Tunnel surrounding rock damage identification method for tectonic junction area
By applying geological logging, CT, SEM and XRD techniques in tectonic knot areas, multiple sampling and experiments were conducted on the tunnel surrounding rock to establish damage evaluation indicators. This solved the problems of low efficiency and insufficient accuracy of existing methods in tectonic knot areas, and achieved efficient and accurate identification of tunnel surrounding rock damage.
Patent Information
- Application Number
- CN202511737711.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-25
- Publication Date
- 2026-03-03
AI Technical Summary
In tectonic knot areas, existing acoustic detection methods are difficult to apply effectively due to problems such as difficulty in drilling, long experimental cycles, and large differences in results, resulting in low efficiency and inaccuracy in identifying damage to the surrounding rock of tunnels.
Combining macroscopic and microscopic parameters, geological logging, computed tomography (CT), scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques were used to conduct multiple samplings and experiments on the surrounding rock of the tunnel, establish a damage evaluation index for the surrounding rock, and determine the degree of damage through cluster analysis.
This paper presents a simple, economical, and accurate method for identifying tunnel surrounding rock damage, which expands its applicability under complex geological conditions and improves identification efficiency and accuracy.
Smart Images
Figure CN121595598A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of rock mass damage technology, and in particular to a method for identifying damage to the surrounding rock of tunnels in tectonic zones. Background Technology
[0002] Tunnel excavation damages the surrounding rock mass, increasing the risk of rock bursts, collapses, and other accidents, which can lead to serious construction safety incidents and pose a significant threat to the lives and property of construction workers. Because tunnel excavation creates artificial free faces, it disrupts the original stress state of the surrounding rock, causing stress redistribution. Therefore, timely damage identification of the surrounding rock mass is crucial for the layout of underground engineering axes, the selection of excavation methods, and the selection of appropriate support parameters.
[0003] However, the aforementioned problems are particularly prominent in special geological regions such as tectonic knots. A tectonic knot refers to the boundary region between one tectonic unit and multiple tectonic units, forming a geological unit by the superposition of multiple tectonic units within this region. In this geological tectonic region, frequent geological activity and repeated stress rotations lead to a high degree of damage within the rock mass.
[0004] Currently, acoustic wave detection is mainly used to identify the degree of rock mass damage. Its main principle is a testing technique based on the propagation of elastic waves within the rock mass. Specifically, a rock mass is left between the transmitter and receiver of the instrument, allowing sound waves to propagate within it for detection. By observing the changes in sound wave velocity, amplitude, and frequency due to factors such as rock mass structure, stress state, water content, and weathering degree, a preliminary assessment of the changes in the rock mass's mechanical properties can be made.
[0005] However, directly applying this method in tectonic knot areas presents the following problems: the method requires drilling holes in the surrounding rock of the tunnel before the experiment, but drilling holes in the fractured rock areas of tectonic knot areas is extremely difficult; moreover, there are no specific regulations in the existing technology regarding the arrangement of the acoustic boreholes, which leads to a significant impact of the borehole location on the results; in addition, to obtain detection information for a region, it is often necessary to repeat the experiment multiple times to determine the damage of the surrounding rock in the region. The long experimental cycle, dangerous experimental environment, and large differences in experimental results all make it difficult for acoustic detection methods to be effectively applied in tectonic knot areas.
[0006] Therefore, the field of geotechnical engineering urgently needs a time-saving, simple, fast and accurate method for identifying tunnel surrounding rock damage in areas with complex geological conditions and large areas of fractured surrounding rock, such as tectonic knots. Summary of the Invention
[0007] To address the shortcomings of the existing technologies, this invention, for the first time, incorporates macro- and micro-level parameters, including geological logging, computed tomography (CT), scanning electron microscopy (SEM), and X-ray diffraction (XRD), into a unified evaluation system. It proposes a method for identifying tunnel surrounding rock damage in tectonic knot regions, aiming to overcome the deficiencies of existing methods in tectonic knot regions, such as difficulty in implementation, low efficiency, and inaccurate results.
[0008] This invention proposes a method for identifying tunnel surrounding rock damage in tectonic knot areas, the method comprising the following steps:
[0009] For tunnel projects to be identified, during the tunnel excavation process, several representative mileage segments are continuously selected as observation areas at fixed mileage intervals.
[0010] For any observation area, geological reconnaissance of the observation area is conducted, geological information of the observation area is recorded, and a geological map is drawn.
[0011] According to the predefined sampling principles, the surrounding rock in the observation area was sampled multiple times, and the sampling locations were marked on the geological map of the observation area.
[0012] Multiple rock samples obtained in the observation area were subjected to X-ray diffraction (XRD), CT scanning, compressive strength testing, SEM scanning, and Raman spectroscopy. Based on the experimental data, the damage evaluation index of the surrounding rock mass in the observation area was determined.
[0013] Based on the surrounding rock mass damage evaluation parameters of all observation areas, the surrounding rock mass damage coefficient of each observation area is calculated separately.
[0014] By clustering the damage coefficients of the surrounding rock mass in all observation areas, a classification standard for the degree of surrounding rock damage in the tunnel project is established.
[0015] Based on the aforementioned grading standard for the degree of surrounding rock damage, the degree of surrounding rock damage in each observation area is determined according to the rock mass damage coefficient of each observation area.
[0016] Furthermore, the selection criteria for the representative mileage section are as follows: the mileage section includes different types and degrees of geological disasters that occur during tunnel excavation, and the mileage section contains different types of rocks and geological structures.
