Analysis and treatment method for preventing bypass seepage of underground water-sealed cave depot

Abstract

The invention provides an anti-bypass-seepage analysis and treatment method for an underground water-sealed cave depot, and relates to the technical field of underground engineering seepage prevention. A full-process integrated technical system of data acquisition, correlation analysis, model simulation, scheme formulation, iterative optimization, construction implementation and effect verification is constructed. The technical problems that in traditional underground water-sealed cave depot bypass seepage prevention analysis and processing, space and hydraulic correlation between a construction roadway and a main cavern is ignored, the precision of a hydrogeological model is low, a bypass seepage prevention scheme lacks pertinence and is not subjected to quantitative verification, and the construction effect is not subjected to closed-loop optimization are systematically solved, and the accuracy of cave depot bypass seepage prevention analysis is greatly improved; and the differentiated bypass seepage prevention scheme is formulated based on the bypass seepage form, so that the targeted seepage prevention is realized, the engineering cost is reduced, and the scientificity of scheme formulation and the long-term effect of seepage prevention treatment are ensured.

Description

Technical Field

[0001] This invention relates to the field of underground engineering seepage prevention technology, and in particular to an analysis and treatment method for seepage prevention in underground water-sealed caverns. Background Technology

[0002] Underground water-sealed caverns, with their advantages of safety, environmental friendliness, and economy, have become an important method for storing strategic energy sources such as oil and natural gas. Their seepage prevention performance directly determines storage safety. Seepage around the cavern is the core hidden danger in its operation, mainly caused by the hydraulic connection formed by joints and fissures that directly or indirectly connect the water storage in the construction tunnels with the main cavern.

[0003] Existing methods for preventing seepage around the tunnel have significant drawbacks: First, they often analyze the seepage situation in the main tunnel or tunnel fissures separately, ignoring the spatial correlation and hydraulic connection between the two, making it difficult to identify the true seepage channels; Second, hydrogeological models often use equivalent continuous medium models, failing to consider the discrete distribution characteristics of water-conducting fissures, resulting in low model accuracy and large deviations between the simulated seepage field results and reality; Third, the formulation of seepage prevention schemes lacks specificity, often employing a single grouting measure, which easily leads to problems of "over-prevention" or "under-prevention".

[0004] Therefore, it is necessary to propose an analysis and treatment method for preventing seepage around underground water-sealed caverns to solve or at least alleviate the above-mentioned defects. Summary of the Invention

[0005] The main objective of this invention is to provide a method for analyzing and treating seepage prevention in underground water-sealed caverns, in order to solve the problems of poor simulation accuracy and limited methods in existing seepage prevention treatment techniques.

[0006] To achieve the above objectives, this invention provides a method for analyzing and treating seepage around underground water-sealed caverns, comprising the following steps: S1, to obtain geological data of the construction tunnel and main chamber; S2, Draw a structural plan of the connectivity between the construction tunnel and the main tunnel based on the geological data; S3. Based on the preset simulation parameters, the connectivity structure plan, and the geological data, an optimized hydrogeological model is established, and the optimized hydrogeological model is analyzed through numerical simulation to identify seepage channels. S4. Develop an anti-seepage scheme for the seepage channel and input the parameters of the anti-seepage scheme into the optimized hydrogeological model to calculate the seepage volume of the cavern after grouting. S5, determine whether the seepage rate of the cavern after grouting has dropped to within the design threshold of seepage rate; if yes, it is selected as the preferred anti-seepage scheme and proceeds to step S6; if no, adjust the parameters of the anti-seepage scheme and return to step S4. S6, Construction shall be carried out according to the preferred anti-seepage scheme; S7, verify whether the anti-seepage parameters of each cavern after construction meet the requirements; if any one of the anti-seepage effects of the cavern does not meet the preset requirements, adjust the preset simulation parameters and return to step S3.

[0007] Preferably, the geological data includes seepage parameters of the water storage tunnel section of the construction tunnel, water-conducting fracture parameters of the main tunnel, and hydrogeological parameters: wherein, The seepage parameters of the water storage tunnel section of the construction roadway are obtained through the following steps: the seepage volume is divided into multiple levels by graded recording, and the rock mass lithology and fracture conditions near the seepage point under each level are recorded; The parameters of the water-conducting fractures in the main tunnel are obtained through the following steps: the exposed tunnel walls of the main tunnel are probed, and the parameters of the water-conducting fractures in the main tunnel are statistically analyzed based on geological logging data; wherein, the parameters of the water-conducting fractures in the main tunnel include the dip direction, dip angle, opening, extension length, filling material type, and spatial relative position of the water-conducting fractures and the seepage points in the tunnel. The hydrogeological parameters were obtained through the following steps: test boreholes were laid out on the inside and outside of the cavern, and the rock permeability coefficient and the permeability characteristics of the fracture filling material in different lithological sections were measured.

[0008] Preferably, step S2 specifically includes the following steps: S21, Draw a diagram showing the spatial relationship between the construction tunnel and the main tunnel; S22. Based on the spatial relationship diagram and the water-conducting fracture parameters of the main tunnel, draw a plan view of the connectivity between the construction tunnel and the main tunnel.

