Method for assessing flood risk for grout injection and filling technology for isolated rock.

Abstract

This invention provides a method for evaluating flood risk for inoculated rock grout injection filling technology, and includes the steps of: creating a basic dataset for inoculated rock grout injection in coal seams; analyzing the motion laws of the inoculated rock of coal seams using the basic dataset and predicting the height of permeable crack zones; drawing a cross-sectional diagram of the working surface for inoculated rock grout injection to analyze flood risk and make a preliminary judgment on flood risk due to inoculated rock grout injection; constructing a spatial development model for inoculated rock grout injection to simulate the entire process of actual inoculated rock grout injection; evaluating the flood risk due to inoculated rock grout injection from multiple perspectives, including engineering analogy, semi-empirical determination, and theoretical analysis; and optimizing the grout injection design based on the flood risk of inoculated rock grout injection filling. [Effect] Overcomes the problem of not being able to scientifically and effectively evaluate the flood risk of grout injection filling in isolated rock.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This invention claims priority to the Chinese patent application filed with the China National Intellectual Property Administration on September 20, 2024, application number 202411313329.3, with the title of the invention "Method for evaluating flood risk for grout injection filling technology for covered rock isolation," the entire contents of which are incorporated by reference to this invention and constitute part of this invention for all purposes.

[0002] The present invention relates to the technical field of data processing for grout injection to isolate covered rock, and more specifically to a method for evaluating flood risk for grout injection filling technology to isolate covered rock. [Background technology]

[0003] The grout injection and filling technology for isolated rock is becoming a promising new green mining technology, offering a favorable solution to challenging issues such as coal mining beneath structures, reducing gangue discharge, and mitigating and preventing impacts.

[0004] Currently, the most common method used to assess the flood risk of grout injection filling in isolated rock is the modified groundwater coefficient method. This method assesses the flood risk while considering the self-weight on the rock layer beneath the grout injection site and the pressure of the grout injection. The evaluation index used for the basement groundwater coefficient method is adapted as the standard used, meaning that in areas with simple structures, grout injection is considered safe if the groundwater coefficient is less than 0.1 Pa / m. However, due to the influence of various factors such as the properties of the grout and the stratigraphy of the grout injection site, the grout that isolates the rock continues to flow like groundwater, and the pressure is not constant. Therefore, significant errors may occur in the evaluation standards of the modified groundwater coefficient method. Another commonly used method is a comprehensive assessment method for the flood risk of grout injection filling of insulated rock. This method involves selecting the main influencing factors of grout injection filling of insulated rock, including multiple indicators such as grout injection pressure, grout properties, grout injection depth, thickness of the underlying rock layer, and mechanical properties of the rock layer, establishing an evaluation system, and assessing the flood risk by performing prediction and separation of results using multiple comprehensive evaluation methods, such as hierarchical structure analysis and entropy weighting. However, this method relies solely on mathematical analysis using statistical data, lacks scientific rigor, and cannot provide effective support for actual construction.

[0005] Therefore, a scientific and effective method for assessing flood risk for grout injection and filling technology used to isolate covered rocks is desired. [Overview of the project]

[0006] The main objective of this invention is to provide a method for evaluating the flood risk of grout injection filling technology for isolated rock, in order to solve the problem that the flood risk of grout injection filling in the conventional technology cannot be scientifically and effectively evaluated.

[0007] To achieve the above objective, the present invention provides a method for evaluating the risk of flooding for a grout injection and filling technology that isolates covered rock, and specifically, a method for evaluating the risk of flooding for a grout injection and filling technology that includes the following steps S1 to S6.

[0008] Step S1: Collect mine data and analyze hydrogeological data to create a basic dataset for overburden isolation grout injection in the coal seam.

[0009] Step S2: Analyze the movement law of the overburden of the coal seam based on the basic dataset of overburden isolation grout injection in Step S1, and predict the height of the water-conducting fracture zone.

[0010] Step S3: Based on Step S2, draw a cross-sectional view of the water hazard analysis of the working surface for overburden isolation grout injection, and make a preliminary judgment on the water hazard caused by overburden isolation grout injection.

[0011] Step S4: Construct a spatial development model for overburden isolation grout injection, simulate the entire process of actual overburden isolation grout injection, and clarify the real-time changes in the grouting parameters and rock mass stress in the grouting space of overburden isolation grout injection.

[0012] Step S5: Evaluate the water hazard risk caused by overburden isolation grout injection from multiple perspectives including engineering analogy, semi-empirical judgment, and theoretical analysis.

[0013] Step S6: Optimize the grouting design based on the water hazard risk of overburden isolation grout injection filling, and ensure the construction safety of grouting.

[0014] Furthermore, Step S2 specifically includes the following Steps S2.1 and S2.2.

[0015] Step S2.1: Based on the basic dataset of overburden isolation grout injection, calculate and analyze the development position, rock quality, thickness, fracture distance, and other parameters of each key layer of the coal seam roof based on the theory of key strata for strata control, clarify the development position of the overburden separation layer of the coal seam roof, record all the strata positions where overburden isolation grout injection is possible in the coal seam roof, and determine the distance H between each grouting stratum position and the coal seam roof.

[0016] Step S2.2: Based on measured data of permeable crack zones on other working surfaces of the mine, the crack mining ratio of the development height of the permeable crack zones in the mine is obtained. Referring to the data on the thickness of the coal seam revealed at each borehole on the working surface for insulated rock isolation grout injection, the development height of the permeable crack zones at the location of each borehole is calculated, and the development height of the permeable crack zones at different locations on the working surface for insulated rock isolation grout injection is calculated using the kriging interpolation method.

[0017] Furthermore, step S3 specifically includes steps S3.1 and S3.2 below.

