Ground grouting and water plugging method for inclined shaft penetrating through strong permeable pebble bed

Abstract

The invention discloses a ground grouting and water plugging method for an inclined shaft to penetrate through a strong permeable pebble bed, and particularly relates to the technical field of grouting and water plugging. Identifying a seepage abnormal high-flux region, extracting a spatial distribution feature vector of a potential water-sand coupling channel, establishing a grouting target point cloud, calculating a connectivity index, and outputting a channel seepage-prone grade in combination with average particle size distribution of pebble particles and porosity; constructing a ground grouting hole laying network according to the sorting result, laying multi-point micro grouting holes in a high-connectivity region, and setting grouting path priorities; in the pre-grouting stage, the slurry permeation radius and the pore sealing rate are monitored, an actual effective grouting section is recognized, layered variable-slurry-property materials are adopted for combined grouting, and the grouting pressure and the backflow slurry sand content are monitored in real time; the water plugging completion degree is judged by comparing the sand content of the backflow slurry with the initial pore structure characteristics; according to the method, accurate recognition and directional plugging of the complex seepage channel in the permeable pebble bed can be achieved, and the water plugging effect and the construction safety are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of grouting and water plugging, and particularly relates to a method for grouting and water plugging of a strong water-permeable pebble layer through a slant well. BACKGROUND

[0002] In current urban underground engineering, deep foundation pit construction and railway tunnel crossing engineering, the geological environment of a strong water-permeable pebble layer through a slant well is extremely complex. The pebble layer structure is loose, the particle size is uneven, and the water flow is strong, which leads to the risk of gushing water, gushing sand and even collapse caused by the flow of pebbles carried by underground water, and seriously threatens the safety of construction. Traditional water plugging technology usually relies on surface grouting or wellhead curtain grouting, which can only achieve local plugging and is difficult to effectively control the water permeation path. Especially in the working condition that the structure crossing angle of the slant well is greater than 25°, the thickness of the pebble layer is more than 4 meters, and the hydraulic gradient is higher than 0.7, the grout is prone to flow loss along the pore, and a stable grout film cannot be formed in the target area, resulting in water plugging failure.

[0003] In addition, there are often hidden micro-fissures and "water-sand coupling channels" in the strong water-permeable pebble layer, and the positions are random. The traditional grouting process cannot accurately identify the position and trend of such channels, leading to frequent leakage of grout, deviation of grouting body, and leakage. The existing technology lacks a systematic plugging strategy based on the combination of micro water permeation structure identification and ground grouting path optimization, and it is difficult to achieve synchronous directional plugging of potential multiple channels in the pebble layer, thereby improving the water plugging success rate and construction safety. SUMMARY

[0004] The purpose of the present application is to provide a method for grouting and water plugging of a strong water-permeable pebble layer through a slant well to solve the problems in the background art.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme: a method for grouting and water plugging of a strong water-permeable pebble layer through a slant well, comprising: obtaining surface geological radar data and a three-dimensional resistivity inversion model of a pebble layer where a target slant well section is located, constructing a seepage abnormal high flux area identification model, and obtaining a spatial distribution feature vector of a potential water-sand coupling channel in the pebble layer; establishing a grouting targeting point cloud model based on the spatial distribution feature vector, calculating the connectivity index of each potential water permeation channel, combining the average particle size distribution and porosity of the pebble particles, and outputting the channel permeability grade ranking result; According to the channel permeability grade ranking result, a ground grouting hole layout network is constructed, multiple point micro grouting holes are preferentially arranged in high connectivity areas, and a grouting path transmission priority is set; Performing a low-pressure pre-ann test on the multiple point micro grouting holes, monitoring the grout penetration radius and pore closure rate, identifying the actual effective grouting section, and adjusting the grouting parameters; In the identified effective grouting section, the main grouting operation is implemented, the layered variable grouting material combination grouting is adopted, and the real-time monitoring of the grouting pressure change and the backflow slurry sand content is implemented. The backflow slurry sand content is compared with the initial pore structure characteristics, the grouting water plugging completion degree is judged, if the sealing standard is not reached, the secondary targeted micro-injection reinforcement process is started until the water plugging closed state is stable.

[0006] Preferably, the model for identifying the seepage anomaly high-flux region is constructed, comprising: Multi-azimuth scanning is implemented on the surface layer of the pebble layer by using a multi-pole high-frequency geological radar, a radar wave reflection energy gradient matrix is extracted, and a three-dimensional energy anomaly initial distribution map is constructed based on a statistical anomaly value algorithm; A resistance-energy joint fitting model is constructed in combination with the low-resistance body connectivity characteristics in the three-dimensional resistivity inversion model, a residual minimum offset optimization method is used to fit the energy-resistivity space coupling relationship, and a coupling flux indicator field is formed; A region growth evolution algorithm is implemented on the coupling flux indicator field, a potential seepage high-flux region boundary is automatically generated based on the change trend of the continuous permeation path, and a volume flow rate and a direction vector set thereof are calculated; The terrain slope field and the ground stress disturbance field are introduced as constraint conditions to correct the horizontal distribution deviation of the anomaly region boundary, and the multi-scale high-flux seepage path in the underground pebble layer is accurately identified.

[0007] Preferably, the spatial distribution characteristic vector of the potential water-sand coupling channel in the pebble layer is obtained, comprising: On the basis of the seepage anomaly high-flux region identification model, a three-dimensional skeleton extraction method of the high-flux path main line is constructed, a main seepage channel is extracted by implementing multi-scale skeleton thinning processing on the continuous high-flux region; Based on the position of the main seepage channel, the local perturbation resistivity fluctuation characteristics, the radar energy attenuation rate and the formation particle size change rate of each node along the line are sampled, and a multi-modal fusion coupling channel local state feature set is constructed; The feature set is subjected to feature dimension reduction and vectorization processing, a graph neural network model is used for path structure identification and node connectivity relationship learning, and a spatial distribution characteristic vector of each potential channel is output. The spatial distribution characteristic vector is subjected to similarity matching evaluation with a preset water permeability typical structure database, an identification confidence threshold is set, an effective channel path with water-sand coupling potential is screened out as a grouting target point optimization reference.

[0008] Preferably, the grouting target point cloud model is established based on the spatial distribution characteristic vector, and the connectivity index of each potential water permeable channel is calculated, comprising: According to the channel node coordinates in the spatial distribution feature vector, each node is projected as an independent point in a three-dimensional coordinate system, and the node disturbance intensity and the channel direction vector are used as the weight attributes of the point to form a three-dimensional point cloud set containing multiple attributes; In the point cloud set, the spatial distance and direction consistency between nodes are used as the connection conditions to construct the channel skeleton link piece by piece, and the effective permeation zone of the channel is determined according to the overlapping degree of the possible permeation range of the adjacent points; Based on the effective permeation zone, virtual grouting simulation is performed on the head and tail points of each channel, the transmission coverage rate of the grout between the channel nodes is counted, and the ratio of the transmission coverage rate to the total number of channel nodes is used as the connectivity index; When the connectivity index of a certain channel reaches a preset threshold value, the channel is marked as a grouting priority path in the point cloud model, and the high-weight point cloud is encrypted in the point cloud for guiding the hole positioning.

