A tunnel grouting hole analysis method based on spatial crack correlation analysis

Abstract

The present invention belongs to the technical field of tunnel fissure grouting hole layout, and discloses a tunnel grouting hole layout analysis method for spatial fissure correlation analysis. By scanning the distribution position and geometric contour of the cracks in the surrounding rock of the tunnel face, a crack connection network is constructed, and the actual water conduction path is identified in combination with a pumping test, and grouting ports are arranged at its key nodes to achieve precise matching of grouting holes and seepage channels. The scientificity and pertinence of the hole layout can be improved by integrating the spatial distribution of the cracks with the hydraulic connectivity, and the sealing ability of the slurry on the water-conducting cracks can be significantly enhanced, which is beneficial to improving the grouting efficiency and the water-stopping effect. At the same time, on the basis of arranging the grouting holes based on the hydraulic connection path, the neck features of each crack in the crack connection network are further identified and segmented. Therefore, the supplementary arrangement of the grouting ports is implemented in combination with the relative relationship between the spatial position of such segments and the existing grouting holes, thereby realizing the refined and dynamically optimized arrangement of the grouting ports.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel fissure grouting hole arrangement, and specifically discloses a tunnel grouting hole arrangement analysis method for spatial fissure correlation analysis. Background Art

[0002] During tunnel construction, when crossing complex geological conditions such as fault fracture zones or areas with developed joints, numerous cracks often develop in the rock mass. This results in a loose surrounding rock structure and poor self-stabilization, which can easily lead to geological hazards such as collapse and block fall, seriously threatening construction safety and hindering project progress. To effectively address these challenges, fissure grouting technology is widely used in engineering practice. By injecting grout into the cracks to fill, cement, and reinforce them, it improves the overall stability and bearing capacity of the surrounding rock, ensuring safe and controllable tunnel construction and operation.

[0003] Grouting hole layout is a key factor influencing grouting effectiveness. Whether grouting can achieve the desired reinforcement goal depends largely on whether the grout can effectively fill and seal the fracture network in the rock mass. Therefore, before grouting operations, it is necessary to detect the spatial distribution characteristics of fractures and formulate a reasonable grouting hole layout plan based on this information.

[0004] Currently, relevant technologies have proposed solutions to the problem of tunnel grouting hole layout. For example, Chinese invention patent publication number CN118278265A discloses a tunnel grouting hole layout method and system based on spatial correlation analysis of rock mass fractures. This method constructs a three-dimensional geometric model of the fracture field, extracts the center coordinates of the fitted circles of each fracture structural surface, and uses a clustering algorithm to perform spatial cluster analysis on the center points to form representative groups. The optimal grouting hole trajectory is then generated based on the fitting of each clustering result, and a global hole layout plan is formulated. This method fully considers the spatial geometric distribution characteristics of the fractures, allowing grouting holes to more effectively penetrate areas with dense fractures, improving slurry diffusion efficiency and filling coverage, and enhancing the grouting reinforcement and water-stopping effects.

[0005] While the above-mentioned method makes good use of fracture geometry during hole placement, it ignores the hydraulic connectivity between fractures. Hydraulic connectivity refers to the presence and degree of connectivity between different fractures, reflecting the actual seepage path of groundwater within the rock mass. This characteristic cannot be directly derived from the fracture geometry. Ignoring hydraulic connectivity may result in grouting holes not covering the seepage path, thereby reducing the grouting sealing effect.

[0006] Furthermore, this type of hole placement method based on geometric distribution is more suitable for fractures with regular and evenly distributed contours. However, under actual geological conditions, fractures often have localized narrowing sections, known as neck sections. These areas have poor water conductivity and high grout diffusion resistance. Relying solely on geometric information to arrange grouting holes may miss these high-risk areas, resulting in grouting blind spots. This not only weakens the overall grouting effect but also may lead to safety hazards such as groundwater leakage and surrounding rock instability, affecting the long-term stability of the tunnel structure. Summary of the Invention

[0007] To this end, one purpose of an embodiment of the present application is to provide a tunnel grouting hole layout analysis method based on spatial crack correlation analysis, which realizes the main layout of grouting holes by associating the spatial distribution characteristics of tunnel cracks with hydraulic connectivity, and on this basis, supplementary layout of grouting holes is carried out in combination with the neck characteristics of the cracks, thereby effectively solving the problems mentioned in the background technology.

