism.

[0127] The acoustic emission microseismic monitoring system in this application monitors the vibrations generated by surrounding rock fractures to assess the damage and safety status of the tunnel surrounding rock, thereby providing a basis for disaster prediction and control. By monitoring rock mass stability in real time, potential safety hazards can be promptly identified and addressed, geological disasters such as rockbursts can be avoided, and the safety of construction personnel and equipment can be guaranteed. Based on monitoring data, construction plans can be adjusted, such as by changing excavation speeds and support methods, to adapt to different geological conditions and reduce the occurrence of safety accidents. By accurately predicting geological disasters such as rockbursts, construction schedules can be rationally arranged, project delays caused by emergencies can be avoided, and construction efficiency can be improved. Combined with modern information technology, real-time data transmission and processing can be achieved, providing intelligent support for project management and further improving the efficiency and accuracy of project management. This application uses an acoustic emission microseismic monitoring system to analyze the surrounding rock excavation response during TBM and drill-and-blast excavation. This not only improves project safety, optimizes construction plans, and increases construction efficiency, but also enables intelligent management, providing a key guarantee for the smooth implementation of underground projects.

[0128] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may 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 applicable to hard rock, characterized in that: include: Drill holes from the excavated roadway toward the TBM roadway to be excavated, and deploy acoustic emission sensors and microseismic sensors in the holes to form an acoustic emission and microseismic monitoring system for the TBM section. The TBM section acoustic emission and microseismic monitoring system is formed by drilling holes from the excavated roadway toward the TBM roadway to be excavated and placing acoustic emission sensors and microseismic sensors in the holes. Specifically, the system includes: Drill holes from the excavated roadway toward the TBM roadway to be excavated, both in up- and down-dip directions. The acoustic emission sensors focus on monitoring spandrels, arch corners, and the middle of the roadway sidewalls, monitoring the acoustic emission response of the surrounding rock at different distances from the middle of the roadway sidewall. Install acoustic emission sensors at preset positions in a preset borehole, with multiple acoustic emission sensors forming an array structure around half of the TBM tunnel wall; the monitoring range of multiple acoustic emission sensors covers half of the TBM tunnel, and multiple acoustic emission sensors form an array structure as much as possible; or multiple acoustic emission sensors are arranged only on the side of the TBM tunnel close to the excavated tunnel, and the distance between the sensor closest to the tunnel sidewall in each borehole and the tunnel sidewall is set to 0.3m-1m; Install microseismic sensors at pre-set locations in pre-set boreholes, with at least four sensors deployed on each horizontal side of the TBM tunnel. Microseismic sensors are deployed on both sides of the TBM tunnel, with at least four sensors deployed on each side. During the TBM excavation process, the TBM section acoustic emission microseismic monitoring system was 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; The analysis of the surrounding rock response process 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 a precursor to 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 a magnitude greater than or equal to M1 during the monitoring period T; M2 represents the number of earthquake events with a 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. The surrounding rock fracture damage mechanism is analyzed based on the Es / Ep indicator. The Es / Ep indicator is used to analyze the fracture damage of surrounding rocks under different stress conditions, including shear failure, mixed failure, and tensile failure. When the Es / Ep value is high, the surrounding rock is more likely to suffer shear failure. When the Es / Ep value is moderate, the surrounding rock suffers mixed failure, with both shear and tensile failure. When the Es / Ep value is low, the surrounding rock is more likely to suffer tensile failure. The moment tensor theory is introduced to solve the moment tensor inversion parameters of microseismic events and decompose the moment tensor to reveal the micro-fracture mechanism of the surrounding rock. Drill holes from the excavated tunnel toward the 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. The drilling and blasting section acoustic emission and microseismic monitoring system is formed by drilling holes from the excavated tunnel toward the tunnel to be excavated and blasting, and arranging acoustic emission sensors and microseismic sensors in the holes. Specifically, the system includes: Drill holes from the excavated roadway toward the drill-and-blast roadway to be excavated. The drilling directions include up-dip, near-horizontal, and down-dip. Acoustic emission sensors are installed at preset locations in the preset boreholes in three directions: up-dip, near-horizontal, and down-dip. Multiple acoustic emission sensors are located on the side of the drill-and-blast tunnel close to the excavated tunnel. Microseismic sensors are installed at pre-set locations in pre-set boreholes in both the up-dip and down-dip directions, with at least four sensors deployed on each horizontal side of the drill-and-blast tunnel. Key areas for microseismic monitoring are spandrels, arch corners, and the middle of the tunnel sidewalls, monitoring the microseismic response of the surrounding rock at different distances from the middle of the tunnel sidewalls. During the drilling and blasting excavation process, the drilling and blasting section acoustic emission and microseismic monitoring system was used to obtain the drilling and blasting section acoustic emission and microseismic monitoring data; The surrounding rock response process of the drilling and blasting tunnel excavation was analyzed based on the acoustic emission microseismic monitoring data of the drilling and blasting section; The TBM and drilling and blasting excavation processes are guided by the surrounding rock response process analysis results of TBM tunnels and drilling and blasting tunnels.

2. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 1 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, specifically including: During the TBM excavation process, acoustic emission sensors deployed along the TBM section are used to monitor the number of acoustic emission impacts at different locations and times. Microseismic sensors deployed along the TBM section are used to monitor microseismic events caused by rock damage or rock fracture.

3. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 2, characterized in that: The analysis of the surrounding rock response process of the TBM tunnel based on the acoustic emission microseismic monitoring data of the TBM section specifically includes: According to the variation pattern 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. A negative exponential function is used to fit the relationship between the acoustic emission impact number per unit time and time.

4. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 1, characterized in that: During the drilling and blasting excavation process, the drilling and blasting section acoustic emission and microseismic monitoring system is used to monitor and obtain the drilling and blasting section acoustic emission and microseismic monitoring data, specifically including: During the drilling and blasting excavation process, acoustic emission sensors placed 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 damage or rock fracture.

5. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 4, characterized in that: The process of analyzing the surrounding rock response of the drilling and blasting tunnel based on the acoustic emission microseismic monitoring data of the drilling and blasting section specifically includes: According to the variation 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.

6. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 5, characterized in that: The process of analyzing the surrounding rock response of the drilling and blasting tunnel based on the acoustic emission microseismic monitoring data of the drilling and blasting section specifically includes: Based on the spatiotemporal evolution law, amplitude-frequency distribution and mechanism of microseismic events, the progressive damage process of surrounding rock and its controlling factors are analyzed.

7. The acoustic emission microseismic monitoring and analysis method for hard rock according to claim 1, characterized in that: The above-mentioned guidance of the TBM and drill-and-blast excavation processes based on the surrounding rock response process analysis results of the TBM roadway and the drill-and-blast roadway specifically includes: Based on the analysis results of the surrounding rock response process of TBM tunnels and drill-and-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.

Images