A method for accurately predicting rock burst strength and location through rock mass wave velocity

Abstract

The application provides a method for accurately predicting rock burst strength and position through rock mass wave velocity, and belongs to the technical field of rock burst disaster advanced prediction in deep underground engineering construction. According to the two-body interaction theory, the TSP longitudinal wave velocity accurate detection function is fully tapped, the longitudinal wave velocity discontinuous position within the range of 100m in front of the working face is accurately detected, and the position and grade probability of the possible rock burst are determined according to the wave velocity value difference. The method provided by the application has the advantages of simplicity, rapidness, low cost, high accuracy and the like, a new function is endowed to the TSP detection method, and an effective means can be provided for short-term and imminent prediction of rock burst in deep underground engineering.

Description

Technical Field

[0001] This invention belongs to the field of advanced prediction technology of rockburst disaster in deep underground engineering construction, and relates to a method for accurately predicting the intensity and location of rockbursts by short-term rock mass wave velocity. Background Technology

[0002] During the excavation of deep-buried tunnels, the initial equilibrium of the surrounding rock stress field is disrupted due to excavation and unloading, leading to stress redistribution. Stress concentration zones form in the surrounding rock due to geological conditions, and the strain energy accumulated within the rock mass is suddenly released. This causes the surrounding rock near the tunnel face to loosen, fracture, eject, or even be thrown, often accompanied by sounds and vibrations. This dynamic instability and failure of the surrounding rock is commonly referred to as rockburst. Rockbursts occur extremely frequently in deep-buried tunnel construction, often slowing down project progress, increasing construction risks, and raising costs. To improve construction efficiency and ensure the safety of construction personnel, rapid prediction of rockburst hazards and early warning of danger to workers are crucial.

[0003] Currently, the most effective rapid rockburst prediction and early warning method is microseismic monitoring technology, which has a high accuracy rate. However, microseismic monitoring requires continuous 24-hour monitoring. Moreover, conducting a single microseismic monitoring and early warning operation is expensive, requires a high degree of specialization in data processing, and demands significant human and material resources. Summary of the Invention

[0004] To address the problems of existing technologies, this invention provides a method for predicting rockburst intensity and location using rock mass wave velocity. This method utilizes rock mass wave velocity measured by advanced geological exploration equipment to predict rockburst intensity and location. By measuring the rock mass wave velocity within a certain distance ahead of the tunnel face, this method predicts rockburst intensity and location simultaneously with the inversion of surrounding rock integrity. The method proposed in this invention has the advantages of simplicity, speed, low cost, and high accuracy, and can provide an effective means for short-term rockburst prediction in deeply buried underground engineering projects.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for accurately predicting the intensity and location of rockbursts based on rock mass wave velocity includes the following steps:

[0007] The first step is to conduct advanced geological prediction of the surrounding rock or strata within a certain range in front of the tunnel face (the certain range refers to an effective distance of 100-150m for predicting wave velocity using TSP seismic wave detection technology) during tunnel excavation, measure its longitudinal wave velocity, and make a wave velocity map at least 100m in front of the tunnel face.

[0008] The second step is to determine the location of the rockburst: based on the 100-meter wave velocity map of the TSP face in the previous step, the area where the wave velocity changes significantly is used as the possible range of the rockburst to predict the possible rockburst area map, and then superimpose it on the longitudinal wave velocity map in the previous step.

[0009] The third step is to determine the predicted rockburst level: based on the correlation between rockburst occurrence intensity and P-wave velocity of the rock mass, the probability of rockburst occurrence at each level is determined. The P-wave velocities of the rock mass selected in the second step as the rockburst occurrence area are compared. If the wave velocity of a certain rockburst segment falls within multiple velocity ranges, the average value of the corresponding levels of each rockburst is taken as the probability of that rockburst level occurring in that segment, and this value is superimposed on the P-wave velocity map from the previous step.