[0009] Preferably, the average particle size distribution and porosity of the pebble particles are combined to output the channel permeability ranking result, including: At each potential channel node, the particle size data of the pebble particles obtained by drilling sampling or acoustic testing is collected, and the average particle size value in the channel range is calculated; at the same time, the porosity is determined by water injection test or resistivity conversion method, and the particle size and porosity are assigned to the corresponding nodes in the three-dimensional point cloud model; The average particle size and porosity values of each node are superimposed on the channel skeleton to calculate the effective permeation parameters of the channel per unit length; Based on the average permeation parameters of the whole channel, all potential channels are compared horizontally, and the ranking result of the channel permeability is obtained according to the numerical value from high to low.

[0010] Preferably, the ground grouting hole layout network is constructed, and multiple-point micro grouting holes are preferentially arranged in high-connectivity areas, and the grouting path transmission priority is set, including: After the permeability ranking is completed, the channels with high permeability and connectivity greater than a preset threshold value are selected as the priority control objects, and marker points are arranged on the ground within the projection range of the channels, and the grouting influence area is delineated around the marker points according to the extension direction of the channels; In the grouting influence area, multiple-point micro grouting holes are arranged at an interval of 1 to 2 meters according to the channel trend, and the hole diameter is selected to be less than 50 mm; The completed micro grouting hole groups are grouped, each group corresponding to the head or key node position of a high-connectivity channel, and the hole groups with high connectivity and high permeation parameters are preferentially selected in the grouting sequence, and gradually extended to adjacent medium-permeability channels; In setting the transmission priority of the grouting path, the principle of first high connectivity main channel and then secondary branch channel is adopted, and if the connectivity of two channels is the same, the channel with larger particle size and higher porosity is selected as the first grouting path.

[0011] Preferably, the monitoring of the slurry permeation radius and the pore sealing rate identifies the actual effective grouting section and adjusts the grouting parameters, including: In the execution of low-pressure pre-grouting, a seepage pressure gauge and a resistivity probe are arranged in the adjacent grouting hole or monitoring hole to record the water pressure change and the resistivity reduction range in the slurry diffusion process in real time, so as to estimate the permeation radius of the slurry in the pebble layer; In the grouting process, the return flow meter and the sand content determination device are used to record the rate of gradual decline of the return flow per unit time, and the decline rate is taken as the field representation value of the pore sealing rate; The permeation radius and the pore sealing rate are compared, and when the permeation radius is less than the designed coverage range or the pore sealing rate is lower than the set sealing rate threshold, it is determined that the section grouting has not reached the effective state, and the grouting pressure or the slurry ratio needs to be adjusted; When the adjusted parameters make the permeation radius cover the designed section and the pore sealing rate reaches or exceeds the preset standard, it is confirmed that the section is an actual effective grouting section.

[0012] Preferably, the real-time monitoring of the grouting pressure change and the return slurry sand content includes: The effective grouting section is divided into several layered units in the depth direction, with the thickness of each layer controlled between 0.5 m and 1.0 m, and early strength cement slurry, rapid-setting cement-silicate slurry or expansion-type composite slurry is selected as the grouting material according to the pore characteristics of different layers; In the grouting process of each layer, low-viscosity slurry is first injected to fill small pores, and then high-viscosity or expansion-type slurry is gradually switched to block large pores; During the main grouting process, a pressure sensor and a flow recording device are set to monitor the change curve of the grouting pressure in real time; At the same time, the return slurry is continuously sampled, and when the sand content decreases by more than a preset proportion and the pressure curve remains stable, it is confirmed that the layer has been effectively sealed, and then the next layer continues to be grouted.

[0013] Preferably, the return slurry sand content is compared with the initial pore structure characteristics to judge the completion degree of grouting water sealing, including: After the main grouting is completed, the pore structure characteristic parameters determined by drilling sampling and acoustic testing at the initial grouting stage are obtained, including the average particle size, porosity and pore connectivity, and are taken as the comparison reference; The change trend of the slurry sand content in the return pipeline is continuously detected, when the sand content is kept below the permeation critical value corresponding to the initial pore structure in a set monitoring period, it is determined that the pore in this section is closed; If the comparison result shows that the sand content is still higher than the permeation critical value, or there is a stage of rebound, it is determined that the closing effect is insufficient, the micro grouting hole is re-arranged at the adjacent position of this section and the secondary directional micro grouting is carried out to reinforce the pores which are not completely closed. After the secondary micro grouting, the return flow detection is carried out again, when the sand content is stably kept in the low value interval and the duration exceeds the preset standard, it is confirmed that the water plugging closing state is stable, and the grouting operation in this section is ended.

[0014] In the above technical solution, the technical effects and advantages provided by the present application are as follows: 1. The present application can realize the accurate identification and priority sorting of the seepage channel before the ground grouting hole arrangement by constructing the seepage abnormal high flux area identification, extracting the potential water-sand coupling channel feature vector, establishing the grouting target point cloud, calculating the connectivity index and outputting the easy permeation grade combined with the pebble particle size and porosity, thereby avoiding the grouting blind area caused by the traditional experience-based determination. The seepage radius and the pore closure rate are detected in real time through the low-pressure pre- grouting test, the actual effective grouting section can be dynamically identified, and the secondary target micro grouting can be performed when necessary to continuously optimize the water plugging effect.

[0015] 2. The present application realizes the closed-loop process of "channel identification-grouting hole arrangement-grouting implementation-water plugging verification", which has the significant advantages of quantification, visualization and controllability. The advantages are as follows: first, the grouting hole arrangement is based on the connectivity and permeation grade, which reduces the slurry loss; second, the layered variable grouting material combination is adopted, which takes into account the fine pore filling and large pore plugging; third, the return sand content and pore structure characteristics are compared to establish the criterion of water plugging completion degree, which ensures the long-term stability of the plugging effect, thereby significantly improving the construction safety of the inclined well crossing the strong permeable pebble layer. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art based on these drawings.

