Tunnel grouting hole arrangement analysis method for spatial crack correlation analysis

Abstract

The invention belongs to the technical field of tunnel crack grouting and hole arrangement, and discloses a tunnel grouting and hole arrangement analysis method for spatial crack correlation analysis, which comprises the following steps: scanning the distribution position and geometric contour of surrounding rock cracks of a tunnel face to construct a crack communication network, and identifying an actual water guide path in combination with a water pumping test; the grouting openings are formed in the key nodes, accurate matching of the grouting holes and the seepage channels is achieved, scientificity and pertinence of hole distribution can be improved by fusing fracture space distribution and hydraulic connectivity, the plugging capacity of grout to water guiding fractures is remarkably improved, the grouting efficiency and the water stopping effect are improved, and the construction period is shortened. Meanwhile, neck feature recognition and section division are further performed on each crack in the crack communication network on the basis of arranging the grouting holes based on the hydraulic communication path, so that supplementary arrangement of the grouting ports is implemented by combining the relative relationship between the spatial position of the section and the existing grouting holes; and refined and dynamic optimized layout of the grouting ports is realized.

Description

Technical Field

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

[0002] In tunnel engineering construction, when passing through complex geological conditions such as fault fracture zones or joint-developed areas, a large number of fissures are generally developed in the rock mass, resulting in loose surrounding rock structure, poor self-stabilizing ability, and prone to geological disasters such as collapse and rockfall, seriously threatening construction safety and affecting project progress. To effectively address the above challenges, fissure grouting technology is widely used in engineering practice. By injecting grout into the fissures, filling, cementing, and strengthening are achieved, thereby improving the overall stability and bearing capacity of the surrounding rock and ensuring the safety and controllability of tunnel construction and operation.

[0003] The layout of grouting holes is a key link affecting the grouting effect. Whether the grouting can achieve the expected reinforcement goal depends to a large extent on whether the grout can effectively fill and seal the fissure network in the rock mass. Therefore, before grouting operations, it is necessary to detect the spatial distribution characteristics of the fissures and formulate a reasonable grouting hole layout plan based on this.

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

[0005] Although the above method makes good use of the fissure geometric information during the hole layout process, it ignores the hydraulic connectivity between the fissures. Hydraulic connectivity refers to whether there is an effective water flow channel and its connectivity between different fissures, which reflects the actual seepage path of groundwater in the rock mass. This characteristic cannot be directly obtained from the geometric shape of the fissures. If the hydraulic connectivity is ignored, it may lead to the failure of the grouting hole layout to cover the seepage path, thereby reducing the grouting plugging effect.

[0006] In addition, this type of hole layout method based on geometric distribution is more suitable for the case where the fissure contour is regular and the distribution is uniform. However, in actual geological conditions, there are often local constriction sections, namely neck sections, in the fissures. The water conduction performance in these areas is poor and the resistance to slurry diffusion is large. If the grouting holes are arranged only relying on geometric information, such high-risk parts may be missed, resulting in grouting blind areas. This will not only weaken the overall grouting effect, but also may cause potential safety hazards such as groundwater leakage and surrounding rock instability, affecting the long-term stability of the tunnel structure. Summary of the Invention

[0007] For this reason, an object of an embodiment of the present application is to provide a tunnel grouting hole layout analysis method for spatial fissure correlation analysis, which realizes the main layout of grouting holes by correlating the spatial distribution characteristics of tunnel fissures with hydraulic connection, and on this basis, combines the neck characteristics of fissures to supplement the layout of grouting holes, effectively solving the problems mentioned in the background technology.

[0008] The object of the present invention can be achieved by the following technical solutions: A tunnel grouting hole layout analysis method for spatial fissure correlation analysis, including the following steps: Step 1: Arrange a three-dimensional laser scanning device on the tunnel face to collect the distribution position and geometric contour of fissures, and construct a fissure connection network including topological connection relationships.