[0008] The purpose of the present invention can be achieved through the following technical solutions: A tunnel grouting hole analysis method for spatial crack correlation analysis, comprising the following steps: Step 1: Deploy a three-dimensional laser scanning device on the tunnel face to collect the distribution position and geometric contour of the cracks, and construct a crack connection network containing topological connection relationships.

[0009] Step 2: Bury pumping wells and observation wells at the intersection of the fracture network to conduct pumping tests, and identify the hydraulic connection path by analyzing the water level drawdown data of the observation wells.

[0010] Step 3: Mark the path nodes along the hydraulic connectivity path and evaluate the hydraulic connectivity strength by integrating the number of connected fractures at the path nodes with the water conductivity during the pumping test.

[0011] Step 4: Locate the path node positions and perform distribution status analysis using the distance between adjacent nodes. If the path nodes are clustered, select the node with the maximum hydraulic connectivity strength among the clustered path nodes to arrange the grouting holes. If the path nodes are discretely distributed, arrange the holes independently at the path nodes.

[0012] Step 5: For each crack in the crack connection network, the neck feature is identified using the width change curve formed by the width data in the crack geometric profile, thereby determining the crack neck section, and based on the comparison between the location of the crack neck section and the location of the surrounding grouting ports, additional grouting ports are arranged.

[0013] Combining all the above technical solutions, the positive effects of the present invention are as follows: 1. The present invention constructs a fracture connectivity network by scanning and modeling the distribution position and geometric contours of the surrounding rock cracks of the tunnel face, and identifies the actual water conduction path in combination with the pumping test, and arranges grouting ports at its key nodes to achieve precise matching of grouting holes and seepage channels. It can improve the scientificity and pertinence of hole layout by integrating the spatial distribution of cracks with hydraulic connectivity, significantly enhance the slurry's ability to seal water-conducting cracks, and help improve grouting efficiency and water-stopping effect.

[0014] 2. Based on the arrangement of grouting holes according to hydraulic connection paths, the present invention further identifies the neck features and divides the fractures in the fracture connection network into sections. The supplementary arrangement of grouting ports is implemented in combination with the spatial position of such sections and the relative relationship with the existing grouting holes, thereby realizing the refinement and dynamic optimization of the grouting ports. This not only improves the grouting coverage, but also enhances the ability to seal key water-conducting parts in the fractures, effectively avoids the generation of grouting blind spots, and significantly improves the overall effect of grouting reinforcement and engineering safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative effort.

[0016] Figure 1 The present invention is a flowchart of the steps for implementing the method.

[0017] Figure 2 This is an implementation flow chart of the present invention for performing distribution state analysis by locating the path node position using the adjacent node distance.

[0018] Figure 3 This is a schematic diagram of a crack in the present invention in which a plurality of sampling points are arranged at set intervals on one side of the crack's contour line in the direction from the starting point to the end point of the crack in its geometric contour. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] See also Figure 1As shown, the present invention proposes a tunnel grouting hole analysis method for spatial crack correlation analysis, which includes the following steps: Step 1: Deploy a three-dimensional laser scanning device on the tunnel face to collect the distribution position and geometric contour of the cracks, and construct a crack connection network containing topological connection relationships.

[0021] The specific implementation process of the above steps is as follows: a three-dimensional laser scanning device is used to scan the surrounding rock surface at the tunnel face to obtain high-precision point cloud data and construct a three-dimensional point cloud model of the rock surface.

[0022] Local surface fitting is performed on the three-dimensional point cloud model of the rock surface to calculate the normal vector information of each point, and the normal vector angle between adjacent points is obtained and compared with the preset angle threshold. For example, the angle threshold is 45°. When the normal vector angle between adjacent points exceeds the angle threshold, it is determined to be located in the crack boundary area, and the development path of the crack boundary is traced along the surface from this point to extract the crack geometric contour.