[0017] Furthermore, the geological information of the observation area includes: construction log information, surrounding rock damage information, geological structure information, surface image information of the surrounding rock, and geological information of structural surfaces;
[0018] The work content of the geological reconnaissance includes:
[0019] Record the construction log information of the observation area, and the construction log information shall include at least: the advance footage and the station number of the working face;
[0020] Record the surrounding rock damage information in the observation area. The surrounding rock damage information includes at least: the location of the damage, the type of damage, the degree of damage, the scale of damage, and the support scheme adopted in response to the damage.
[0021] Record geological structural information of the observation area, including at least: the type of structure, the scale of the structure, and the geological effects caused by the structure during construction;
[0022] Full coverage point-by-point photography of the longitudinal profile of the tunnel within the observation area, ensuring overlapping areas between adjacent photos. Simultaneously, continuous video recording of the left side wall, left shoulder, arch, right shoulder, and right side wall of the tunnel within the observation area, and using all captured images and videos as surface image information of the surrounding rock.
[0023] Record the geological information of the structural surfaces in the observation area. The relevant geological information includes at least: the attitude information, spatial location information, mechanical properties, rock mass structural characteristics, and water discharge conditions of the structural surfaces; wherein the attitude information includes: dip angle and dip direction; the spatial location information includes: station number and location; the mechanical properties include: opening degree, infill material condition, undulation state, and roughness; the rock mass structural characteristics include: quartz bands, dark bands, gneiss, and plate cracks, and record their respective attitudes and widths; the water discharge conditions include: dripping, gushing, and inrushing water.
[0024] Furthermore, the method for drawing the geological map is as follows:
[0025] Using the tunnel cross-section as the clock face and the tunnel arch direction as the 12 o'clock direction, establish a clock coordinate system and draw the tunnel axial distribution diagram.
[0026] Along the tunnel mileage within the observation area, the observation area is divided into several mileage segments according to a preset interval;
[0027] The geological information corresponding to each mileage segment is marked one by one on the tunnel axial distribution map to generate a geological map of each mileage segment, thereby obtaining a geological map of the observation area.
[0028] Furthermore, the predefined sampling principle is as follows: in each sampling process, four types of rock samples are taken from the observation area as a group of rock samples, and the volume of each rock sample is not less than 15cm×15cm×15cm. The sampling rules for each type of rock sample are as follows:
[0029] Sampling principles for single-lithological rock samples: Sampling should be carried out on different types of rocks within the observation area, and the sampling locations for each type of rock should be distributed at different locations on the cave ceiling and cave wall, with no fewer than 3 samples taken at the same sampling location.
[0030] Sampling principles for rock samples at lithologic interfaces: At least three different sampling locations should be selected at the lithologic interface within the observation area, and each rock sample should contain two or more lithologies.
[0031] Sampling principles for mineral banded rock samples: Within the observation area, samples should be taken from the interior of the mineral bands, with a minimum of 3 samples per band.
[0032] Sampling principles for rock samples from the surrounding rock failure area: For the surrounding rock failure area within the observation area, samples shall be taken at the failure center and the edge of the failure area, and the number of samples taken at the same sampling location shall not be less than 3.
[0033] Furthermore, the multiple rock samples obtained in the observation area were subjected to X-ray diffraction (XRD), CT scanning, compressive strength testing, SEM scanning, and Raman spectroscopy, respectively. Based on the obtained experimental data, the specific content of the surrounding rock mass damage evaluation index for the observation area was determined as follows:
[0034] A set of rock samples obtained from the observation area were selected, and rock composition analysis was performed on the rock samples using X-ray diffraction (XRD) experiments to determine the rock species within the observation area. The number of rock species within the observation area was then used as a rock species parameter. ;
[0035] A set of rock samples was selected from the observation area, and CT scans were performed on these samples. Based on the scan results, the number of open microfractures per unit volume for each type of rock sample was counted. The maximum value among all counted open microfractures was then used as the microfracture density parameter within the rock mass. ;
[0036] A set of rock samples was selected from the observation area, and their compressive strength was tested. The compressive strength of different rock samples was obtained, and the highest compressive strength value was selected as the rock compressive strength parameter. ;
[0037] A set of rock samples obtained from the observation area were selected, and SEM scanning was performed on the rock samples. Based on the scanning results, the rock fracture mode of the rock samples was determined, and then the rock fracture mode was defined as the rock fracture mode parameter. The rock fracture modes include: mixed failure modes and single fracture modes;
[0038] A set of rock samples was selected from the observation area, and Raman experiments were performed on the samples to obtain Raman spectra of different rock samples. By comparing and analyzing the differences in peak positions, it was determined whether the rocks had been altered, and then the alteration coefficient was determined based on the results. ;in The value can be either unaltered or altered.
[0039] The obtained rock type parameters Density parameters of microfractures inside the rock mass Rock compressive strength parameters Rock fracture mode parameters and alteration coefficient As a parameter for evaluating the damage of the surrounding rock mass in the observation area.
[0040] Furthermore, the specific details of calculating the damage coefficient of the surrounding rock mass for each observation area based on the surrounding rock mass damage evaluation index for all observation areas are as follows:
[0041] For any observation area, based on the surrounding rock mass damage evaluation index of all observation areas, the surrounding rock mass damage evaluation parameters of the observation area are standardized to obtain the standardized score of the surrounding rock mass damage evaluation of the observation area.
[0042] The objective weight of each standardized score in the standardized score of the surrounding rock mass damage evaluation in this observation area was calculated using the CRITIC weighting method.
[0043] Based on the calculated objective weight of each standardized score, the standardized scores for the surrounding rock mass damage evaluation of the observation area are weighted and summed to obtain the damage coefficient of the surrounding rock mass in the observation area. .