[0017] Figure 1 The method flowchart of the present application. DETAILED DESCRIPTION

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] For examples, please refer to Figure 1 As shown in this embodiment, the surface grouting and water plugging method for inclined shafts crossing highly permeable gravel layers includes: Obtain surface geological radar data and three-dimensional resistivity inversion model of the pebble layer where the target inclined well section is located, construct a high-throughput seepage anomaly identification model, and obtain the spatial distribution feature vector of potential water-sand coupling channels in the pebble layer. Based on the spatial distribution feature vector, a grouting target point cloud model is established, the connectivity index of each potential permeable channel is calculated, and the permeability level of the channels is ranked by combining the average particle size distribution and porosity of the pebble particles. Based on the ranking of the permeability levels of the channels, a ground grouting hole layout network is constructed, with priority given to laying out multiple micro-grouting holes in areas with high connectivity, and the grouting path transmission priority is set. Low-pressure pre-grouting detection tests were performed on the multi-point micro-grouting holes to monitor the grout penetration radius and pore closure rate, identify the actual effective grouting section, and adjust the grouting parameters. In the identified effective grouting sections, the main grouting operation is carried out, using a combination of layered variable grouting materials, and the changes in grouting pressure and the sand content of the backflow grout are monitored in real time. The sand content of the reflux slurry is compared with the initial pore structure characteristics to determine the completion of grouting and water plugging. If the sealing standard is not met, a secondary targeted micro-injection reinforcement process is initiated until the water plugging closure state is stable.

[0020] In this invention, a model for identifying high-flux areas with abnormal seepage is constructed, and based on this, the spatial distribution feature vector of potential water-sediment coupling channels in the pebble layer is obtained to achieve high-precision identification of grouting target points, specifically including: At the construction site, select a surface area within 30 meters of the projected area of ​​the inclined shaft, and arrange the transmitting and receiving antennas of the high-frequency pulse ground-penetrating radar at 1-meter intervals. It is recommended to use antennas with a frequency of 500 MHz and set three pole spacings (0.5 meters, 1.0 meters, and 1.5 meters for transmitting and receiving, respectively), so that it can penetrate to a maximum depth of about 10 meters into the pebble layer.

[0021] Echo waveform data at different polar distances were collected at each location point. The main reflection band within the target layer (pebble layer) was extracted, and its total energy was calculated. An energy voxel array was constructed in a three-dimensional spatial grid. The first-order gradient of each voxel was calculated by the energy difference between it and its six adjacent voxels, and the second-order rate of change was calculated using the central difference method. Finally, the gradient variation matrix of the space radar reflection energy was obtained.

[0022] After standardizing the matrix, the Z-Score anomaly identification method is applied, which involves subtracting the global mean from each data point and dividing by the standard deviation. Regions with Z values ​​greater than 2.5 are selected and marked as initial energy anomaly areas to form a three-dimensional distribution map.

[0023] Thirty electrodes were arranged on the ground with the center of the inclined shaft as the center, and multiple pairs of electrodes were measured using the direct current method. The voltage and current values ​​measured by each pair of electrodes were used to calculate the apparent resistivity, and the three-dimensional resistivity distribution map of the underground was reconstructed by using an inversion algorithm (finite element method with Occam regularization constraint is recommended).

[0024] Based on the inversion results, regions with resistivity lower than 20% of the background average and continuously distributed with surrounding low-resistivity bodies were selected within the radar anomaly area, and their three-dimensional isosurfaces were plotted.

[0025] In a 3D grid aligned with the radar energy gradient matrix and resistivity model, the radar energy gradient and resistivity values ​​are extracted point by point, and a linear fitting function is constructed using the least squares method. To improve accuracy, the squared residual of each fitting point is calculated, and the parameters of the fitting curve are adjusted using the gradient descent algorithm until the overall residual decreases below a set threshold (10% is recommended).

[0026] The flux factor for each grid point is obtained by inversely normalizing the fitting error of that point (the smaller the error, the stronger the coupling) and normalizing it with the product of the radar gradient value and resistivity. The value of this factor represents the degree of superposition between the water flow capacity and the energy-resistivity dual anomaly at that point.

[0027] All voxels with flux factors greater than 1.5 times the average value of the entire field are selected as initial abnormal seed points. The FloodFill spatial expansion algorithm is used to determine whether the adjacent 8 neighboring voxels meet the growth condition (factor value greater than the average value), and the expansion continues until all seed points are stable.

[0028] For each independent anomalous cluster, its three-dimensional boundary is recorded and the average direction vector of the line connecting the center points is calculated. Combined with the DEM (Digital Elevation Model) data of the inclined shaft area, a slope gradient map is extracted; then, in-situ stress disturbance data (obtained through strain gauges or previous seismic wave inversion) is introduced to construct a stress field distribution map.

[0029] Based on these two fields, the boundary point position of each anomalous cluster is offset and corrected: if the slope direction is at an obtuse angle to the flux direction, the boundary is reduced by 0.5 meters along the slope direction; if the stress concentration area coincides with the anomalous boundary, the radius is enlarged by 0.8 meters. Finally, the boundary shape is adjusted to generate an accurate distribution map of potential high flux seepage areas.

[0030] For each anomalous block, the central connection method is used to trace the main path. First, the first main node is determined in the block body according to the point with the largest factor value. Then, the path line is generated by connecting the points one by one according to the maximum directional continuity.

[0031] After obtaining the continuous paths, a sparsification method based on the principal curvature change rate is used: if the directional angle of a certain path segment varies by no more than 5° within three consecutive nodes, its intermediate point is deleted and the two endpoints are linearly connected; if the distance between two paths is less than 0.5 meters, they are merged into a main channel. This ultimately forms a simplified skeleton structure line, representing the main permeation channels that may exist in the pebble layer.

[0032] At each node location of the main channel, samples are taken within a 1-meter radius before and after it to extract three types of key parameters: Resistivity perturbation amplitude: The standardized perturbation value obtained by dividing the difference between the node value and the mean value within a 1-meter radius by the standard deviation is used to determine whether the saturation state has changed abruptly. Radar energy attenuation rate: Calculate the difference in radar energy within 0.5 meters along the channel direction and divide it by the distance. The unit is attenuation in dB per meter. Formation grain size variation rate: Based on the borehole profile data or laser grain size analysis results before construction, the grain size distribution curve is extracted in the node and surrounding area. The difference between the median grain size within a 1-meter range before and after is divided by the distance and used as the grain size gradient.

[0033] The three types of data form a complete set of three-dimensional nodal local perturbation features.

[0034] Each main channel is treated as a graph structure, with channel nodes as vertices and the directional angle and perturbation feature similarity between adjacent nodes as edge weights. A graph neural network learning process is run in each graph: initially, the node feature vectors are input; in each iteration, adjacent node information is propagated, and node weights and edge connectivity are updated.

[0035] The training objective of the graph neural network is to maximize the connectivity score within the entire path and identify breakpoints or anomalous branches. After training, the spatial distribution feature vector of each path is extracted from the network, including: total length, average flux intensity, location of the maximum perturbation point, mean particle size gradient, and extreme radar attenuation values.

[0036] Prepare a standard permeable structure sample library, including characteristic data of typical water and sediment transport channels known in existing projects, with the characteristic vector content being consistent with the aforementioned.

[0037] Calculate the cosine similarity between the vector of each newly generated channel and each record in the database. When the similarity is higher than 0.85 and the connectivity score of the channel exceeds 0.7, the path is judged to be a high-probability water-sand coupling channel.