[0023] It should be understood that cracks are essentially areas of sudden changes in the geometric structure of the rock surface. On an ideal rock surface without cracks, the normal vector changes between adjacent points should be relatively gentle and the angle should be small. When cracks exist, the rock surfaces on both sides tilt in different directions, resulting in a significant increase in the normal vector angle. By calculating the normal vector angle of adjacent points in the three-dimensional point cloud model of the rock surface, the geometric discontinuity characteristics of the rock surface can be effectively reflected, thereby enabling targeted crack identification.

[0024] It should be pointed out that the setting of the angle threshold can be based on the statistical analysis of the normal vector characteristics of the sample point cloud data in the known crack area, combined with the comprehensive evaluation results of the recognition accuracy and false positive rate, to determine the threshold parameter with the best recognition performance.

[0025] Based on the geometric contours of the cracks, the spatial topological relationship between adjacent cracks is analyzed to identify whether there are geometric intersections, end connections, and transition section connections. If any of the connection forms is met, it is determined that an intersection connection relationship exists.

[0026] It should be noted that geometric intersection refers to the intersection of two or more cracks in space; end connection refers to the termination of one crack inside another crack; transition section connection refers to the existence of a connection section with a gradual transition between two cracks.

[0027] Multiple fractures that are identified as having an intersecting connection relationship are merged into a fracture group.

[0028] A fracture connectivity network with a topological structure is constructed based on the distribution position, geometric outline and intersection position of each fracture within the fracture group.

[0029] The construction of a fracture connectivity network can effectively characterize the spatial topological relationship between fractures on the rock mass surface. Tunnel face fractures typically do not exist in isolation, but rather exhibit intertwined and interconnected developmental characteristics. During grouting reinforcement, the diffusion path of the slurry is closely related to the connectivity between fractures. Therefore, hole layout design must be based on the spatial distribution and connectivity of the fractures. As a structured expression, the fracture connectivity network can intuitively reflect the overall distribution of the fracture system and provide basic support for the layout of grouting ports.

[0030] Step 2: Bury pumping wells and observation wells at the intersection of the fracture network to conduct pumping tests, and identify the hydraulic connection path by analyzing the water level drawdown data of the observation wells.

[0031] It's important to note that intersections in a fracture network are typically where multiple fractures converge, reflecting the actual hydraulic connections between the fractures and representing key areas of high permeability and active water exchange within the rock mass. Compared to conducting pumping tests at randomly selected locations within the fracture network, conducting tests at these intersections is more effective in observing the response of fracture water levels to pumping, effectively identifying connected pathways with actual water conductivity and improving the efficiency and accuracy of hydraulic connectivity assessment.

[0032] As a preferred implementation of the above scheme, the above steps are specifically implemented as follows: the intersection points in the fracture connectivity network are numbered and arranged in the order of spatial distribution, and then each pumping well is selected in sequence as the target pumping well for a single pumping test according to the order, and the remaining pumping wells remain stationary, thereby constructing multiple pumping tests.

[0033] By following the control variable principle, only the working state of one pumping well is changed at a time, and the other conditions remain constant, thereby ensuring that the test process has good controllability and facilitating the accurate identification of the hydraulic response relationship between the pumping well and the observation well.

[0034] For each pumping test, the target pumping well is controlled to continuously pump water at a constant flow rate during the pumping period, and the water level changes of all observation wells are synchronously recorded to form water level time series data.

[0035] It should be noted that maintaining a constant flow of water for a certain period of time during the pumping test is conducive to establishing a stable seepage field, and synchronously monitoring the water level changes in each observation well can ensure that the response data between different observation wells are temporally consistent, which is convenient for comparative analysis.

[0036] It should be pointed out that the observation wells located at the same intersection as the target pumping wells are not included in the water level monitoring process of the observation wells. This is to eliminate the influence of local strong disturbance effects on the hydraulic response identification and ensure that the extracted water level change information truly reflects the hydraulic connectivity characteristics of the fracture.

[0037] Based on the water level time series data, the water level change curves of each observation well in each pumping test were drawn, and the water level drawdown and water level response lag time were extracted from them, and then compared with the water level connectivity judgment conditions. The water level connectivity judgment conditions are: the water level drawdown is greater than or equal to the drawdown threshold and the water level response lag time is less than or equal to the lag time threshold. In this way, the observation wells that meet the water level connectivity judgment conditions are screened out to form a pumping well-observation well response pair with the pumping wells in the current pumping test.