[0044] Furthermore, the standardization process is as follows:
[0045] Rock type parameters of the observation area Density parameters of microfractures inside the rock mass Rock compressive strength parameters Each rock type is mapped to a unified interval to obtain a standardized score for the rock type in the observation area. Standardized scoring of microfracture density within the rock mass Standardized score of rock compressive strength ;
[0046] If the rock fracture mode parameters in this observation area If the fracture mode is a single fracture mode, then the standardized score of the rock fracture mode in this observation area is... Take 0.5; if the rock fracture mode parameters in this observation area If the fracture mode is mixed, then the normalized score of the rock fracture mode in this observation area is... Take 1;
[0047] If the alteration coefficient of the observation area If no alteration is observed, then the alteration-standardized score for that observation area is... Set to 0; if the alteration coefficient of the observation area is... If it is alteration, then the alteration standardized score for this observation area is... Take 1;
[0048] Standardized scoring of rock types Standardized scoring of microfracture density within the rock mass Standardized scoring of rock compressive strength Standardized scoring of rock fracture modes and alteration standardized score This serves as a standardized score for evaluating the damage to the surrounding rock mass in the observation area.
[0049] Furthermore, the specific content of establishing the grading standard for the degree of surrounding rock damage in the tunnel project by clustering the damage coefficients of the surrounding rock mass in all observation areas is as follows:
[0050] The K-means clustering method was used to divide the damage coefficients of the surrounding rock mass in all observation areas into three clusters, and the centroid of each cluster was calculated after the clustering was completed.
[0051] Arrange the centroids of the three clusters in descending order of numerical value, and define the three clusters as high damage, medium damage and low damage in the order of arrangement to establish a classification standard for the degree of surrounding rock damage in the tunnel project.
[0052] The beneficial effects of adopting the above technical solution are as follows:
[0053] This invention proposes a method for identifying tunnel surrounding rock damage in tectonic knot areas. Compared with existing methods, this method offers a new approach that considers a series of identification methods from macroscopic to microscopic perspectives for tectonic knot areas. Compared with other methods, this method can more simply, economically, and conveniently determine the degree of rock mass damage. Furthermore, this method expands the applicability of surrounding rock damage identification methods and facilitates their widespread application in underground engineering. Attached Figure Description
[0054] Figure 1 This is a flowchart of a tunnel surrounding rock damage identification method for tectonic knot areas in this embodiment;
[0055] Figure 2 This is a schematic diagram illustrating a method for identifying tunnel surrounding rock damage in tectonic knot areas, as described in this embodiment.
[0056] Figure 3 This is a geological map of the observation area drawn in this embodiment;
[0057] Figure 4 These are schematic diagrams of rock samples taken on-site in this embodiment; (a) is a schematic diagram of a white granite sample; (b) is a schematic diagram of a black granite sample; (c) is a schematic diagram of a quartz sample; and (d) is a schematic diagram of a fractured granite sample.
[0058] Figure 5 The following are the CT scan results in this embodiment; (a) is the scan result of sample No. 1, a black granite sample; (b) is the scan result of sample No. 2, which has developed quartz bands; (c) is the scan result of sample No. 3, a lithological interface sample; and (d) is the scan result of sample No. 4, a thick quartz band sample.
[0059] Figure 6 The following are SEM scan results of the destruction near the lithological interface in this embodiment; (a) is the SEM scan result of the black granite rock sample; (b) is the SEM scan result of the white granite rock sample; and (c) is the SEM scan result of the rock sample at the lithological interface.
[0060] Figure 7 The following are the SEM scan results of the granite sample in this embodiment; where (a) is a rock structure growth direction diagram; (b) is a transgranular failure result diagram; and (c) is a translational slip line phenomenon diagram.
[0061] Figure 8 The images show the SEM scan results of quartz stripe damage in this embodiment; where (a) is an intergranular fracture diagram; and (b) is a diagram of the micropore structure inside the rock.
[0062] Figure 9 The following are the SEM experimental results of rock mass failure in the fractured zone in this embodiment; where (a) is the transgranular failure diagram; and (b) is the internal damage diagram of the rock mass.
[0063] Figure 10 The results are from the Raman experiment in this embodiment. Detailed Implementation
[0064] To facilitate understanding of this application, specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments. The following embodiments are illustrative of the invention but are not intended to limit its scope. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.
[0065] Example 1:
[0066] This embodiment presents a method for identifying tunnel surrounding rock damage in tectonic knot areas, such as... Figure 1 and Figure 2 As shown, the method includes the following steps:
[0067] For tunnel projects to be identified, during the tunnel excavation process, several representative mileage segments are selected continuously at fixed mileage intervals as observation areas.
[0068] The selection criteria for the representative mileage section are as follows: the mileage section includes different types and degrees of geological disasters that occur during tunnel excavation, and the mileage section contains different types of rocks and geological structures.
[0069] In this embodiment, taking a deep-buried TBM tunnel in the eastern Himalayan tectonic knot region as an example, a 200m section representing the surrounding rock information during tunnel excavation is selected as an observation area, with another observation area selected every 50m to update the degree of rock mass damage in a timely manner. The observation area should include different types and degrees of hazards occurring during tunnel excavation, such as rock bursts, collapses, spalling, and rockfalls, as well as different types of rocks and mineral veins and geological structures within the tunnel mileage, such as faults and folds. A geological map is drawn as follows. Figure 3 .
[0070] For any observation area, geological reconnaissance is conducted to record the geological information of the observation area and draw a geological map.
[0071] The geological information of the observation area includes: construction log information, surrounding rock damage information, geological structure information, surface image information of the surrounding rock, and geological information of structural surfaces.