[0038] These channels are the target paths for priority grouting and water plugging. Their three-dimensional spatial coordinates are extracted and imported into the ground hole layout software to guide the layout of grouting holes and the design of the grouting sequence.

[0039] During the construction of inclined shafts traversing highly permeable pebble layers, relying solely on methods such as ground-penetrating radar and resistivity inversion to obtain high-flux seepage areas is insufficient to accurately determine the location and priority order of grouting holes. To transform the identified spatial distribution feature vectors into a basis that can be directly used for engineering operations, this implementation not only establishes a grouting target point cloud set but also further clarifies the priority order of water-blocking for different channels by calculating the connectivity index and permeability level of the channels.

[0040] First, based on the spatial distribution feature vector obtained from the high-flux seepage anomaly identification process, the coordinates of the channel nodes are extracted. The three-dimensional coordinates (x, y, z) of each node are projected onto a three-dimensional coordinate system, forming a set of discrete points. On this basis, the disturbance intensity and channel direction vector corresponding to that node are assigned as additional attributes to each point. The disturbance intensity can be understood as the degree of difference between the geological physical parameters at that node and the background values, such as the standardized deviation of resistivity or radar energy. The channel direction vector originates from the local tangent direction of the channel framework, representing the extension direction of the seepage channel at that node. The resulting three-dimensional point cloud set not only contains geometric location but also attribute information reflecting seepage capacity and directionality.

[0041] After forming the point cloud set, the points need to be connected segment by segment according to the spatial relationships between them to reconstruct a continuous channel skeleton. The connection conditions mainly include two aspects: first, the spatial distance between adjacent nodes must not exceed a set threshold; second, the angle between the direction vectors of adjacent nodes should be less than a certain limit to ensure directional continuity. The distance threshold can be defined as 0.8 meters, meaning that two points are considered adjacent when the distance between them is less than 0.8 meters; the direction threshold can be set to 10 degrees, meaning that adjacent nodes are considered connected when the angle between their direction vectors is less than 10 degrees. By constructing connections segment by segment according to the above conditions, the channel skeleton can be formed.

[0042] After obtaining the channel framework, it is necessary to further determine the possible permeation range of the grout during the grouting process. Specifically, taking each pair of adjacent nodes as the center, the radius of possible grout permeation is estimated based on pore characteristics and disturbance intensity, and a permeation zone is generated in three-dimensional space. If the permeation zones of adjacent nodes overlap, this segment of the channel is considered to form a continuous and effective permeation channel, thus defining the effective permeation zone of that channel.

[0043] After the channel framework and effective permeability zone are determined, virtual grouting simulation needs to be performed on each potential channel. The specific method is as follows: select the first node of the channel as the hypothetical grouting hole location, apply a set grouting pressure to the inside of the channel, and calculate the grout transfer coverage rate between nodes. The transfer coverage rate refers to the proportion of nodes that can be covered after the grout diffuses from one node to the next. The calculation method is to count the number of nodes within the permeability zone and compare it with the total number of nodes in the channel; the ratio is the coverage rate.

[0044] The connectivity index of a channel is defined as the ratio of the number of nodes covered by the grout as it diffuses from the beginning to the end of the channel to the total number of nodes in the channel. The value of this index ranges from 0 to 1; a higher value indicates better connectivity. For example, if a channel contains 50 nodes, and virtual grouting covers 45 of them, the connectivity index of that channel is 0.9.

[0045] After calculating the indicators, it is necessary to determine which channels should be prioritized for grouting based on their connectivity. A connectivity threshold of 0.7 is set; that is, when a channel's connectivity index is greater than or equal to 0.7, the channel is considered a path with high connectivity. For these channels, a higher-order labeling process is applied to the point cloud dataset, increasing the weight of the path nodes in subsequent borehole positioning. In this way, the point cloud dataset can guide construction personnel to prioritize these paths for borehole placement and grouting operations.

[0046] At each potential channel node, pebble particle size data are obtained using borehole sampling or acoustic testing. The collected data are then statistically analyzed to obtain the average particle size within the node range. Simultaneously, the permeability rate is measured through on-site water injection tests, and the porosity at that node is calculated using empirical porosity formulas; alternatively, resistivity conversion methods are used to derive the porosity value through empirical relationships. The average particle size and porosity are stored as additional attributes in the corresponding nodes of the 3D point cloud model.

[0047] On the channel framework, for each unit length of path, the effective permeability parameter is defined as the product of particle size and porosity. Specifically, if the average particle size of a channel segment is 20 mm and the porosity is 0.35, then the effective permeability parameter for that segment can be defined as 7 (20 multiplied by 0.35). The larger this parameter value, the more easily water-sediment coupling infiltration occurs in that channel segment. By accumulating the effective permeability parameters of all channel units and taking the average, the overall effective permeability parameter of the entire channel can be obtained.

[0048] After obtaining the effective permeability parameters for each channel, all potential channels are compared horizontally. They are then sorted from highest to lowest value and divided into three categories: channels with a parameter value greater than 1.2 times the overall average are classified as highly permeable; those between 0.8 and 1.2 times are classified as moderately permeable; and those less than 0.8 times are classified as lowly permeable. This classification not only reflects the relative permeability between channels but also provides a clear priority order for grouting operations.

[0049] For example, if the effective permeability parameter of channel A is 12, that of channel B is 7, that of channel C is 4, and the overall average is 7.5, then channel A belongs to the high permeability level, channel B to the medium permeability level, and channel C to the low permeability level.

[0050] During the grouting and water plugging process of an inclined shaft traversing a highly permeable pebble layer, simply obtaining the spatial distribution feature vector of the channel and the permeability ranking is insufficient to directly guide the borehole layout. To transform the calculation results into an executable grouting scheme, it is necessary to further construct a grouting hole layout network on the ground.

[0051] After obtaining the permeability ranking results of the channels, channels belonging to the high permeability level and with a connectivity index greater than a preset threshold are selected as priority control targets. The connectivity index, as previously defined, is the ratio of grout delivery coverage to the total number of channel nodes in the virtual grouting simulation, and its value ranges from zero to one. Based on the experience of this implementation method, the threshold can be set to 0.7. When the connectivity index of a channel is greater than 0.7, it indicates that the channel has a strong continuous water conveyance capacity and must be prioritized for control.

[0052] Subsequently, the three-dimensional spatial framework of the channel is projected vertically onto the ground surface to obtain the ground projection line of the channel. Marking points are placed at the projection line locations as reference benchmarks for subsequent grouting hole layout. Considering that the diffusion radius of the grout is affected by both porosity and formation pressure conditions, a grouting influence zone needs to be delineated around the projection line. The radius of the influence zone can be estimated using the following formula: the radius of the influence zone equals the average porosity multiplied by an empirical coefficient of groundwater pressure. For example, when the average porosity is 0.35 and the groundwater pressure is converted to 0.8 MPa, taking an empirical coefficient of 5, the radius of the influence zone is approximately 1.4 m. Thus, a grouting influence zone can be delineated within a 1.5-meter radius on both sides of the channel projection line.

