A method for testing a damage zone of a surrounding rock of an underground space

Abstract

The application discloses a kind of underground space surrounding rock excavation damage zone test method, belong to rock mass damage test technical field, comprising: first, different depth rock sampling and do ultrasonic test, determine rock sample attenuation characteristic and wave velocity;Then determine the comprehensive damage index range of different damage grade rock samples according to this;Then, in the process of excavation, sensor is laid out to collect ultrasonic and acoustic emission data;Then, an initial calculation model is constructed, and a surrounding rock three-dimensional wave velocity model is obtained by using the collected data inversion;Finally, the damage grade is determined according to the comprehensive damage index and marked in the model, and the damage zone test is realized.The method establishes the mapping relationship between damage degree and wave velocity change, proposes the threshold value of comprehensive damage index range in different partitions, realizes quantitative and hierarchical classification, and also inverts a three-dimensional wave velocity model based on test and monitoring data, realizes three-dimensional presentation and hierarchical labeling of damage zone.

Description

Technical Field

[0001] This invention belongs to the field of rock mass damage testing technology, specifically relating to a method for testing the damage zone of surrounding rock excavation in underground space. Background Technology

[0002] With increasing global demand for resources and rapid urbanization, rock engineering projects such as mining and underground tunnel construction are extending into deeper and more complex geological environments. Excavation leads to a redistribution of stress in the surrounding rock, accelerating the initiation, expansion, and connection of joints and fissures within the rock mass, weakening rock mass parameters, and forming an excavation damage zone (EDZ). Compared to undisturbed rock masses, engineering rock masses are typically in a state of varying degrees of damage due to natural geological activities, disasters, and mining operations. The excavation damage zone has poor bearing capacity and is highly susceptible to engineering geological disasters such as splitting, spalling, and rock bursts, exhibiting strong suddenness and destructiveness, seriously threatening the safety of personnel and equipment, as well as the stability of deep-ground engineering projects.

[0003] Indoor testing can describe rock mass damage by directly observing microcracks or indirectly observing changes in physical and mechanical properties. Direct methods obtain the number and distribution of microcracks directly through observation, and mainly include scanning electron microscopy (SEM) and computed tomography (CT). Indirect methods mainly include stress-strain methods, acoustic emission methods, acoustic wave methods, digital image correlation methods, and infrared radiation detection methods. Field testing methods for rock mass excavation damage zones include multi-point displacement gauge methods, ultrasonic methods, microseismic monitoring methods, ground-penetrating radar methods, seismic wave methods, resistivity methods, permeability methods, borehole television methods, and radiometric element methods. However, testing the excavation damage zone of surrounding rock through indoor tests often requires on-site sampling, which has a certain lag. On-site characterization of rock mass damage mostly relies on point or line scale tests. Neither of these can obtain the in-situ rock mass damage characteristics in real time at a three-dimensional scale. Reflecting the on-site rock mass damage situation through point or line scales often makes it difficult to comprehensively and effectively obtain the three-dimensional spatial range of surrounding rock damage. Insufficient measurement points can lead to the omission of some weak rock layers. Moreover, rock mass damage indicators are mostly determined based on experience, lacking theoretical and scientific basis, and have limited quantitative evaluation capabilities for damage, making it difficult to be effectively applied in engineering practice.

[0004] Therefore, in existing technologies, the measurement of surrounding rock damage mostly relies on point and line scale measurements, and there is a lack of quantitative evaluation methods, making it difficult to accurately classify different damage levels (such as high damage zone, excavation damage zone, excavation-affected zone, and undisturbed zone). Summary of the Invention

[0005] In view of the above-mentioned shortcomings in the prior art, the test method for excavation damage zone of underground space surrounding rock provided by the present invention solves the problems of existing methods for identifying excavation damage zone in the process of underground space surrounding rock excavation, such as the lack of a clear damage assessment method, strong subjectivity, and low spatial resolution.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: a method for testing the damage zone of surrounding rock excavation in underground space, comprising the following steps:

[0007] S1. Take rock samples at different depths from the excavation damage zone of the underground space surrounding rock and conduct ultrasonic testing to determine the attenuation characteristics and wave velocity of rock samples with different degrees of damage.