[0018] Step S3.1: Based on exploration, supplementary exploration, and hydrogeological borehole data within the work surface, draw cross-sectional diagrams of the permeable and impermeable layers of the work surface for insulated rock grout injection, add upper boundary surface curves of the development height of permeable crack zones, and create a flood analysis cross-sectional diagram of the insulated rock grout injection work surface by drawing borehole information, fault information, insufficiently blocked boreholes, and oil / gas well information on the cross-sectional diagram based on the design data for insulated rock grout injection in the mine and the analysis data for the mine's water channels.

[0019] Step S3.2: Based on the flood analysis cross-sectional view of the work surface for grout injection into the insulated rock, perform a preliminary flood analysis.

[0020] Furthermore, step S3.2 specifically includes steps S3.2.1 and S3.2.2 below.

[0021] Step S3.2.1: Analyze the positional relationship between the layer of the inoculated rock isolation grout injection and the permeable crack zone on the work surface. If the layer of the inoculated rock isolation grout injection is within the range of the permeable crack zone, it will cause both ceiling flooding and flooding due to the inoculated rock isolation grout injection, therefore the grout injection work is inappropriate.

[0022] Step S3.2.2: If the grout injection layer is above a permeable fracture zone, the relationship between the location of the permeable layer above the permeable fracture zone and the layer of the cladding isolation grout injection should be analyzed. If there is a water-rich permeable layer below the cladding isolation layer and no stable impermeable layer, the grout injection work is inappropriate. If there is a stable impermeable layer below the cladding isolation grout injection layer, then the positional relationship between the grout injection boreholes and faults, insufficiently blocked boreholes, and oil and gas well channels should be clarified to ensure that the grout injection boreholes are located outside the safety coal columns of each channel.

[0023] Furthermore, step S4 specifically includes steps S4.1 to S4.3 below.

[0024] Step S4.1: Select the design stratigraphy for the insulated grout injection that satisfies the conditions of Step S3, and analyze it by referring to the motion laws of the insulated rock in S2 to further clarify the motion laws of the insulated rock near the insulated grout injection stratigraphy. Determine the displacement and deformation amounts of the upper and lower stratigraphy of the insulated grout injection space using the Ritz method, obtain the maximum height ΔW of the insulated grout injection space, construct an insulated grout injection space evolution model according to the "inverted funnel" shape of the insulated grout injection space, import it into numerical simulation software (COMSOL®), and calculate the formula for the geometric dimensions of the insulated grout injection space.

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[0025] The formula for calculating the maximum height of the grout injection space for insulated rock is,

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[0026] Step S4.2: Simulate the entire process of grout injection to isolate the inlaid rock and obtain specific information on the grout diffusion process during grout injection, the laws governing the change in the stress field, and the stress change process of the upper and lower rock layers in the grout injection space.

[0027] Step S4.3: Based on changes in the stratigraphic depth of the inoculated rock grout injection, the grout injection material, the grout injection pressure, and other parameters, sequential grout diffusion simulations for the corresponding inoculated rock grout injection are performed. The time-dependent changes in pressure within the grout injection space under each work condition are recorded, and the maximum grout injection pressure Pmax during grout injection is selected as the calculated value for flood damage assessment due to inoculated rock grout injection.

[0028] Furthermore, step S4.2 specifically includes steps S4.2.1 through S4.2.5 below.

[0029] Step S4.2.1: The Navier-Stokes equations shown below are used as the control equations for grout-water flow.

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[0030] Step S4.2.2: In order to ensure that the description of the grout-water two-phase flow process in the grout injection space of the coated rock isolation satisfies the mass conservation law, it is described using the continuity equation expressed by the following formula.

Number

[0031] Step S4.2.3: In order to describe the real-time change process of the grout-water two-phase displacement interface, the Level Set interface tracking method is used to mark the grout-water two-phase interface, and the control equation is expressed by the following formula,

Number

[0032] Step S4.2.4: The corresponding interfacial tension term F st in the Navier-Stokes equation is expressed by the following formula,

Number

[0033] Step S4.2.5: Based on the mesh generation tool and transient solver incorporated in the numerical simulation software, the calculation and description of the entire process of grout injection and grout-water displacement in the grout injection space of the coated rock isolation are realized, and the grout diffusion process, the change law of the stress field, the stress change process of the upper and lower rock layers of the grout injection space, and other specific information during the coated rock isolation grout injection are obtained.

[0034] Furthermore, step S5 specifically includes steps S5.1 to S5.4 below.

[0035] Step S5.1: T ≥ threshold T in the following equation s The area is defined as a highly hazardous area with a risk of flooding due to grout injection to isolate the overhanging rock.

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[0036] Step S5.2: Evaluate the flood risk caused by grout injection to isolate the overhanging rock using the priority layer determination method.

[0037] Step S5.3: Depending on the "inverted funnel" shape of the overhang rock isolation grout injection space, the lower isolation layer of the overhang rock isolation grout injection space is considered as a curved elastic slab, and the fracture threshold of the lower isolation layer of the overhang rock isolation grout injection space is calculated based on the geometric characteristics of the rock layer and the fracture criteria.

[0038] Step S5.4: Based on the results of the assessment of the seepage risk for grout injection of three types of cladding rock abscission, in order to ensure the safety of grout injection on the work surface for cladding rock isolation grout injection, the evaluation results require that the safety requirements of at least two types of assessment methods be met. If the safety requirements cannot be met, proceed to Step S6.

[0039] Furthermore, step S5.3 specifically includes steps S5.3.1 through S5.3.4 below.

[0040] Step S5.3.1: Based on the basic dataset for grout injection to isolate the overhanging rock and the theory for determining the priority layer, the location of the priority layer in the overhanging rock under normal conditions is obtained.

