Underground vault fissure surrounding rock seepage control and grouting water stopping method

Abstract

The application provides a kind of underground cave fissure surrounding rock seepage control and grouting water stopping method, belongs to underground water sealed cave technical field, comprising: establishing the two-dimensional fissure network groundwater mathematical model of groundwater seepage field in reservoir area;Simulate the water inflow during construction period and operation period;Build the linkage relationship of hydrogeological conditions, grouting seepage control index, water inflow calculation, design the proportion of pre-grouting and post-grouting and grouting area;Using three-dimensional geological comprehensive analysis platform, advance analysis of poor geological body and water permeable structure and take targeted prevention and control measures in advance;Determine the arrangement of pre-grouting drilling and carry out pre-grouting;After the initial pre-grouting drilling is completed and the grout is finally cured, drill inspection holes and observe the seepage in the inspection holes;Determine the arrangement of post-grouting drilling and carry out post-grouting;Verify the effect of post-grouting.The technical effect of the application is that the design is reasonable, has the advantages of strong systematicness, high reliability, convenient operation, low cost, wide application range and the like.

Description

Technical Field

[0001] This invention belongs to the field of underground water-sealed cavern technology, specifically relating to a method for controlling seepage in fractured surrounding rock and grouting to stop water in underground caverns. Background Technology

[0002] Currently, the grouting design and construction of underground water-sealed caverns mainly refer to the experience of hydropower projects and the standards of the hydropower industry. However, the construction principles of hydropower are different from those of underground water-sealed caverns, and the seepage control indicators of the two are also different. Therefore, in the process of copying the grouting technology, a series of problems have arisen. During the construction of many large underground water-sealed caverns, the grouting volume exceeded the estimated project volume and seepage control problems existed.

[0003] According to the "Design Standard for Underground Water-Sealed Rock Cavern Oil Depots" (GB / T 50455-2020), the seepage rate of the treated cavern tanks should not exceed 200 cubic meters per day per million cubic meters of storage capacity, which is approximately equivalent to a seepage control index of 0.1 Lu. The low permeability of the rock mass and seepage control index of underground water-sealed caverns determine the complexity and difficulty of their grouting technology.

[0004] Currently, existing underground water-sealed caverns mainly adopt pre-grouting and post-grouting for water sealing in oil storage caverns. This approach is often piecemeal and lacks a systematic approach, resulting in poor overall effectiveness, complex operation, and high costs, with grouting costs reaching hundreds of millions of yuan.

[0005] Since the control of groundwater seepage and grouting for water stoppage are crucial to the success of the entire underground water-sealed cavern, and are also core technical challenges, it is urgent to establish a method for controlling seepage in the fractured surrounding rock of underground caverns and grouting for water stoppage based on the construction principles of underground water-sealed caverns and the seepage control characteristics of fractured surrounding rock. This method aims to systematically improve the grouting effect, reduce grouting costs, and safeguard the safe construction and smooth commissioning of underground water-sealed caverns. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art, and to provide a new technical solution for the seepage control and grouting water-stopping method of the surrounding rock of underground caverns with fissures.

[0007] According to one aspect of the present invention, a method for controlling seepage in the surrounding rock of underground cavern fissures and for grouting to stop water seepage is provided, comprising the following steps:

[0008] Step S1: Based on the characteristics of the fissure water environment in the groundwater-sealed cavern reservoir, establish a two-dimensional fissure network groundwater mathematical model of the groundwater seepage field in the reservoir area; use the two-dimensional fissure network groundwater mathematical model to perform a pure flow analysis of groundwater without considering fluid-structure interaction and simulate the inflow during the construction and operation periods.

[0009] Step S2: Establish the linkage relationship between hydrogeological conditions, grouting seepage control indicators, and water inflow calculation. Combine construction efficiency and grouting effectiveness ratio to design the ratio of pre-grouting and post-grouting and the grouting area.

[0010] Step S3: Utilize the three-dimensional geological comprehensive analysis platform, combined with the results of various geophysical tests during construction, to analyze unfavorable geological bodies and permeable structures in advance and take targeted prevention and control measures in advance.

[0011] Step S4: Determine the layout of pre-grouting boreholes according to the pre-grouting ratio and grouting area, and perform pre-grouting; after the initial pre-grouting boreholes are completed and the grout has set, drill inspection holes and observe the amount of seepage in the inspection holes; the initial pre-grouting boreholes are arranged in a ring shape.

[0012] Step S5: Determine the layout of post-grouting boreholes and perform post-grouting based on the post-grouting ratio, grouting area, grouting purpose, degree of rock fracture development, grouting pressure, and effective radius of grout diffusion.

[0013] Step S6: Verify the post-grouting effect.

[0014] Optionally, in step S6, a water volume inspection scheme or a water pressure test scheme is used to verify the post-grouting effect;

[0015] When the groundwater level is higher than or equal to the elevation of the water curtain system, a water volume testing scheme shall be adopted.

[0016] When the groundwater level is lower than the elevation of the water curtain system, a pressure water test scheme shall be adopted. Among them, the number of pressure water test boreholes shall not be less than 10% of the number of post-grouting boreholes, and the water permeability of the pressure water test shall be qualified if it is higher than 0.3Lu. Otherwise, the post-grouting seepage reduction work shall continue.

[0017] Optionally, in step S1, the model parameters of the two-dimensional fracture network groundwater mathematical model are set according to the design scheme of the underground cavern, the layered data revealed by the on-site exploration boreholes, and the results of the comprehensive pressure test. The simulation stage is divided into two stages: the construction period and the operation period. The inflow of water in each stage is simulated and calculated to guide the subsequent seepage control and grouting water-stopping work. The model parameters are optimized and adjusted according to the actual project situation and seepage control objectives.

[0018] Optionally, in step S2, the overall surrounding rock seepage control and grouting water-stopping target values ​​of the underground water-sealed cavern are set according to the ratio of pre-grouting and post-grouting and the grouting area.

[0019] Optionally, in step S5, the spacing of the post-grouting boreholes is 1.5m to 2.0m, the length of the post-grouting boreholes is 5m to 9m, and the arrangement of the post-grouting boreholes is either circular or linear.

[0020] Optionally, in step S1, after the two-dimensional fractured network groundwater mathematical model is used to simulate and calculate the inflow during the construction and operation periods and obtain simulation data, the monitoring data and simulation data are compared and analyzed based on the hydrological monitoring data during the construction period, and the monitoring data is used to assign local values ​​to the model in order to optimize and adjust the final simulation results.