[0072] The work content of the geological reconnaissance includes:
[0073] Record the construction log information of the observation area, which includes at least the advance footage and the station number of the working face.
[0074] Record the surrounding rock damage information in the observation area. The surrounding rock damage information includes at least: the location of the damage, the type of damage, the degree of damage, the scale of damage, and the support scheme adopted in response to the damage.
[0075] Record geological structural information of the observation area, including at least: the type of structure, the scale of the structure, and the geological effects caused by the structure during construction.
[0076] Full-coverage point-by-point photography of the longitudinal profile of the tunnel within the observation area was carried out, ensuring that there were overlapping areas between adjacent photos. At the same time, continuous video recordings were made of the left tunnel wall, left arch shoulder, arch crown, right arch shoulder, and right tunnel wall within the observation area, and all the captured images and videos were used as surface image information of the surrounding rock.
[0077] Record the geological information of the structural surfaces in the observation area. The relevant geological information includes at least: the occurrence information, spatial location information, mechanical properties, rock mass structural characteristics and water discharge conditions of the structural surfaces.
[0078] The occurrence information includes dip angle and dip direction; the spatial positioning information includes station number and location; the mechanical properties include opening degree, infill material condition, undulation state and roughness; the rock mass structural features include quartz bands, dark bands, gneiss and plate cracks, and their respective occurrence and width are recorded; the water discharge conditions include drip, stream and inrush.
[0079] In this embodiment, a geological reconnaissance is conducted in the observation area. The main tasks of the geological reconnaissance include:
[0080] 1) Record the construction log for the tunnel observation mileage section, including construction information such as advance measurement and face station number.
[0081] 2) Record information on surrounding rock damage, including the location, type, degree, scale of damage, and support scheme.
[0082] 3) Record geological structure information within the observation mileage range, including structure type, scale, and impact on construction.
[0083] 4) Record the overall condition of the surrounding rock by taking surface images. Specifically, take photos of each observable point in the tunnel's longitudinal section from 0 to 12 o'clock, ensuring overlap between adjacent points to guarantee data integrity. Record video of the left tunnel wall, left arch shoulder, arch crown, right arch shoulder, and right tunnel wall.
[0084] 5) Record other relevant geological information during the observation period, such as: the station number, location, dip angle, and dip direction of the structural plane; properties including whether it is closed or slightly open or open, whether it is filled and the description of the filling material, whether it is straight or slightly undulating or undulating, whether it is smooth or slightly rough or rough; the occurrence and width of quartz bands, dark bands, foliation and slab cracks; water outflow conditions, including dripping, streaking and gushing water.
[0085] The method for drawing the geological map is as follows:
[0086] Using the tunnel cross-section as the clock face and the tunnel arch direction as the 12 o'clock direction, establish a clock coordinate system and draw the tunnel axial distribution diagram.
[0087] The observation area is divided into several mileage segments along the tunnel mileage within the observation area according to a preset interval.
[0088] The geological information corresponding to each mileage segment is marked one by one on the tunnel axial distribution map to generate a geological map of each mileage segment, thereby obtaining a geological map of the observation area.
[0089] In this embodiment, the geological map is drawn as follows: The tunnel cross-section is divided into 0-12 o'clock directions according to clockwise orientation, and the tunnel axial distribution diagram is drawn with the 0 o'clock direction as the center. Based on the recorded overall information of the surrounding rock, the starting position of the structural plane, the range of disaster occurrence, water outlet points, and other surrounding rock information are marked on the geological map using different methods and colors of annotation. Geological information maps are drawn for every 50-meter recording interval.
[0090] Based on predefined sampling principles, multiple samples were taken from the surrounding rock within the observation area, and the sampling locations were marked on the geological map of the observation area.
[0091] The predefined sampling principle is as follows: In each sampling process, four types of rock samples are taken from the observation area as a group of rock samples, and the volume of each rock sample is not less than 15cm×15cm×15cm. The sampling rules for each type of rock sample are as follows:
[0092] Sampling principles for single-lithological rock samples: Sampling should be carried out on different types of rocks within the observation area, with each type of rock sampled at different locations on the cave ceiling and cave walls, and at least 3 samples taken from the same sampling location.
[0093] Sampling principles for rock samples at lithologic interfaces: At least three different sampling locations should be selected at the lithologic interface within the observation area, and each rock sample should contain two or more lithologies.
[0094] Sampling principles for mineral banded rock samples: Within the observation area, samples should be taken from the interior of the mineral bands, with a minimum of 3 samples per band.
[0095] Sampling principles for rock samples from the surrounding rock failure area: For the surrounding rock failure area within the observation area, samples shall be taken at the failure center and the edge of the failure area, and the number of samples taken at the same sampling location shall not be less than 3.
[0096] In this embodiment, some samples of the surrounding rock obtained within the observation area are as follows: Figure 4 As shown, the sampling principle is as follows:
[0097] For different types of rocks, samples were taken from different locations on the cave ceiling and cave wall, with no fewer than 3 samples taken from the same location, and the sample volume was no less than 15cm×15cm×15cm.
[0098] At least three different locations should be selected at the lithological interface to take samples, ensuring that each sample contains two or more lithologies and that the sample volume is not less than 15cm×15cm×15cm.
[0099] Take samples from inside the mineral bands, with a minimum of 3 samples and a sample volume of at least 15cm×15cm×15cm.
[0100] For hazards such as rockbursts, samples should be taken at both the center and the edge of the damage. At least three samples should be taken from the same location, with each sample measuring at least 15cm × 15cm × 15cm.
[0101] The location of the obtained sample is compared with the drawn geological map, and the sampling location is marked on the geological map.