[0041] Step S5.3.2: Based on the method for predicting the height of permeable crack zones at the location of the priority layer, if the distance between the location of the main priority layer and the upper boundary of the coal seam is less than 7 to 10 times the thickness of the coal seam, the height of the ceiling penetration crack will be equal to the thickness of the bedrock. If the distance between the location of the main priority layer and the upper boundary of the coal seam exceeds 7 to 10 times the thickness of the coal seam, the height of the ceiling penetration crack will be equal to the location of the first priority layer where the height to the coal seam is greater than 7 to 10 times the thickness of the coal seam.

[0042] Step S5.3.3: Assuming that the maximum pressure Pmax of the grout injection during grout injection is considered an additional load and applied entirely to the bottom boundary of the inlaid rock isolation space, the position of the inlaid rock priority layer when injecting grout to isolate the inlaid rock is recalculated using the priority layer theory.

[0043] Step S5.3.4: By comparing the location of the original priority layer with that of the insulated rock isolation grout injection, it is shown that if the location of the insulated rock priority layer changes, the height of the permeable crack zone development increases accordingly, causing fracture and penetration of the insulated rock due to the insulated rock isolation grout injection, and thus creating a risk of flooding due to the insulated rock isolation grout injection. If the location of the priority layer does not change, it is shown that the height of the permeable crack zone development does not change due to the insulated rock isolation grout injection.

[0044] Furthermore, step S5.4 specifically includes steps S5.4.1 through S5.4.5 below.

[0045] Step S5.4.1: Based on equations (1) and (2), calculate the geometric dimensions a and b of the lower isolation layer of the infill rock isolation grout injection space, and calculate the thickness M of the isolation layer.

[0046] Step S5.4.2: Based on the thin plate theory, considering the self-weight of the rock layer, the pressure of grout injection for isolation of the overlying rock, and the bearing capacity of the rock layer, the deflection w of the isolation rock layer is calculated using the following formula.

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[0047] Step S5.4.3: At the maximum pressure of grout injection into the insulated rock, the maximum and minimum main stresses at the height z=h / 2 of the neutral plane of the isolation rock layer are calculated using the following formula:

number

[0048] B1 and B2 are expressed by the following equations:

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[0049] Step S5.4.4: In accordance with the Mohr-Coulomb criterion, the criteria for determining rock layer fracture are established as follows: σ1-((1+sinφ') / (1-sinφ'))σ3=2Ccosφ' / (1-sinφ') (11) In the formula, C is the cohesive force of the rock, and φ' is the internal friction angle.

[0050] Step S5.4.5: Establish the following formula for determining isolation layer failure in grout injection filling of the overhanging rock abscission:

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[0051] Furthermore, step S6 specifically includes steps S6.1 to S6.3 below.

[0052] Step S6.1: Adjust the grout injection material to reduce the density of the grout, thereby reducing the self-weight load of the grout and mitigating the load on the lower isolation layer of the grout injection space of the insulated rock isolation.

[0053] Step S6.2: Reduce the pressure of grout injection and lower the final pressure of grout injection in the grout injection work for the isolation of the rock cover to reduce the load on the lower isolation layer of the grout injection space for the isolation of the rock cover.

[0054] Step S6.3: Improve the fracture resistance of the isolation layer by raising the grout injection layer, reducing the grout injection depth, and increasing the thickness of the isolation layer.

[0055] The present invention has the following beneficial effects. This invention primarily provides a method for evaluating flood risk under the conditions of grout injection filling to isolate covered rock, and solves the problems of current flood risk evaluation methods, such as the lack of quantitative evaluation methods and the limitations and ambiguities associated with them.

[0056] To more clearly illustrate specific embodiments of the present invention or technical means in the prior art, the drawings used in describing specific embodiments or the prior art are briefly described below. Clearly, the drawings described below are some embodiments of the present invention, and a person skilled in the art can derive other drawings from these without any creative work. [Brief explanation of the drawing]

[0057] [Figure 1] This is a flowchart of the method for evaluating flood risk for the grout injection and filling technology for isolated rocks according to the present invention. [Modes for carrying out the invention]

[0058] The technical means of the present invention will be described in plain and comprehensive terms below with reference to the drawings, but obviously the embodiments described are not all embodiments of the present invention, but rather some embodiments. Any other embodiments that an artist of the art could obtain by building upon the embodiments of the present invention without creative work are included within the scope of the protection of the present invention.

[0059] The method for evaluating the flood risk for the insulated rock isolation grout injection filling technology shown in Figure 1 specifically includes the following steps S1 to S6.

[0060] Step S1: Collect mine data and perform hydrogeological data analysis to create a basic dataset for grout injection to isolate coal seams.

[0061] Step S2: Using the basic dataset for inoculated rock isolation grout injection created in Step S1, analyze the motion laws of the inoculated rock of the coal seam and predict the height of the permeable fracture zone.

[0062] Step S3: Based on Step S2, draw a cross-sectional diagram of the work surface for injecting grout to isolate the covered rock, and make a preliminary assessment of the potential for flood damage due to the grout injection to isolate the covered rock.

[0063] Step S4: Construct a development model of the inlaid rock isolation grout injection space to simulate the entire process of actual inlaid rock isolation grout injection, and clarify the real-time changes in grout injection parameters and rock body stress in the inlaid rock isolation grout injection space.

[0064] Step S5: Evaluate the flood risk from grout injection into insulated rock from multiple perspectives, including engineering analogies, semi-empirical assessments, and theoretical analysis.

[0065] Step S6: Based on the flood risk of grout injection filling in the insulated rock, optimize the grout injection design and ensure the safety of the grout injection work.