[0009] Preferably, step S3 specifically includes the following steps: S31, Establish a preliminary hydrogeological model; S32, add the preset simulation parameters, the connectivity structure plan, and the geological data to the preliminary hydrogeological model and analyze them to establish the optimized hydrogeological model; S33, Darcy's law is used in the optimized hydrogeological model for numerical simulation to calculate the seepage channels.

[0010] Preferably, step S33 specifically includes the following steps: S331, conduct a water pressure test on the rock mass surrounding the sealing plug and at the hydraulically connected rock mass, and combine the water pressure test data with the formula. Obtain the equivalent permeability coefficient of the rock mass surrounding the sealing plug and the hydraulically connected rock mass. ;in, The seepage flow rate per unit time. The length of the seepage path. The head difference between the two ends of the seepage flow. The cross-sectional area of ​​the sample is perpendicular to the seepage direction; S332, combining water pressure test data and according to the formula Obtain the equivalent fracture aperture in the rock mass surrounding the sealing plug and in the hydraulically connected rock mass. ;in, The dynamic viscosity of water, It is the acceleration due to gravity; S333, based on the optimized hydrogeological model and combined with the equivalent permeability coefficient Equivalent fracture aperture Pressure head was applied to the water curtain tunnel and the construction tunnel, and numerical simulation analysis was performed to obtain the seepage channel.

[0011] Preferably, step S4 specifically includes the following steps: S41, Post-grouting is carried out on the arch and sidewalls; the depth of the post-grouting holes on the arch and sidewalls is 5m, and multiple post-grouting holes on the arch and sidewalls are arranged in a quincunx pattern with a spacing of 2.0m×2.0m between rows; S42, Post-grouting is performed on the base plate; wherein, the depth of the post-grouting holes in the base plate is 6m, and the post-grouting holes of multiple base plates are arranged in a quincunx pattern with a spacing of 2.0m×2.0m between rows; S43, clay and bentonite are used to backfill the tunnel sections outside the sealing plug; S44, C25P6 concrete was used to backfill and seal the drainage ditch; S45, input the grouting scheme parameters and backfilling scheme parameters into the optimized hydrogeological model to calculate the seepage volume of the cavern after grouting.

[0012] Preferably, step S7 specifically includes the following steps: S71, Inspection holes are set up in the grouting area to determine whether the permeability coefficient of the rock mass after grouting is within the design threshold of permeability coefficient.

[0013] Preferably, step S71 is followed by the step: S72, water is stored in the backfill area of ​​the tunnel until the backfill height is submerged, and the water level drop is monitored to see if it is within the design threshold.

[0014] Preferably, step S72 is followed by the step: S73, water level gauges and piezometers are installed in the cavern, and the changes in groundwater level and piezometer around the cavern are continuously monitored to see if they meet the requirements; the monitoring period is ≥6 months.

[0015] Preferably, step S31 specifically includes the following steps: S311, Establish a survey database; S312, Create a borehole model based on the exploration database; S313, Based on the borehole model, establish geological models of the overburden, weathering layer, water level, alteration zone, and dense joint zone to obtain the preliminary hydrogeological model.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for the analysis and treatment of seepage prevention in underground water-sealed caverns. By constructing an integrated technical system encompassing data acquisition, correlation analysis, model simulation, scheme formulation, iterative optimization, construction implementation, and effect verification, this method systematically solves the technical problems in traditional underground water-sealed cavern seepage prevention analysis and treatment, such as neglecting the space and hydraulic correlation between construction tunnels and main caverns, low accuracy of hydrogeological models, lack of specificity and quantitative verification of seepage prevention schemes, and lack of closed-loop optimization of construction effects. This significantly improves the accuracy of cavern seepage prevention analysis. Furthermore, it formulates differentiated seepage prevention schemes based on the seepage pattern to achieve "targeted seepage prevention," thereby reducing engineering costs and ensuring the scientific nature of the scheme formulation and the long-term effectiveness of the seepage prevention treatment. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a process flow diagram of the overall method in one embodiment of the present invention; Figure 2 This is a diagram showing the layout of anti-seepage grouting holes in a construction tunnel according to one embodiment of the present invention; Figure 3 This is a layout diagram of a clay backfill scheme for a construction tunnel according to one embodiment of the present invention; Figure 4 This is a layout diagram of the backfilling scheme for the drainage ditch on the bottom slab of a construction tunnel according to one embodiment of the present invention; Figure 5 This is a comparison diagram of rock permeability coefficients before and after grouting in one embodiment of the present invention; wherein, (a) is the effect diagram before grouting, and (b) is the effect diagram after grouting.

[0019] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0020] Explanation of icon numbers: 110. Arch; 120. Sidewall; 130. Base plate; 140. Grouting hole; 150. Sealing plug; 160. Clay and bentonite; 170. C25P6 concrete. Detailed Implementation

[0021] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0022] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0024] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0025] Please see the appendix Figure 1 ~Appendix Figure 5 An embodiment of the present invention provides a method for analyzing and treating seepage around underground water-sealed caverns, comprising the following steps: S1. Obtain geological data of the construction tunnel and main cavern. It is worth noting that traditional methods of collecting data from tunnels or main caverns separately are relatively limited. This application realizes the collaborative collection and joint analysis of geological data from both, avoiding the identification deviation of seepage channels caused by data fragmentation. By standardizing the collection methods, the geological data is made quantifiable and analyzable, providing accurate data support for subsequent numerical simulations. This enables a comprehensive measured characterization of the geological conditions in the cavern area, providing measured basic data for subsequent hydraulic correlation analysis of tunnels and main caverns and the construction of hydrogeological models, ensuring the objectivity and accuracy of subsequent analyses from the source.