[0021] Optionally, in step S3, a three-dimensional geological integrated analysis platform is used to manage and analyze massive amounts of geological information in an integrated manner; wherein, massive amounts of geological information include previous borehole and in-hole test data, geophysical data, geological mapping and geological sketches that affect the water inflow of the site.

[0022] Optionally, in step S6, the water pressure test adopts the single-point method, and the test pressure is 80% of the grouting pressure, not exceeding 1 MPa.

[0023] Optionally, in step S4, the grouting range of the pre-grouting boreholes in the oil storage cavern is 6m-8m outside the excavation outline, the circumferential distance between two adjacent pre-grouting boreholes is no more than 3m, and the bottom distance between two adjacent pre-grouting boreholes is no more than 4m.

[0024] Optionally, in step S4, it is determined whether secondary pre-grouting boreholes need to be arranged based on the amount of seepage in the inspection hole. When secondary pre-grouting boreholes need to be arranged, secondary pre-grouting boreholes are set between the primary pre-grouting boreholes, or the starting position of the secondary pre-grouting boreholes is moved back 0.5 meters to 1.0 meters into the hole, and the arrangement of the secondary pre-grouting boreholes is in a quincunx pattern.

[0025] One technical advantage of this invention is that:

[0026] In the embodiments of this application, in a first aspect, the present invention addresses the current situation of poor grouting effect and high grouting cost in underground water-sealed cavern oil storage chambers. Based on the two-dimensional fracture network groundwater mathematical model of the groundwater seepage field and the three-dimensional geological comprehensive analysis platform, it constructs the linkage relationship between hydrogeological conditions, grouting seepage control indicators, and water inflow calculation. Combining construction efficiency and grouting effectiveness ratio, it rationally designs the ratio of pre-grouting to post-grouting, thereby achieving the purpose of refined design of the ratio of pre-grouting to post-grouting and the grouting area.

[0027] Secondly, this invention solves the problems of lack of systematic grouting and unclear division of pre-grouting and post-grouting ratios in existing underground water-sealed caverns. It fully considers the permeability of surrounding rock fissures and the impact of construction efficiency on grouting and sealing, and adopts a grouting strategy of pre-grouting as the main method, post-grouting as a supplement, local advanced prevention and control, and post-effect verification. It also analyzes in detail the calculation methods and application conditions of seepage control indicators for pre-grouting and post-grouting, as well as the effect verification after grouting, thereby significantly improving the efficiency of grouting and water stopping, and reducing grouting costs and construction period.

[0028] Thirdly, the present invention adopts a grouting strategy of pre-grouting as the main method, post-grouting as the auxiliary method, local advanced prevention and control, and post-effect verification. The position, spacing, length, inclination, length of segmented grout stop plugs, grouting outline and other parameters of the grouting holes can be adjusted according to the actual working conditions, and there is a large optimization space.

[0029] Fourthly, the method for controlling seepage in the surrounding rock of underground cavern fissures and grouting to stop water in this invention has the advantages of being highly targeted, having good grouting effect, low grouting cost, convenient operation, and wide applicability. It can be quickly applied to the construction of large underground water-sealed caverns and similar underground engineering and underground space projects in my country. Attached Figure Description

[0030] Figure 1 This is a schematic flowchart of a method for controlling seepage in the surrounding rock of an underground cavern with fissures and for grouting to stop water flow, according to an embodiment of the present invention.

[0031] Figure 2 The diagram shows the equipotential lines of the water head in the tunnel during the construction period, as described in this embodiment of the invention.

[0032] Figure 3 The diagram shows the equipotential lines of the water head in the tunnel during the operation period of this invention.

[0033] Figure 4 This is a statistical chart of the permeability coefficient of natural rock masses according to an embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram of the interface of the three-dimensional geological comprehensive analysis platform according to an embodiment of the present invention;

[0035] Figure 6 This is a diagram showing the pre-grouting layout for the horizontal excavation of the lower step in an oil storage cavern according to an embodiment of the present invention.

[0036] Figure 7 This is a diagram showing the pre-grouting layout for the vertical excavation of the lower step in an oil storage cavern according to an embodiment of the present invention.

[0037] Figure 8 This is a schematic diagram of the single-point post-grouting hole arrangement according to an embodiment of the present invention;

[0038] Figure 9 This is a schematic diagram of the arrangement of grouting holes after fracture flow according to an embodiment of the present invention;

[0039] Figure 10 This is a schematic diagram of the grouting hole arrangement after planar leakage according to an embodiment of the present invention. Detailed Implementation

[0040] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0041] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0042] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0043] According to one aspect of the present invention, a method for controlling seepage in the surrounding rock of underground cavern fissures and grouting to stop water is provided. This method systematically provides a complete set of technologies and solutions for controlling seepage in the surrounding rock of underground cavern fissures and grouting to stop water, promoting the long-term and large-scale underground storage of energy media such as crude oil and LPG (Liquefied Petroleum Gas) and ensuring the safety of the energy structure. It also has important application value for various underground engineering and underground space projects such as underground water-sealed oil storage depots, underground LPG storage depots, underground hydrogen storage depots, and underground compressed air energy storage depots.

[0044] Specifically, see Figure 1 The method for controlling seepage in the fractured surrounding rock of this underground cavern and for grouting to stop water seepage includes the following steps:

[0045] Step S1: Based on the characteristics of the deep burial and high-pressure fractured water environment of the underground water-sealed cavern, a two-dimensional fractured network groundwater mathematical model of the groundwater seepage field in the reservoir area is established. Using this two-dimensional fractured network groundwater mathematical model, a pure flow analysis of groundwater is performed without considering fluid-structure interaction, and the inflow volume during the construction and operation periods is simulated and calculated. Simultaneously, combined with monitoring data from the construction period and other information, the numerical model is validated, and finally, a reasonable inflow volume for the underground water-sealed cavern is simulated and calculated.

[0046] For example, the hydrogeological conceptual model serves as the foundation and premise of the two-dimensional fractured network groundwater mathematical model. The hydrogeological conceptual model is as follows: heterogeneous anisotropy, with the upper boundary being the boundary of precipitation recharge, evaporation and well discharge, the lower boundary being the impermeable boundary, and underground caverns and water curtains being generalized as constant head boundaries.