[0102] Multiple rock samples obtained in the observation area were subjected to X-ray diffraction (XRD), CT scanning, compressive strength testing, SEM scanning, and Raman spectroscopy. Based on the experimental data, the damage evaluation index of the surrounding rock mass in the observation area was determined.
[0103] The multiple rock samples obtained in the observation area were subjected to X-ray diffraction (XRD), CT scan, compressive strength testing, SEM (semiconductor electron microscopy), and Raman spectroscopy experiments. Based on the obtained experimental data, the specific content of the surrounding rock mass damage evaluation index for the observation area was determined as follows:
[0104] A set of rock samples obtained from the observation area were selected, and rock composition analysis was performed on the rock samples using X-ray diffraction (XRD) experiments to determine the rock species within the observation area. The number of rock species within the observation area was then used as a rock species parameter. .
[0105] In this embodiment, 5g of sample was weighed from each type of rock sample, ground into powder, and then subjected to XRD experiment to detect the internal composition of the rock and determine the main rock types inside the tunnel. The experimental results are shown in Table 1.
[0106] Table 1. XRD experimental results of rock samples
[0107]
[0108] The above experimental results indicate that the surrounding rock inside a deep-buried TBM tunnel in the eastern Himalayan tectonic knot region is mainly composed of muscovite granite and biotite granite mixed with quartz bands, with some localized fractured granite, totaling four rock types. .
[0109] A set of rock samples was selected from the observation area, and CT scans were performed on these samples. Based on the scan results, the number of open microfractures per unit volume for each type of rock sample was counted. The maximum value among all counted open microfractures was then used as the microfracture density parameter within the rock mass. .
[0110] In this embodiment, the rock samples used for CT scanning experiments should include: single-lithology rock samples, mineral-banded rock samples, and rock samples from the surrounding rock failure area. CT scanning experiments are performed on the rock samples, and the experimental results are as follows: Figure 5 As shown, where Figure 5 As shown in (a), sample No. 1, a black granite, has a few through-type fractures, which cause significant damage to the rock mass and weaken its stability. Furthermore, the presence of hidden quartz bands within it significantly impacts its overall strength. Sample No. 2, with its quartz bands, exhibits more pronounced and numerous micro-fractures that intersect at large angles, greatly affecting the overall stability of the rock mass and making it prone to significant damage. Figure 5 As shown in (b), the No. 3 lithological interface sample has almost no microfractures, exhibits high overall integrity, and is not prone to structural damage. Figure 5 As shown in (c), the No. 4 thick-layered quartz banded sample has fewer internal microfractures that do not penetrate the entire rock mass, such as... Figure 5 As shown in (d). However, CT results revealed that the internal quartz bands were all connected in a dendritic pattern, and cutting the surrounding black granite would easily cause structural damage, such as... Figure 5 As shown. By statistically analyzing the number of open microfractures in the rock samples, every 0.01m... 3 Five open microfractures were found in the rock mass. .
[0111] A set of rock samples was selected from the observation area, and their compressive strength was tested. The compressive strength of different rock samples was obtained, and the highest compressive strength value was selected as the rock compressive strength parameter. .
[0112] In this embodiment, rock samples of different types were taken for compressive strength testing. The rock samples were cut into cuboids of 5mm × 5mm × 7mm using a diamond wire cutter, with at least three samples per sample. A compressor was used to apply pressure at a rate of 0.1mm / min to obtain the compressive strength of different rock types. The experimental results are shown in Table 2. As shown in Table 2, the highest rock compressive strength of 64 MPa was selected as the rock compressive strength parameter. .
[0113] Table 2 Typical compressive strength of surrounding rock
[0114]
[0115] A set of rock samples obtained from the observation area were selected, and SEM scanning was performed on the rock samples. Based on the scanning results, the rock fracture mode of the rock samples was determined, and then the rock fracture mode was defined as the rock fracture mode parameter. The rock fracture modes include: mixed failure modes and single fracture modes.
[0116] In this embodiment, the rock samples used for SEM scanning should include: natural fracture surfaces of rocks of different lithologies, fracture surfaces at lithological boundaries, and fracture surfaces generated within areas damaged by disasters such as rockbursts. For each rock sample, a 1cm × 1cm × 0.1cm sample is taken for SEM scanning. Analysis of the SEM scanning results shows that:
[0117] like Figure 6 As shown, in areas where failure occurs near the lithological interface, the black granite generally exhibits a thin-layered, tabular structure, such as... Figure 6 (a) The main fracture mode is a mixture of intergranular and transgranular fracture, and the fracture mechanism is a mixture of tension and shear. White granite mainly exhibits strong transgranular fracture with intense shear failure, such as... Figure 6 As shown in (b), the two lithological failure modes differ significantly at the lithological interface, and the structural plane is extremely unstable, such as... Figure 6 As shown in (c).
[0118] like Figure 7 As shown, the fractured granite fracture surface is mainly characterized by transgranular failure and mixed intergranular failure. The fracture mechanism is tensile fracture, with obvious thin-layered plate-like structure and translational slip lines. The growth directions of the structure intersect at large angles, which may be due to multiple changes in the direction of geostress during tectonic movement, making it prone to intergranular failure.
[0119] like Figure 8As shown, when the quartz bands are damaged, the cross-section crystals are granular, the structure is well preserved, and it exhibits obvious strong brittle intergranular fracture. This intergranular fracture is caused by tensile failure due to tensile stress. There are also a large number of tiny pore structures, which may be bubbles formed when magma intrudes and encounters seawater and rapidly cools.
[0120] like Figure 9 As shown, when the rock mass in the fractured zone is damaged, the cross-section is relatively flat and smooth, showing obvious transgranular damage, which is mainly caused by shear failure.