[0026] S2. Based on the geological data, draw a structural plan view of the connectivity between the construction tunnel and the main cavern. It should be noted that this is based on the measured geological data obtained in S1. Establish the spatial relationship and structural connectivity between the construction tunnel and the main cavern, and intuitively present the structural zones where the two may form hydraulic connections. This will help delineate high-risk areas for seepage around the tunnel for subsequent detailed hydrogeological model construction, reduce the amount of invalid calculations in subsequent numerical simulations, and finally draw a structural plan view of the connectivity between the construction tunnel and the main cavern. This will realize the visual expression of the structural connectivity between the two, initially indicate the structural areas where seepage around the tunnel may form, and identify the risk of seepage around the tunnel.

[0027] S3. Based on preset simulation parameters, the connectivity structure plan, and the geological data, an optimized hydrogeological model is established. Numerical simulation analysis of this optimized hydrogeological model is then used to identify seepage channels. It should be noted that a progressive modeling method, from initial modeling to refined optimization, is used to construct an optimized hydrogeological model that closely matches the actual geological conditions on site. Combined with numerical simulation, the groundwater seepage pattern under water storage conditions in the construction tunnel is reconstructed, achieving quantitative and precise positioning of seepage channels. This facilitates the subsequent designation of anti-seepage schemes based on the seepage channels. Refinement refers to making the model more realistic and improving the accuracy of calculations through the superposition and integration of multiple data. Modeling is based on the initially acquired geological data and the drawn connectivity structure plan. During modeling, additional preset simulation parameters are added, such as water-conducting structures and grouting pressure, to improve simulation accuracy and form an optimized hydrogeological model. Numerical simulation analysis is then performed based on this optimized hydrogeological model to identify seepage channels (seepage areas), facilitating the development of anti-seepage schemes.

[0028] S4. A seepage prevention scheme is formulated for the seepage channel, and the parameters of the seepage prevention scheme are input into the optimized hydrogeological model to calculate the seepage volume of the cavern after grouting. It is worth noting that, based on the characteristics of the seepage channel identified in S3, a differentiated and targeted seepage prevention scheme is formulated to achieve "targeted seepage prevention". The seepage prevention effect of the scheme is verified in advance through numerical simulation to avoid rework losses caused by unreasonable schemes after direct construction.

[0029] S5, determine whether the seepage volume of the cavern after grouting has decreased to within the design threshold of seepage volume; if yes, it is selected as the preferred anti-seepage scheme and proceeds to step S6; if no, adjust the parameters of the anti-seepage scheme and return to step S4; it can be understood that the seepage volume index of the cavern anti-seepage design is used as the judgment standard to judge the effect of the anti-seepage scheme pre-verified in S4. Through the closed-loop iteration of "scheme design - effect simulation - parameter adjustment", the final determined anti-seepage scheme meets the anti-seepage effect requirements and improves the scientificity and economy of the scheme; if the requirements are met (≤0.1m³ / d), this set of data is used as the preferred anti-seepage scheme; if the requirements are not met (>0.1m³ / d), adjust the grouting pressure, water curtain hole spacing and other parameters, and return to step S4 to substitute into the optimized hydrogeological model to recalculate the seepage volume of the cavern after grouting, iterating until the requirements are met to obtain the location of the preferred anti-seepage scheme.

[0030] S6. Construction is carried out according to the preferred anti-seepage scheme. Based on the preferred anti-seepage scheme obtained after iterative optimization, standardized and regulated anti-seepage construction is carried out on site in accordance with the grouting parameters, backfill materials, construction procedures and other requirements specified in the scheme. The digital optimization scheme is transformed into actual anti-seepage engineering measures on site. Standardized construction ensures that the implementation effect of anti-seepage measures is highly consistent with the numerical simulation prediction effect, ensuring that the anti-seepage measures can accurately block the identified seepage channels and realize the implementation of seepage control.

[0031] S7, verify whether the anti-seepage parameters of each cavern after construction meet the requirements; if any one of the anti-seepage effects of the cavern does not meet the preset requirements, adjust the preset simulation parameters and return to step S3; it should be understood that due to the error between the actual situation and the simulation situation, and various unexpected factors, after construction according to the preferred anti-seepage scheme, it is necessary to verify the anti-seepage effect in real time, that is, verify whether the anti-seepage parameters of each cavern after construction meet the requirements. If any one of them does not meet the requirements, the preset simulation parameters (such as the water guiding structure in the model, the grouting pressure, etc.) need to be adjusted to re-simulate and reconstruct. If the requirements are met, the anti-seepage analysis and treatment of the underground water-sealed cavern is completed.