[0009] Step 2: Bury a pumping well and an observation well at the intersection point of the fissure connection network to conduct a pumping test, and identify the hydraulic connection path by analyzing the water level drawdown data of the observation well.

[0010] Step 3: Mark the path nodes along the hydraulic connection path, and evaluate the hydraulic connection strength by integrating the number of connected fissures of the path nodes and the water conduction performance in the pumping test.

[0011] Step 4: Locate the position of the path nodes and perform a distribution state analysis using the adjacent node spacing. If the path nodes are clustered, select the node with the maximum hydraulic connection strength among the clustered path nodes to arrange the grouting holes. If the path nodes are discretely distributed, arrange the grouting holes independently at the path nodes.

[0012] Step 5: Identify the neck characteristics of each fissure existing in the fissure connection network by using the width change curve formed by the width data in the fissure geometric contour, thereby determining the fissure neck section, and supplement the layout of the grouting ports based on the comparison between the position of the fissure neck section and the layout position of the surrounding grouting ports.

[0013] Combining all the above technical solutions, the positive effects of the present invention are as follows: 1. By scanning and modeling the distribution position and geometric profile of the surrounding rock fissures of the tunnel face to construct a fissure connection network, and combining pumping tests to identify the actual water-conducting paths, grouting ports are arranged at its key nodes, achieving an accurate match between the grouting holes and the seepage channels. It is possible to improve the scientificity and pertinence of hole arrangement by integrating the spatial distribution of fissures and hydraulic connectivity, significantly enhancing the plugging ability of the grout to water-conducting fissures, and being beneficial to improving the grouting efficiency and water-stopping effect.

[0014] 2. On the basis of arranging grouting holes based on the hydraulic connection paths, the present invention further identifies the neck characteristics and divides the sections of each fissure in the fissure connection network. Thus, combined with the spatial position of this type of section and the relative relationship with the existing grouting holes, supplementary arrangement of grouting ports is implemented, realizing the refined and dynamic optimization arrangement of grouting ports. This not only improves the grouting coverage range, but also enhances the plugging ability of the key water-conducting parts in the fissures, effectively avoiding the generation of grouting blind areas, and significantly improving the overall effect of grouting reinforcement and engineering safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described with reference to the accompanying drawings. However, the embodiments in the drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the following drawings.

[0016] Figure 1 It is a flowchart of the method implementation steps of the present invention.

[0017] Figure 2 It is a flowchart of the implementation for analyzing the distribution state by using the adjacent node spacing to locate the position of the path node in the present invention.

[0018] Figure 3 It is a schematic diagram of arranging a number of sampling points at a set spacing on one side contour line of the fissure along the direction from the starting point to the ending point in its geometric profile in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] See Figure 1As shown in the figure, the present invention proposes a tunnel grouting hole layout analysis method for spatial fracture correlation analysis, including the following steps: Step 1: Arrange a three-dimensional laser scanning device on the tunnel face to collect the distribution positions and geometric contours of the fractures, and construct a fracture connectivity network including topological connection relationships.

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

[0022] Perform local surface fitting on the three-dimensional point cloud model of the rock surface to calculate the normal vector information of each point, and obtain the included angle between the normal vectors of adjacent points and compare it with a preset angle threshold. Exemplarily, the included angle threshold is 45°. When the included angle between the normal vectors of certain adjacent points exceeds the angle threshold, it is determined that it is located in the fracture boundary area, and the development path of the fracture boundary is traced along the surface starting from this point to extract the fracture geometric contour.

[0023] It should be understood that fractures are essentially mutation areas of the geometric structure on the rock mass surface. On an ideal rock surface without fractures, the change in the normal vectors between adjacent points should be relatively gentle and the included angle is small. When there are fractures, the rock masses on both sides tilt in different directions, resulting in a significant increase in the included angle of the normal vectors. By calculating the included angle of the normal vectors of adjacent points in the three-dimensional point cloud model of the rock surface, the geometric discontinuity characteristics of the rock mass surface can be effectively reflected, so as to identify fractures targeted.