[0053] Within the grouting influence zone, multiple micro-grouting holes are laid out according to the channel direction. The spacing between the holes is controlled between 1 and 2 meters. Too large a spacing will make it difficult for the grout to form a continuous curtain, while too small a spacing will increase construction costs and construction interference. This implementation method recommends a hole spacing of 1.5 meters to balance coverage and construction efficiency.

[0054] Each grouting hole is drilled using a small-diameter borehole, with the diameter controlled below 50 mm. The advantages of a small diameter are fast drilling speed, minimal disturbance, and the ability of the grout to diffuse quickly after entering the pores, reducing the risk of borehole collapse or mud loss. The drilling depth should be determined based on the vertical distance from the top of the inclined shaft to the target channel, and generally can be terminated 0.5 meters above the top of the channel to avoid drilling through the main channel and causing a water inrush.

[0055] Using the above method, a linear group of micro-grouting holes can be formed within the projection range of each highly connected channel. The location and number of the hole group are determined by the channel length and the width of the grouting influence zone.

[0056] After completing the ground drilling layout, all grouting holes need to be grouped. The grouping principle is as follows: each high-connectivity channel corresponds to a group of holes, and the division is centered on the channel's beginning or key node. The beginning node refers to the location where the channel connects to the groundwater source or the main seepage direction; the key node refers to the point in the channel where the seepage parameters change abruptly or bifurcate. Through this grouping method, each group of holes can achieve effective control over the target channel.

[0057] In designing the grouting sequence, pore groups with a connectivity index greater than 0.7 and a permeability parameter 20 percentage points higher than the average are selected as the initial grouting targets. The permeability parameter, as defined above, is the product of average particle size and porosity. For example, when the average particle size of a channel is 20 mm and the average porosity is 0.35, its permeability parameter is 7. If the overall average is 6, then the permeability parameter of this channel is 17 percentage points higher than the average, which is considered high, and grouting should be prioritized for this channel.

[0058] After the initial grouting is completed, the grouting area is gradually extended to adjacent medium-permeable channels to ensure that the grouting body forms a closed curtain and blocks the water-sediment coupling channels. This allows for a gradual transition from the main channel to the secondary channel, ensuring the sealing effect.

[0059] In prioritizing grouting paths, this implementation follows the principle of "main channels first, branch channels second." That is, highly connected main channels are treated first, followed by secondary branch channels. If two channels have comparable connectivity, their formation particle size and porosity are compared. Channels with larger particle sizes and higher porosity are more prone to water-sediment cross-contamination, posing a higher risk of water blockage; therefore, they should be the primary grouting path.

[0060] The specific priority setting method is as follows: all channels are sorted from high to low according to their connectivity index. When the connectivity difference between two channels is less than 0.05, they are considered equivalent. At this time, a correction factor is introduced, that is, the penetration parameters of the two channels are compared. If the penetration parameter of one channel is more than 10% higher than that of the other, then the channel is selected as the primary betting path.

[0061] For example, if channel A has a connectivity of 0.85 and channel B has a connectivity of 0.83, the difference is only 0.02, which is considered equivalent. If channel A has a penetration parameter of 9 and channel B has a penetration parameter of 7, then channel A's parameter is about 28% higher, and channel A should be selected first.

[0062] During grouting in inclined shafts traversing highly permeable pebble layers, simply relying on the designed perforation layout and grouting sequence is insufficient to guarantee water shut-off effectiveness. Due to the uneven particle composition and complex porosity distribution of the pebble layer, the diffusion range of the grout and the pore sealing efficiency often exhibit significant uncertainty. Therefore, this invention incorporates a monitoring and feedback mechanism during the low-pressure pre-grouting stage. By real-time monitoring of the grout penetration radius and pore sealing rate, the actual effective grouting section is identified, and the grouting pressure or grout mix ratio is dynamically adjusted based on the results, thereby improving the reliability and efficiency of water shut-off.

[0063] During low-pressure pre-grouting, monitoring holes are installed in the adjacent area of ​​the grouting hole, with the hole spacing generally controlled within the range of 1 m to 2 m. A piezometer and a resistivity probe are installed in the monitoring hole. The piezometer is used to record changes in pore water pressure in real time, and the resistivity probe is used to reflect changes in the electrical characteristics of the pores after the grout enters. The piezometer can be selected with a range of 0–1 MPa and an accuracy of 0.01 MPa. The resistivity probe uses a four-electrode structure and is positioned within the target depth range.

[0064] When grout is injected from the injection hole at low pressure (generally less than 0.3 MPa), the water pressure in adjacent monitoring holes will gradually increase, and the resistivity value will decrease significantly as the grout replaces the pore water. By recording the water pressure change curve and the range of resistivity decrease in real time, the location of the grout diffusion front can be estimated.

[0065] The permeation radius is defined as the farthest radial distance from the grout front to the center of the grouting hole. It is calculated as follows: when the increase in seepage pressure in the monitoring hole exceeds 10% of the initial background value, or the decrease in resistivity exceeds 15% of the original value, the grout is considered to have reached the monitoring hole location. Combining the spatial distance between the grouting hole and the monitoring hole, the permeation radius in that direction can be estimated. The average permeation radius of the grout in different directions is obtained through observations from multiple monitoring holes.

[0066] For example, if a water pressure increase of 0.05 MPa and a resistivity decrease of 20% are detected in a monitoring hole at a position of 1.5 m, it indicates that the slurry has diffused to that location, with a penetration radius of at least 1.5 m.

[0067] During the grouting process, a flow meter and a sand content measuring device are installed in the return pipeline to record the flow rate and sand content of the return grout in real time. The flow meter can be an electromagnetic flow meter with a measurement accuracy of not less than ±2%; the sand content measuring device can be an optical turbidimeter, which can continuously monitor within the range of 0–50 g / L.

[0068] The pore closure rate is defined as the rate at which the return flow rate decreases per unit time, reflecting the efficiency with which pores are gradually filled by the slurry. Specifically, it is calculated by dividing the difference in return flow rate over consecutive 5-minute intervals by the time interval. For example, if the return flow rate decreases from 10 L / min to 7 L / min within 5 minutes, the closure rate is 0.6 L / min.

[0069] In addition, considering the trend of sand content changes, when the sand content in the return slurry decreases significantly, it indicates that the slurry has effectively blocked the sandy pores.

[0070] The pore sealing rate threshold is set at 0.5 L per minute. When the monitored value is lower than this threshold, it indicates that the grout diffusion is hindered or the pores are not effectively filled, and the grouting parameters need to be adjusted. When the sealing rate is higher than this threshold and continues for more than 10 minutes, it indicates that the pores in this section have entered an effective sealing state.