[0121] In summary, the rock mass fracture mode in the current observation area is recorded as mixed failure, and it is determined that... .
[0122] A set of rock samples was selected from the observation area, and Raman experiments were performed on the samples to obtain Raman spectra of different rock samples. By comparing and analyzing the differences in peak positions, it was determined whether the rocks had been altered, and then the alteration coefficient was determined based on the results. ;in The value can be either unaltered or altered.
[0123] In this embodiment, Raman experiments were conducted on rock samples of different types. The different rock samples were pulverized into powder using a pulverizer, placed in a Raman spectrometer, and the laser wavelength and power were selected. The optical path was adjusted to start the device for Raman spectroscopy measurement, and the peak positions of the Raman spectra were recorded. Figure 10 As shown. A comparative analysis of the peak positions of various rocks is conducted, and the alteration coefficient is obtained by determining whether the rocks have undergone alteration based on the peak position and number of peaks. .
[0124] The obtained rock type parameters Density parameters of microfractures inside the rock mass Rock compressive strength parameters Rock fracture mode parameters and alteration coefficient As an indicator for evaluating the damage of the surrounding rock mass in the observation area.
[0125] Based on the surrounding rock mass damage evaluation index of all observation areas, the surrounding rock mass damage coefficient of each observation area is calculated.
[0126] The specific details of calculating the damage coefficient of the surrounding rock mass for each observation area based on the surrounding rock mass damage evaluation index of all observation areas are as follows:
[0127] For any observation area, based on the surrounding rock mass damage evaluation index of all observation areas, the surrounding rock mass damage evaluation parameters of the observation area are standardized to obtain the standardized score of the surrounding rock mass damage evaluation of the observation area.
[0128] The standardization process is as follows:
[0129] Rock type parameters of the observation area Density parameters of microfractures inside the rock mass Rock compressive strength parameters Each rock type is mapped to a unified interval to obtain a standardized score for the rock type in the observation area. Standardized scoring of microfracture density within the rock mass Standardized score of rock compressive strength .
[0130] In this embodiment, to eliminate the influence of different units on the results, it is necessary to standardize each indicator so that the parameter values are mapped to... Within the interval, we obtain The mapping formula is shown below:
[0131]
[0132] in express , and The amount of data corresponding to any one of the indicators; express , and The minimum value of any one of the indicators; express , and The maximum value of any one of the indicators; express , and any one of the indicators The j-th data point is the original data before normalization; express , and any one of the indicators The standardized score obtained after normalization of the j-th data point.
[0133] If the rock fracture mode parameters in this observation area If the fracture mode is a single fracture mode, then the standardized score of the rock fracture mode in this observation area is... Take 0.5; if the rock fracture mode parameters in this observation area If the fracture mode is mixed, then the normalized score of the rock fracture mode in this observation area is... Take 1.
[0134] If the alteration coefficient of the observation area If no alteration is observed, then the alteration-standardized score for that observation area is... Set to 0; if the alteration coefficient of the observation area is... If it is alteration, then the alteration standardized score for this observation area is... Take 1.
[0135] In this embodiment, due to and This is a qualitative indicator, therefore... and Quantified into standardized scores, denoted as and .
[0136] Standardized scoring of rock types Standardized scoring of microfracture density within the rock mass Standardized scoring of rock compressive strength Standardized scoring of rock fracture modes and alteration standardized score This serves as a standardized score for evaluating the damage to the surrounding rock mass in the observation area.
[0137] The objective weight of each standardized score in the standardized score for the evaluation of damage to the surrounding rock mass in the observation area was calculated using the CRITIC weighting method.
[0138] In this embodiment, for any standardized score in the standardized scoring of surrounding rock mass damage evaluation, the standard deviation is used to represent the index difference, that is, the standard deviation of the current standardized score is calculated, as shown in the following formula:
[0139]
[0140]
[0141] in Indicates the first The average of the standardized scores; Let represent the standard deviation of the i-th standardized score.
[0142] The correlation coefficient is used to represent the conflict of indicators. That is, the correlation coefficient between the current standardized score and the other standardized scores in the standardized score of the surrounding rock mass damage evaluation is calculated separately. The calculation formula is as follows:
[0143]
[0144] in Indicates the first The standardized score and the first The correlation coefficient between the standardized scores, and , This indicates the number of standardized scores in the standardized scoring of the surrounding rock mass damage assessment. The first The j-th data point corresponding to each standardized score; Indicates the first The average of the standardized scores;
[0145] Based on the correlation coefficient between the current standardized score and the other standardized scores in the standardized score for surrounding rock mass damage assessment, the conflict coefficient of the current standardized score is calculated and expressed as:
[0146]
[0147] in Let represent the conflict coefficient of the i-th standardized score.
[0148]
[0149] in For the first The amount of information in a standardized score. The larger the value, the greater the role of the i-th standardized score in the entire evaluation index system, and the more weight it should be assigned, i.e.:
[0150]
[0151] in is the objective weight of the i-th standardized score.
[0152] Based on the calculated objective weight of each standardized score, the standardized scores for the surrounding rock mass damage evaluation of the observation area are weighted and summed to obtain the damage coefficient of the surrounding rock mass in the observation area. .
[0153] The damage coefficient of the surrounding rock mass The calculation method is as follows:
[0154]
[0155] in , , , and They are respectively , , , and Objective weighting.
[0156] In this embodiment, for the acquired multiple sets Parameters are used to record the damage status of the corresponding surrounding rock mass. The CRITIC method is used to analyze these parameters. Additional weights are applied to comprehensively measure the impact of the indicators on the damage coefficient of the surrounding rock mass, and the damage coefficient Q of the surrounding rock mass is calculated.
