Method and system for detecting the development of fissures inside a rock sample

Abstract

This invention discloses a method for detecting the development of internal fractures in rock samples, comprising: preparing a rock sample; setting up n seismic sources on one side of the rock sample and m sensors on the other side; exciting the seismic sources, and the sensors receiving and recording the wave velocity distribution data of the seismic waves to form a P-wave velocity distribution map A; conducting a rock mechanics experiment on the rock sample; exciting the seismic sources again, and the sensors receiving and recording the wave velocity distribution data of the seismic waves again to form a P-wave velocity distribution map B; comparing and analyzing the wave velocity distribution information in P-wave velocity distribution maps A and B to determine the development of internal fractures in the rock sample; and simultaneously disclosing a detection system applied to the above detection method. The detection method and system of this invention provide comprehensive and accurate detection results, which is beneficial to engineering construction safety, and are simple in design and easy to operate.

Description

Technical Field

[0001] This invention relates to the field of geological exploration, and in particular to a detection method and system for detecting the development of internal fractures in rock samples. Background Technology

[0002] For deep underground engineering, especially special underground engineering in mountainous areas, the detection of the elastoplastic mechanical characteristics and internal fracture development of rock samples in the construction area is of great significance and importance. It can provide information on the stress-strain laws of the surrounding rock for support design, construction safety, and numerical simulation. The commonly used detection equipment and method is to conduct indoor true triaxial mechanical tests using a true triaxial apparatus. This involves collecting cubic rock blocks on-site or artificially casting cubic blocks of materials with similar proportions to the on-site rock. Under real three-dimensional geostress conditions, the dynamic response of deep rock masses under disturbances such as excavation, blasting, or lining is simulated. Through calculation and conversion, the elastoplastic mechanical characteristics of the rock mass samples and the range of internal fracture development are obtained under geological conditions close to those on-site.

[0003] The primary observation target in the experiment was the change in the internal material of the rock mass sample before and after loading, particularly the development and integrity of fractures within the sample within a radius equal to one tunnel diameter. This would reveal the process and extent of surrounding rock disturbance during tunnel formation. Existing detection methods typically involve pre-installing a limited number of sensors inside the sample or deploying them on the sample surface to capture strain or stress information during the experiment, thereby analyzing the required sample-related information. However, limitations such as sensor size and the potential interference of sensors with the sample's mechanical parameters restrict the number of sensors used for detection, and their placement cannot be too close to the tunnel wall. This results in the analyzed information failing to fully reflect the mechanical and internal fracture distribution characteristics of the sample, thus failing to provide comprehensive and reliable data support. Summary of the Invention

[0004] This invention provides a method and system for detecting the development of internal fractures in rock samples. This method can comprehensively and directly reflect the distribution characteristics of internal fractures in rock samples, providing a basis for comprehensive mechanical characteristic analysis. The specific technical solution is as follows:

[0005] A method for detecting the development of internal fractures in a rock sample includes the following steps:

[0006] Prepare rock mass samples;

[0007] n seismic sources are set up on one side of the rock mass sample, and m sensors are set up on the other side;

[0008] The source of the earthquake is excited and the seismic wave generated by the source is transmitted through the rock sample. The sensor receives and records the wave velocity distribution data of the seismic wave, forming a longitudinal wave velocity distribution map A.

[0009] Conduct a rock mechanics experiment on the rock mass sample;

[0010] The seismic source is excited again, and the seismic waves generated by the source are transmitted through the rock sample. The sensor receives and records the wave velocity distribution data of the seismic waves again, forming the P-wave velocity distribution map B.

[0011] By comparing and analyzing the wave velocity distribution information in P-wave velocity distribution diagram A and P-wave velocity distribution diagram B, the internal fracture development of the rock mass sample after simulated excavation of the chamber was obtained.

[0012] Furthermore, when preparing the rock mass sample, each plane of the rock mass sample is ground to make the rock mass sample into a cuboid shape. The seismic source and the sensor are located on the first and second sides of the cuboid, respectively. n seismic sources are evenly distributed on the first side and m sensors are evenly distributed on the second side.

[0013] Furthermore, the n seismic sources are arranged in a matrix to form a seismic source array unit, which covers the first side of the rock mass sample.

[0014] Furthermore, the m sensors are arranged in a matrix to form a sensor array unit, which covers the second side of the rock sample.