[0047] The two-dimensional fracture network mathematical model of groundwater seepage field in the reservoir area, which can be obtained from the hydrogeological conceptual model, is as follows:

[0048] ;

[0049] , ;

[0050] , ;

[0051] , ;

[0052] W=W infil (x,y,z,t)-W evap (x,y,z,t)+W well (x,y,z,t).

[0053] In the above formula, W Source and sink parameters include evaporation, rainfall infiltration, well pumping volume, and spring discharge, etc., measured in cubic meters (m³). 3 / d. Where W infil Represents unsaturated infiltration, which is related to surface rainfall intensity and soil moisture content; W evap Represents groundwater evaporation, which is related to groundwater depth and vegetation transpiration; W well This represents the well pumping and injection volume; a positive value indicates injection, and a negative value indicates pumping.

[0054] μ This is the dynamic storage rate, which is related to the water head, and the unit is m. -1 The expression is: μ =μ0+β( p 0-ρgH).

[0055] Where μ0 is the initial water storage ratio, and β is the medium compressibility coefficient. p 0 represents the initial pore water pressure, ρ represents the density of water, and g represents the gravitational acceleration, reflecting the influence of changes in water head on water storage capacity.

[0056] The initial effluent rate can be calculated using the following formula: .

[0057] In the above formula: x, y, and z are the x-coordinate, y-coordinate, and elevation z-coordinate of a certain point (m); t is time (d); k is a constant; K is the elastic water release coefficient; n is the direction of the outer normal of the boundary; Ω is the groundwater seepage zone; H0 is the initial groundwater level (m); H1 is the water level of the cavern or water curtain (m); μ is the water storage ratio (m³). -1Kxx, Kyy, and Kzz are the permeability coefficients (m / d) in the main x, y, and z directions, respectively, reflecting the spatial differences in permeability in different directions, influenced by fracture orientation and lithological stratification; B1 is the first type of boundary, representing the location (m) of the cavern and water curtain; B2 is the second type of boundary; q(x, y, z, t) represents the flow rate at different locations and times along the boundary, in cubic meters per second (m³). 3 / d, inflow is negative, outflow is positive.

[0058] When performing a pure flow analysis of groundwater without considering fluid-structure interaction, the model parameters set in this embodiment are as follows, based on the design scheme of the underground cavern, the layered data revealed by the on-site exploration boreholes, and the results of the comprehensive pressure water test:

[0059] 1) For slightly weathered rock mass (ungrouted state), take 8.5×10 -6 cm / scm / s; the permeability coefficient after grouting is taken as 1×10 - 6 cm / scm / s, the grouting outline is 6m;

[0060] 2) The water curtain system is installed 25m above the top of the oil storage cavern, at an elevation of 1635m;

[0061] 3) The design water level is 1670m, and the working pressure of the water curtain system is 0.63MPa;

[0062] 4) Water curtain holes are 100mm in diameter and spaced 10m apart;

[0063] 5) There are 16 underground oil storage caverns with a total length of 12,870 m, a net spacing of 36 m between caverns, and an average length of 804 m. During construction, the working pressure of the oil storage tanks is set to 0, and the water head around the oil storage caverns is set to the cavern elevation H + 0 bar. During operation, the working pressure of the oil storage tanks is set to 15 bar, and the water head around the oil storage caverns is set to the cavern elevation H + 15 bar.

[0064] Numerical simulation of the seepage field was performed using the Feflow finite element software's groundwater flow module, employing a two-dimensional Darcy seepage field finite element simulation. The model boundary length extended 300m beyond both chambers, with the vertical range extending from the water table to 200m below the floor of the oil storage chamber. The excavation boundary of the oil storage chamber was set to 0 m pressure head; the water curtain (borehole) system was set to a total head of 1670 m.

[0065] The simulation phase was divided into two stages: the construction phase and the operation phase. The inflow data for each stage were accurately calculated to guide subsequent seepage control and grouting for water shut-off. The calculation results of this embodiment are briefly described below:

[0066] 1) Calculation results after excavation of the main oil storage cavern during the construction period: The calculation results of the seepage field in the site area after excavation of the main oil storage cavern are as follows: Figure 2 As shown.

[0067] 2) Calculation results for the oil storage cavern during operation: During operation, an oil and gas pressure of 0.20 MPa is considered to be applied to the oil storage cavern. The equipotential line diagram and flow field diagram of the calculation model are shown below. Figure 3 .

[0068] This embodiment uses numerical simulation to calculate that the water inflow after the oil storage cavern is fully excavated, following the water curtain system's supply during construction, is 11899.2 m³. 3 / d; After applying oil and gas pressure during operation, the water inflow in the simulated cavern decreased to 8361.6 m³. 3 / d, as shown in Table 1.

[0069] Table 1 shows the statistical table of water inflow in water curtain tunnels and oil storage caverns calculated by numerical simulation method.

[0070]

[0071] After the numerical model calculation is completed, the monitoring data (i.e., measured data) and simulation data are compared and analyzed based on the hydrological monitoring data during the construction period. The monitoring data is then used to assign local values ​​to the model in order to optimize and adjust the final simulation results.

[0072] Step S2 establishes the linkage relationship between hydrogeological conditions, grouting seepage control indicators, and water inflow calculation. Combining construction efficiency and grouting effectiveness ratio, the proportion of pre-grouting and post-grouting, as well as the grouting area, are designed to achieve the purpose of refined design of the proportion of pre-grouting and post-grouting and the grouting area.

[0073] The inflow control target during the operation of the underground water-sealed cavern is no more than 200 cubic meters per day per million cubic meters of storage capacity. The seepage control target for grouting is approximately equivalent to improving the overall permeability coefficient to 1×10⁻⁶. -6 cm / scm / s.

[0074] Taking this embodiment as an example, the target inflow during operation is 1000 m³. 3 / d is equivalent to reducing the average permeability coefficient of the entire reservoir area from 8.5×10 -6 cm / s decreased to 1×10 -6 cm / scm / s, the inflow rate is 8361.6m³ / s from the simulated value. 3 / d decreased to 1000m 3 / d.

[0075] According to the permeability coefficient statistical chart of this embodiment ( Figure 4If pre-grouting is used to directly control the water inflow to the target value, then 99.2% of the oil storage cavern area will need to be pre-grouted, affecting the construction progress of the entire project.