[0032] In a preferred embodiment of the present invention, the geological data includes seepage parameters of the water storage section of the construction tunnel, water-conducting fracture parameters of the main tunnel, and hydrogeological parameters: wherein, The seepage parameters of the water storage tunnel section of the construction roadway are obtained through the following steps: the seepage volume is divided into multiple levels by graded recording, and the rock mass lithology and fracture conditions near the seepage point under each level are recorded. Among them, the seepage points in the construction roadway most directly and effectively reflect the distribution of the water-conducting structure in the construction roadway, and are also important locations most likely to form seepage channels after the construction roadway is impounded. Therefore, a graded recording standard can be adopted to divide the seepage volume into four levels: trace, small, medium, and large. The lithology and fracture development of the rock mass near the seepage point under each level are recorded simultaneously to realize the correlation between seepage characteristics and surrounding geological conditions, and to accurately locate high-risk seepage points in the roadway. Among them, trace refers to <0.5L / min (wet marks only), small refers to 0.5~2L / min (dripping), medium refers to 2~10L / min (fine stream), and large refers to >10L / min (stream / gushing water). The standardized seepage volume classification makes the seepage characteristics quantifiable and comparable, avoiding the ambiguity of traditional qualitative descriptions. The linkage record of seepage points and surrounding geological conditions provides a direct basis for subsequent spatial correlation analysis of seepage-fracture in the roadway-main chamber, and quickly locates the seepage source that may form a seepage channel in the roadway.

[0033] The parameters of the water-conducting fractures in the main tunnel are obtained through the following steps: the exposed tunnel walls of the main tunnel are probed, and the parameters of the water-conducting fractures in the main tunnel are statistically analyzed based on geological logging data; wherein, the parameters of the water-conducting fractures in the main tunnel include the tendency, dip angle, opening, extension length, filling material type, and spatial relative position of the water-conducting fractures and the seepage points in the tunnel. It is important to note that the exposed cavern walls refer to the rock surface exposed after the excavation of the underground cavern. A full-coverage detection of the exposed cavern walls of the main cavern can be conducted using ground-penetrating radar (detection depth ≥ 5m) or a real-scene recording 3D geological model, avoiding the omission of water-conducting fractures and ensuring the integrity of fracture data. Combined with previous geological logging data, the dip direction, dip angle, aperture, extension length, and infill type of the water-conducting fractures can be statistically analyzed. The spatial relative positions of the water-conducting fractures and seepage points in the tunnel can also be marked, achieving a refined and spatial characterization of the water-conducting fractures in the main cavern. This provides core geometric evidence for subsequent identification of the hydraulic connectivity between the two, solving the problem of traditional methods neglecting the spatial characteristics of fractures.

[0034] The hydrogeological parameters were obtained through the following steps: test boreholes were drilled both inside and outside the cavern, and the permeability coefficient of the rock mass and the permeability characteristics of the fracture-filled material in different lithological sections were measured. It is worth noting that the permeability coefficient of the rock mass in different lithological sections can be determined through pressure water tests, while the permeability characteristics of the fracture-filled material are determined through laboratory permeability tests. This allows for precise regional and typological determination of the hydraulic permeability characteristics of the rock mass and fracture-filled material in the cavern area. The regional drilling ensures that the permeability parameters closely match the actual geological zoning characteristics of the cavern, avoiding the crudeness of traditional single permeability coefficient assignment. The combination of field and laboratory tests simultaneously obtains the permeability characteristics of the overall rock mass and the fracture-filled material, comprehensively characterizing the seepage characteristics of the fractured rock mass and providing a measured basis for subsequent parameter assignment in the hydrogeological model.

[0035] In a preferred embodiment of the present invention, step S2 specifically includes the following steps: S21, Draw a diagram showing the spatial relationship between the construction tunnel and the main tunnel; S22. Based on the spatial relationship diagram and the water-conducting fracture parameters of the main tunnel, draw a plan view of the connectivity between the construction tunnel and the main tunnel. It should be noted that, based on the spatial coordinates, dimensions, and relative positions of the construction tunnel and the main cavern (which can be obtained during data acquisition in step S1), an engineering geological mapping method is used to draw a spatial relationship map between the two. This visually presents the basic spatial characteristics of the tunnel and the main cavern, such as their spatial arrangement, adjacent distances, and relative orientations, thus establishing a spatial framework for subsequent connectivity analysis. Based on this spatial relationship map, and combined with the water-conducting fracture parameters of the main cavern, the spatial location of seepage points in the tunnel, and the structural exposure of both, the development and extension characteristics of joints and fractures in the water-retaining section of the construction tunnel and the corresponding main cavern section are systematically analyzed. The structural connectivity between the two is visualized through mapping, and potential hydraulic connections are preliminarily identified. This achieves a systematic analysis and visual representation of the structural connectivity between the construction tunnel and the main cavern, overcoming the shortcomings of traditional methods that neglect spatial and hydraulic connections. This allows for the delineation of high-risk seepage zones for subsequent component optimization and hydrogeological model construction, enabling preliminary screening of seepage risks and reducing the computational load of subsequent numerical simulations.

[0036] In a preferred embodiment of the present invention, step S3 specifically includes the following steps: S31. Establish a preliminary hydrogeological model. It is understandable that the preliminary hydrogeological model, as a basic model, is mainly established based on the survey data, laying the foundation for the subsequent establishment and optimization of the hydrogeological model.