[0010] The innovative analysis of this invention is as follows: According to the two-body interaction theory, the source of a rockburst generally occurs at the junction of intact rock masses, i.e., near the structural plane. Based on this theory, this invention fully utilizes the precise detection function of the TSP (Transformer Spinner) to accurately detect the location of discontinuities in P-wave velocity within 100m in front of the tunnel face, and determines the location and probability of a potential rockburst based on the difference in wave velocity values.

[0011] The beneficial effects of this invention are as follows: The method proposed in this invention has the advantages of being simple, fast, inexpensive, and highly accurate, giving new functions to the TSP detection method and providing an effective means for short-term prediction of rockbursts in deeply buried underground engineering projects. Attached Figure Description

[0012] Figure 1 A diagram showing the wave velocity measured within 100m in front of the tunnel face;

[0013] Figure 2 The area within 100m in front of the tunnel face is delineated as a potential rockburst zone;

[0014] Figure 3 This represents the percentage of rock bursts of different intensities occurring within different P-wave velocities. Detailed Implementation

[0015] The present invention will be further described below with reference to specific embodiments.

[0016] A method for predicting rockburst intensity and location based on rock mass wave velocity includes the following steps:

[0017] The first step is to conduct advanced geological prediction of the surrounding rock or strata within a certain range ahead of the tunnel face during tunnel excavation, and to determine its P-wave velocity. In this embodiment, the effective distance for predicting the wave velocity using TSP seismic wave detection technology is approximately 100-150m. Specific operation process: Generally, the TSP seismic wave detection system receives seismic waves using a three-component geophone. Two seismic wave receiving holes are arranged on the left and right walls of the tunnel, each with a diameter of 50mm. The left wall receiving hole has a depth of 1.8m and a height approximately 1.60m above the floor slab; the right wall receiving hole has a depth of 1.70m and a height approximately 1.2m above the floor slab. Twenty-four excitation holes are arranged on the left wall to excite seismic waves, with a hole spacing of 1.50m, a hole diameter of 40mm, and a depth of 1.20-1.8m. All excitation holes are filled with 100g of explosive, and the height of the excitation holes is approximately 1.2m above the floor slab. TSP detection intervals are 100m, with a 10m overlap. Detection is repeated at 90m intervals, continuing this pattern. Actual measured wave velocities are plotted as follows: Figure 1 As shown.

[0018] The second step is rockburst location determination: Based on the 100-meter waveform diagram of the TSP face from the previous step, areas where wave velocity changes significantly are identified as potential rockburst areas for prediction, forming a potential rockburst area map, which is then overlaid on the P-wave velocity map from the previous step. For example... Figure 2 As shown, this 100m range is divided into 6 sections representing potential rockburst zones. The size of the zones is... Figure 1 Based on the waveform variation range, it can be determined that rockbursts of a certain degree will occur within the following six ranges starting from the working face: 14-18m, 29-38m, 55-64m, 70-77m, 77-82m, and 87-97m.

[0019] The third step is to determine the rockburst prediction level: The P-wave velocity is divided into four groups every 500 m / s: 4500–5000 m / s, 5000–5500 m / s, 5500–6000 m / s, and 6000–6500 m / s. The proportion of rockbursts of different intensities corresponding to each group is plotted as follows: Figure 3 The following judgment principles are given:

[0020] Group A: The longitudinal wave velocity of the rock mass is in the range of 4500-5000 m / s. The rockburst intensity is mainly slight (accounting for about 70% of the total number of rockbursts), followed by moderate (accounting for about 30% of the total number of rockbursts), and strong rockbursts are rarely produced.

[0021] Group B: The longitudinal wave velocity of the rock mass is in the range of 5000-5500 m / s. The rockburst intensity is mainly moderate rockburst (accounting for about 60% of the total number of rockbursts), followed by slight rockburst (accounting for about 40% of the total number of rockbursts), and strong rockbursts are rarely produced.