[0076] The pre-grouting period is calculated as follows: the average length of each pre-grouting operation is 20m, the average pre-grouting time is approximately 3 days, and the overlap length of the pre-grouting is 4m. Therefore, the pre-grouting time for a 16m section of the tunnel is 3 days. In this embodiment, the total length of the oil storage cavern is 12870m, of which approximately 1500m is on the critical path and affects the overall project schedule, requiring approximately 279 days for excavation. However, the project's planned excavation time for the upper layer of the oil storage cavern is 5 months. Therefore, using pre-grouting for 99.2% of the oil storage cavern area does not meet the project's construction schedule, and the pre-grouting ratio needs to be reduced.

[0077] This embodiment combines construction efficiency and grouting effectiveness ratio to control the construction period within 150 days. Furthermore, because the grouting efficiency of pre-grouting is much higher than that of post-grouting, pre-grouting should be used as much as possible for rock mass permeability reduction treatment. The ratio of pre-grouting to post-grouting should be rationally designed, and it is recommended to use pre-grouting initially to reduce the rock mass permeability coefficient to 4.18 × 10⁻⁶. -6 If the flow rate is cm / s and post-grouting is used to achieve the target value, then the pre-grouting area accounts for 51.78%.

[0078] Table 2 is a summary of the pre-grouting ratio and seepage control indicators.

[0079]

[0080] According to the settings in Table 2, the seepage control index for pre-grouting is set to 4.18 × 10⁻⁶ in this embodiment. -6 The permeability coefficient of the rock mass is cm / s, and the pre-grouting ratio is set at 51.78%. The pre-grouting area is a rock mass with a permeability coefficient higher than 4.18×10 cm / s. -6 In the region with a permeability coefficient of cm / s, the post-grouting area is where the rock mass permeability coefficient is 4.18×10 cm / s. -6 cm / s and 1.0×10 -6 The region between cm / s.

[0081] Step S3 involves using a three-dimensional geological comprehensive analysis platform, combined with the results of various geophysical tests during construction, to analyze unfavorable geological bodies and permeable structures in advance and take targeted prevention and control measures to effectively reduce the difficulty of seepage control in areas with large water inflow.

[0082] The aforementioned steps are the methods for controlling the overall seepage of the surrounding rock and grouting to stop water in underground water-sealed caverns. In addition, during the construction of underground water-sealed caverns, local adverse geological structures or permeable joints are prone to occur. If advanced prevention and seepage reduction treatments are not taken, it may cause large-scale water inrush and gushing events, greatly increasing the difficulty of grouting inside the cavern.

[0083] A three-dimensional geological integrated analysis platform is used to manage and analyze massive amounts of geological information, including data from previous borehole drilling and in-hole testing, geophysical data, geological mapping, and geological sketches—information that affects the water inflow in the site. Combined with the results of various geophysical tests conducted during construction, such as TSP seismic wave analysis, ground-penetrating radar, and transient electromagnetic methods, adverse geological bodies and permeable structures are analyzed in advance, allowing for targeted prevention and control measures to be implemented proactively, effectively reducing the difficulty of seepage control in areas with large water inflows.

[0084] like Figure 5 As shown in the figure, the interface diagram of the three-dimensional geological comprehensive analysis platform in this embodiment adds excavation information, geological sketch information, and seepage point information of construction tunnels, water curtain tunnels, water curtain connecting tunnels, connecting tunnels, and oil storage caverns. As the construction and excavation progresses, it timely predicts and warns of water-rich zones and unfavorable geological zones ahead, and takes effective control measures such as advance grouting and advance reinforcement in advance.

[0085] It should be noted that, Figure 5 This invention demonstrates how, through three-dimensional geological analysis software, information on the layout of underground engineering structures such as construction tunnels, water curtain tunnels, water curtain connecting tunnels, connecting tunnels, and oil storage caverns is input. Then, the excavated geological information (adverse geological bodies, permeable structures, etc.) is superimposed onto the model in the form of thin plates. The dimensions and spatial information of these thin plates are related to the actual geological data. After integrating all information management, 360-degree rotation and scaling can be achieved.

[0086] During construction, before excavating a thin slab area with poor geological conditions or permeable structures, targeted preventive measures will be taken to control construction safety.

[0087] Preventive measures for adverse geological conditions include: advanced pre-grouting, advanced anchor bolts, advanced small guide pipes, advanced pipe roofs, and other advanced support measures, as well as controlling the blasting advance, which will be reduced from the normal 3m blasting advance to 1-2m to control safety risks.

[0088] Preventive measures for permeable structures: Based on the water discharge situation, pre-grouting is arranged. The length of the pre-grouting borehole is usually between 10-20m, and the spacing between boreholes is 1.5-2.0m. The control outline of the pre-grouting is usually 3-4m outside the net clearance of the cavern. The pre-grouting is in the shape of a fan or claw to cover the rock mass to be excavated in front, so as to control the water discharge after excavation.

[0089] Since the above-mentioned measures are all conventional design solutions and are not within the scope of protection of this application, therefore... Figure 5 Explain it to facilitate understanding.

[0090] Step S4: Determine the layout of pre-grouting boreholes according to the pre-grouting ratio and grouting area, and perform pre-grouting; after the initial pre-grouting boreholes are completed and the grout has set, drill inspection holes and observe the seepage volume in the inspection holes; wherein, the arrangement of the initial pre-grouting boreholes is circular.

[0091] Based on the pre-grouting seepage control index determined in the aforementioned steps, the flow control index within the pre-grouting borehole is calculated. For example, in this embodiment, the pre-grouting seepage control index is set to 4.18 × 10⁻⁶. -6 The flow rate in the inspection hole can be calculated using the following formula: cm / s

[0092] Q = k × P × L;

[0093] In the formula: Q is the flow rate in the inspection hole, in L / min; k is the target permeability of the pre-grouting, in Lu, 1 Lu≈10×10 -6 cm / s; P is the water pressure value in the inspection hole, in MPa; L is the length of the pre-grouting borehole, in m.

[0094] In this embodiment, the pre-grouting borehole length L is uniformly 20m, the target permeability k≈0.418Lu, and the measured water pressure in a certain inspection hole is 1MPa. Therefore, the flow control index in the inspection hole is Q≈0.418×1×20=0.836 L / min. If the measured value in the inspection hole exceeds this flow rate, pre-grouting is required.