[0024] It should be noted 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 fracture area, and combined with the comprehensive evaluation results of the recognition accuracy rate and the misjudgment rate to determine the threshold parameter with the best recognition performance.

[0025] Analyze the spatial topological relationship between adjacent fractures based on the fracture geometric contour to identify whether there are connection forms such as geometric intersection, end connection, and transition section connection. If any one of the connection forms is satisfied, it is determined that there is an intersection connection relationship.

[0026] It should be noted that geometric intersection means that two or more fractures intersect in space; end connection means that one fracture terminates inside another fracture; transition section connection means that there is a gradually transitional connection section between two fractures.

[0027] Merge multiple fractures identified as having an intersection connection relationship into a fracture group.

[0028] Construct a fracture connectivity network with a topological structure based on the distribution positions, geometric contours, and intersection point positions of each fracture within the fracture group.

[0029] The above-mentioned construction of the fracture connectivity network can effectively characterize the spatial topological relationship between the fractures on the rock mass surface. The fractures on the tunnel face usually do not exist in isolation, but show the development characteristics of interlacing and connecting with each other. During the grouting reinforcement process, the diffusion path of the grout is closely related to the connectivity between the fractures. Therefore, the hole layout design must be based on the spatial distribution and connection relationship of the fractures. As a structured expression method, the fracture connectivity network can intuitively reflect the overall distribution pattern of the fracture system and provide a basic support for the layout of grouting ports.

[0030] Step 2: Install a pumping well and observation wells at the intersection points of the fracture connectivity network to conduct a pumping test, and identify the hydraulic connection paths by analyzing the water level drawdown data of the observation wells.

[0031] It should be noted that the intersection points in the fracture connectivity network are usually the locations where multiple fractures intersect, which reflects the actual water-conducting connection relationship between the fractures and represents the key areas in the rock mass with strong permeability and active water flow exchange. Compared with randomly selecting multiple locations in the fracture connectivity network for pumping tests, conducting tests at these intersection points is more conducive to significantly observing the change response of the fracture water level during the pumping process, thereby efficiently identifying the connected paths with actual water-conducting ability and improving the efficiency and accuracy of hydraulic connectivity identification.

[0032] As an optimal implementation of the above solution, the above steps are specifically implemented as follows: Number and arrange the intersection points in the fracture connectivity network in the order of their spatial distribution, and then sequentially select each pumping well as the target pumping well for a single pumping test, while the remaining pumping wells remain stationary, so as to construct multiple pumping tests.

[0033] By following the principle of controlling variables above, only the working state of one pumping well is changed each time, and the remaining conditions are kept constant, thus ensuring good controllability of the test process and being conducive to accurately identifying the hydraulic response relationship between the pumping well and the observation wells.

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

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

[0036] It should be noted that during the water level monitoring of the observation wells, the observation wells arranged at the same intersection point as the target pumping well are not included, aiming to eliminate the influence of local strong disturbance effects on the identification of hydraulic response and ensure that the extracted water level change information truly reflects the characteristics of fracture hydraulic connectivity.

[0037] Based on the water level time series data, draw the water level change curves of each observation well in each pumping test, extract the drawdown and the lag time of water level response from them, and then compare with the water level connection determination conditions. The water level connection determination conditions are: the 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. Thus, select the observation wells that meet the water level connection determination conditions and the pumping well in the current pumping test to form a pair of pumping well - observation well response pairs.

[0038] In the specific implementation of the above operation, the drawdown threshold and the lag time threshold in the water level connection determination conditions can be obtained from existing engineering cases by conducting pumping tests on multiple fracture intersection points and combining the known water conduction paths manually marked for comparative analysis. The average drawdown and lag time of effective responses in typical fracture systems are used as the threshold basis. In one example, the drawdown threshold is 0.2m and the lag time threshold is 30 minutes.