[0038] In the specific implementation of the above operations, the water level drop threshold and lag time threshold in the water level connectivity judgment condition can be obtained by conducting pumping tests on multiple fracture intersections in existing engineering cases, and combining with the manually marked known water conduction paths for comparative analysis to statistically analyze the average drop and lag time of effective responses in typical fracture systems as the threshold basis. In one example, the water level drop threshold is 0.2m and the lag time threshold is 30 minutes.

[0039] The water level drawdown is defined as the difference between the lowest water level in the observation well during pumping and the initial highest water level. This reflects the magnitude of the groundwater level drop under pumping and is an important indicator for determining whether effective hydraulic connectivity exists between fractures. The water level response lag, defined as the time interval from the start of pumping to the occurrence of a discernible water level drop in the observation well, characterizes the velocity of groundwater flow and transmission within the fracture system.

[0040] By extracting the water level drop and the water level response lag time from the water level change curve and analyzing them in combination with the set judgment threshold, a quantitative criterion can be provided for identifying the actual water conduction relationship between fractures.

[0041] It should be explained that groundwater flow in rock fractures follows Darcy's law and its extended form. During pumping, the water level in the target pumping well drops, forming a localized low-head region, which prompts groundwater to migrate from the high-head region toward the pumping well, manifesting as a seepage process driven by a pressure gradient. If an observation well exhibits a significant water level drop during pumping and a short response lag time, this indicates a clear hydraulic response relationship between the observation well and the target pumping well, revealing hydraulic connectivity between the two. This hydraulic connectivity actually represents the existence of an effective groundwater flow path between the fracture intersection where the pumping well is located and the fracture intersection where the observation well is located. The greater the water level drop and the shorter the response lag time, the stronger the hydraulic connectivity between the two and the greater the water conductivity of the fracture system.

[0042] The intersection positions of the pumping wells and observation wells corresponding to each effective response pair are mapped to nodes in graph theory, and connecting edges are established between nodes with hydraulic connectivity to construct hydraulic connectivity paths.

[0043] Based on the principles of graph theory, the fracture intersections are modeled as network nodes, and the fracture pairs with significant hydraulic response relationships are abstracted as edges between nodes, thereby constructing hydraulic connectivity paths that reflect the actual water conduction characteristics. This helps to clearly characterize the hydraulic connectivity structure in the fracture system and provide a topological basis for the subsequent grouting hole layout.

[0044] The present invention conducts pumping tests at the intersection of the fracture connection network to identify and determine the hydraulic connection path of groundwater in the fracture system. It can identify the real water-conducting channel from the perspective of physical response. Compared with the traditional method of relying on geological speculation or deducing hydraulic connectivity based on local fracture geometric characteristics, this method has higher accuracy.

[0045] Step S3: Mark the path nodes along the hydraulic connectivity path, and evaluate the hydraulic connectivity strength by integrating the number of connected fractures at the path nodes with the water conductivity in the pumping test.

[0046] As a specific implementation process of the above steps: the intersection points on the hydraulic connection path are used as path nodes, and the number of fractures connected by each path node is obtained.

[0047] It should be noted that, based on the identification of the hydraulic connectivity path based on the pumping test, the intersection points on the path are used as candidate nodes for the grouting port layout, rather than indiscriminate screening among all the intersection points in the entire fracture connectivity network. This effectively narrows the preferred range for the layout of grouting holes, allowing the grouting operation to focus on the actual water-conducting path, avoiding ineffective hole layout in non-water-conducting areas, and reducing the number of drill holes and grouting material consumption.

[0048] For each path node, when it is used as the target pumping well in the pumping test, the observation wells with which it is hydraulically connected are counted, and the corresponding water level drawdown and water level response lag are extracted. Then, the water conductivity is calculated based on the water level connectivity judgment condition.

[0049] As a way to implement the above scheme, the water conduction performance is specifically analyzed as follows: when each path node is used as the target pumping well in the pumping test, the water level drawdown and the water level response lag time of the observation well with which it is hydraulically connected are compared with the water level connectivity judgment condition to obtain the difference ratio of the water level drawdown relative to the drawdown threshold and the difference ratio of the water level response lag time relative to the lag time threshold, which are recorded as the effective drawdown ratio and the response advance ratio, respectively.