[0095] Optionally, in step S4, the grouting range of the pre-grouting boreholes in the oil storage cavern is 6m-8m outside the excavation outline, the circumferential distance between two adjacent pre-grouting boreholes is no more than 3m, and the bottom distance between two adjacent pre-grouting boreholes is no more than 4m.

[0096] In actual construction, depending on the construction method and the height of each step, some holes are arranged around the perimeter.

[0097] 1) If the oil storage cavern has three steps and all are excavated horizontally, the arrangement of the pre-grouting holes is as follows: Figure 6 As shown, the pre-grouting hole positions should be matched according to the height of each step. It is recommended that the outer insertion angle of each pre-grouting borehole be 10°-20° outward from the roadway axis. The outer insertion angle can also be calculated based on the influence range of the actual blasting loosening zone and the length of the pre-grouting hole.

[0098] 2) If the upper step of the oil storage cavern is excavated horizontally, the arrangement of the pre-grouting holes is as follows: Figure 7As shown, the pre-grouting hole positions should be matched according to the height of each step. It is recommended that the outer angle of each pre-grouting borehole be 10°-20° outward parallel to the tunnel axis. During the excavation of the upper layer of the oil storage cavern, the middle and lower steps should arrange pre-grouting boreholes downward perpendicular to the axis of the oil storage cavern in advance, according to the water output of the upper layer. The circumferential spacing between two adjacent pre-grouting boreholes should be 2.5m. The depth of the pre-grouting boreholes should exceed the bottom plate of the oil storage cavern by more than 2m. It is recommended that the outer angle of each pre-grouting borehole on the left and right sidewalls be 15° outward perpendicular to the axis of the oil storage cavern, and the outer angle of each grouting borehole on the bottom plate be 20° outward parallel to the axis of the oil storage cavern. The outer angle can also be calculated based on the influence range of the actual blasting loosening zone and the length of the pre-grouting hole.

[0099] After the initial pre-grouting is completed and the grout has initially set, inspection holes should be drilled to observe the amount of water seepage within the holes, in order to determine whether secondary pre-grouting holes need to be installed. Inspection holes should preferably be located on the working face at least 3 meters away from the nearest initial pre-grouting hole.

[0100] If the water outflow from the inspection hole still exceeds the standard after the initial pre-grouting is completed, a second pre-grouting hole can be added between the initial pre-grouting holes, or a second ring of pre-grouting holes can be arranged, depending on the actual situation. The initial pre-grouting holes form the first ring of pre-grouting holes, and the secondary pre-grouting holes can also form the second ring of pre-grouting holes.

[0101] If the grouting density is increased between the first ring of pre-grouting boreholes, the design parameters of the secondary pre-grouting boreholes are the same as those of the first ring of pre-grouting boreholes.

[0102] If a second ring of pre-grouting boreholes is to be arranged, the opening position and hole depth should be reduced by 0.5-1.0m based on the first ring of pre-grouting boreholes, and the outer insertion angle should be slightly adjusted. The circumferential spacing and hole bottom spacing of the second ring of pre-grouting boreholes should be the same as those of the first ring of pre-grouting boreholes, and finally arranged in a quincunx pattern with the first ring of pre-grouting boreholes.

[0103] If the water flow in the inspection holes or advance water exploration holes still exceeds the standard after the second round of pre-grouting drilling, additional grouting holes can be added within the second round of pre-grouting holes. Similarly, if the water flow exceeds the standard, more grouting holes can be added.

[0104] Step S5: Determine the layout of the post-grouting boreholes based on the post-grouting ratio, grouting area, grouting purpose, degree of rock fracture development, grouting pressure, and effective radius of grout diffusion, and perform post-grouting to ensure that the boreholes intersect with as many fractures as possible.

[0105] The number of post-grouting boreholes depends on the leakage area and the grouting diffusion radius. Generally, the spacing between post-grouting boreholes should be 1.5~2.0m. The length of post-grouting boreholes in the tunnel is generally 5~6m, and can be extended to 8~9m in some areas.

[0106] The post - grouting borehole layout should preferably be circular or linear. Generally, the following situations exist:

[0107] 1) Single - point gushing water in a strand. It is possible to arrange the nozzle grouting holes along the water - flowing point. The grouting holes should preferably be arranged at the positions with wider fissures and their intersection parts. The hole depth should preferably exceed 6m, the hole spacing is generally 1 - 1.5m, and the drilling inclination angle should be set according to the occurrence of the actual water - gushing fissure, as Figure 8 shown.

[0108] 2) Groundwater flows out along a certain fissure. It is possible to set one row or several rows of grouting holes along the direction intersecting with the water - gushing fissure. The grouting holes should preferably be arranged cross - wise on both sides of the crack. The drilling should penetrate the crack obliquely. The horizontal distance between the drilling and the crack should preferably be greater than 0.5m. The spacing of single - row holes is generally 1 - 1.5m, the hole depth should preferably exceed 6m, and the drilling inclination angle is generally 45° - 60°, and should be adjusted accordingly according to the occurrence of the actual water - gushing fissure; when the buried depth of the water - gushing fissure intersects more than 3m, as Figure 9 shown.

[0109] 3) The fissure situation at the leakage part is complex, and the leakage shows sheet leakage. It is advisable to arrange holes around the leakage area. The grouting holes can be arranged in a circular shape. The hole spacing is generally 1.5 - 2.0m. The depth of the post - grouting holes in the main tunnel should preferably exceed 6m. The drilling inclination angle should be set according to the occurrence of the actual water - gushing fissure. First, inject the outer - ring grouting holes, and then inject the inner - ring grouting holes. It is advisable to construct according to the sequence between rings, densification within rings, and sectionalization within holes, as Figure 10 shown.

[0110] Step S6: Verify the effect of post - grouting.

[0111] Optionally, in step S6, a water volume inspection plan or a water pressure test plan is used to verify the effect of post - grouting;

[0112] When the groundwater level is higher than or equal to the elevation of the water curtain system, a water volume inspection plan is adopted;

[0113] When the groundwater level is lower than the elevation of the water curtain system, a water pressure test plan is adopted; among them, the number of boreholes for the water pressure test is not less than 10% of the number of post - grouting boreholes, and when the permeability rate of the water pressure test is higher than 0.3Lu, it is qualified, otherwise, continue the post - grouting seepage reduction work. The water pressure test can not only be used to inspect and supplement the post - grouting boreholes, but also be used to evaluate the regional permeability, improve the post - grouting technology, and enhance the grouting effect.