[0039] The drawdown in the above is defined as the difference between the lowest water level and the initial highest water level in the observation well during pumping, which reflects the decline amplitude of the groundwater level under pumping and is an important indicator for judging whether there is effective hydraulic connection between fractures. The lag time of water level response is defined as the time interval from the start of pumping to the appearance of a recognizable water level decline in the observation well, which is used to characterize the flow and transmission speed of groundwater in the fracture system.

[0040] By extracting the drawdown and the lag time of water level response from the water level change curve and combining with the set determination threshold for analysis, it can provide a quantitative criterion for identifying the actual water conduction relationship between fractures.

[0041] It should be explained that the flow of groundwater in rock mass fractures follows Darcy's law and its extended forms. During pumping, the water level of the target pumping well drops to form a local low - head area, which prompts groundwater to migrate from the high - head area towards the pumping well, showing a seepage process driven by the pressure gradient. If an observation well shows a significant drawdown and a short response lag time during pumping, it indicates that there is an obvious hydraulic response relationship between the observation well and the target pumping well, revealing that the two have a hydraulic connection relationship. This hydraulic connection relationship actually represents the existence of an effective groundwater flow path between the fracture intersection point where the pumping well is located and the fracture intersection point where the observation well is located. Among them, the greater the drawdown and the shorter the response lag time, the stronger the hydraulic connection between the two, and the stronger the water conduction ability of the fracture system.

[0042] Map the positions of the intersection points of the pumping well and the observation well corresponding to each group of effective response pairs to nodes in graph theory, and establish connection edges between the nodes with hydraulic connection relationships to construct a hydraulic connection path.

[0043] Based on the graph theory principle, the fracture intersection points are modeled as network nodes, and the fracture pairs with significant hydraulic response relationships are abstracted as the edges between nodes, thereby constructing a hydraulic connection path that reflects the actual water-conducting characteristics, which helps to clearly depict the hydraulic connection structure in the fracture system and provides a topological basis for the subsequent layout of grouting holes.

[0044] By conducting pumping tests at the intersection points of the fracture connection network, the present invention identifies and determines the hydraulic connection paths of groundwater in the fracture system, and can identify real water-conducting channels from the perspective of physical response. Compared with the traditional method that relies on geological speculation or deduces hydraulic connectivity based on local fracture geometric characteristics, this method has higher accuracy.

[0045] Step S3: Mark the path nodes along the hydraulic connection path, and evaluate the hydraulic connection strength by integrating the number of fractures connected by the path nodes and their water-conducting performance in the pumping test.

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

[0047] It should be noted that based on the identification of the hydraulic connection path through the pumping test, the intersection points on this path are used as candidate nodes for the layout position of the grouting port, rather than randomly screening all the intersection points in the entire fracture connection network. Thus, the preferred range of the grouting hole layout is effectively reduced, making the grouting operation focus on the actual water-conducting path, avoiding ineffective hole drilling in non-water-conducting areas, and reducing the number of drill holes and the consumption of grouting materials.

[0048] For each path node, when it is used as the target pumping well in the pumping test, the observation wells with hydraulic connection relationships with it are counted, and the corresponding water level drawdown and the lag time of the water level response are extracted. Then, combined with the water level connection determination condition, the water-conducting performance is calculated.

[0049] As a way that the above solution can be realized, the water-conducting performance is specifically analyzed as follows: When each path node is used as the target pumping well in the pumping test, the difference ratio of the water level drawdown and the lag time of the water level response of the observation wells with hydraulic connection relationships with it compared with the water level connection determination condition is obtained, which are respectively recorded as the effective drawdown ratio and the response lead ratio.