[0015] Furthermore, n seismic sources are activated one by one. When each seismic source is activated, m sensors simultaneously receive and collect seismic wave data information, collecting a total of mn data information.

[0016] Furthermore, the collected mn seismic wave data were calculated and analyzed using seismic tomography inversion software to obtain a three-dimensional distribution map of the P-wave velocity of the rock mass sample.

[0017] Furthermore, a true triaxial apparatus was used to simulate the stress conditions in the actual geological environment, and three-dimensional stress loading was applied to the rock mass sample.

[0018] A detection system for detecting the development of internal fractures in a rock sample, applied in the aforementioned method for detecting the development of internal fractures in a rock sample, includes:

[0019] The sample stage is used to place rock samples.

[0020] The source array unit and the sensor array unit are respectively attached to two opposite sides of the rock mass sample. The sensor array unit can receive the seismic wave data information generated after the source array unit is excited.

[0021] The data analysis unit is used to collect and process seismic wave data received by the sensor array unit;

[0022] The control unit controls the coordinated operation of the sample stage, stress loading unit, seismic source array unit, sensor array unit, and data analysis unit.

[0023] Furthermore, the source array unit includes multiple sources arranged in a matrix, and the sensor array unit includes multiple sensors arranged in a matrix.

[0024] Furthermore, the data analysis unit includes seismic tomography inversion software.

[0025] The detection method and system for detecting the development of internal fractures in rock samples of the present invention can simulate the dynamic response and long-term stability of deep rock masses under real three-dimensional geostress conditions caused by disturbances such as excavation and blasting or lining. By detecting the longitudinal wave velocity distribution of rock samples before and after the test, the internal fracture distribution characteristics of the rock samples can be comprehensively and directly reflected. The detection results are comprehensive and accurate, providing a reliable basis for comprehensive mechanical characteristic analysis, which is beneficial to the construction safety of the project. Moreover, the detection system is relatively simple in design and the detection method is easy to operate and implement. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the array-type seismic tomography process for rock mass samples in this invention.

[0027] Figure 2 This is a longitudinal wave velocity diagram of the internal central section of the rock mass sample before loading in this invention.

[0028] Figure 3 This is a longitudinal wave velocity diagram of the internal central section of the rock mass sample after loading in this invention. Detailed Implementation

[0029] To better understand the purpose, structure, and function of this invention, the detection method and system for detecting the development of internal fractures in rock samples will be described in further detail below with reference to the accompanying drawings.

[0030] The detection method for detecting the development of internal fractures in rock samples in this invention includes the following steps:

[0031] 1. Prepare rock samples. Collect rock blocks from the construction area on site as rock samples, and grind each plane of the rock sample to make it into a cuboid shape; or, through artificial casting, use quartz sand, barite powder and other particles to mix with each other to make concrete cubes or resin cubes that meet the material ratio requirements of the rock on site.

[0032] 2. A seismic source is placed on one side of the rock mass sample, and a sensor is placed on the other side. The seismic source and sensor are located on the first and second opposite sides of the rectangular rock mass sample, respectively. There are n seismic sources and m sensors. The n seismic sources are evenly distributed on the first side, and the m sensors are evenly distributed on the second side, to facilitate a thorough exploration of the entire internal structure of the rock mass sample. The sensors and seismic sources can be fixed to the rock mass sample using metal adhesive.

[0033] 3. Excite the seismic source and allow the seismic waves generated by the source to penetrate through the rock sample. At the same time, the sensor receives and records the wave velocity distribution data of the seismic waves. The wave velocity distribution data is calculated and analyzed using seismic tomography inversion software to form a P-wave velocity distribution map A.

[0034] Specifically, during the experiment, n seismic sources were activated one by one. When each seismic source was activated, m sensors simultaneously received and collected seismic wave data information, collecting a total of mn data information. The collected mn seismic wave data information was calculated and analyzed using seismic tomography inversion software to obtain a three-dimensional distribution map A of the longitudinal wave velocity of the rock mass sample.

[0035] 4. Conduct a rock mechanics test on the rock mass sample.

[0036] 5. The seismic source is excited again, so that the seismic waves generated by the source are transmitted through the rock sample. At the same time, the sensor receives and records the wave velocity distribution data of the seismic waves again, forming the P-wave velocity distribution map B.