[0066] Specifically, in step S1, basic data such as mine geology, hydrogeology, boreholes, and design of infill rock isolation grout injection are collected to create a basic dataset for infill rock isolation grout injection of coal seams, and basic parameters such as the lithology of each rock group in the mining top of the coal seam of the mine, the thickness M of the isolation layer, mechanical properties (compressive strength, elastic modulus), water abundance (unit seepage rate, permeability coefficient, water abundance level (weak water abundance, medium water abundance, strong water abundance, very strong water abundance)) are clarified. Specifically, step S2 includes steps S2.1 and S2.2 below.

[0067] Step S2.1: Based on the basic dataset for inclusion rock isolation grout injection, and based on the theory of key rock layers for rock layer control, calculate and analyze the development location, rock type, thickness, fracture distance, and other parameters of each key layer on the coal seam top to clarify the development location of inclusion rock abscission on the coal seam top, record all stratigraphic positions on the coal seam top where inclusion rock isolation grout injection is possible, and determine the distance H between each grout injection stratigraphic position and the coal seam top.

[0068] Step S2.2: Based on measured data of permeable crack zones on other working surfaces of the mine, the crack mining ratio of the development height of the permeable crack zones in the mine is obtained. Referring to the data on the thickness of the coal seam revealed at each borehole on the working surface for insulated rock isolation grout injection, the development height of the permeable crack zones at the location of each borehole is calculated, and the development height of the permeable crack zones at different locations on the working surface for insulated rock isolation grout injection is calculated using the kriging interpolation method.

[0069] The calculation of the height of permeable crack zones at different locations on the working surface for grout injection into the insulated rock, using the kriging interpolation method, specifically includes the following calculation steps.

[0070] (1) Based on measured data of permeable crack zones on other working surfaces of the mine, the crack mining ratio K of the development height of the permeable crack zones in the mine is obtained, the position coordinates of the boreholes are entered, and the development height of the permeable crack zones at each borehole location is calculated by referring to the thickness revealed in the coal seam at the location of the boreholes, and H(x i ,y i ) = K*M(x i ,y i The development height dataset D(x) of the permeable crack zone is calculated using ). i ,y i ,H i ) Create.

[0071] (2) Using the empirical semivariogram function, construct a spatial variation model expressed by the following equation:

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[0072] (3) Construct the Kriging equation as shown below and find the weight vectors,

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[0073] By solving the above linear equation, we obtain the weight vector λ = [λ1, λ2, ..., λ m ] T You can obtain this.

[0074] (4) Within the survey area, the height of the development of permeable crack zones is calculated and predicted, and the results are visualized as shown in the following formula.

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[0075] Specifically, step S3 includes steps S3.1 and S3.2 below.

[0076] Step S3.1: Based on exploration, supplementary exploration, and hydrogeological borehole data within the work surface, draw cross-sectional diagrams of the permeable and impermeable layers of the work surface for insulated rock grout injection, add upper boundary surface curves for the development height of permeable crack zones, and create a flood analysis cross-sectional diagram of the insulated rock grout injection work surface by drawing information such as borehole information (location, burial depth), fault information (location, penetrated strata), insufficiently blocked boreholes (location, burial depth), and oil and gas wells (location, burial depth) on the cross-sectional diagram, based on the design data for insulated rock grout injection in the mine and the analysis data for the mine's water channels.

[0077] Step S3.2: Based on the flood analysis cross-sectional view of the work surface for grout injection into the insulated rock, perform a preliminary flood analysis.

[0078] Specifically, step S3.2 includes steps S3.2.1 and S3.2.2 below.

[0079] Step S3.2.1: Analyze the positional relationship between the layer of the inoculated rock isolation grout injection and the permeable crack zone on the work surface. If the layer of the inoculated rock isolation grout injection is within the range of the permeable crack zone, it will cause both ceiling flooding and flooding due to the inoculated rock isolation grout injection, therefore the grout injection work is inappropriate.

[0080] Step S3.2.2: If the grout injection layer is above a permeable fracture zone, the relationship between the location of the permeable layer above the permeable fracture zone and the layer of the cladding isolation grout injection should be analyzed. If there is a water-rich permeable layer below the cladding isolation layer and no stable impermeable layer, the grout injection work is inappropriate. If there is a stable impermeable layer below the cladding isolation grout injection layer, then a detailed analysis of the ongoing cladding isolation grout injection should be conducted to clarify the positional relationship between the grout injection boreholes and faults, insufficiently blocked boreholes, and oil and gas well water channels, ensuring that the grout injection boreholes are located outside the safety coal columns of each water channel.

[0081] Specifically, step S4 includes steps S4.1 through S4.3 below.

[0082] Step S4.1: Select a design strata for grout injection to isolate the covered rock that satisfies the conditions of Step S3, and analyze it by referring to the laws of motion of the covered rock in S2 to specifically clarify the laws of motion of the covered rock near the strata for grout injection to isolate the covered rock. Determine the displacement and deformation amounts of the upper and lower strata of the grout injection space to isolate the covered rock using the Ritz method, obtain the maximum height ΔW of the grout injection space to isolate the covered rock, construct a grout injection space evolution model according to the "inverted funnel" shape of the grout injection space to isolate the covered rock, and import it into numerical simulation software (COMSOL®). The formula for calculating the geometric dimensions of the grout injection space to isolate the covered rock is then determined.

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[0083] The formula for calculating the maximum height of the grout injection space for insulated rock is,

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[0084] Step S4.2: The entire process of grout injection to isolate the covered rock is simulated to obtain specific information on the grout diffusion process during grout injection, the laws governing the change in the stress field, and the stress change process of the upper and lower rock layers in the grout injection space, thereby providing data support for evaluating the flood risk caused by grout injection to isolate the covered rock.