[0022] Group C: The longitudinal wave velocity of the rock mass is in the range of 5500-6000 m / s, and the probability of slight, moderate and strong rock bursts is the same (each accounting for 1 / 3);

[0023] Group D: The longitudinal wave velocity of the rock mass is in the range of 6000 to 6500 m / s. The rockburst intensity is mainly strong rockburst (accounting for about 70% of the total number of rockbursts), while the total of slight and moderate rockbursts accounts for about 30%.

[0024] Based on the correlation between rockburst occurrence intensity and longitudinal wave velocity of the rock mass, the probability of rockburst level is determined. The longitudinal wave velocities of the rock mass within the rockburst occurrence area selected in the previous step are compared. If the wave velocity of a certain rockburst segment falls within multiple wave velocity ranges, the average value of the corresponding rockburst levels is taken as the probability of a certain type of rockburst level occurring in that segment. For example: the first possible rockburst area is within 14-18m in front of the tunnel face... Figure 2 It can be determined that the wave velocity within this range is mainly 4600–5300 m / s, falling within groups A and B. Therefore, the probability of a "minor rockburst" is determined to be the average of 70% from group A and 40% from group B, meaning the probability of a minor rockburst occurring within 14–18 m in front of the tunnel face is 55%. The probability of a "moderate rockburst" is determined to be the average of 30% from group A and 60% from group B, meaning the probability of a moderate rockburst occurring within 14–18 m in front of the tunnel face is 45%.

[0025] The severity of each other rockburst segment is determined in this way.

[0026] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A method for accurately predicting the intensity and location of rockbursts based on rock mass wave velocity, characterized in that, The method described above utilizes the TSP (Transformer Stationary Space Spinner) precise P-wave velocity detection function to accurately detect locations of P-wave velocity discontinuities within a certain range ahead of the tunnel face, and determines the location and probability of potential rockbursts based on the velocity differences; it includes the following steps: The first step is to conduct advanced geological forecasting of the surrounding rock or strata within a certain range in front of the tunnel face during tunnel excavation, measure its longitudinal wave velocity, and make a wave velocity map at least 100m in front of the tunnel face. The second step is to determine the location of the rockburst: based on the 100-meter wave velocity map of the TSP face in the first step, the area where the wave velocity changes significantly is used as the possible range of the rockburst to predict the possible area of ​​the rockburst and to overlay it on the longitudinal wave velocity map in the first step. The third step is to determine the predicted level of rockburst: based on the relationship between the intensity of rockburst occurrence and the longitudinal wave velocity of the rock mass, determine the probability of rockburst occurrence at each level; the longitudinal wave velocity of the rock mass selected in the second step within the rockburst occurrence area is compared; if the wave velocity of a certain rockburst segment falls within multiple wave velocity ranges, the average value of each corresponding level of rockburst is taken as the probability of that level of rockburst occurring in that segment, and superimposed on the longitudinal wave velocity map from the previous step. The P-wave velocity is divided into four groups every 500 m / s: 4500–5000 m / s, 5000–5500 m / s, 5500–6000 m / s, and 6000–6500 m / s. The following judgment criteria are given: Group A: The longitudinal wave velocity of the rock mass is in the range of 4500 to 5000 m / s, the rockburst intensity is mainly slight, followed by moderate, and strong rockbursts are rarely produced; Group B: The longitudinal wave velocity of the rock mass is in the range of 5000 to 5500 m / s, the rockburst intensity is mainly moderate rockburst, followed by slight rockburst, and strong rockburst is rarely produced; Group C: The longitudinal wave velocity of the rock mass is in the range of 5500 to 6000 m / s. The probability of slight, moderate and strong rock bursts is the same, each accounting for 1 / 3. Group D: The longitudinal wave velocity of the rock mass is in the range of 6000 to 6500 m / s, and the rockburst intensity is mainly strong rockburst, with a small number of slight and moderate rockbursts.

2. The method for accurately predicting rockburst intensity and location based on rock mass wave velocity according to claim 1, characterized in that, The "certain range" mentioned in the first step refers to an effective distance of 100-150m for predicting wave velocity using TSP seismic wave detection technology.

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