[0008] S2. Based on the attenuation characteristics and wave velocity of rock samples with different damage levels, determine the range of comprehensive damage index for rock samples with different damage levels.

[0009] S3. During the excavation of the underground space in the test area, sensors are deployed to continuously collect on-site ultrasonic test data and acoustic emission monitoring data;

[0010] S4. Construct an initial calculation model of the test area, and use the ultrasonic test data and acoustic emission monitoring data collected on site to perform rock mass inversion of the surrounding rock target and obtain a three-dimensional wave velocity model of the surrounding rock.

[0011] S5. Based on the comprehensive damage index of rock samples corresponding to the ultrasonic test data and acoustic emission monitoring data collected in the test area, determine the damage level and mark it in the three-dimensional wave velocity model of the surrounding rock to realize the test of the excavation damage area.

[0012] Furthermore, step S2 includes the following sub-steps:

[0013] S201. Determine the damage indices of the rock sample, including the anisotropy coefficient. and wave speed decline rate , This represents the P-wave velocity of the rock sample perpendicular to the sidewall. This indicates the wave velocity of the rock sample along the sidewall direction. Indicates the wave velocity of rock samples in the undisturbed area. Indicates the wave velocity of the rock sample in the measurement area;

[0014] S202. Normalize the rock sample damage index;

[0015] S203. Calculate the comprehensive damage index based on the normalized rock sample damage indices. , This represents the normalized rate of decrease in wave velocity. Represents the normalized anisotropy coefficients. and They represent and The weighting coefficients, A sensitivity parameter indicating the imbalance of damage to indicators.

[0016] Furthermore, in step S2, the damage levels include the High Damage Zone (HDZ), the Excavation Damage Zone (EDZ), the Excavation Influence Zone (EIZ), and the Undisturbed Zone (UDZ), with their corresponding comprehensive damage index ranges being CDI. EDZ ~1. CDI EIZ ~CDI EDZ 0~CDI EIZ and 0;

[0017] Among them, CDI EDZ The CDI (Combined Damage Index) represents the boundary threshold between the highly damaged zone and the excavated damaged zone. EIZ This represents the boundary threshold of the comprehensive damage index for the excavation damage zone and the excavation-affected zone.

[0018] Furthermore, in step S4, the method for constructing the initial computational model includes:

[0019] S401. Divide the test area into different rock strata and determine the modeling area range based on the geological map of the tunnel section;

[0020] S402. Divide the modeling area into grids according to the model scale, and determine the sensor coordinates based on the grid nodes;

[0021] S403. Assign wave velocity and anisotropy values ​​to the grid nodes based on the measured wave velocity of the lithology within the modeling area, assign different values ​​to different lithologies and joint and fracture development levels, and assign zero values ​​to the grid nodes outside the modeling area to complete the initial calculation model construction.

[0022] Furthermore, in step S4, the method for obtaining the three-dimensional wave velocity model of the surrounding rock includes:

[0023] S404. During the excavation of the underground space in the test area, the time when the sensor collects ultrasonic test data and acoustic emission monitoring data of the surrounding rock target is recorded is... ;

[0024] S405. Using the constructed initial calculation model, calculate the arrival time between the source point and the ultrasonic path based on the assigned nodal wave velocity and ray path, and record it as the theoretical arrival time. ;

[0025] S406. Perform error analysis on the L2 norm of the difference between the theoretical arrival time and the observed arrival time of adjacent sensors;

[0026] S407. Determine whether the error is less than the set minimum error;

[0027] If so, proceed to step S408;

[0028] If not, the initial computational model is then optimized using the constructed joint objective function containing strata and joints / fractures, and the process returns to step S404; the optimization parameters include grid node wave velocity and anisotropy.