[0114] During the operation of the groundwater - sealed cavern, the control index for the water inflow is that the water inflow per million cubic meters of reservoir capacity does not exceed 200 cubic meters per day. When the groundwater level of the entire reservoir area is higher than or equal to the elevation of the water curtain system, the control index for the post - grouting of the oil storage cavern is set as follows:

[0115] 1) There is a leakage point, there should be no linear flow and no leakage of sediment, and the single - point water seepage volume is less than 0.5L / min;

[0116] 2) The area of ​​a single wet stain (without visible water on the surface) is less than 3m². 2 Any water flow on the wet surface, regardless of the amount of water, is considered excessive.

[0117] 3) The seepage rate per 100m³ of tunnel should be less than 7L / min or 10m³. 3 / d;

[0118] 4) The average leakage rate of the entire project shall not exceed 1L / m². 2 ·d, to meet the water inflow requirements of each cavity tank;

[0119] 5) Any 100m 2 The average leakage rate on the waterproof area should not exceed 2L / m². 2 ·d.

[0120] If any of the above control indicators are not met, post-grouting for seepage reduction is required.

[0121] When the groundwater level in the entire reservoir area is lower than the elevation of the water curtain system, especially when it is close to or lower than the elevation of the oil storage cavern, the seepage fissures inside the cavern are in a state of desaturation due to the very low groundwater level, making water volume testing prone to inaccuracies. After the groundwater level rises, the seepage fissures may experience an increase in seepage under the action of higher groundwater pressure, thus requiring areas that have passed the previous grouting test to undergo further grouting to reduce seepage.

[0122] Therefore, for working conditions with low groundwater levels (i.e., when the groundwater level is lower than the elevation of the water curtain system), a pressure water test is adopted. The number of boreholes for pressure water testing should be no less than 10% of the number of boreholes drilled for post-grouting. A permeability of more than 0.3 Lu in the pressure water test is considered qualified; otherwise, post-grouting for seepage reduction should continue.

[0123] To minimize disturbance to construction, the water pressure test adopts a single-point method, with a test pressure of 80% of the grouting pressure, not exceeding 1 MPa. The borehole water pressure test pressure for on-site grouting tests can be optimized and adjusted according to project needs and geological conditions.

[0124] The pressure test should be conducted under stable pressure, with the flow rate measured every 1 to 3 minutes. The test can be terminated when the difference between the maximum and minimum values ​​in four consecutive readings is less than 10% of the final value, or when the difference between the maximum and minimum values ​​is less than 1 L / min, and the final value is taken as the calculated value.

[0125] The result of the water pressure test can be expressed as permeability k, with the unit being Lu (Lu). The calculation formula is the same as the formula in step S4: Q = k × P × L.

[0126] Water pressure testing can be used not only to inspect and supplement post-grouting boreholes, but also to evaluate regional permeability, improve post-grouting processes, and enhance grouting effects. The operating steps are as follows:

[0127] 1) If the permeability of the water pressure test is greater than 1 Lu, the area has strong permeability. After densification, the spacing between grouting boreholes should be increased to 1-1.5 m, and the depth of the grouting holes should be increased to 8 m. Prepare a mixed grout with an initial setting time of no more than 20 min and a final setting time of no more than 2 h. The grouting pressure should be the hydrostatic pressure (measured value) + 2.0 MPa. When the injection rate is less than 0.5 L / min•m, the grouting can be stopped after maintaining the final pressure for 30 min.

[0128] 2) The permeability of the water pressure test is between 0.3-1 Lu. The permeability of this area is moderate. According to the distribution of joints and fissures, the spacing of the grouting boreholes can be increased to 1-1.5 m after local densification, and the depth of the grouting holes can be increased to 8 m. A mixed grout with an initial setting time of no more than 30 min and a final setting time of no more than 2 h should be prepared. The grouting pressure is the hydrostatic pressure (measured value) + 1.5 MPa. When the injection rate is less than 0.5 L / min•m, the grouting can be stopped after maintaining the final pressure for 30 min.

[0129] 3) If the permeability of the pressure test is less than 0.3 Lu, the permeability of the area is weak, and post-grouting water-stopping work is not required.

[0130] In the embodiments of this application, in a first aspect, the present invention addresses the current situation of poor grouting effect and high grouting cost in underground water-sealed cavern oil storage chambers. Based on the two-dimensional fracture network groundwater mathematical model of the groundwater seepage field and the three-dimensional geological comprehensive analysis platform, it constructs the linkage relationship between hydrogeological conditions, grouting seepage control indicators, and water inflow calculation. Combining construction efficiency and grouting effectiveness ratio, it rationally designs the ratio of pre-grouting to post-grouting, thereby achieving the purpose of refined design of the ratio of pre-grouting to post-grouting and the grouting area.

[0131] Secondly, this invention solves the problems of lack of systematic grouting and unclear division of pre-grouting and post-grouting ratios in existing underground water-sealed caverns. It fully considers the permeability of surrounding rock fissures and the impact of construction efficiency on grouting and sealing, and adopts a grouting strategy of pre-grouting as the main method, post-grouting as a supplement, local advanced prevention and control, and post-effect verification. It also analyzes in detail the calculation methods and application conditions of seepage control indicators for pre-grouting and post-grouting, as well as the effect verification after grouting, thereby significantly improving the efficiency of grouting and water stopping, and reducing grouting costs and construction period.

[0132] Thirdly, the present invention adopts a grouting strategy of pre-grouting as the main method, post-grouting as the auxiliary method, local advanced prevention and control, and post-effect verification. The position, spacing, length, inclination, length of segmented grout stop plugs, grouting outline and other parameters of the grouting holes can be adjusted according to the actual working conditions, and there is a large optimization space.

[0133] Fourthly, the method for controlling seepage in the surrounding rock of underground cavern fissures and grouting to stop water in this invention has the advantages of being highly targeted, having good grouting effect, low grouting cost, convenient operation, and wide applicability. It can be quickly applied to the construction of large underground water-sealed caverns and similar underground engineering and underground space projects in my country.

[0134] Optionally, in step S1, the model parameters of the two-dimensional fracture network groundwater mathematical model are set according to the design scheme of the underground cavern, the layered data revealed by the on-site exploration boreholes, and the results of the comprehensive pressure test. The simulation stage is divided into two stages: the construction period and the operation period. The inflow of water in each stage is simulated and calculated to guide the subsequent seepage control and grouting water-stopping work. The model parameters can be optimized and adjusted according to the actual project situation and seepage control objectives.