[0050] The specific expression of the effective drawdown ratio in the above is: , where It represents the effective drawdown ratio, Indicates that the water level has dropped. represents the drawdown threshold. The effective drawdown ratio reflects the intensity of the observation well’s response to the target pumping well’s pumping. The larger the value, the stronger the water conductivity. The specific expression of the response advance ratio is: , where represents the response lead ratio, Indicates the water level response lag time, It represents the lag time threshold. The response advance ratio reflects the water flow transmission speed. The larger the value, the faster the water flow transmission and the better the water conduction performance.

[0051] The product of the effective drawdown ratio and the response advance ratio is taken as the water conductivity.

[0052] The product of the effective drawdown ratio and the response lead ratio is defined as the hydraulic conductivity index. The advantage of both being dimensionless parameters reflects the water level response intensity and flow transmission efficiency of the observation well under pumping, respectively. Only when both the effective drawdown ratio and the response lead ratio are high does hydraulic conductivity significantly increase, reflecting the synergistic contribution of water level drawdown and response lag time to fracture hydraulic conductivity. This construction approach not only enables a comprehensive, quantitative assessment of multiple factors but also better reflects the actual physical mechanisms of groundwater flow and response in fracture systems.

[0053] The hydraulic connectivity strength is defined as an exponential function with the number of connected fractures as the base and the water conductivity as the exponent. The hydraulic connectivity strength of each path node is obtained by combining the number of fractures connected to each path node with the water conductivity using the above definition.

[0054] Applied to the above scheme, the hydraulic connectivity strength expression is: , where represents the hydraulic connectivity strength, Indicates the number of fractures connected by the path nodes, represents the water conductivity of the path node, It represents the empirical correction coefficient, which is used to adjust the influence weight of water conductivity.

[0055] It should be noted that the above comprehensive assessment of the hydraulic connectivity strength of path nodes is achieved by integrating the number of connected fractures and water conductivity. The number of connected fractures reflects the connectivity advantage of the node in the spatial structure, while the water conductivity characterizes the actual water flow transmission capacity. The fusion in the form of an exponential function makes the influence of water conductivity on the overall strength show a nonlinear enhancement effect, highlighting the weight of nodes with strong hydrological response capabilities in the overall connectivity assessment. Even if a node has a small number of connected fractures, if its water conductivity is excellent, it may still show a high hydraulic connectivity strength. Conversely, if the water conductivity is weak, its overall strength will be significantly suppressed even if the structural connectivity is good.

[0056] See also Figure 2As shown, step S4: locate the path node position and perform distribution status analysis using the distance between adjacent nodes. If the path nodes are clustered, the nodes with the maximum hydraulic connectivity strength are selected from the clustered path nodes to arrange the grouting holes. If the path nodes are discretely distributed, the holes are arranged independently at the path nodes.

[0057] In an optional implementation of the above scheme, the distribution position of the positioning path nodes is performed using the distance between adjacent nodes to analyze the node distribution status. See the following process: based on the distribution position of each path node, the path nodes directly adjacent to it are obtained to form an adjacent area.

[0058] The distance between any adjacent nodes in the adjacent area where each path node is located is calculated and compared with the preset spatial threshold distance, and then the adjacent nodes with a distance less than the spatial threshold are screened out and marked as neighboring node pairs.

[0059] The above-mentioned mid-space threshold distance is used to distinguish between neighbor and non-neighbor node pairs. The threshold can be determined based on the average spacing of the fracture network, and is exemplarily 5 meters.

[0060] The number of neighboring node pairs in each adjacent area is counted, and the neighboring node ratio is calculated based on the total number of all neighboring node pairs in the adjacent area.

[0061] The proportion of neighbor nodes is compared with the set distribution state determination threshold. If the proportion of neighbor nodes reaches or exceeds the threshold, for example, the distribution state determination threshold is 0.7, it is determined that the path nodes in the adjacent area are clustered. Conversely, if the proportion of neighbor nodes is lower than the threshold, it is determined to be a discrete distribution.