[0037] S32, add the preset simulation parameters, the connectivity structure plan, and the geological data to the preliminary hydrogeological model and analyze them to establish the optimized hydrogeological model; by integrating the connectivity structure plan obtained in step S2, the full-dimensional geological data obtained in step S1, and the preset simulation parameters required for seepage simulation into the preliminary hydrogeological model, and combining real-time data such as borehole imaging and cavern seepage monitoring during construction, including newly detected major fracture structures such as the statistical information of fractures in the main cavern floor, analyze and identify the main guiding structures around the sealing plug 150, the water curtain tunnel, and the construction tunnel. Water channels and fracture networks were added to the preliminary hydrogeological model to verify and correct its geometry, structural features, and parameter assignments. This ensured that the model closely matched the actual geological structure and seepage characteristics on site, ultimately forming an optimized hydrogeological model. This refinement of the hydrogeological model significantly improved its consistency with the actual situation on site. The optimized hydrogeological model possesses accurate geometric features and realistic geological properties, providing a high-precision calculation model for subsequent numerical simulation of the seepage field. This fundamentally solves the problems of low accuracy and large deviations between simulation results and reality in traditional models.

[0038] S33. In the optimized hydrogeological model, Darcy's law is used for numerical simulation to calculate the seepage channels. It is worth noting that in the model, Darcy's law physical field is used to apply pressure head to the water curtain tunnel and construction tunnel to simulate the impact of water storage on tunnel seepage. By calculating the seepage field, the main seepage areas and seepage channels can be obtained, thus simulating different seepage bypass forms in advance to formulate seepage prevention schemes.

[0039] In a preferred embodiment of the present invention, step S33 specifically includes the following steps: S331, a water pressure test is conducted on the rock mass surrounding the sealing plug 150 and the hydraulically connected rock mass. The water pressure test data is then combined with the formula... Obtain the equivalent permeability coefficient of the rock mass surrounding the sealing plug 150 and the hydraulically connected rock mass. ;in, The seepage flow rate per unit time. The length of the seepage path. The head difference between the two ends of the seepage flow. The cross-sectional area of ​​the sample is perpendicular to the seepage direction. In this case, a field pressure water test was conducted in the surrounding rock mass with strong hydraulic connectivity around the sealing plug (150 mm) to obtain measured data such as water flow rate Q and hydraulic gradient. Based on Darcy's law, the equivalent permeability coefficient of the rock mass in this area was calculated using a formula. This enables a quantitative characterization of the overall seepage capacity of fractured rock masses.

[0040] S332, combining water pressure test data and according to the formula Obtain the equivalent fracture aperture of the rock mass surrounding the sealing plug 150 and the hydraulically connected rock mass. ;in, The dynamic viscosity of water, This refers to gravitational acceleration; it should be noted that, based on the pressure test and the relationship between hydraulic gradient and flow rate: The equivalent fracture aperture mentioned above can be derived by deduction. By applying the calculation formula and substituting the data from the water pressure test, the equivalent fracture aperture at the rock mass surrounding the sealing plug at 150mm and at the hydraulically connected rock mass can be calculated. This method reduces the seepage capacity of rock mass to the core geometric features of fractures, thereby achieving a quantitative characterization of the seepage capacity of discrete water-conducting fractures.

[0041] S333, based on the optimized hydrogeological model and combined with the equivalent permeability coefficient Equivalent fracture aperture Pressure head was applied to the water curtain tunnel and construction tunnel, and numerical simulation analysis was performed to obtain the seepage channels. It is worth noting that the calculated equivalent permeability coefficient... Equivalent fracture aperture By assigning corresponding regions to the optimized hydrogeological model, Darcy's law physical field is used to apply pressure head to the water curtain tunnel and construction tunnel in the model to simulate the actual hydraulic conditions after water impoundment in the construction tunnel. The seepage field distribution in the cavern area is solved through numerical calculation, and seepage paths with continuous high seepage flow and high seepage velocity are identified, which are the seepage bypass channels. By simulating the actual water impoundment conditions, the migration law of groundwater from the construction tunnel to the main cavern is accurately restored, realizing the quantitative and precise location of the seepage bypass channels. It can also simulate the seepage field changes under different water impoundment conditions, restore different forms of seepage bypass laws, provide clear treatment targets for the subsequent targeted anti-seepage bypass scheme, and solve the problem of blind identification of seepage bypass channels in traditional methods.

[0042] Furthermore, step S4 specifically includes the following steps: S41, post-grouting is carried out on the arch crown 110 and the side wall 120; among them, the depth of the post-grouting holes 140 of the arch crown 110 and the side wall 120 is 5m, and the multiple post-grouting holes 140 of the arch crown 110 and the side wall 120 are arranged in a quincunx pattern with a spacing of 2.0m×2.0m between rows. S42, post-grouting is performed on the bottom plate 130; among them, the depth of the post-grouting holes 140 of the bottom plate 130 is 6m, and the post-grouting holes 140 of the bottom plate 130 are arranged in a quincunx pattern with a spacing of 2.0m×2.0m between rows; it is worth noting that, in order to ensure the anti-seepage grouting effect, the anti-seepage grouting of the construction roadway is divided into two parts: post-grouting of the arch 110 and sidewall 120 systems and post-grouting of the bottom plate 130 system, and the angle of the grouting hole 140 should intersect with the water-conducting structure at a large angle. The grout is hydraulically injected into the surrounding rock fissures. After the grout fills and solidifies, it seals the water-conducting fissures and reduces the permeability of the surrounding rock of the arch 110, sidewall 120 and bottom plate 130. It is worth mentioning that during construction, it is strictly required that the bottom slab 130 of all construction tunnel sections below the design water level be cleared down to the bedrock before the bottom slab 130 is poured. This is to reduce the amount of seepage around the bottom slab 130 after the construction tunnel is filled with water, and also to improve the effect of subsequent grouting of the bottom slab 130 system. Please refer to the appendix for details. Figure 2 .