[0071] During the design phase, a coverage area is typically defined, for example, requiring a penetration radius of no less than 1.5 m to ensure that a continuous curtain can be formed between adjacent grouting holes. When the measured penetration radius is less than 1.5 m, the section is deemed not to have met the coverage requirements.

[0072] If the measured pore sealing rate is less than 0.5 L / min and the backflow sand content does not decrease significantly within 20 minutes, it indicates that the grout has failed to enter the main permeation channels and the grouting effect is insufficient.

[0073] When the above situation occurs, the grouting parameters need to be adjusted. Common measures include: Increase grouting pressure: gradually increase from 0.3 MPa to 0.5 MPa to increase driving force to promote grout diffusion.

[0074] Change the slurry mix ratio: for example, adjust the water-cement ratio from 1:1 to 0.8:1 to increase the slurry consistency and improve the sealing ability.

[0075] Adding accelerators: shortens the slurry setting time and avoids excessive slurry loss.

[0076] When the adjusted parameters result in a penetration radius of 1.5 m or more, a pore closure rate consistently above 0.5 L / min, and a return sand content decrease of more than 50%, the section is confirmed as an effective grouting section. This section will be a key control area in the subsequent main grouting stage.

[0077] When carrying out the main grouting operation in the identified effective grouting section, in order to ensure that the grout can fully fill the pores of the pebble layer and achieve effective sealing, it is necessary to monitor the pressure changes and sand content of the backflow grout in real time during the grouting process.

[0078] After entering the effective grouting section, it is first necessary to divide it into several layered units along the depth direction. The thickness of each layered unit is controlled between 0.5 m and 1.0 m. The thickness mainly depends on the complexity of the formation porosity distribution and the uniformity of particle size in the pebble layer. When the formation porosity is relatively fine, a smaller thickness (such as 0.5 m) can be selected for precise control; when the formation porosity is large and uniform, the thickness can be appropriately increased (such as 1.0 m) to improve construction efficiency.

[0079] Different types of grouting materials are selected based on the pore characteristics in different layered units: When the pores are mainly manifested as fine cracks, early-strength cement grout is selected. Its characteristics are low viscosity, rapid penetration into micro-cracks, and solidification in a short time.

[0080] When the pores are of medium size and connected to the aquifer, quick-setting cement-water glass grout is selected. Its characteristics are short initial setting time, rapid solidification, and prevention of continuous erosion by groundwater.

[0081] When the pore size is large and the pebbles are loosely distributed, an expansive composite grout is selected. Its characteristic is that the volume expands during the curing process, which can achieve strong sealing of large pores and voids.

[0082] This "material selection based on layer" approach ensures that different pore structures can achieve targeted treatment effects, rather than using a single grout which could lead to grouting failure.

[0083] In the specific grouting process, each layer unit adopts a process that gradually transitions from low viscosity to high viscosity.

[0084] Initial grouting stage: First, inject a low-viscosity grout (such as diluted early-strength cement grout with a water-cement ratio of 1.5:1) to quickly enter small pores and capillary cracks using its fluidity, thus achieving preliminary filling.

[0085] Transition grouting stage: As the low-viscosity grout gradually diffuses, it switches to a medium-viscosity grout (such as cement grout with a water-cement ratio of 1:1 or cement-water glass grout), further filling the medium-diameter pores and forming a semi-closed state.

[0086] Terminal sealing stage: In the later stage of grouting in this layer, high viscosity or expansive composite grout (such as cement grout with a water-cement ratio of 0.8:1 combined with an expansive agent) is injected to achieve complete sealing of large pores and overall reinforcement.

[0087] This multi-stage switching process can simulate the natural evolution of slurry in pores from "thin to thick" to ensure that pores of different sizes are effectively filled.

[0088] During the main grouting process, pressure sensors and flow recording devices are installed at each grouting hole to monitor changes in the grouting pressure curve in real time.

[0089] The pressure sensor range is recommended to be set at 0–2 MPa with an accuracy of ±0.01 MPa.

[0090] The flow device can be an electromagnetic flow meter to record the amount of grout entering the injection site in real time.

[0091] Under normal circumstances, the grouting pressure curve should show a trend of "gradually increasing and tending to stabilize".

[0092] If an abnormal surge occurs (e.g., the pressure increases by more than 0.2 MPa within 1 minute), it indicates that the grout may have encountered a closed end or be blocked by large particles. Grouting should be paused, and it should be checked whether to switch grout or reduce the grouting rate.

[0093] When an abnormal drop occurs (e.g., a pressure drop of more than 0.2 MPa within 1 minute), it indicates that the slurry may be rapidly flowing into unsealed channels or loose layers, requiring timely adjustment of the slurry mix ratio, increasing viscosity, or adding an accelerator.

[0094] Real-time analysis of the pressure curve can dynamically reflect the distribution of slurry in the pores.

[0095] To verify the pore sealing effect, a continuous sampling device was installed in the return pipe to detect the sand content of the slurry.

[0096] The detection equipment can be an optical turbidimeter, with a monitoring range of 0–50 g / L and a sampling frequency of once per minute.

[0097] At the beginning of grouting, the sand content of the return grout is usually high (e.g., above 20 g / L). As the grout gradually seals the pores, the sand content will gradually decrease.

[0098] The preset ratio is set to 50%. When the sand content of the reflux slurry decreases by more than 50% of the initial value and the pressure curve remains stable, it is determined that the pores of the layer have been effectively sealed.

[0099] For example, if the sand content is 20 g / L at the initial stage of grouting, and it drops to below 10 g / L and remains there for more than 10 minutes, while the grouting pressure is stable at around 1.0 MPa, then the stratification has reached the effective grouting standard.

[0100] The layered unit is considered to have been effectively sealed when the following conditions are met: The grouting pressure curve is stable and without abnormal fluctuations; The sand content of the reflux slurry decreased by more than 50% and remained at a low value for more than 10 minutes; The grouting volume reached more than 90% of the design value.

[0101] Once confirmed, the grouting in that layer can be stopped and the process can proceed to the next layer. The above process is repeated until the entire effective grouting section is completed.

[0102] In grouting and water plugging operations, although layered variable grouting can significantly improve the filling effect of grout on the pores of the pebble layer, the large differences in particle composition and complex pore structure of the pebble layer still pose a risk of incomplete sealing or leakage channels in some sections. Therefore, this invention, after the main grouting is completed, judges the completion degree of grouting and water plugging by comparing the sand content of the return grout with the initial pore structure characteristics; if insufficient sealing is found, a secondary targeted micro-injection reinforcement process is initiated, and the stability of the water plugging state is continuously monitored and verified, thereby ensuring the grouting quality and sealing effect.

[0103] Before the main grouting begins, the initial pore structure characteristic parameters of the grouting section are obtained by combining borehole sampling with acoustic testing.