[0029] S408. Based on the current optimal parameters, obtain the three-dimensional wave velocity model of the surrounding rock.

[0030] Furthermore, the error The calculation formula is:

[0031]

[0032] In the formula, the subscript Indicates the sensor index.

[0033] Furthermore, in step S407, the joint objective function for the formation and joints / fractures is:

[0034]

[0035] In the formula, Let m represent the joint objective function, and m represent the parameter matrix, which includes wave velocity and anisotropic parameters. , , This represents the weight coefficient of each sub-item. Represents the data fitting term. Represents the stratigraphic structure constraint terms. This represents the constraint terms for joint and fracture structures.

[0036] Furthermore, step S5 includes the following sub-steps:

[0037] S501. In ultrasonic test data and acoustic emission monitoring data, the average value of 10 adjacent nodes in the vertical direction is taken as the P-wave velocity of the rock sample perpendicular to the sidewall, and the average value of 10 adjacent nodes in the parallel direction is taken as the rock sample velocity along the sidewall direction.

[0038] S502. Calculate the comprehensive damage index of the corresponding area based on the P-wave velocity of the rock sample perpendicular to the sidewall and the wave velocity of the rock sample along the sidewall direction.

[0039] S503. Based on the range of the comprehensive damage index of the rock sample, determine the damage level of the corresponding area and mark it in the three-dimensional wave velocity model of the surrounding rock to realize the test of the excavation damage zone.

[0040] The beneficial effects of this invention are as follows:

[0041] (1) Through on-site multi-depth rock sampling and ultrasonic testing, a mapping relationship between damage degree and wave velocity change was established. Threshold ranges of comprehensive damage index for different zones such as high damage zone, excavation damage zone, excavation influence zone and undisturbed zone were proposed. Thus, a quantitative and graded classification standard for the surrounding rock damage zone in underground space was realized, providing a scientific basis for the fine identification and safety assessment of excavation damage zone.

[0042] (2) Based on ultrasonic velocity test and acoustic emission monitoring data, the three-dimensional wave velocity model of the surrounding rock was inverted using tomographic imaging technology, and different damage areas were divided according to the comprehensive damage index, realizing the three-dimensional presentation and hierarchical labeling of the surrounding rock excavation damage area. Attached Figure Description

[0043] Figure 1 A flowchart of the testing method for the excavation zone of surrounding rock in underground space provided by the present invention.

[0044] Figure 2 This invention provides a schematic diagram of the division of different damage zones in the surrounding rock of an underground excavation space and the damage of rock samples. Detailed Implementation

[0045] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0046] This invention provides a method for testing the damage zone of surrounding rock excavation in underground spaces, such as... Figure 1 As shown, it includes:

[0047] S1. Take rock samples at different depths from the excavation damage zone of the underground space surrounding rock and conduct ultrasonic testing to determine the attenuation characteristics and wave velocity of rock samples with different degrees of damage.

[0048] S2. Based on the attenuation characteristics and wave velocity of rock samples with different damage levels, determine the range of comprehensive damage index for rock samples with different damage levels.

[0049] S3. During the excavation of the underground space in the test area, sensors are deployed to continuously collect on-site ultrasonic test data and acoustic emission monitoring data;

[0050] S4. Construct an initial calculation model of the test area, and use the ultrasonic test data and acoustic emission monitoring data collected on site to perform rock mass inversion of the surrounding rock target and obtain a three-dimensional wave velocity model of the surrounding rock.

[0051] S5. Based on the comprehensive damage index of rock samples corresponding to the ultrasonic test data and acoustic emission monitoring data collected in the test area, determine the damage level and mark it in the three-dimensional wave velocity model of the surrounding rock to realize the test of the excavation damage area.