[0157] By clustering the damage coefficients of the surrounding rock mass in all observation areas, a classification standard for the degree of surrounding rock damage in the tunnel project is established.
[0158] The specific content of establishing the grading standard for the degree of surrounding rock damage in the tunnel project by clustering the damage coefficients of the surrounding rock mass in all observation areas is as follows:
[0159] The K-means clustering method was used to divide the damage coefficients of the surrounding rock mass in all observation areas into three clusters, and the centroid of each cluster was calculated after the clustering was completed.
[0160] Arrange the centroids of the three clusters in descending order of numerical value, and define the three clusters as high damage, medium damage and low damage in the order of arrangement to establish a classification standard for the degree of surrounding rock damage in the tunnel project.
[0161] In this embodiment, after collecting and organizing multiple sets of data, the collected data are clustered into 3 clusters according to the K-means clustering method, as shown in the following formula:
[0162]
[0163] in The core objective function of the K-means clustering algorithm is to adjust the cluster partitioning to achieve the desired cluster size. Minimize the value of ; K is the number of clusters; This is the cluster index value; Let m be the data point set of the m-th cluster; for Data points within; Let be the centroid of the m-th cluster. The damage coefficients of the surrounding rock mass were obtained by standardizing and clustering the collected data, as shown in Table 3 below.
[0164] Table 3. Degree of damage to surrounding rock mass
[0165]
[0166] Based on the aforementioned grading standard for the degree of surrounding rock damage, the degree of surrounding rock damage in each observation area is determined according to the rock mass damage coefficient of each observation area.
[0167] In this embodiment, the standardized score for the damage assessment of the surrounding rock mass in the current observation area is calculated based on the above experimental results as follows: , , , and The weight values are calculated using the CRITIC method. , , , and Therefore, the damage coefficient of the surrounding rock mass in the current observation area is calculated as follows: As shown in Table 1, the degree of damage to the surrounding rock in the current observation area is moderate.
[0168] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope defined by the present invention.
Claims
1. A method for identifying tunnel surrounding rock damage in tectonic knot areas, characterized in that, This method includes the following steps: For tunnel projects to be identified, during the tunnel excavation process, several representative mileage segments are continuously selected as observation areas at fixed mileage intervals. For any observation area, geological reconnaissance of the observation area is conducted, geological information of the observation area is recorded, and a geological map is drawn. According to the predefined sampling principles, the surrounding rock in the observation area was sampled multiple times, and the sampling locations were marked on the geological map of the observation area. Multiple rock samples obtained in the observation area were subjected to X-ray diffraction (XRD), CT scan, compressive strength testing, SEM scanning, and Raman spectroscopy. Based on the experimental data, the damage evaluation index of the surrounding rock mass in the observation area was determined. Based on the surrounding rock mass damage evaluation parameters of all observation areas, the surrounding rock mass damage coefficient of each observation area is calculated separately. By clustering the damage coefficients of the surrounding rock mass in all observation areas, a classification standard for the degree of surrounding rock damage in the tunnel project is established. Based on the aforementioned grading standard for the degree of surrounding rock damage, the degree of surrounding rock damage in each observation area is determined according to the rock mass damage coefficient of each observation area.
2. The method for identifying tunnel surrounding rock damage in tectonic knot areas according to claim 1, characterized in that, The selection criteria for the representative mileage section are as follows: the mileage section includes different types and degrees of geological disasters that occur during tunnel excavation, and the mileage section contains different types of rocks and geological structures.
3. The method for identifying tunnel surrounding rock damage in tectonic knot areas according to claim 2, characterized in that, The geological information of the observation area includes: construction log information, surrounding rock damage information, geological structure information, surface image information of the surrounding rock, and geological information of structural surfaces; The work content of the geological reconnaissance includes: Record the construction log information of the observation area, and the construction log information shall include at least: the advance footage and the station number of the working face; Record the surrounding rock damage information in the observation area. The surrounding rock damage information includes at least: the location of the damage, the type of damage, the degree of damage, the scale of damage, and the support scheme adopted in response to the damage. Record geological structural information of the observation area, including at least: the type of structure, the scale of the structure, and the geological effects caused by the structure during construction; Full coverage point-by-point photography of the longitudinal profile of the tunnel within the observation area, ensuring overlapping areas between adjacent photos. Simultaneously, continuous video recording of the left side wall, left shoulder, arch, right shoulder, and right side wall of the tunnel within the observation area, and using all captured images and videos as surface image information of the surrounding rock. Record the geological information of the structural surfaces in the observation area. The relevant geological information includes at least: the attitude information, spatial location information, mechanical properties, rock mass structural characteristics, and water discharge conditions of the structural surfaces; wherein the attitude information includes: dip angle and dip direction; the spatial location information includes: station number and location; the mechanical properties include: opening degree, infill material condition, undulation state, and roughness; the rock mass structural characteristics include: quartz bands, dark bands, gneiss, and plate cracks, and record their respective attitudes and widths; the water discharge conditions include: dripping, gushing, and inrushing water.
4. The method for identifying tunnel surrounding rock damage in tectonic knot areas according to claim 3, characterized in that, The method for drawing the geological map is as follows: Using the tunnel cross-section as the clock face and the tunnel arch direction as the 12 o'clock direction, establish a clock coordinate system and draw the tunnel axial distribution diagram. Along the tunnel mileage within the observation area, the observation area is divided into several mileage segments according to a preset interval; The geological information corresponding to each mileage segment is marked one by one on the tunnel axial distribution map to generate a geological map of each mileage segment, thereby obtaining a geological map of the observation area.