[0104] Obtaining the average particle size: During borehole sampling, sieving tests or laser particle size analysis are used to statistically analyze the particle size distribution curve of the pebble layer samples and calculate the weighted average particle size. For example, if the particle size range in a certain section of the sample is 10 mm to 50 mm, and the statistical results show that the weighted average particle size is 25 mm, then this value is used as the average particle size parameter for that section.

[0105] Porosity is determined by measuring the ratio of pore volume to total volume through a borehole saturation test, or by using an empirical formula to calculate porosity based on resistivity test results. If the measured results show that the pore volume accounts for 0.32% of the total volume, then the porosity is 32%.

[0106] Pore ​​connectivity was determined through acoustic testing. Ultrasonic transducers were deployed within the borehole to measure the propagation velocity and attenuation coefficient of sound waves within the soil and rock mass. If the attenuation coefficient exceeded a certain critical value, it indicated high pore connectivity. For example, if the sound wave attenuation on a test profile was 0.25 dB / m, higher than the background value of 0.15 dB / m, then the pore connectivity was considered strong.

[0107] These three parameters (average particle size, porosity, and pore connectivity) serve as a benchmark for defining the critical permeability value for this section. The critical permeability value is defined as "the threshold sand content at which slurry and sand particles can be continuously carried out by the water flow under the given pore structure conditions." For example, when the average particle size is 25 mm, the porosity is 32%, and the connectivity is high, the critical permeability value can be calculated from an empirical curve to be 15 g / L.

[0108] After the main grouting is completed, the sand content of the return grout is continuously monitored by an online sampling device arranged in the return pipe.

[0109] The monitoring equipment uses an optical turbidimeter with an accuracy of ±0.1 g / L and a sampling interval of 1 minute.

[0110] The monitoring period is generally set to 30 to 60 minutes to ensure that the data covers the steady-state period after grouting.

[0111] The monitoring results are recorded as curves showing the changing trend of the backflow sand content. If the backflow sand content remains below 15 g / L (i.e., the critical permeability value) throughout the entire monitoring period, it indicates that the slurry has basically blocked the pore structure, and the sand particles no longer migrate with the water flow, thus the section has reached an effective blocking state.

[0112] When the comparison results show that the sand content remains higher than the permeability critical value during the monitoring period, or shows a phased rebound, it indicates that the pores have not been completely filled by the grout, or that new leakage channels have appeared. In this case, secondary targeted micro-injection reinforcement is required immediately.

[0113] Reinforcement hole layout: Re-lay micro-grouting holes on both sides of the identified leakage section. The hole spacing should be controlled within 1.0 m, and the hole diameter less than 40 mm to minimize construction disturbance. The depth of the reinforcement holes should extend 0.5 m above and below the identified leakage layer to ensure complete coverage of the leakage area.

[0114] Grouting parameter selection: High viscosity grout or expansive grout is used for reinforcement grouting, such as cement grout with a water-cement ratio of 0.8:1 mixed with an expansive agent to ensure that the grout can seal the residual pores in a short time.

[0115] Construction control: During reinforcement grouting, a step-by-step pressurization method is adopted, with the initial pressure controlled at 0.3 MPa and gradually increased to 0.6 MPa to avoid channel expansion caused by one-time high pressure.

[0116] This targeted, localized, small-scale reinforcement can quickly eliminate the risk of leakage without wasting a large amount of grout.

[0117] After the second micro-injection is completed, the reflux sand content needs to be tested again, and a comprehensive judgment should be made in combination with the pressure curve.

[0118] Sand content judgment criteria: If the sand content of the reflux drops below the critical permeability value (e.g., 15 g / L) and remains in this low range for more than 20 minutes, it indicates that the pore sealing effect is stable.

[0119] Pressure curve judgment criteria: When the grouting pressure curve remains stable during the injection process (fluctuation amplitude does not exceed ±0.05 MPa), it indicates that the grout has formed a continuous solidified body in the pores and no longer experiences large-scale loss.

[0120] Closure status confirmation: When both of the above conditions are met at the same time, the water blocking closure status of the section is confirmed to be stable, and the grouting operation of the section can be ended.

[0121] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for ground grouting and water plugging for inclined shafts crossing through strong water-permeable pebble layers, characterized in that: The application relates to a method for constructing a ground grouting hole layout network based on a water-sand coupling channel in a gravel layer. The method comprises the following steps: acquiring surface geological radar data and a three-dimensional resistivity inversion model of a target inclined shaft section in a gravel layer, constructing a seepage abnormal high-flux region identification model, and obtaining a spatial distribution feature vector of a potential water-sand coupling channel in the gravel layer; establishing a grouting target point cloud model based on the spatial distribution feature vector, calculating a connectivity index of each potential water permeation channel, combining the average particle size distribution and the porosity of the gravel particles, and outputting a channel easy-to-permeate grade ranking result; according to the channel easy-to-permeate grade ranking result, constructing a ground grouting hole layout network, preferentially arranging multiple-point micro grouting holes in a high-connectivity region, and setting a grouting path transmission priority; performing a low-pressure pre-annulus test on the multiple-point micro grouting holes, monitoring the slurry penetration radius and the pore closure rate, identifying an actual effective grouting section, and adjusting grouting parameters; in the identified effective grouting section, implementing main grouting operation, adopting layered variable-slurry material combined grouting, and real-time monitoring of grouting pressure change and backflow slurry sand content; 2. The method according to claim 1, wherein the method is characterized in that: comparing the backflow slurry sand content with initial pore structure features, judging grouting water plugging completion degree, and if the grouting water plugging completion degree does not reach a closure standard, starting a secondary targeted micro grouting reinforcement process until the water plugging closure state is stable. The method for constructing the seepage abnormal high-flux region identification model comprises the following steps: using a multi-pole high-frequency geological radar to implement multi-directional scanning on a surface layer of the gravel layer, extracting a radar wave reflection energy gradient matrix, and based on a statistical abnormal value algorithm, constructing a three-dimensional energy abnormal initial distribution graph; combining a low-resistance body connectivity feature in the three-dimensional resistivity inversion model, constructing a resistance-energy joint fitting model, fitting an energy-resistivity space coupling relationship through a residual minimum deviation optimization method, and forming a coupling flux indicator field; applying a region growth evolution algorithm to the coupling flux indicator field, automatically generating a potential seepage high-flux region boundary based on a continuous permeation path change trend, and calculating a volume flow rate and a direction vector set of the potential seepage high-flux region boundary; 3. The method according to claim 2, wherein the method is characterized in that: introducing a terrain slope field and a ground stress disturbance field as constraint conditions, correcting horizontal distribution deviation of the abnormal region boundary, and realizing accurate identification of a multi-scale high-flux seepage path in the underground gravel layer. The method for obtaining the spatial distribution feature vector of the potential water-sand coupling channel in the gravel layer comprises the following steps: on the basis of the seepage abnormal high-flux region identification model, constructing a three-dimensional skeleton extraction method of a high-flux path main trunk, implementing multi-scale skeleton thinning processing on a continuous high-flux region, and extracting a main seepage channel; based on the position of the main seepage channel, sampling local perturbation resistivity fluctuation features, radar energy attenuation rates and stratum particle size change rates of each node along the main seepage channel, and constructing a multi-modal fusion coupling channel local state feature set; performing feature dimension reduction and vectorization processing on the feature set, adopting a graph neural network model to learn path structure identification and node connectivity relationship, and outputting a spatial distribution feature vector of each potential channel; performing similarity matching evaluation on the spatial distribution feature vector and a preset water permeability typical structure database, setting an identification confidence threshold, screening out effective channel paths with water-sand coupling potential as grouting target point optimization references.