[0062] It should be understood that when multiple path nodes are clustered in space, it indicates that the fracture intersection areas represented by these nodes have a high hydraulic correlation. At this time, if grouting holes are arranged at each node, it may lead to overlapping of grouting influence areas, waste of resources, and even cause slurry diffusion interference. By selecting the nodes with the highest hydraulic connectivity intensity in this area as representative locations to arrange grouting holes, it is possible to concentrate on blocking key water channels, improve grouting efficiency, reduce the number of invalid drilling holes, and avoid pressure interference caused by simultaneous grouting of multiple holes.

[0063] When the spacing between path nodes is large and the spatial distribution is relatively discrete, it indicates that the fracture intersection areas represented by each node are relatively independent and the hydraulic connection between them is weak. In this case, independent hole arrangement is performed to prevent missing important water-conducting fractures and enhance the sealing effect of the overall fracture network.

[0064] Step S5: The neck features of each crack in the crack connection network are identified using the width change curve formed by the width data in the crack geometric profile, thereby determining the crack neck section, and supplementing the grouting ports based on the comparison between the location of the crack neck section and the location of the surrounding grouting ports.

[0065] Optionally, the neck feature is identified as follows: Figure 3 As shown, for each crack in the crack connection network, a number of sampling points are arranged at set intervals on one side of the contour line along the direction from the starting point to the end point of the crack in its geometric contour, and the crack width value at each sampling point is obtained.

[0066] A sliding window is set on the crack width change curve constructed with the point coordinates as the horizontal axis and the crack width as the vertical axis. The window moves point by point along the crack width change curve, and the average width of each window is calculated.

[0067] In the specific operation of the above scheme, the sliding window size should be set according to the length of the crack, exemplarily 5 consecutive sampling points.

[0068] Defining the local reduction ratio indicator ,in Indicates the crack width change curve The crack width at the sampling point, Indicates the crack width variation curve The average width of the window in which the sampling points are located.

[0069] It should be understood that the local reduction ratio index mentioned above is used to characterize the degree of width shrinkage of the current point relative to the local area. When the crack width of a sampling point is smaller than the average width of the sliding window where the sampling point is located, it indicates that there is local narrowing at the sampling point.

[0070] The local reduction ratio index of each sampling point in the crack change curve is compared with the preset neck recognition threshold. If the local reduction ratio index of a sampling point reaches the neck recognition threshold, it is determined that there is local narrowing at that location, that is, it has neck characteristics, and the point is marked as the neck position.

[0071] Further optionally, the crack neck section is determined by the following operation: marking a plurality of neck positions on the crack width variation curve, and arranging these neck positions in sequence according to the crack geometric direction.

[0072] According to the above sorting, it is determined in turn whether there is a non-neck position inserted between adjacent neck positions. If there is no non-neck position between adjacent neck positions, they are classified into a group of continuous neck positions.

[0073] For each set of continuous neck positions, the starting point and ending point are extracted as the spatial boundary of the neck segment.

[0074] Optionally, additional grouting ports are arranged based on the comparison between the location of the fracture neck section and the locations of the surrounding grouting ports as follows: based on the starting point and the ending point of the fracture neck section, its geometric center point is extracted as the representative position of the section.

[0075] The distribution locations of existing grouting ports on the hydraulic connection path are obtained, and the Euclidean distances between the representative position of the fracture neck section and all surrounding grouting ports are calculated to identify the nearest grouting port.

[0076] The grouting diffusion radius is determined based on the distribution position of the nearest grouting port, and the spatial distance between the representative position of the fracture neck section and the nearest grouting port is calculated and then compared with the grouting diffusion radius. If it exceeds the grouting diffusion radius, the neck section is judged to be a grouting blind area.

[0077] In the specific implementation of the above scheme, the grouting diffusion radius can be determined according to the distribution position of the grouting ports. The grouting parameters and diffusion effects in the historical grouting data can be combined to perform statistical analysis and regression modeling on the relevant parameters, and then an estimation model of the grouting diffusion radius can be inverted. Through this model, the quantitative prediction of the grouting diffusion range of the grouting ports can be achieved.

[0078] For the neck section determined to be a grouting blind area, additional grouting ports are arranged at its representative position to enhance the grouting control capability of this critical narrowing section.

[0079] The above-mentioned supplementary deployment can effectively improve the coverage of grouting projects in high-risk areas of the fracture network and optimize the allocation of grouting resources.