[0135] The above implementation method helps to improve the accuracy of simulation calculations, thereby ensuring the effectiveness of subsequent seepage control and grouting water-stopping work.

[0136] Optionally, in step S2, the overall surrounding rock seepage control and grouting water-stopping target values ​​for the underground water-sealed cavern are set according to the ratio of pre-grouting to post-grouting and the grouting area. This enables overall surrounding rock seepage control and grouting water-stopping for the underground water-sealed cavern.

[0137] Optionally, in step S5, the spacing between the post-grouting boreholes is 1.5m to 2.0m, the length of the post-grouting boreholes is 5m to 9m, and the arrangement of the post-grouting boreholes is either circular or linear. Post-grouting boreholes not only improve the water-stopping effect and enhance the overall water-stopping effect, but also enhance structural stability. By injecting grout into specific areas, it can fill and press down fissures in underground caverns, increasing the integrity and strength of the soil and rock mass, thereby improving the stability and bearing capacity of underground structures.

[0138] Optionally, in step S1, after simulating and calculating the inflow during the construction and operation periods using the two-dimensional fractured network groundwater mathematical model and obtaining simulation data, the monitoring data and simulation data are compared and analyzed based on the hydrological monitoring data during the construction period. The monitoring data is then used to assign local values ​​to the model to optimize and adjust the final simulation results. This helps ensure the accuracy of the simulation calculation results.

[0139] Optionally, in step S3, a three-dimensional geological integrated analysis platform is used to manage and analyze massive amounts of geological information in an integrated manner; wherein, massive amounts of geological information include previous borehole and in-hole test data, geophysical data, geological mapping and geological sketches that affect the water inflow of the site.

[0140] In the above implementation, the use of a three-dimensional geological comprehensive analysis platform not only improves the level of geological information management but also provides strong technical support for all stages of engineering projects. The application of this technology enables complex geological problems to be solved more scientifically and efficiently.

[0141] Optionally, in step S4, it is determined whether a secondary pre-grouting borehole needs to be arranged based on the amount of seepage in the inspection hole. When a secondary pre-grouting borehole needs to be arranged, a secondary pre-grouting borehole can be set between the primary pre-grouting boreholes, or the starting position of the secondary pre-grouting borehole can be moved back 0.5 meters to 1.0 meters into the hole. The arrangement of the secondary pre-grouting boreholes is in a quincunx pattern.

[0142] In this embodiment, the underground cavern fissure surrounding rock seepage control and grouting water-stopping method is based on the development of finite element numerical simulation and fissure water movement theory and seepage control principles. It establishes a method for simulating the seepage field, calculating the inflow, refining grouting, and verifying the grouting effect throughout the underground water-sealed cavern. First, a groundwater seepage field model is established in the reservoir area to simulate and calculate the inflow during construction and operation. Second, the linkage relationship between hydrogeological conditions, grouting seepage control indicators, and inflow calculation is constructed. Combining construction efficiency and grouting effectiveness ratio, the proportion of pre-grouting and post-grouting is rationally designed. Then, a three-dimensional geological comprehensive analysis platform is used to analyze adverse geological bodies and permeable structures in advance, and targeted prevention and control measures are taken in advance to effectively reduce the seepage control difficulty in areas with large inflow. Next, the pre-grouting scheme and post-grouting scheme for the oil storage cavern are refined. Finally, the grouting effect is assessed using two schemes: water volume inspection and water pressure test. The water volume inspection is applicable to conditions where the groundwater level is higher than the elevation of the water curtain system.

[0143] Therefore, this method for seepage control and grouting water stoppage in fractured surrounding rock of underground caverns has advantages such as strong systematicity, high reliability, convenient operation, low cost, and wide applicability. It solves the long-standing problem of seepage control and grouting water stoppage in existing underground water-sealed caverns. It has invented a systematic solution from seepage field simulation, water inflow calculation, grouting ratio division, seepage control index setting, grouting design to grouting effect verification. It can meet the seepage control requirements of underground water-sealed caverns simply by following the process. It has extremely high tolerance for geological conditions and is suitable for grouting water stoppage in various types of high-depth, low-permeability fractured surrounding rock. Moreover, by constructing a linkage relationship between hydrogeological conditions, grouting seepage control indicators, and water inflow calculation, and combining construction efficiency and grouting effectiveness ratio, the goal of refined grouting and seepage control is achieved. This effectively solves the problems of uncontrolled water inflow and low grouting effectiveness in previous underground water-sealed caverns. The control parameters can be appropriately adjusted according to the actual working conditions, with a large optimization space. It can provide a systematic, reliable, convenient, low-cost, and widely applicable method for seepage control and grouting water stoppage in underground water-sealed caverns. It can be quickly applied to the construction of underground water-sealed caverns, effectively reducing the grouting cost and construction period of underground caverns, improving the economic benefits of cavern construction, and ensuring the safety of the energy structure.