4. The method according to claim 3, wherein the method is characterized in that: The grouting target point cloud model is established based on the spatial distribution feature vector, and a connectivity index of each potential water permeable channel is calculated, including: According to the channel node coordinates in the spatial distribution feature vector, each node is projected as an independent point in a three-dimensional coordinate system, and a three-dimensional point cloud set containing multiple attributes is formed by using the node disturbance intensity and the channel direction vector as the weight attributes of the points; In the point cloud set, the spatial distance and direction consistency between nodes are used as the connection conditions to construct the channel skeleton link piece by piece, and the effective permeable zone of the channel is determined according to the overlapping degree of the possible slurry permeation range between adjacent points; Based on the effective permeable zone, virtual grouting simulation is performed on the head and tail points of each channel, the transmission coverage rate of slurry between channel nodes is counted, and the ratio of the transmission coverage rate to the total number of channel nodes is taken as the connectivity index; When the connectivity index of a channel reaches a preset threshold value, the channel is marked as a grouting priority path in the point cloud model, and the high-weight point cloud is encrypted for guidance positioning.

5. The inclined shaft crossing strong water-permeable pebble layer ground grouting and water plugging method according to claim 4, characterized in that: The average particle size distribution and porosity of the pebble particles are combined to output the channel permeability grade sorting result, including: At each node of the potential channel, the particle size data of the pebble particles obtained by drilling sampling or acoustic testing is collected, and the average particle size value in the channel range is calculated; at the same time, the porosity is determined by water injection test or resistivity conversion method, and the particle size and porosity are assigned to the corresponding nodes in the three-dimensional point cloud model; The average particle size and porosity values of each node are superimposed on the channel skeleton to calculate the effective permeation parameter of the channel per unit length; Taking the average permeation parameter of the whole channel as the benchmark, all potential channels are compared horizontally, and the channels are sorted from high to low according to the numerical value to obtain the channel permeability grade sorting result.

6. The method for grouting and water plugging of inclined shaft crossing strong water-permeable pebble stratum according to claim 5, characterized in that: The ground grouting hole layout network is constructed, and multiple-point micro grouting holes are preferentially arranged in high-connectivity areas, and the grouting path transmission priority is set, including: After the permeability grade sorting is completed, channels with high permeability grade and connectivity greater than a preset threshold value are selected as priority control objects, and marker points are arranged on the ground within the projection range of the channels, and the grouting influence area is delineated around the marker points according to the channel extension direction; In the grouting influence area, multiple-point micro grouting holes are arranged at an interval of 1 to 2 meters according to the channel trend, and the hole diameter is selected to be less than 50 millimeters; The completed micro grouting hole groups are grouped, each group corresponding to the head or key node position of a high-connectivity channel, and the hole group with high connectivity and high permeation parameter is preferentially selected in the grouting sequence, and gradually extended to adjacent medium-permeability channels; When setting the grouting path transmission priority, the channels are sorted according to the principle of high-connectivity main channels first and secondary branch channels second, and if the connectivity of two channels is the same, the channel with large particle size and high porosity is preferentially selected as the first grouting path.

7. The method according to claim 6, wherein the method is characterized in that: The slurry permeation radius and pore sealing rate are monitored, the actual effective grouting section is identified, and the grouting parameters are adjusted, including: When performing low-pressure pre-grouting, a permeameter and a resistivity probe are arranged in adjacent grouting holes or monitoring holes to record the water pressure change and resistivity reduction range in the slurry diffusion process in real time, so as to estimate the slurry permeation radius in the pebble layer; In the grouting process, the backflow slurry flow meter and sand content measuring device are used to record the rate of gradual decline of the backflow volume per unit time, and the decline rate is taken as the field characterization value of the pore sealing rate; The permeation radius and the pore sealing rate are compared. When the permeation radius is less than the designed coverage range or the pore sealing rate is lower than the set sealing rate threshold, it is determined that the section grouting has not reached an effective state, and the grouting pressure or slurry ratio needs to be adjusted; When the adjusted parameters make the permeation radius cover the designed section and the pore sealing rate reaches or exceeds the preset standard, it is confirmed that the section is an actually effective grouting section.

8. The method according to claim 7, wherein the method is characterized in that: The real-time monitoring of the grouting pressure change and the backflow slurry sand content includes: The effective grouting section is divided into several layered units in the depth direction, with each layer thickness controlled between 0.5 m and 1.0 m, and early strength cement slurry, rapid-setting cement-silicate slurry or expansion-type composite slurry is selected as the grouting material according to the pore characteristics of different layers; During the grouting process of each layer, low-viscosity slurry is first injected to fill small pores, and then high-viscosity or expansion-type slurry is gradually switched to block large pores; During the main grouting process, a pressure sensor and a flow recording device are set to monitor the change curve of the grouting pressure in real time; At the same time, the backflow slurry is continuously sampled, and when the sand content decreases by more than the preset proportion and the pressure curve remains stable, it is confirmed that the layer has completed effective sealing, and then the next layer continues grouting.

9. The method according to claim 8, characterized in that: The sand content of the backflow slurry is compared with the initial pore structure characteristics to determine the completion degree of grouting and water sealing, including: After the main grouting is completed, the pore structure characteristic parameters determined by drilling sampling and acoustic testing at the initial grouting stage are obtained, including average particle size, porosity and pore connectivity, and are taken as the comparison reference; The change trend of the slurry sand content is continuously detected in the backflow pipeline. When the sand content remains below the permeation critical value corresponding to the initial pore structure within the set monitoring period, it is determined that the pores in this section have been sealed; If the comparison result shows that the sand content is still higher than the permeation critical value or there is a stage of rebound, it is determined that the sealing effect is insufficient, and micro-grouting holes are re-arranged in the vicinity of the section and secondary directional micro-grouting is performed to reinforce the pores that have not been completely sealed; After the secondary micro-grouting, the backflow detection is performed again. When the sand content is stably maintained in the low value range and the duration exceeds the preset standard, it is confirmed that the water sealing closed state is stable, and the grouting operation in this section is ended.

Images