[0085] Step S4.3: Based on changes in the stratigraphic depth of the inoculated rock grout injection, the grout injection material, the grout injection pressure, and other parameters, sequential grout diffusion simulations for the corresponding inoculated rock grout injection are performed. The time-dependent changes in pressure within the grout injection space under each work condition are recorded, and the maximum grout injection pressure Pmax during grout injection is selected as the calculated value for flood damage assessment due to inoculated rock grout injection.

[0086] Specifically, step S4.2 includes steps S4.2.1 through S4.2.5 below.

[0087] Step S4.2.1: To accurately describe the two-phase flow process of grout and groundwater (grout-water) within the grout injection space isolated by the rock cover, the Navier-Stokes equations shown below are used as the control equations for grout-water flow.

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[0088] Step S4.2.2: In order to ensure that the description of the grout-water two-phase flow process in the grout injection space of the covered rock isolation satisfies the law of conservation of mass, the continuity equation expressed in the following equation is used.

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[0089] Step S4.2.3: To describe the real-time change process of the grout-water two-phase substitution interface, the grout-water two-phase interface is marked using the interface tracking method Level Set, and the control equation is expressed by the following equation:

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[0090] Step S4.2.4: Corresponding interfacial tension term F in the Navier-Stokes equations st This can be expressed by the following equation:

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[0091] As described above, equations (3) to (6) allow us to obtain a level-set-Navier-Stokes coupled mathematical model of grout-water two-phase flow within a grout-injected space isolated from the revetment rock.

[0092] Step S4.2.5: Based on the mesh generation tool and transient solver incorporated into the numerical simulation software, the entire process of grout injection and grout-water replacement in the insulated rock isolation grout injection space is calculated and described, and the grout diffusion process during insulated rock isolation grout injection, the stress field change laws, the stress change process of the upper and lower rock layers in the grout injection space, and other specific information are obtained.

[0093] Specifically, step S5 includes steps S5.1 through S5.4 below.

[0094] Step S5.1: Evaluate the flood risk due to grout injection for insulated rock using an engineering analogy, and during the evaluation, use the evaluation coefficient for groundwater risk as an evaluation index, and set the threshold T for the flood risk coefficient due to grout injection for insulated rock. s This should be determined according to the working surface of the already constructed inclusion rock isolation grout injection in the adjacent or main mine. T ≥ threshold T in the following equation: s The area is defined as a highly hazardous area with a risk of flooding due to grout injection to isolate the overhanging rock.

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[0095] Step S5.2: Evaluate the flood risk caused by grout injection to isolate the overhanging rock using the priority layer determination method.

[0096] Step S5.3: Depending on the "inverted funnel" shape of the overhang rock isolation grout injection space, the lower isolation layer of the overhang rock isolation grout injection space (bottom boundary, permeable crack zone, and intervening rock layer) is considered as a curved elastic slab, and the fracture threshold of the lower isolation layer of the overhang rock isolation grout injection space is calculated based on the geometric characteristics of the rock layer and fracture criteria.

[0097] Step S5.4: Based on the results of the assessment of the seepage risk for the three types of infill rock abscission grout injection in Steps S5.1 to S5.3, the evaluation results are required to satisfy the safety requirements of at least two types of assessment methods in order to ensure the safety of the work surface grout injection for infill rock isolation grout injection. If the safety requirements cannot be met, proceed to Step S6.

[0098] Specifically, step S5.3 includes steps S5.3.1 through S5.3.4 below.

[0099] Step S5.3.1: Based on the basic dataset for grout injection to isolate the overhanging rock and the theory for determining the priority layer, the location of the priority layer in the overhanging rock under normal conditions is obtained.

[0100] Step S5.3.2: Based on the method for predicting the height of permeable crack zones at the location of the priority layer, if the distance between the location of the main priority layer and the upper boundary of the coal seam is less than 7 to 10 times the thickness of the coal seam, the height of the ceiling penetration crack will be equal to the thickness of the bedrock. If the distance between the location of the main priority layer and the upper boundary of the coal seam exceeds 7 to 10 times the thickness of the coal seam, the height of the ceiling penetration crack will be equal to the location of the first priority layer where the height to the coal seam is greater than 7 to 10 times the thickness of the coal seam.

[0101] Step S5.3.3: Assuming that the maximum pressure Pmax of the grout injection during grout injection is considered an additional load and applied entirely to the bottom boundary of the inlaid rock isolation space, the position of the inlaid rock priority layer when injecting grout to isolate the inlaid rock is recalculated using the priority layer theory.

[0102] Step S5.3.4: By comparing the location of the original priority layer with that of the insulated rock isolation grout injection, it is shown that if the location of the insulated rock priority layer changes, the height of the permeable crack zone development increases accordingly, causing fracture and penetration of the insulated rock due to the insulated rock isolation grout injection, and thus creating a risk of flooding due to the insulated rock isolation grout injection. If the location of the priority layer does not change, it is shown that the height of the permeable crack zone development does not change due to the insulated rock isolation grout injection.

[0103] Specifically, step S5.4 includes steps S5.4.1 through S5.4.5 below.

[0104] Step S5.4.1: Based on equations (1) and (2), calculate the geometric dimensions a and b of the lower isolation layer of the infill rock isolation grout injection space, and calculate the thickness M of the isolation layer.

[0105] Step S5.4.2: Based on the thin plate theory, considering the self-weight of the rock layer, the pressure of grout injection for isolation of the overlying rock, and the bearing capacity of the rock layer, the deflection w of the isolation rock layer is calculated using the following formula.