[0052] In step S1 of this embodiment of the invention, samples are taken from the surrounding rock in the underground space. Rock samples at different depths (i.e., different degrees of damage) are selected to ensure that the samples can represent the typical characteristics of different areas of excavation damage (including the high damage zone HDZ, the excavation damage zone EDZ, the excavation influence zone EIZ, and the undisturbed zone UDZ), providing a complete sample system for subsequent excavation damage zone division.

[0053] Furthermore, ultrasonic tests were conducted on rock samples at different depths in the excavated damage zone to measure the P-wave velocity of the rock samples perpendicular to and along the sidewall. The attenuation characteristics and wave velocities of rock samples at different degrees were obtained by measuring the ultrasonic amplitude attenuation and ultrasonic arrival time.

[0054] Step S2 in this embodiment of the invention includes the following sub-steps:

[0055] S201. Determine the damage indices of the rock sample, including the anisotropy coefficient. and wave speed decline rate , This represents the P-wave velocity of the rock sample perpendicular to the sidewall. This indicates the wave velocity of the rock sample along the sidewall direction. Indicates the wave velocity of rock samples in the undisturbed area. Indicates the wave velocity of the rock sample in the measurement area;

[0056] S202. Normalize the rock sample damage index;

[0057] Specifically, the formula for normalization is:

[0058]

[0059]

[0060] In the formula, and These represent the minimum and maximum anisotropy coefficients, respectively. and These represent the wave velocity descent rate, respectively;

[0061] S203. Calculate the comprehensive damage index based on the normalized rock sample damage indices. , This represents the normalized rate of decrease in wave velocity. Represents the normalized anisotropy coefficients. and They represent and The weighting coefficients, Sensitivity parameters that indicate the imbalance of index impairment, such as Represents Manhattan distance, Represents Euclidean distance.

[0062] In this embodiment of the invention, the comprehensive damage index A value close to 0 indicates a lower degree of rock mass damage, while a value close to 1 indicates a more severe degree of damage.

[0063] Therefore, as Figure 2 As shown, the damage levels in this embodiment include the High Damage Zone (HDZ), the Excavation Damage Zone (EDZ), the Excavation Influence Zone (EIZ), and the Undisturbed Zone (UDZ), with corresponding comprehensive damage index ranges of CDI. EDZ ~1. CDI EIZ ~CDI EDZ 0~CDI EIZ and 0;

[0064] Among them, CDI EDZ The CDI (Combined Damage Index) represents the boundary threshold between the highly damaged zone and the excavated damaged zone. EIZ This represents the boundary threshold of the comprehensive damage index for the excavation damage zone and the excavation-affected zone.

[0065] In step S3 of this embodiment of the invention, during the excavation of the underground space in the test area, periodic active ultrasonic tests are carried out, and blasting vibration and rock fracture signals are continuously collected to obtain ultrasonic test data and on-site acoustic emission monitoring data.

[0066] In step S4 of this embodiment of the invention, the method for constructing the initial computational model includes:

[0067] S401. Divide the test area into different rock strata and determine the modeling area range based on the geological map of the tunnel section;

[0068] Specifically, the modeling area should include the spatial distribution of all sensors and potential acoustic emission events, and the excavation space should be left empty;

[0069] S402. Divide the modeling area into grids according to the model scale, and determine the sensor coordinates based on the grid nodes;

[0070] Specifically, a cubic mesh can be used to divide the 3D model;

[0071] S403. Assign wave velocity and anisotropy values ​​to the grid nodes based on the measured wave velocity of the lithology within the modeling area, assign different values ​​to different lithologies and joint and fracture development levels, and assign zero values ​​to the grid nodes outside the modeling area to complete the initial calculation model construction.