5. The method for identifying tunnel surrounding rock damage in tectonic knot areas according to claim 4, characterized in that, The predefined sampling principle is as follows: In each sampling process, four types of rock samples are taken from the observation area as a group of rock samples, and the volume of each rock sample is not less than 15cm×15cm×15cm. The sampling rules for each type of rock sample are as follows: Sampling principles for single-lithological rock samples: Sampling should be carried out on different types of rocks within the observation area, and the sampling locations for each type of rock should be distributed at different locations on the cave ceiling and cave wall, with no fewer than 3 samples taken at the same sampling location. Sampling principles for rock samples at lithologic interfaces: At least three different sampling locations should be selected at the lithologic interface within the observation area, and each rock sample should contain two or more lithologies. Sampling principles for mineral banded rock samples: Within the observation area, samples should be taken from the interior of the mineral bands, with a minimum of 3 samples per band. Sampling principles for rock samples from the surrounding rock failure area: For the surrounding rock failure area within the observation area, samples shall be taken at the failure center and the edge of the failure area, and the number of samples taken at the same sampling location shall not be less than 3.
6. The method for identifying tunnel surrounding rock damage in tectonic knot areas according to claim 5, characterized in that, The various rock samples obtained within the observation area were subjected to X-ray diffraction (XRD), CT scan, compressive strength testing, SEM (semiconductor electron microscopy), and Raman spectroscopy experiments. Based on the obtained experimental data, the specific content of the surrounding rock mass damage evaluation index for the observation area was determined as follows: A set of rock samples obtained from the observation area were selected, and rock composition analysis was performed on the rock samples using X-ray diffraction (XRD) experiments to determine the rock species within the observation area. The number of rock species within the observation area was then used as a rock species parameter. ; A set of rock samples was selected from the observation area, and CT scans were performed on these samples. Based on the scan results, the number of open microfractures per unit volume for each type of rock sample was counted. The maximum value among all counted open microfractures was then used as the microfracture density parameter within the rock mass. ; A set of rock samples was selected from the observation area, and their compressive strength was tested. The compressive strength of different rock samples was obtained, and the highest compressive strength value was selected as the rock compressive strength parameter. ; A set of rock samples obtained from the observation area were selected, and SEM scanning was performed on the rock samples. Based on the scanning results, the rock fracture mode of the rock samples was determined, and then the rock fracture mode was defined as the rock fracture mode parameter. ; The rock fracture modes include: mixed failure modes and single fracture modes; A set of rock samples was selected from the observation area, and Raman experiments were performed on the samples to obtain Raman spectra of different rock samples. By comparing and analyzing the differences in peak positions, it was determined whether the rocks had been altered, and then the alteration coefficient was determined based on the results. ;in The value can be either unaltered or altered. The obtained rock type parameters Density parameters of microfractures inside the rock mass Rock compressive strength parameters Rock fracture mode parameters and alteration coefficient As a parameter for evaluating the damage of the surrounding rock mass in the observation area.
7. The method for identifying tunnel surrounding rock damage in tectonic knot areas according to claim 6, characterized in that, The specific details of calculating the damage coefficient of the surrounding rock mass for each observation area based on the surrounding rock mass damage evaluation index of all observation areas are as follows: For any observation area, based on the surrounding rock mass damage evaluation index of all observation areas, the surrounding rock mass damage evaluation parameters of the observation area are standardized to obtain the standardized score of the surrounding rock mass damage evaluation of the observation area. The objective weight of each standardized score in the standardized score of the surrounding rock mass damage evaluation in this observation area was calculated using the CRITIC weighting method. Based on the calculated objective weight of each standardized score, the standardized scores for the surrounding rock mass damage evaluation of the observation area are weighted and summed to obtain the damage coefficient of the surrounding rock mass in the observation area. .
8. The method for identifying tunnel surrounding rock damage in tectonic knot areas according to claim 7, characterized in that, The standardization process is as follows: Rock type parameters of the observation area Density parameters of microfractures inside the rock mass Rock compressive strength parameters Each rock type is mapped to a unified interval to obtain a standardized score for the rock type in the observation area. Standardized scoring of microfracture density within the rock mass Standardized score of rock compressive strength ; If the rock fracture mode parameters in this observation area If the fracture mode is a single fracture mode, then the standardized score of the rock fracture mode in this observation area is... Take 0.5; if the rock fracture mode parameters in this observation area If the fracture mode is mixed, then the normalized score of the rock fracture mode in this observation area is... Take 1; If the alteration coefficient of the observation area If no alteration is observed, then the alteration-standardized score for that observation area is... Set to 0; if the alteration coefficient of the observation area is... If it is alteration, then the alteration standardized score for this observation area is... Take 1; Standardized scoring of rock types Standardized scoring of microfracture density within the rock mass Standardized scoring of rock compressive strength Standardized scoring of rock fracture modes and alteration standardized score This serves as a standardized score for evaluating the damage to the surrounding rock mass in the observation area.
9. The method for identifying tunnel surrounding rock damage in tectonic knot areas according to claim 8, characterized in that, The specific content of establishing the grading standard for the degree of surrounding rock damage in the tunnel project by clustering the damage coefficients of the surrounding rock mass in all observation areas is as follows: The K-means clustering method was used to divide the damage coefficients of the surrounding rock mass in all observation areas into three clusters, and the centroid of each cluster was calculated after the clustering was completed. Arrange the centroids of the three clusters in descending order of numerical value, and define the three clusters as high damage, medium damage and low damage in the order of arrangement to establish a classification standard for the degree of surrounding rock damage in the tunnel project.