[0050] The specific expression of the effective drawdown ratio mentioned above is , where represents the effective drawdown ratio, represents the water level drawdown, Denote the drawdown threshold. The effective drawdown ratio reflects the intensity of the pumping response of the observation well to the target pumping well. The larger the value, the stronger the water conductivity. The specific expression of the response lead ratio is , where denotes the response lead ratio, denotes the lag time of the water level response, denotes the lag time threshold. The response lead ratio reflects the water flow transmission speed. The larger the value, the faster the water flow transmission and the better the water conductivity performance.

[0051] Take the product value of the effective drawdown ratio and the response lead ratio as the water conductivity performance.

[0052] In the above, the product of the effective drawdown ratio and the response lead ratio is defined as the water conductivity performance index. The advantage is that both are dimensionless parameters, which respectively reflect the water level response intensity and water flow transmission efficiency of the observation well under pumping. Only when both the effective drawdown ratio and the response lead ratio are relatively high, the water conductivity performance will increase significantly, reflecting the synergistic contribution of water level drawdown and response lag time to the fissure water conductivity. This construction method not only realizes the comprehensive quantitative evaluation of multiple factors, but also conforms more to the actual physical mechanism of groundwater flow and response in the fissure system.

[0053] Define the hydraulic connectivity intensity as an exponential function with the number of connected fissures as the base and the water conductivity performance as the exponent. Thus, the number of connected fissures of each path node combined with the water conductivity performance is used to obtain the hydraulic connectivity intensity of the path node according to the above definition.

[0054] Applied to the above scheme, the expression of the hydraulic connectivity intensity is , where denotes the hydraulic connectivity intensity, denotes the number of connected fissures of the path node, denotes the water conductivity performance of the path node, denotes the empirical correction coefficient, which is used to adjust the influence weight of the water conductivity performance.

[0055] It should be noted that the above comprehensively evaluates the hydraulic connectivity intensity of the path node by fusing the number of connected fissures and the water conductivity performance. Among them, the number of connected fissures reflects the connectivity advantage of the node in the spatial structure, while the water conductivity performance depicts the actual water flow transmission ability. And the use of the exponential function form for fusion makes the influence of the water conductivity performance on the overall intensity show a non-linear enhancement effect, highlighting the weight of the node with strong hydrological response ability in the overall connectivity evaluation. Even if a node has a small number of connected fissures, if its water conductivity performance is excellent, it may still show a relatively high hydraulic connectivity intensity; on the contrary, if the water conductivity performance is weak, even if the structural connectivity is good, its comprehensive intensity will be significantly inhibited.

[0056] See Figure 2As shown in the figure, step S4: Locate the position of the path nodes. Perform distribution state analysis using the distance between adjacent nodes. If the path nodes are clustered, select the node with the maximum hydraulic connection 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.

[0057] In an alternative implementation of the above solution, to locate the distribution position of the path nodes, perform node distribution state analysis using the distance between adjacent nodes. Refer to the following process: Obtain the adjacent area composed of the path nodes directly adjacent to each path node based on the distribution position of each path node.

[0058] Calculate the distance between any adjacent nodes within the adjacent area where each path node is located, and compare it with the preset spatial threshold distance. Then, screen out the adjacent nodes smaller than the spatial threshold and mark them as near-neighbor node pairs.

[0059] The above spatial threshold distance is used to distinguish near-neighbor and non-near-neighbor node pairs. This threshold can be determined based on the average spacing of the fracture network, and is, for example, 5 meters.

[0060] Count the number of near-neighbor node pairs in each adjacent area, and calculate the proportion of near-neighbor nodes in combination with the total number of all adjacent node pairs in this adjacent area.

[0061] Compare the proportion of near-neighbor nodes with the set distribution state determination threshold. If the proportion of near-neighbor nodes reaches or exceeds this threshold, for example, the distribution state determination threshold is 0.7, then it is determined that the path nodes in this adjacent area are clustered. On the contrary, if the proportion of near-neighbors is lower than this threshold, it is determined to be discretely distributed.