[0037] Specifically, during the experiment, n seismic sources were used to excite the rock mass sample one by one. At each source excitation, m sensors simultaneously received and acquired seismic wave data, resulting in the acquisition of mn data points. Seismic tomography inversion software was used to calculate and analyze the acquired mn seismic wave data points, obtaining a three-dimensional distribution map B of the P-wave velocity of the rock mass sample.

[0038] 6. By comparing and analyzing the wave velocity distribution information in P-wave velocity distribution diagram A and P-wave velocity distribution diagram B, the local wave velocity of the rock mass sample decreases, indicating that new fractures were generated in that area during the experiment. The relative change in wave velocity can characterize the fracture density of the rock mass sample. Thus, the internal fracture development of the rock mass sample after the simulated excavation of the chamber can be obtained.

[0039] In step 2 above, preferably, as follows: Figure 1As shown, n seismic sources are arranged in a matrix to form a seismic source array unit, which covers the first side of the rock sample; m sensors are arranged in a matrix to form a sensor array unit, which covers the second side of the rock sample. This matrix arrangement allows the seismic rays generated between the seismic sources and sensors to penetrate the entire rock sample densely and uniformly, reducing blind spots and making the resulting P-wave velocity distribution map more accurate and reliable.

[0040] The value of n is not less than 4, and the value of m is not less than 4. According to the detection accuracy requirements, the smaller the detection accuracy requirement, the more seismic sources and sensors are in the source array unit and sensor array unit. That is, the larger n and m are, the smaller the set spacing between the seismic sources and the smaller the spacing between the sensors.

[0041] This invention also relates to a detection system for detecting the development of internal fractures in rock samples, applied to the aforementioned detection method for detecting the development of internal fractures in rock samples, specifically including:

[0042] The sample stage is used to place rock samples to facilitate testing of the rock samples.

[0043] The source array unit and the sensor array unit are respectively attached to two opposite sides of the rock mass sample. The sensor array unit can receive the seismic wave data information generated after the source array unit is excited.

[0044] The data analysis unit is connected in communication with the sensor array unit and is used to collect and process seismic wave data information received by the sensor array unit.

[0045] The control unit controls the coordinated operation of the sample stage, stress loading unit, seismic source array unit, sensor array unit, and data analysis unit.

[0046] Specifically, the source array unit includes multiple sources arranged in a matrix; the sensor array unit includes multiple sensors arranged in a matrix; and the data analysis unit includes seismic tomography inversion software. By processing the data through the seismic tomography inversion software, a P-wave velocity distribution map can be obtained, and then the development of fractures inside the rock mass sample after the test can be analyzed.

[0047] The following specific embodiment will be used to further explain in detail the detection method and detection system for detecting the development of internal fractures in rock samples according to the present invention.

[0048] Step 1: Collect rock blocks at the construction site as rock mass samples, and grind the rock mass samples into cubes with dimensions of 50cm×50cm×50cm.

[0049] Step two, place the rock mass sample on the sample stage, such as... Figure 1 As shown, a seismic source array is arranged on one side of the rock mass sample, and a sensor array is arranged on the other parallel side. The spacing between two adjacent sensors is 5 cm, arranged in 10 rows and 10 columns, for a total of 100 sensors; the spacing between two adjacent seismic sources is 5 cm, arranged in 10 rows and 10 columns, for a total of 100 sensors, corresponding to the sensor array.

[0050] Step 3, as Figure 1 As shown, seismic sources are excited sequentially. During the excitation of each source, the sensor simultaneously receives and acquires seismic wave data. Each excitation yields 100 transmitted wave records, resulting in a total of 10,000 transmitted wave records after all sources are excited. The seismic wave rays generated by sources at different locations intersect each other; the more numerous and denser the intersections, the higher the detection accuracy.

[0051] Step four: Conduct a rock mechanics test on the rock mass sample.

[0052] Step 5: Sequentially excite 100 seismic sources again and enable 100 sensors to receive and collect seismic wave data, obtaining 10,000 transmitted wave records.