[0043] S43, for the support tunnel section beyond the sealing plug 150, clay and bentonite 160 are used for backfilling; the combination of clay and bentonite utilizes the complementary properties of the materials, resulting in a long-lasting seepage prevention effect after backfilling; by extending the seepage path, the possibility of seepage bypass is reduced from a hydraulic perspective, breaking through the traditional single grouting seepage prevention approach and achieving a dual seepage prevention effect of "sealing + hydraulic optimization," further reducing the risk of seepage bypass; thus reducing the length of the water storage tunnel section, extending the seepage path, and blocking the direct hydraulic connection between the support tunnel and the main tunnel, please refer to the appendix for details. Figure 3 .

[0044] S44, the drainage ditch was backfilled and sealed with C25P6 170 concrete. Based on the deep-hole grouting pilot hole pressure test data, the rock mass in the construction tunnel floor section, affected by tunnel blasting excavation, was highly disturbed and had high permeability. After water impoundment in the construction tunnel, the drainage ditch was highly likely to become a weak point for seepage around the tunnel. Therefore, before water impoundment in the construction tunnel, the drainage ditch was backfilled and sealed with C25P6 170 concrete (waterproof concrete with strength grade C25 and impermeability grade P6) to improve the overall seepage prevention effect of the construction tunnel. Sealing this weak point for seepage around the drainage ditch comprehensively ensured the seepage prevention system of the construction tunnel and improved the overall seepage prevention effect. Please refer to the appendix for details. Figure 4 .

[0045] S45, input the grouting scheme parameters and backfilling scheme parameters into the optimized hydrogeological model to calculate the seepage volume of the cavern after grouting. It should be noted that the key parameters of the grouting and backfilling schemes (such as the rock permeability coefficient after grouting, the backfill layer thickness, as well as seepage prevention parameters and water curtain level) are input into the optimized hydrogeological model. Numerical simulation is used to recalculate the seepage field distribution of the cavern after grouting and backfilling. The calculation process involves substituting the algorithm from the model into the input; this is an existing technology and will not be detailed here. This quantitatively calculates the overall seepage volume of the cavern after grouting, enabling early prediction of the seepage prevention scheme's effectiveness. This avoids rework losses due to poor seepage prevention after direct construction and reduces construction risks.

[0046] Furthermore, step S7 specifically includes the following steps: S71. Inspection holes are installed in the grouting area to determine whether the permeability coefficient of the rock mass after grouting is within the design threshold. It should be understood that inspection holes are specifically installed in the grouting area after construction, and the permeability coefficient of the surrounding rock after grouting is determined by on-site water pressure tests, requiring a value ≤1×10⁻⁶. -3 m / d is used to directly quantify the seepage prevention effect of the grouting area and determine whether the grouting has effectively sealed the water-conducting fissures. This allows for precise location of areas where the grouting effect is substandard, providing a basis for possible subsequent supplementary grouting and ensuring that the grouting seepage prevention effect meets the standards.

[0047] Furthermore, step S71 is followed by the following step: S72 involves impounding water in the backfill area of ​​the tunnel until the backfill height is submerged, and monitoring whether the water level drop is within the design threshold. It should be noted that conducting a water impoundment test in the backfill area after construction is completed involves submerging the backfill height to simulate the actual water impoundment conditions of the construction tunnel. By monitoring the water level drop during the impoundment process (requiring a drop of ≤1cm / d), the overall seepage prevention effect of the backfill area is tested, and it is determined whether the backfill effectively blocks the hydraulic connection. Quantitative monitoring of the water level drop directly reflects the seepage prevention effect of the backfill area, compensating for the limitations of only testing the rock permeability coefficient, and achieving a comprehensive test of the combined seepage prevention effect of grouting and backfilling.

[0048] Furthermore, step S72 is followed by the following step: S73, water level gauges and piezometers are installed in the cavern, and the changes in groundwater level and piezometer around the cavern are continuously monitored to see if they meet the requirements; the monitoring period is ≥6 months. It is important to note that monitoring equipment such as water level gauges and piezometers should be deployed in the cavern area for continuous monitoring for no less than 6 months. This will capture the dynamic changes in groundwater level and seepage pressure around the cavern in real time. By analyzing the stability of the monitoring data, the long-term effectiveness of the seepage prevention measures can be assessed. Simultaneously, it will provide real-time warnings of potential new seepage risks. For example, the groundwater level should be 100P+20 above the cavern arch (P: oil and gas storage pressure, unit: MPa), and the seepage pressure should be greater than P. Long-term monitoring overcomes the limitations of traditional short-term testing, enabling long-term verification of the seepage prevention effect and ensuring that the effectiveness of the seepage prevention measures is consistent with the cavern's design service life. Real-time water level and seepage pressure monitoring can promptly detect seepage anomalies during cavern operation, providing dynamic early warning of seepage risks and ensuring the long-term safe operation of the cavern. If the monitoring results are unsatisfactory, model parameters can be adjusted and the plan optimized in a timely manner, forming a closed-loop process of construction, inspection, long-term monitoring, and plan optimization, thereby improving the long-term effectiveness and reliability of cavern seepage prevention.