[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 for each node, it may lead to overlapping of grouting influence areas, waste of resources, and even interference with slurry diffusion. By selecting the node with the maximum hydraulic connection strength in this area as the representative position to arrange the grouting holes, it is possible to concentrate on blocking the key water-conducting channels, improve the grouting efficiency, reduce the number of ineffective drill holes at the same time, and avoid pressure interference caused by simultaneous grouting of multiple holes.

[0063] When the distance 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, arrange the holes independently to prevent omission of important water-conducting fractures and enhance the sealing effect of the overall fracture network.

[0064] Step S5: For each crack existing in the crack connection network, use the width change curve formed by the width data in the crack geometric contour to identify the neck characteristics, thereby determining the crack neck section, and supplement and arrange the grouting holes based on the comparison between the position of the crack neck section and the layout positions of the surrounding grouting holes.

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

[0066] Set a sliding window on the crack width change curve constructed with the point position coordinates as the horizontal axis and the crack width as the vertical axis, move point by point along the crack width change curve, and calculate the average width of each window.

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

[0068] Define the local reduction ratio index , where represents the crack width at the th sampling point in the crack width change curve, represents the average width of the window where the th sampling point is located in the crack width change curve.

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

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

[0071] Further optionally, the following operations are used to determine the crack neck section: Mark multiple neck positions on the crack width change curve, and arrange these neck positions in sequence according to the crack geometric trend.

[0072] Judge in sequence whether there are non-neck positions inserted between adjacent neck positions according to the above sorting. If there are no non-neck positions between adjacent neck positions, they are grouped into a set of continuous neck positions.

[0073] Extract the starting point and the ending point of each set of continuous neck positions as the spatial boundaries of the neck section.

[0074] Continuing further optionally, the supplementary layout of grouting holes is realized based on the comparison between the position of the fracture neck section and the layout positions of the surrounding grouting holes as follows: The geometric center point of the fracture neck section is extracted from its starting point and ending point as the representative position of this section.

[0075] Obtain the distribution positions of the existing grouting holes on the hydraulic connection path, and calculate the Euclidean distances between the representative position of the fracture neck section and all the surrounding grouting holes, and identify the nearest grouting hole from them.

[0076] Determine the grouting diffusion radius based on the distribution position of the nearest grouting hole, and calculate the spatial distance between the representative position of the fracture neck section and the nearest grouting hole, and then compare it with the grouting diffusion radius. If it exceeds the grouting diffusion radius, it is judged that this neck section belongs to the grouting blind area.

[0077] In the specific implementation of the above solution, determining the grouting diffusion radius according to the distribution position of the grouting holes can be achieved by combining the grouting parameters and diffusion effects in the historical grouting data, conducting statistical analysis and regression modeling on the relevant parameters, and then inversely deriving the estimation model of the grouting diffusion radius. Through this model, the quantitative prediction of the grouting diffusion range of the grouting holes can be realized.

[0078] For the neck section determined to be the grouting blind area, a grouting hole is supplemented and laid out at its representative position to enhance the grouting control ability for this key narrowing section.

[0079] Through the above supplementary layout, the coverage degree of the grouting project for the high-risk parts in the fracture network can be effectively improved, and the grouting resource allocation can be optimized.

[0080] The parameters involved in the above formula are all dimensionless and their numerical values are taken for calculation. The preset parameters in the formula are set by those skilled in the art according to the actual situation.