[0072] In step S4 of this embodiment of the invention, the method for obtaining the three-dimensional wave velocity model of the surrounding rock includes:

[0073] S404. During the excavation of the underground space in the test area, the time when the sensor collects ultrasonic test data and acoustic emission monitoring data of the surrounding rock target is recorded is... ;

[0074] S405. Using the constructed initial calculation model, calculate the arrival time between the source point and the ultrasonic path based on the assigned nodal wave velocity and ray path, and record it as the theoretical arrival time. ;

[0075] S406. Perform error analysis on the L2 norm of the difference between the theoretical arrival time and the observed arrival time of adjacent sensors;

[0076] S407. Determine whether the error is less than the set minimum error;

[0077] If so, proceed to step S408;

[0078] If not, the initial computational model is then optimized using the constructed joint objective function containing strata and joints / fractures, and the process returns to step S404; the optimization parameters include grid node wave velocity and anisotropy.

[0079] S408. Based on the current optimal parameters, obtain the three-dimensional wave velocity model of the surrounding rock.

[0080] In this embodiment, error The calculation formula is:

[0081]

[0082] In the formula, the subscript Indicates the sensor index.

[0083] In step S407 of this embodiment, the joint objective function including strata and joints / fractures is:

[0084]

[0085] In the formula, Let m represent the joint objective function, and m represent the parameter matrix, which includes wave velocity and anisotropic parameters. , , This represents the weight coefficient of each sub-item. Represents the data fitting term. Represents the stratigraphic structure constraint terms. This represents the constraint terms for joint and fracture structures.

[0086] Step S5 of this embodiment of the invention includes the following sub-steps:

[0087] S501. In ultrasonic test data and acoustic emission monitoring data, the average value of 10 adjacent nodes in the vertical direction is taken as the P-wave velocity of the rock sample perpendicular to the sidewall, and the average value of 10 adjacent nodes in the parallel direction is taken as the rock sample velocity along the sidewall direction.

[0088] S502. Calculate the comprehensive damage index of the corresponding area based on the P-wave velocity of the rock sample perpendicular to the sidewall and the wave velocity of the rock sample along the sidewall direction.

[0089] S503. Based on the range of the comprehensive damage index of the rock sample, determine the damage level of the corresponding area and mark it in the three-dimensional wave velocity model of the surrounding rock to realize the test of the excavation damage zone.

[0090] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

[0091] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for testing the damage zone of surrounding rock excavation in underground spaces, characterized in that, Includes the following steps: S1. Take rock samples at different depths from the excavation damage zone of the underground space surrounding rock and conduct ultrasonic testing to determine the attenuation characteristics and wave velocity of rock samples with different degrees of damage. S2. Based on the attenuation characteristics and wave velocity of rock samples with different damage levels, determine the range of comprehensive damage index for rock samples with different damage levels. S3. During the excavation of the underground space in the test area, sensors are deployed to continuously collect on-site ultrasonic test data and acoustic emission monitoring data; S4. Construct an initial calculation model of the test area, and use the ultrasonic test data and acoustic emission monitoring data collected on site to perform rock mass inversion of the surrounding rock target and obtain a three-dimensional wave velocity model of the surrounding rock. S5. Based on the comprehensive damage index of rock samples corresponding to the ultrasonic test data and acoustic emission monitoring data collected in the test area, determine the damage level and mark it in the three-dimensional wave velocity model of the surrounding rock to realize the test of the excavation damage area. Step S2 includes the following sub-steps: S201. Determine the damage indices of the rock sample, including the anisotropy coefficient. and wave speed decline rate , This represents the P-wave velocity of the rock sample perpendicular to the sidewall. This indicates the wave velocity of the rock sample along the sidewall direction. Indicates the wave velocity of rock samples in the undisturbed area. Indicates the wave velocity of the rock sample in the measurement area; S202. Normalize the rock sample damage index; S203. Calculate the comprehensive damage index based on the normalized rock sample damage indices. , This represents the normalized rate of decrease in wave velocity. Represents the normalized anisotropy coefficients. and They represent and The weighting coefficients, A sensitivity parameter indicating the imbalance of damage to indicators.