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[0106] Step S5.4.3: At the maximum pressure of grout injection into the insulated rock, the maximum and minimum main stresses at the height z=h / 2 of the neutral plane of the isolation rock layer are calculated using the following formula:

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[0107] B1 and B2 are expressed by the following equations:

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[0108] Step S5.4.4: In accordance with the Mohr-Coulomb criterion, the criteria for determining rock layer fracture are established as follows: σ1-((1+sinφ') / (1-sinφ'))σ3=2Ccosφ' / (1-sinφ') (11) In the formula, C is the cohesive force of the rock, and φ' is the internal friction angle.

[0109] Step S5.4.5: Establish the following formula for determining isolation layer failure in grout injection filling of the overhanging rock abscission:

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[0110] Specifically, if the evaluation results of the grout injection for insulated rock isolation fail to meet the safety requirements in step S5.4, adjustments should be made in four aspects, considering the importance of the grout injection parameters: the grout injection material, the grout injection pressure, the grout injection stratigraphy, or the grout injection location.

[0111] Step S6 specifically includes steps S6.1 through S6.3 below.

[0112] Step S6.1: Adjust the grout injection material and reduce parameters such as grout density to reduce the self-weight load of the grout and alleviate the load on the lower isolation layer of the grout injection space of the insulated rock isolation.

[0113] Step S6.2: Reduce the pressure of grout injection and lower the final pressure of grout injection in the grout injection work for the isolation of the rock cover to reduce the load on the lower isolation layer of the grout injection space for the isolation of the rock cover.

[0114] Step S6.3: Improve the fracture resistance of the isolation layer by raising the grout injection layer, reducing the grout injection depth, and increasing the thickness of the isolation layer.

[0115] Of course, the above description is not a limitation on the present invention, and the present invention is not limited to the above examples, but also includes modifications, alterations, additions or substitutions made by those skilled in the art within the substantial scope of the present invention.

[0116] As engineers in this field will know, embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention may also be provided as hardware embodiments, software embodiments, or embodiments combining software and hardware. Furthermore, the present invention may be provided as a computer program product implemented on a computer-compatible storage medium (including, but not limited to, magnetic disk memory and optical disk memory) containing one or more computer-compatible program codes.

[0117] The present invention has been described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. Note that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, may be implemented by computer program commands. By providing these computer program commands to a general-purpose computer, a dedicated computer, an embedded processor, or the processor of another programmable data processing device, a single device can be generated that implements one or more processes in a flowchart and / or one or more blocks in a block diagram, based on commands executed by the computer or the processor of another programmable data processing device.

[0118] These computer program commands may be stored in computer-readable memory that can guide the computer or other programmable data processing devices to perform specific actions. This allows the commands stored in the computer-readable memory to generate a product that includes a command device for implementing one or more steps in a flowchart and / or one or more blocks in a block diagram.

[0119] These computer program commands may be installed on a computer or other programmable data processing device to perform a series of operational steps on the computer or other programmable device to generate processing by the computer. This allows the commands executed on the computer or other programmable device to provide steps for realizing one or more steps in a flowchart and / or one or more blocks in a block diagram.

[0120] As engineers in this field will understand, all or some of the steps in the above embodiment may be completed by instructing the relevant hardware with a computer program. The program may be stored on a computer-readable storage medium. The program may include the steps of each embodiment of the above method when executed. The storage medium may be a magnetic disk, an optical disk, read-only memory (ROM), random access memory (RAM), etc.