[0080] The parameters involved in the above formulas are all dimensionless and calculated using their numerical values. The preset parameters in the formulas are set by those skilled in the art according to actual conditions.

[0081] The above embodiments may be implemented in whole or in part through software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments may be implemented in whole or in part in the form of a computer program product.

[0082] Those skilled in the art will appreciate that the modules and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0083] In addition, each functional module in each embodiment of the present application may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0084] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

[0085] Finally, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A tunnel grouting hole analysis method for spatial crack correlation analysis, characterized in that: The following steps are involved: Step 1: Deploy a 3D laser scanning device on the tunnel face to collect the distribution location and geometric contours of the cracks and construct a crack connectivity network including topological connection relationships; Step 2: Pumping wells and observation wells are buried at the intersection of the fracture network to conduct pumping tests. The hydraulic connection paths are identified by analyzing the water level drawdown data of the observation wells. Step 3: Mark the path nodes along the hydraulic connectivity path and evaluate the hydraulic connectivity strength by integrating the number of connected fractures at the path nodes with the water conductivity during the pumping test. Step 4: Locate the path node positions and perform distribution analysis using the distance between adjacent nodes. If the path nodes are clustered, select the node with the maximum hydraulic connectivity strength among the clustered path nodes to place the grouting holes. If the path nodes are discrete, place the holes independently at the path nodes. Step 5: For each crack in the crack connection network, the neck feature is identified using the width change curve formed by the width data in the crack geometric profile, thereby determining the crack neck section, and based on the comparison between the location of the crack neck section and the location of the surrounding grouting ports, additional grouting ports are arranged.

2. The tunnel grouting hole analysis method for spatial crack correlation analysis according to claim 1, characterized in that: The specific implementation process of step 1 is as follows: At the tunnel face, a 3D laser scanning device is used to scan the surrounding rock surface to obtain high-precision point cloud data and construct a 3D point cloud model of the rock surface; Perform local surface fitting on the 3D point cloud model of the rock surface to calculate the normal vector information of each point, and obtain the normal vector angle between adjacent points and compare it with the preset angle threshold. When the normal vector angle between adjacent points exceeds the angle threshold, it is determined to be located in the crack boundary area, and the development path of the crack boundary is traced along the surface from this point to extract the crack geometric contour; Based on the geometric contours of the cracks, the spatial topological relationship between adjacent cracks is analyzed to identify whether there are geometric intersections, end connections, and transition section connections. If any of these connection forms are met, it is determined that there is an intersection connection relationship. Merge multiple fractures identified as having intersecting connections into a fracture group; A fracture connectivity network with a topological structure is constructed based on the distribution position, geometric outline and intersection position of each fracture within the fracture group.

3. The tunnel grouting hole analysis method for spatial crack correlation analysis according to claim 1, characterized in that: The pumping test is carried out as follows: The intersection points in the fracture connectivity network were numbered and arranged in the order of their spatial distribution. Each pumping well was then selected in sequence as the target pumping well for a single pumping test, while the remaining pumping wells remained stationary, thereby constructing multiple pumping tests.

4. The tunnel grouting hole analysis method for spatial crack correlation analysis according to claim 3, characterized in that: The identification of the hydraulic connection path by analyzing the water level drawdown data of the observation wells is described in the following process: For each pumping test, the target pumping well is continuously pumped at a constant flow rate during the pumping period, and the water level changes of all observation wells are synchronously recorded to form water level time series data; Based on the water level time series data, the water level change curves of each observation well in each pumping test are drawn, and the water level drawdown and water level response lag time are extracted from them, and then compared with the water level connectivity judgment conditions. The water level connectivity judgment conditions are: the water level drawdown is greater than or equal to the drawdown threshold and the water level response lag time is less than or equal to the lag time threshold. In this way, the observation wells that meet the water level connectivity judgment conditions are selected to form a pumping well-observation well response pair with the pumping well in the current pumping test. The intersection positions of the pumping wells and observation wells corresponding to each effective response pair are mapped to nodes in graph theory, and connecting edges are established between nodes with hydraulic connectivity to construct hydraulic connectivity paths.