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

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

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

[0084] As described above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

[0085] Finally, the above is only the preferred embodiment of the present invention and is not used to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A tunnel grouting hole layout analysis method for spatial fissure correlation analysis, characterized in that It includes the following steps: Step 1: Deploy a three-dimensional laser scanning device at the tunnel face to collect the distribution positions and geometric profiles of fissures, and construct a fissure connection network including topological connection relationships; Step 2: Bury a pumping well and an observation well at the intersection points of the fissure connection network to conduct a pumping test, and identify the hydraulic connection paths by analyzing the water level drawdown data of the observation wells; Step 3: Mark the path nodes along the hydraulic connection paths, and evaluate the hydraulic connection strength by integrating the number of connected fissures of the path nodes and the water conductivity performance in the pumping test; Step 4: Locate the positions of the path nodes and perform a distribution state analysis using the adjacent node spacing. If the path nodes are clustered, select the node with the maximum hydraulic connection strength among the clustered path nodes to deploy grouting holes. If the path nodes are discretely distributed, drill holes independently at the path nodes; Step 5: Identify the neck characteristics of each fissure existing in the fissure connection network using the width change curve formed by the width data in the fissure geometric profile, thereby determining the fissure neck section, and supplement the deployment of grouting holes based on the comparison between the position of the fissure neck section and the surrounding grouting port deployment positions.

2. The tunnel grouting hole layout analysis method for spatial fissure correlation analysis according to claim 1, characterized in that: The specific implementation process of the above Step 1 is as follows: Use a three-dimensional laser scanning device at the tunnel face to scan the surrounding rock surface to obtain high-precision point cloud data and construct a three-dimensional point cloud model of the rock surface; Perform local surface fitting on the three-dimensional point cloud model of the rock surface to calculate the normal vector information of each point, and compare the normal vector angle between adjacent points with a preset angle threshold. When the normal vector angle between a certain adjacent point exceeds the angle threshold, it is determined that it is located in the fissure boundary area, and the development path of the fissure boundary is traced along the surface starting from this point to extract the fissure geometric profile; Analyze the spatial topological relationship between adjacent fissures based on the fissure geometric profile to identify whether there are connection forms such as geometric intersection, end connection, and transition section connection. If any one of the connection forms is satisfied, it is determined that there is an intersection connection relationship; Merge multiple fissures identified as having an intersection connection relationship into a fissure group; Construct a fissure connection network with a topological structure based on the distribution positions, geometric profiles, and intersection point positions of each fissure within the fissure group.

3. The tunnel grouting hole layout analysis method for spatial fissure correlation analysis according to claim 1, characterized in that: The implementation of the pumping test is as follows: Number and arrange the intersection points in the fissure connection network in the order of their spatial distribution, and then sequentially select each pumping well as the target pumping well for a single pumping test, and keep the other pumping wells stationary, so as to construct multiple pumping tests.

4. The tunnel grouting hole layout analysis method for spatial fracture correlation analysis according to claim 3, wherein: The process of identifying the hydraulic connection paths by analyzing the water level drawdown data of the observation wells is as follows: For each pumping test, control the target pumping well to continuously pump water at a constant flow rate during the pumping period, and simultaneously record the water level changes of all observation wells synchronously to form water level time series data; Based on the water level time series data, draw the water level change curves of each observation well in each pumping test, extract the drawdown and the lag time of water level response therefrom, and then compare with the water level connection determination conditions. The water level connection determination conditions are as follows: the 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. Thus, select the observation wells that meet the water level connection determination conditions and the pumping well in the current pumping test to form a pair of pumping well-observation well response pairs; Map the intersection positions of the pumping well and the observation well corresponding to each group of effective response pairs to nodes in graph theory, and establish connection edges between the nodes with hydraulic connection relationships to construct a hydraulic connection path.

5. The tunnel grouting hole layout analysis method for spatial fissure correlation analysis according to claim 4, characterized in that: The implementation of step 3 is as follows: Take the intersection points on the hydraulic connection path as path nodes, and count the number of fractures connected to each path node; For each path node, when it is used as the target pumping well in the pumping test, count the observation wells with which it has a hydraulic connection relationship, and extract the corresponding drawdown and the lag time of water level response, and analyze the water conductivity in combination with the water level connection determination conditions; Define the hydraulic connection strength as an exponential function with the number of connected fractures as the base and the water conductivity as the exponent. Thus, use the above definition to obtain the hydraulic connection strength of the path node by combining the number of fractures connected to each path node with the water conductivity.