[0144] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for controlling seepage and grouting to stop water in fractured surrounding rock of underground caverns, characterized in that, Includes the following steps: Step S1: Based on the characteristics of the fissure water environment in the groundwater-sealed cavern reservoir, establish a two-dimensional fissure network groundwater mathematical model of the groundwater seepage field in the reservoir area; use the two-dimensional fissure network groundwater mathematical model to perform a pure flow analysis of groundwater without considering fluid-structure interaction and simulate the inflow during the construction and operation periods. Step S2: Establish the linkage relationship between hydrogeological conditions, grouting seepage control indicators, and water inflow calculation. Combine construction efficiency and grouting effectiveness ratio to design the ratio of pre-grouting and post-grouting and the grouting area. Step S3: Utilize the three-dimensional geological comprehensive analysis platform, combined with the results of various geophysical tests during construction, to analyze unfavorable geological bodies and permeable structures in advance and take targeted prevention and control measures in advance. Step S4: Determine the arrangement of pre-grouting boreholes based on the pre-grouting ratio and grouting area, and perform pre-grouting. After the initial pre-grouting drilling is completed and the grout has set, inspection holes are drilled and the amount of seepage in the inspection holes is observed; the initial pre-grouting drilling holes are arranged in a ring shape. Step S5: Determine the layout of post-grouting boreholes and perform post-grouting based on the post-grouting ratio, grouting area, grouting purpose, degree of rock fracture development, grouting pressure, and effective radius of grout diffusion. Step S6: Verify the post-grouting effect; The hydrogeological conceptual model serves as the basis for the two-dimensional fractured network groundwater mathematical model. The hydrogeological conceptual model is characterized by heterogeneity and anisotropy, with the upper boundary being the boundary of precipitation recharge, evaporation, and well discharge, and the lower boundary being the impermeable boundary. The underground caverns and water curtains are generalized as constant head boundaries. The two-dimensional fracture network mathematical model of groundwater seepage field in the reservoir area, which can be obtained from the hydrogeological conceptual model, is as follows: ； ， ； ， ； ， ； W=W infil (x,y,z,t) W evap (x,y,z,t)+W well (x,y,z,t); In the above formula, W Source and sink items include evaporation, rainfall infiltration recharge, well pumping volume, and spring discharge volume, measured in cubic meters (m³). 3 / d; where W infil Represents unsaturated infiltration, which is related to surface rainfall intensity and soil moisture content; W evap Represents groundwater evaporation, which is related to groundwater depth and vegetation transpiration; W well This represents the well pumping and injection volume; a positive value indicates injection, and a negative value indicates pumping. μ This is the dynamic storage rate, which is related to the water head, and the unit is m. -1 The expression is: μ =μ0+β( p 0 ρgH); Where μ0 is the initial water storage ratio, and β is the medium compressibility coefficient. p 0 represents the initial pore water pressure, ρ represents the density of water, and g represents the gravitational acceleration, reflecting the influence of changes in water head on water storage capacity; The initial water output rate of μ0 is calculated using the following formula: ; In the above formula: x, y, and z are the x-coordinate, y-coordinate, and elevation z-coordinate of a certain point (m); t is time (d); k is a constant; K is the elastic water release coefficient; n is the direction of the outer normal of the boundary; Ω is the groundwater seepage zone; H0 is the initial groundwater level (m); H1 is the water level of the cavern or water curtain (m); μ is the water storage ratio (m³). -1 Kxx, Kyy, and Kzz are the permeability coefficients (m / d) in the main x, y, and z directions, respectively, reflecting the spatial differences in permeability in different directions, influenced by fracture orientation and lithological stratification; B1 is the first type of boundary, representing the location (m) of the cavern and water curtain; B2 is the second type of boundary; q(x, y, z, t) represents the flow rate at different locations and times along the boundary, in cubic meters per second (m³). 3 / d, inflow is negative, outflow is positive.

2. The method for controlling seepage and grouting to stop water in fractured surrounding rock of underground caverns according to claim 1, characterized in that, In step S6, the effect of post-grouting is verified by a water volume inspection scheme or a water pressure test scheme. When the groundwater level is higher than or equal to the elevation of the water curtain system, a water volume testing scheme shall be adopted. When the groundwater level is lower than the elevation of the water curtain system, a pressure water test scheme shall be adopted. Among them, the number of pressure water test boreholes shall not be less than 10% of the number of post-grouting boreholes, and the water permeability of the pressure water test shall be qualified if it is higher than 0.3Lu. Otherwise, the post-grouting seepage reduction work shall continue.

3. The method for controlling seepage and grouting to stop water in fractured surrounding rock of underground caverns according to claim 2, characterized in that, In step S1, the model parameters of the two-dimensional fracture network groundwater mathematical model are set according to the design scheme of the underground cavern, the layered data revealed by the on-site exploration boreholes, and the results of the comprehensive pressure test. The simulation stage is divided into two stages: the construction period and the operation period. The inflow of water in each stage is simulated and calculated to guide the subsequent seepage control and grouting water-stopping work. The model parameters are optimized and adjusted according to the actual project situation and seepage control objectives.

4. The method for controlling seepage and grouting to stop water in fractured surrounding rock of underground caverns according to claim 1, characterized in that, In step S2, the overall surrounding rock seepage control and grouting water-stopping target values ​​of the underground water-sealed cavern are set according to the ratio of pre-grouting and post-grouting and the grouting area.

5. The method for controlling seepage and grouting to stop water in fractured surrounding rock of underground caverns according to claim 1, characterized in that, In step S5, the spacing of the post-grouting boreholes is 1.5m to 2.0m, the length of the post-grouting boreholes is 5m to 9m, and the arrangement of the post-grouting boreholes is either circular or linear.

6. The method for controlling seepage and grouting to stop water in fractured surrounding rock of underground caverns according to claim 1, characterized in that, In step S1, after the two-dimensional fractured network groundwater mathematical model is used to simulate and calculate the inflow during the construction and operation periods and obtain simulation data, the monitoring data and simulation data are compared and analyzed based on the hydrological monitoring data during the construction period, and the monitoring data is used to assign local values ​​to the model in order to optimize and adjust the final simulation results.

7. The method for controlling seepage and grouting to stop water in fractured surrounding rock of underground caverns according to claim 1, characterized in that, In step S3, a three-dimensional geological integrated analysis platform is used to manage and analyze massive amounts of geological information in an integrated manner. The massive amounts of geological information include previous borehole and in-hole test data, geophysical data, geological mapping and geological sketches that affect the water inflow in the site.

8. The method for controlling seepage and grouting to stop water in fractured surrounding rock of underground caverns according to claim 2, characterized in that, In step S6, the water pressure test adopts the single-point method, and the test pressure is 80% of the grouting pressure, which is not greater than 1 MPa.

9. The method for controlling seepage and grouting to stop water in fractured surrounding rock of underground caverns according to claim 1, characterized in that, In step S4, the grouting range of the pre-grouting boreholes in the oil storage cavern is 6m-8m outside the excavation outline, the circumferential distance between two adjacent pre-grouting boreholes is no more than 3m, and the bottom distance between two adjacent pre-grouting boreholes is no more than 4m.

10. The method for controlling seepage and grouting to stop water in fractured surrounding rock of underground caverns according to claim 9, characterized in that, In step S4, it is determined whether secondary pre-grouting boreholes need to be arranged based on the amount of seepage in the inspection hole. When secondary pre-grouting boreholes need to be arranged, secondary pre-grouting boreholes are set between the primary pre-grouting boreholes, or the starting position of the secondary pre-grouting boreholes is moved back 0.5 meters to 1.0 meters into the hole. The arrangement of the secondary pre-grouting boreholes is in a quincunx pattern.

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