[0049] Furthermore, step S31 specifically includes the following steps: S311, Establish an exploration database; This means that during the exploration period, the project's exploration data, such as engineering geological environment, exploration data, and profile information, will be stored and managed using an engineering geology 3D design system. This will be done in a standardized and digital manner to build a unified exploration database and enable centralized retrieval, integration, and application of various types of exploration data.

[0050] S312, Based on the exploration database, a borehole model is created; then, measured borehole data such as borehole location, borehole depth, geological stratification within the borehole, and groundwater level are retrieved from the exploration database and digitally modeled in the engineering geology 3D design system. The discrete measured borehole data is transformed into a 3D digital borehole entity model, forming precise geological observation anchor points in 3D space. This ensures that the subsequent construction of the geological model has clear measured data support and avoids the model from being out of touch with actual geological conditions.

[0051] S313, Based on the borehole model, establish geological models of the overburden, weathering layer, water level, alteration zone, and dense joint zone to obtain the preliminary hydrogeological model.

[0052] Understandably, based on the three-dimensional coordinates of the borehole model and measured geological data, combined with exploration profile information, geophysical data, and other materials, discrete borehole data are extended into continuous three-dimensional geological bodies through spatial interpolation, boundary delineation, feature fitting, and other technical means. Geological models such as overburden and weathering layers are constructed and assigned corresponding geological attributes. After integration, a preliminary hydrogeological model is formed, realizing a preliminary three-dimensional digital representation of the geological conditions of the cavern area. This provides a basic three-dimensional geometric framework for subsequent optimization of the hydrogeological model, giving subsequent model optimization a clear carrier and improving the progressiveness and accuracy of model construction.

[0053] To facilitate understanding by those skilled in the art, a specific implementation method is provided below: After the excavation was completed, all parties involved in the project conducted a comprehensive inspection of all main and branch construction tunnels and the main tunnel, and discovered a total of 40 sets of construction tunnels connected to the main tunnel.

[0054] Step 1: Collaborative collection of basic data; Roadway seepage monitoring: Monitoring equipment was installed at seepage points and monitored continuously for 30 days. The seepage volume at a large number of seepage points was measured to be 1-10 m³ / d. Main tunnel fracture exploration: Using ground-penetrating radar detection and combined with previous geological logging data, it can be seen that the dip angle of the 64 long fractures is 30°~75°; Hydrogeological parameter testing: The permeability coefficient of granite, measured by pressure water test, is k=2.04×10⁻⁶. -3 m / d, and the permeability of the rock mass in some areas can reach 1~10 Lu.

[0055] Step 2: Correlation analysis of seepage and fractures in the tunnel-main chamber; Based on the structural exposure of the main tunnel and construction roadway, the development and extension of joints and fissures exposed in the water storage tunnel section of the construction roadway and the corresponding main tunnel section were systematically reviewed, and a structural plan of the connectivity between the construction roadway and the main tunnel was drawn.

[0056] Step 3: Optimize the construction of the hydrogeological model and the numerical simulation of the seepage field; By optimizing the hydrogeological model and simulating the seepage field, 40 key seepage channels were identified, all of which were formed by the connection between the seepage point in the tunnel and the long fracture in the main tunnel.

[0057] Step 4: Development and optimization of targeted anti-seepage schemes; The method adopted was "clay backfilling of the construction tunnel + post-grouting of the tunnel arch 110 and sidewalls 120 and post-grouting of the bottom slab 130 + backfilling of the construction tunnel drainage ditch": the grouting holes were 140 with a depth of 5~6m, the spacing between rows was 2.0m×2.0m, and the backfill thickness was 24cm; the simulation verification showed that the seepage volume of the tunnel after grouting met the design requirements.

[0058] Step 5: Implementation and Effectiveness Verification; Construction was carried out according to the approved plan. After construction was completed, the rock mass permeability coefficient k was measured to be ≤1×10⁻⁶ by a water pressure test at the inspection borehole. -3 m / d, and long-term monitoring over 6 months showed that the seepage rate of the cavern remained stable within the design parameters, with good anti-seepage effect, thus completing the anti-seepage analysis and treatment of the underground water-sealed cavern.

[0059] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for analyzing and treating seepage around underground water-sealed caverns, characterized in that, Including the following steps: S1, to obtain geological data of the construction tunnel and main chamber; S2, Draw a structural plan of the connectivity between the construction tunnel and the main tunnel based on the geological data; S3. Based on the preset simulation parameters, the connectivity structure plan, and the geological data, an optimized hydrogeological model is established, and the optimized hydrogeological model is analyzed through numerical simulation to identify seepage channels. S4. Develop an anti-seepage scheme for the seepage channel and input the parameters of the anti-seepage scheme into the optimized hydrogeological model to calculate the seepage volume of the cavern after grouting. S5, determine whether the seepage rate of the cavern after grouting has dropped to within the design threshold of seepage rate; if yes, it is selected as the preferred anti-seepage scheme and proceeds to step S6; if no, adjust the parameters of the anti-seepage scheme and return to step S4. S6, Construction shall be carried out according to the preferred anti-seepage scheme; S7, verify whether the anti-seepage parameters of each cavern after construction meet the requirements; if any one of the anti-seepage effects of the cavern does not meet the preset requirements, adjust the preset simulation parameters and return to step S3.