Claims

1. A computer-executable method for assessing flood risk for a clogging rock isolation grout injection filling technology, comprising, specifically, steps S1 to S6 below: Step S1: Collect mine data and perform hydrogeological data analysis to create a basic dataset for grout injection to isolate coal seams. Step S2: Using the basic dataset for grout injection to isolate the cohesive rock created in Step S1, analyze the motion laws of the cohesive rock in the coal seam and predict the height of the permeable fracture zone. Step S3: Based on Step S2, draw a cross-sectional diagram of the work surface for the grout injection of the insulated rock to analyze flood damage, and make a preliminary assessment of the flood damage caused by the grout injection of the insulated rock. Step S4: Construct a development model of the inlaid rock isolation grout injection space, simulate the entire process of actual inlaid rock isolation grout injection, and clarify the real-time changes in grout injection parameters and rock body stress in the inlaid rock isolation grout injection space. Step S5: Evaluate the flood risk from grout injection into insulated rock from multiple perspectives, including engineering analogies, semi-empirical determination, and theoretical analysis. Step S6: Based on the flood risk of grout injection filling in the insulated rock, optimize the grout injection design and ensure the safety of the grout injection work. Step S5 specifically includes steps S5.1 to S5.4 below, Step S5.1: T ≥ threshold T, expressed by the following formula ｓ The area is defined as a highly hazardous area with a risk of flooding due to grout injection to isolate the overhanging rock. [Number 26] In the formula, T is the flood risk coefficient due to grout injection to isolate the inlaid rock, and γ i and h ｉ These are the unit volume weight and thickness of each rock layer between the bottom boundary of the grout injection space and the upper boundary of the fracture zone, respectively, M 石炭 This is the depth to which the coal seam is buried, H 注入 This is the burial depth of the bottom boundary of the grout injection space, H 通水 This is the height at which the water-permeable crack zone develops. Step S5.2: Evaluate the risk of flooding due to grout injection to isolate the overhanging rock using the priority layer determination method. Step S5.3: Depending on the "inverted funnel" shape of the overhang rock isolation grout injection space, the lower isolation layer of the overhang rock isolation grout injection space is considered as a curved elastic slab, and the fracture threshold of the lower isolation layer of the overhang rock isolation grout injection space is calculated based on the geometric characteristics of the rock layer and the fracture criteria. Step S5.4: Based on the results of the assessment of the seepage risk for grout injection of three types of cladding rock abscission, in order to ensure the safety of grout injection on the work surface for cladding rock isolation grout injection, the evaluation results are required to satisfy the safety requirements of at least two types of assessment methods. If the safety requirements cannot be met, proceed to Step S6. Step S5.3 specifically includes steps S5.3.1 to S5.3.4 below. Step S5.3.1: Based on the basic dataset for grout injection to isolate the overhanging rock and the theory for determining the priority layer, obtain the location of the priority layer of the overhanging rock under normal conditions. Step S5.3.2: Based on the method for predicting the height of the permeable crack zone at the location of the priority layer, if the distance between the location of the main priority layer and the upper boundary of the coal seam is less than 7 to 10 times the thickness of the coal seam, the height of the ceiling penetration crack will be equal to the thickness of the bedrock. If the distance between the location of the main priority layer and the upper boundary of the coal seam exceeds 7 to 10 times the thickness of the coal seam, the height of the ceiling penetration crack will be equal to the location of the first priority layer where the height to the coal seam is greater than 7 to 10 times the thickness of the coal seam. Step S5.3.3: Assuming that the maximum pressure Pmax of the grout injection during grout injection is considered an additional load and applied entirely to the bottom boundary of the inlaid rock isolation space, the position of the inlaid rock priority layer when injecting grout to isolate the inlaid rock is recalculated according to the priority layer theory. Step S5.3.4: By comparing the position of the primary layer of the overhang rock isolation grout injection with the position of the primary layer of the overhang rock, it was shown that if the position of the primary layer of the overhang rock changes, the height of the permeable crack zone development increases accordingly, causing fracture and penetration of the overhang rock due to the overhang rock isolation grout injection, and indicating a risk of flooding due to the overhang rock isolation grout injection. If the position of the primary layer does not change, it was shown that the height of the permeable crack zone development does not change due to the overhang rock isolation grout injection. Step S5.4 specifically includes steps S5.4.1 to S5.4.5 below. Step S5.4.1: Based on equations (1) and (2), calculate the geometric dimensions a and b of the lower isolation layer of the infill rock isolation grout injection space, and calculate the thickness M of the isolation layer. Step S5.4.2: Based on the thin plate theory, considering the self-weight of the rock layer, the pressure of grout injection for isolation of the overlying rock, and the bearing capacity of the rock layer, the deflection w of the isolation rock layer is calculated using the following formula. [Number 27] In the formula, λ is the support coefficient, which is between 0 and 1, and h is the thickness of the isolation layer. Step S5.4.3: At the maximum pressure of grout injection into the insulated rock, the maximum and minimum main stresses at the height z = h / 2 of the neutral plane of the insulated rock layer are calculated using the following formula: [Number 28] where σ １ and σ ３ represent the maximum and minimum principal stresses respectively, σ ｘ and σ ｙ represent the normal stresses in the x - and y - directions respectively, τ ｘｙ represents the shear stress on the xy - plane, B １ and B ２ represent variables, B １ and B ２ This can be expressed by the following equation: [Number 29] Step S5.4.4: In accordance with the Mohr-Coulomb criterion, the criteria for determining rock layer fracture are established as follows: s 1 - ((1+sinφ') / (1-sinφ'))σ ３ =2Ccosφ' / (1-sinφ') (11) In the formula, C is the cohesive force of the rock, and φ' is the internal friction angle. Step S5.4.5: Establish the following formula for determining isolation layer failure in grout injection filling of the overhanging rock abscission layer: [Number 30] In the formula, R ｃ And K is a parameter, R ｃ = 2Fcosφ' / (1-sinφ'), ​​where K = (1+sinφ') / (1-sinφ'), ​​and F is the fracture determination index. When F=1, a fracture occurs in the isolation layer, indicating that there is a risk of seepage due to grout injection into the insulated rock isolation layer under these grout injection conditions. A method for evaluating flood risk for grout injection and filling technology for isolated rock, characterized by the following features.

2. Step S2 specifically includes steps S2.1 and S2.2 below, Step S2.1: Based on the theory of rock layer control priority layers, the development location, rock type, thickness, fracture distance, and other parameters of each priority layer on the coal seam top are calculated and analyzed using the basic dataset for inoculated rock isolation grout injection. The development location of inoculated rock abscission on the coal seam top is clarified, all stratigraphic positions on the coal seam top where inoculated rock isolation grout injection is possible are recorded, and the distance H between each grout injection stratigraphic position and the coal seam top is determined. Step S2.2: Based on measured data of permeable crack zones on other work surfaces of the mine, obtain the crack mining ratio of the development height of the permeable crack zones in the mine; refer to the data on the thickness of the coal seam revealed at each borehole on the work surface for insulated rock grout injection, calculate the development height of the permeable crack zones at the location of each borehole; and calculate the development height of the permeable crack zones at different locations on the work surface for insulated rock grout injection according to claim 1, characterized in that the water damage risk for insulated rock grout injection technology is calculated by kriging interpolation.

3. Step S3 specifically includes steps S3.1 and S3.2 below, Step S3.1: Based on exploration, supplementary exploration, and hydrogeological borehole data within the work surface, draw cross-sectional diagrams of the permeable and impermeable layers of the work surface for insulated rock grout injection, add upper boundary surface curves of the development height of permeable crack zones, and based on the design data for insulated rock grout injection in the mine and the analysis data of the mine's water channels, draw grout injection borehole information, fault information, insufficiently blocked boreholes, and oil and gas well information on the cross-sectional diagram to create a flood analysis cross-sectional diagram of the insulated rock grout injection work surface. Step S3.2: A method for evaluating flood risk for the cohesive rock isolation grout injection filling technology according to claim 1, characterized by performing a preliminary analysis of flood damage based on a cross-sectional diagram of the work surface for cohesive rock isolation grout injection.