6. The tunnel grouting hole layout analysis method for spatial fissure correlation analysis according to claim 5, characterized in that: The specific analysis of the water conductivity is as follows: Compare the drawdown and the lag time of water level response of the observation wells with which each path node has a hydraulic connection relationship when it is used as the target pumping well in the pumping test with the water level connection determination conditions to obtain the difference ratio of the drawdown relative to the drawdown threshold and the difference ratio of the lag time of water level response relative to the lag time threshold, which are respectively recorded as the effective drawdown ratio and the response lead ratio; Take the product value of the effective drawdown ratio and the response lead ratio as the water conductivity.

7. The tunnel grouting hole layout analysis method for spatial fissure correlation analysis according to claim 1, characterized in that: The position of the path node is located by performing a distribution state analysis using the adjacent node spacing. See the following process: Based on the distribution positions of each path node, identify its directly adjacent neighboring nodes and construct an adjacent area; Calculate the distance between adjacent nodes within the adjacent area and compare it with a preset spatial threshold. Select the node pairs with a distance less than the spatial threshold as the near-neighbor node pairs; Count the number of near-neighbor node pairs in each adjacent area, and calculate the proportion of near-neighbor nodes in combination with the total number of all adjacent node pairs in this area; Compare the proportion of near-neighbor nodes with the distribution state determination threshold. If the proportion of near-neighbor nodes reaches or exceeds the threshold, it is determined that the path nodes show an aggregated distribution, otherwise it is determined as a discrete distribution.

8. The tunneling grouting hole layout analysis method for spatial fissure correlation analysis according to claim 1, characterized in that: The identification of the neck characteristics is as follows: For each fracture in the fracture connection network, along the direction of the fracture from the starting point to the ending point in its geometric contour, arrange a number of sampling points at a set spacing on one side of the contour line to obtain the fracture width value at each sampling point; Set a sliding window on the fracture width change curve constructed with the point position coordinates as the horizontal axis and the fracture width as the vertical axis, and move the window point by point along the fracture width change curve, and calculate the average width of each window; Define the local reduction ratio index , where represents the fracture width at the th sampling point in the fracture width change curve, represents the average width of the window where the th sampling point is located in the fracture width change curve; Compare the local reduction ratio index of each sampling point in the fracture change curve with the preset neck recognition threshold. If the local reduction ratio index of a certain sampling point reaches the neck recognition threshold, it is recognized that the sampling point has neck characteristics and is marked as the neck position.

9. The tunnel grouting hole layout analysis method for spatial fracture correlation analysis according to claim 8, characterized in that: The operation of determining the fracture neck section is as follows: Mark multiple neck positions on the fracture width change curve, and arrange these neck positions in sequence according to the fracture geometric trend; Judge in turn whether there are non-neck positions inserted between adjacent neck positions according to the above sorting. If there are no non-neck positions between adjacent neck positions, they are grouped into a set of continuous neck positions; Extract the starting point and ending point of each set of continuous neck positions as the spatial boundary of the neck section.

10. The tunnel grouting hole layout analysis method for spatial fracture correlation analysis according to claim 1, characterized in that: The supplementary layout of the grouting holes is realized as follows: Take the geometric center point of the fracture neck section as the representative position of this section; Obtain the distribution positions of the existing grouting holes on the hydraulic connection path, calculate the Euclidean distance between the representative position of the fracture neck section and all the surrounding grouting holes, and identify the nearest grouting hole from them; Determine the grouting diffusion radius based on the distribution position of the nearest grouting hole, calculate the spatial distance between the representative position of the fracture neck section and the nearest grouting hole, and then compare it with the grouting diffusion radius. If it exceeds the grouting diffusion radius, it is judged that this neck section belongs to the grouting blind area; For the neck section determined to be the grouting blind area, supplement and layout the grouting hole at its representative position.

Images