2. The method for analyzing and treating seepage prevention in underground water-sealed caverns according to claim 1, characterized in that, The geological data includes seepage parameters of the water storage section of the construction tunnel, water-conducting fracture parameters of the main tunnel, and hydrogeological parameters: among which... The seepage parameters of the water storage tunnel section of the construction roadway are obtained through the following steps: the seepage volume is divided into multiple levels by graded recording, and the rock mass lithology and fracture conditions near the seepage point under each level are recorded; The parameters of the water-conducting fractures in the main tunnel are obtained through the following steps: the exposed tunnel walls of the main tunnel are probed, and the parameters of the water-conducting fractures in the main tunnel are statistically analyzed based on geological logging data; wherein, the parameters of the water-conducting fractures in the main tunnel include the dip direction, dip angle, opening, extension length, filling material type, and spatial relative position of the water-conducting fractures and the seepage points in the tunnel. The hydrogeological parameters were obtained through the following steps: test boreholes were set up inside and outside the cavern, and the rock permeability coefficient and the permeability characteristics of the fracture filling material in different lithological sections were measured.

3. The method for analyzing and treating seepage prevention in underground water-sealed caverns according to claim 2, characterized in that, Step S2 specifically includes the following steps: S21, Draw a diagram showing the spatial relationship between the construction tunnel and the main tunnel; S22. Based on the spatial relationship diagram and the water-conducting fracture parameters of the main tunnel, draw a plan view of the connectivity between the construction tunnel and the main tunnel.

4. The method for analyzing and treating seepage prevention in underground water-sealed caverns according to claim 2, characterized in that, Step S3 specifically includes the following steps: S31, Establish a preliminary hydrogeological model; S32, add the preset simulation parameters, the connectivity structure plan, and the geological data to the preliminary hydrogeological model and analyze them to establish the optimized hydrogeological model; S33, Darcy's law is used in the optimized hydrogeological model for numerical simulation to calculate the seepage channels.

5. The method for analysis and treatment of seepage prevention in underground water-sealed caverns according to claim 4, characterized in that, Step S33 specifically includes the following steps: S331, conduct a water pressure test on the rock mass surrounding the sealing plug and at the hydraulically connected rock mass, and combine the water pressure test data with the formula. Obtain the equivalent permeability coefficient of the rock mass surrounding the sealing plug and the hydraulically connected rock mass. ;in, The seepage flow rate per unit time. The length of the seepage path, The head difference between the two ends of the seepage flow. The cross-sectional area of ​​the sample is perpendicular to the seepage direction; S332, combining water pressure test data and according to the formula Obtain the equivalent fracture aperture in the rock mass surrounding the sealing plug and in the hydraulically connected rock mass. ;in, The dynamic viscosity of water, It is the acceleration due to gravity; S333, based on the optimized hydrogeological model and combined with the equivalent permeability coefficient Equivalent fracture aperture Pressure head was applied to the water curtain tunnel and the construction tunnel, and numerical simulation analysis was performed to obtain the seepage channel.

6. The method for analysis and treatment of seepage prevention in underground water-sealed caverns according to claim 1, characterized in that, Step S4 specifically includes the following steps: S41, Post-grouting is carried out on the arch and sidewalls; the depth of the post-grouting holes on the arch and sidewalls is 5m, and multiple post-grouting holes on the arch and sidewalls are arranged in a quincunx pattern with a spacing of 2.0m×2.0m between rows; S42, Post-grouting is performed on the base plate; wherein, the depth of the post-grouting holes in the base plate is 6m, and the post-grouting holes of multiple base plates are arranged in a quincunx pattern with a spacing of 2.0m×2.0m between rows; S43, clay and bentonite are used to backfill the tunnel sections outside the sealing plug; S44, C25P6 concrete was used to backfill and seal the drainage ditch; S45, input the grouting scheme parameters and backfilling scheme parameters into the optimized hydrogeological model to calculate the seepage volume of the cavern after grouting.

7. The method for analysis and treatment of seepage prevention in underground water-sealed caverns according to claim 1, characterized in that, Step S7 specifically includes the following steps: S71, Inspection holes are set up in the grouting area to determine whether the permeability coefficient of the rock mass after grouting is within the design threshold of permeability coefficient.

8. The method for analyzing and treating seepage prevention in underground water-sealed caverns according to claim 7, characterized in that, The step S71 is followed by the following step: S72, water is stored in the backfill area of ​​the tunnel until the backfill height is submerged, and the water level drop is monitored to see if it is within the design threshold.

9. The method for analyzing and treating seepage prevention in underground water-sealed caverns according to claim 8, characterized in that, The step S72 is followed by the following step: S73, water level gauges and piezometers are installed in the cavern, and the changes in groundwater level and piezometer around the cavern are continuously monitored to see if they meet the requirements; the monitoring period is ≥6 months.

10. The method for analyzing and treating seepage prevention in underground water-sealed caverns according to claim 4, characterized in that, Step S31 specifically includes the following steps: S311, Establish a survey database; S312, Create a borehole model based on the exploration database; S313, Based on the borehole model, establish geological models of the overburden, weathering layer, water level, alteration zone, and dense joint zone to obtain the preliminary hydrogeological model.

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