2. The method for testing the damage zone of surrounding rock excavation in underground space according to claim 1, characterized in that, In step S2, the damage levels include the High Damage Zone (HDZ), the Excavation Damage Zone (EDZ), the Excavation Influence Zone (EIZ), and the Undisturbed Zone (UDZ), with corresponding comprehensive damage index ranges of CDI. EDZ ~1. CDI EIZ ~CDI EDZ 0~CDI EIZ and 0; Among them, CDI EDZ The CDI (Combined Damage Index) represents the boundary threshold between the highly damaged zone and the excavated damaged zone. EIZ This represents the boundary threshold of the comprehensive damage index for the excavation damage zone and the excavation-affected zone.

3. The method for testing the damage zone of surrounding rock excavation in underground space according to claim 1, characterized in that, In step S4, the method for constructing the initial computational model includes: S401. Divide the test area into different rock strata and determine the modeling area range based on the geological map of the tunnel section; S402. Divide the modeling area into grids according to the model scale, and determine the sensor coordinates based on the grid nodes; S403. Assign wave velocity and anisotropy values ​​to the grid nodes based on the measured wave velocity of the lithology within the modeling area, assign different values ​​to different lithologies and joint and fracture development levels, and assign zero values ​​to the grid nodes outside the modeling area to complete the initial calculation model construction.

4. The method for testing the damage zone of surrounding rock excavation in underground space according to claim 2, characterized in that, In step S4, the method for obtaining the three-dimensional wave velocity model of the surrounding rock includes: S404. During the excavation of the underground space in the test area, the time when the sensor collects ultrasonic test data and acoustic emission monitoring data of the surrounding rock target is recorded is... ; S405. Using the constructed initial calculation model, calculate the arrival time between the source point and the ultrasonic path based on the assigned nodal wave velocity and ray path, and record it as the theoretical arrival time. ; S406. Perform error analysis on the L2 norm of the difference between the theoretical arrival time and the observed arrival time of adjacent sensors; S407. Determine whether the error is less than the set minimum error; If so, proceed to step S408; If not, the initial computational model is then optimized using the constructed joint objective function containing strata and joints / fractures, and the process returns to step S404; the optimization parameters include grid node wave velocity and anisotropy. S408. Based on the current optimal parameters, obtain the three-dimensional wave velocity model of the surrounding rock.

5. The method for testing the damage zone of surrounding rock excavation in underground space according to claim 4, characterized in that, The error The calculation formula is: In the formula, the subscript Indicates the sensor index.

6. The method for testing the damage zone of surrounding rock excavation in underground space according to claim 4, characterized in that, In step S407, the joint objective function containing the strata and joints / fractures is: In the formula, Let m represent the joint objective function, and m represent the parameter matrix, which includes wave velocity and anisotropic parameters. , , This represents the weight coefficient of each sub-item. Represents the data fitting term. Represents the stratigraphic structure constraint terms. This represents the constraint terms for joint and fracture structures.

7. The method for testing the damage zone of surrounding rock excavation in underground space according to claim 2, characterized in that, Step S5 includes the following sub-steps: S501. In ultrasonic test data and acoustic emission monitoring data, the average value of 10 adjacent nodes in the vertical direction is taken as the P-wave velocity of the rock sample perpendicular to the sidewall, and the average value of 10 adjacent nodes in the parallel direction is taken as the rock sample velocity along the sidewall direction. S502. Calculate the comprehensive damage index of the corresponding area based on the P-wave velocity of the rock sample perpendicular to the sidewall and the wave velocity of the rock sample along the sidewall direction. S503. Based on the range of the comprehensive damage index of the rock sample, determine the damage level of the corresponding area and mark it in the three-dimensional wave velocity model of the surrounding rock to realize the test of the excavation damage zone.

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