4. Step S3.2 specifically includes steps S3.2.1 and S3.2.2 below. Step S3.2.1: Analyze the positional relationship between the layer of the inoculated rock isolation grout injection and the permeable crack zone on the work surface. If the layer of the inoculated rock isolation grout injection is within the range of the permeable crack zone, it will cause both ceiling flooding and flooding due to the inoculated rock isolation grout injection, thus the grout injection work is inappropriate. Step S3.2.2: If the grout injection layer is above a permeable fracture zone, the relationship between the location of the permeable layer above the permeable fracture zone and the layer of the cladding rock isolation grout injection should be analyzed; if there is a water-rich permeable layer below the cladding rock isolation layer and no stable impermeable layer, the grout injection work is inappropriate; if there is a stable impermeable layer below the cladding rock isolation grout injection layer, then the positional relationship between the grout injection boreholes and faults, insufficiently blocked boreholes, and oil and gas well water channels should be clarified, characterized in that the grout injection boreholes are located outside the safety coal columns of each water channel.

5. Step S4 specifically includes steps S4.1 to S4.3 below, Step S4.1: Select a design strata for grout injection to isolate the covered rock that satisfies the conditions of Step S3, and analyze it by referring to the laws of motion of the covered rock in S2 to further clarify the laws of motion of the covered rock near the strata for grout injection to isolate the covered rock. Determine the displacement and deformation amounts of the upper and lower strata of the grout injection space to isolate the covered rock using the Ritz method, obtain the maximum height ΔW of the grout injection space to isolate the covered rock, construct a grout injection space evolution model according to the "inverted funnel" shape of the grout injection space to isolate the covered rock, and import it into numerical simulation software to determine the formula for calculating the geometric dimensions of the grout injection space to isolate the covered rock. [Number 31] In the formula, l is the distance of the work surface, and a ０ β is the length of the slope of the working surface, １ , β ２ b is the fracture angle of the rock layer, b is the length of the grout injection space for isolating the overhanging rock, and a is the width of the grout injection space for isolating the overhanging rock. The formula for calculating the maximum height of the grout injection space for insulated rock is, [Number 32] In the equation, x and y are coordinates, and they are between (0, a) and (0, b), respectively, and q 上 , q 下 These are the lateral uniformly distributed loads in the rock layers above and below the grout injection space, respectively, D 下 , D 上 D represents the compressive stiffness of the rock layer above and below the grout injection space, respectively, and D represents the bending stiffness of the rock layer. Step S4.2: Simulate the entire process of grout injection to isolate the infill rock, and obtain specific information on the grout diffusion process during grout injection, the stress field change law, and the stress change process of the upper and lower rock layers in the grout injection space. Step S4.3: A method for evaluating flood risk for a covered rock isolation grout injection filling technology according to claim 1, characterized by sequentially performing grout diffusion simulations for the corresponding covered rock isolation grout injection based on changes in the stratigraphic depth of the covered rock isolation grout injection, the material of the grout injection, the pressure of the grout injection, and other parameters, recording the time-dependent change in the pressure in the grout injection space under each work condition, and selecting the maximum value Pmax of the grout injection pressure during grout injection as the calculated value for flood risk evaluation due to covered rock isolation grout injection.

6. Step S4.2 specifically includes steps S4.2.1 to S4.2.5 below. Step S4.2.1: The Navier-Stokes equations shown below are used as the control equations for grout-water flow. [Number 33] In the equation, u is the fluid velocity, p is the fluid pressure, ρ is the fluid density, μ is the fluid kinematic viscosity, I is the unit tensor, and F ｓｔ is the interfacial tension term, g is the acceleration due to gravity, and ∇ is the Laplace operator. Step S4.2.2: In order to ensure that the description of the grout-water two-phase flow process in the grout injection space of the covered rock isolation satisfies the law of conservation of mass, the continuity equation expressed in the following equation is used: [Number 34] Step S4.2.3: To describe the real-time change process of the grout-water two-phase substitution interface, the grout-water two-phase interface is marked using the interface tracking method Level Set, and the control equation is expressed by the following equation: [Number 35] In the formula, γ is the initialization parameter, and ε ls is the interface thickness control parameter, Φ is the level set variable, and φ is the level set function. Step S4.2.4: Corresponding interfacial tension term F in the Navier-Stokes equations ｓｔ This can be expressed by the following equation: [Number 36] In the formula, σ Ｆ This is the surface tension coefficient, n ｓ The interface normal vector is N ｓ Ｔ gan ｓ It is the transpose of φ Ｆ This is the non-zero Dirac function at the fluid interface, Step S4.2.5: A method for evaluating the flood risk for the cladding rock isolation grout injection filling technology according to claim 5, characterized in that, based on a mesh generation tool and transient solver incorporated into numerical simulation software, the entire process of grout injection and grout-water replacement in the cladding rock isolation grout injection space is calculated and described, and the grout diffusion process during cladding rock isolation grout injection, the stress field change law, the stress change process of the upper and lower rock layers in the grout injection space, and other specific information are obtained.

7. Step S6 specifically includes steps S6.1 to S6.3 below, Step S6.1: Adjust the grout injection material and reduce the density of the grout to reduce the self-weight load of the grout and reduce the load on the lower isolation layer of the grout injection space of the inlaid rock isolation space. Step S6.2: By reducing the grout injection pressure and lowering the final grout injection pressure in the insulated rock isolation grout injection work, the load on the lower isolation layer of the insulated rock isolation grout injection space is reduced. Step S6.3: A method for evaluating the flood risk for the grout injection filling technology for insulated rock isolation according to claim 1, characterized by raising the grout injection layer, reducing the grout injection depth, and increasing the thickness of the isolation layer to improve the fracture resistance of the isolation layer.

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