[0053] Step 6: Using seismic tomography inversion software, calculate the transmitted wave information from the two recorded times to obtain... Figure 2 The longitudinal wave velocity distribution diagrams A and A shown are shown. Figure 3 As shown in P-wave velocity distribution map B, comparing and analyzing the wave velocity distribution information in P-wave velocity distribution maps A and B, it is clear that under the action of three-dimensional stress, the wave velocity value around the cavity further decreases, and the area of ​​decreased wave velocity increases, indicating that the fractures around the cavity are more developed and the disturbance range expands. Simultaneously, an inhomogeneous layer is generated on both the upper and lower surfaces of the rock mass sample, indicating that after excavation in the simulated chamber, the fractures further develop, leading to a further decrease in wave velocity.

[0054] The detection method and system for detecting the development of internal fractures in rock samples of the present invention can comprehensively and directly reflect the internal fracture distribution characteristics of rock samples by detecting the longitudinal wave velocity distribution of rock samples before and after the test. The detection results are comprehensive and accurate, and can provide a reliable basis for comprehensive mechanical characteristic analysis, which is beneficial to the construction safety of engineering projects. Moreover, the detection system is relatively simple in design and the detection method is easy to operate and implement.

[0055] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the nature and scope of the present invention. Various modifications made to the above embodiments by those skilled in the art after reading this specification are all within the scope of protection of the present invention.

Claims

1. A method for detecting the development of internal fractures in a rock sample, characterized in that, Includes the following steps: Prepare rock mass samples; n seismic sources are set up on one side of the rock mass sample, and m sensors are set up on the other side; The source of the earthquake is excited and the seismic wave generated by the source is transmitted through the rock sample. The sensor receives and records the wave velocity distribution data of the seismic wave, forming a longitudinal wave velocity distribution map A. Conduct a rock mechanics experiment on the rock mass sample; The seismic source is excited again, and the seismic waves generated by the source are transmitted through the rock sample. The sensor receives and records the wave velocity distribution data of the seismic waves again, forming the P-wave velocity distribution map B. By comparing and analyzing the wave velocity distribution information in P-wave velocity distribution diagram A and P-wave velocity distribution diagram B, the internal fracture development of the rock mass sample after simulated excavation of the chamber was obtained.

2. The method for detecting the development of internal fractures in a rock sample as described in claim 1, characterized in that, When preparing the rock mass sample, grind all planes of the rock mass sample to make the rock mass sample into a cuboid shape. The seismic source and the sensor are located on the first and second sides of the cuboid, respectively. n seismic sources are evenly distributed on the first side and m sensors are evenly distributed on the second side.

3. The detection method for detecting the development of internal fractures in a rock sample as described in claim 2, characterized in that, n seismic sources are arranged in a matrix to form a seismic source array unit, which covers the first side of the rock mass sample.

4. The method for detecting the development of internal fractures in a rock sample as described in claim 3, characterized in that, m sensors are arranged in a matrix to form a sensor array unit, which covers the second side of the rock sample.

5. The detection method for detecting the development of internal fractures in a rock sample as described in any one of claims 1 to 4, characterized in that, n seismic sources are activated one after another. When each seismic source is activated, m sensors simultaneously receive and collect seismic wave data, collecting a total of mn data points.

6. The method for detecting the development of internal fractures in a rock sample as described in claim 5, characterized in that, Seismic tomography inversion software was used to calculate and analyze the acquired mn seismic wave data to obtain a three-dimensional distribution map of the P-wave velocity of the rock mass sample.

7. The method for detecting the development of internal fractures in a rock sample as described in claim 1, characterized in that, A true triaxial apparatus was used to simulate the stress conditions in the actual geological environment, and three-dimensional stress loading was applied to the rock mass sample.

8. A detection system for detecting the development of internal fractures in a rock sample, applied in the detection method for detecting the development of internal fractures in a rock sample as described in any one of claims 1 to 7, characterized in that, include: The sample stage is used to place rock samples. The source array unit and the sensor array unit are respectively attached to two opposite sides of the rock mass sample. The sensor array unit can receive the seismic wave data information generated after the source array unit is excited. The data analysis unit is used to collect and process seismic wave data received by the sensor array unit; The control unit controls the coordinated operation of the sample stage, stress loading unit, seismic source array unit, sensor array unit, and data analysis unit.

9. The detection system for detecting the development of internal fractures in a rock sample as described in claim 8, characterized in that, The source array unit includes multiple sources arranged in a matrix, and the sensor array unit includes multiple sensors arranged in a matrix.

10. The detection system for detecting the development of internal fractures in a rock sample as described in claim 8, characterized in that, The data analysis unit includes seismic tomography inversion software.

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