5. The tunnel grouting hole analysis method for spatial crack correlation analysis according to claim 4, characterized in that: The step 3 is implemented as follows: The intersection points on the hydraulic connection path are regarded as path nodes, and the number of fractures connected by each path node is counted; For each path node, when it is used as the target pumping well in the pumping test, the observation wells with which it has hydraulic connectivity are counted, and the corresponding water level drawdown and water level response lag time are extracted and combined with the water level connectivity judgment condition to analyze the water conductivity performance; The hydraulic connectivity strength is defined as an exponential function with the number of connected fractures as the base and the water conductivity as the exponent. The hydraulic connectivity strength of each path node is obtained by combining the number of fractures connected to each path node with the water conductivity using the above definition.

6. The tunnel grouting hole analysis method for spatial crack correlation analysis according to claim 5, characterized in that: The water conductivity performance is specifically analyzed as follows: When each path node is used as the target pumping well in the pumping test, the water level drawdown and water level response lag time of the observation well with which it is hydraulically connected are compared with the water level connection judgment condition to obtain the difference ratio of the water level drawdown to the drawdown threshold and the difference ratio of the water level response lag time to the lag time threshold, which are recorded as the effective drawdown ratio and the response advance ratio respectively. The product of the effective drawdown ratio and the response advance ratio is taken as the water conductivity.

7. The tunnel grouting hole analysis method for spatial crack correlation analysis according to claim 1, characterized in that: The location of the node position of the positioning path is analyzed by performing distribution state analysis using the distance between adjacent nodes. See the following process: Based on the distribution position of each path node, its directly adjacent neighboring nodes are identified and the adjacent area is constructed; Calculate the distance between adjacent nodes in the adjacent area, compare it with the preset spatial threshold, and select the node pairs with a distance less than the spatial threshold as the nearest neighbor node pairs; Count the number of neighboring node pairs in each adjacent area, and calculate the neighboring node ratio based on the total number of all neighboring node pairs in the area; The proportion of neighbor nodes is compared with the distribution status determination threshold. If the proportion of neighbor nodes reaches or exceeds the threshold, the path nodes are determined to be clustered, otherwise they are determined to be discrete.

8. The tunnel grouting hole analysis method for spatial crack correlation analysis according to claim 1, characterized in that: The neck feature recognition process is as follows: For each fracture in the fracture connection network, a number of sampling points are arranged at set intervals on one side of the fracture contour line along the direction from the starting point to the end point of the fracture, and the fracture width value at each sampling point is obtained; On the crack width variation curve constructed with the point coordinates as the horizontal axis and the crack width as the vertical axis, a sliding window is set and moved point by point along the crack width variation curve, and the average width of each window is calculated; Defining the local reduction ratio indicator ,in Indicates the crack width change curve The crack width at the sampling point, Indicates the crack width variation curve The average width of the window where the sampling point is located; The local reduction ratio index of each sampling point in the crack change curve is compared with the preset neck recognition threshold. If the local reduction ratio index of a sampling point reaches the neck recognition threshold, the sampling point is identified as having a neck feature and marked as the neck position.

9. The tunnel grouting hole analysis method for spatial crack correlation analysis according to claim 8, characterized in that: The determination of the fissure neck segment is performed as follows: Mark multiple neck positions on the crack width change curve and arrange these neck positions in sequence according to the crack geometric direction; According to the above sorting, determine whether there is a non-neck position inserted between adjacent neck positions. If there is no non-neck position between adjacent neck positions, they are classified as a group of continuous neck positions; For each set of continuous neck positions, the starting point and ending point are extracted as the spatial boundary of the neck segment.

10. The tunnel grouting hole analysis method for spatial crack correlation analysis according to claim 1, characterized in that: The supplementary arrangement of the grouting ports is realized as follows: The geometric center point of the fissure neck segment was taken as the representative position of the segment; Obtain the distribution of existing grouting ports on the hydraulic connection path, and calculate the Euclidean distance between the representative position of the fracture neck section and all surrounding grouting ports to identify the nearest grouting port; The grouting diffusion radius is determined based on the distribution of the nearest grouting ports, and the spatial distance between the representative position of the fracture neck section and the nearest grouting port is calculated. This distance is then compared with the grouting diffusion radius. If the distance exceeds the grouting diffusion radius, the neck section is considered a grouting blind area. For the neck section determined to be a grouting blind area, additional grouting ports are arranged at its representative position.

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