A method for predicting water inflow in weakly cemented overburden coal mining faces

Abstract

This invention discloses a method for predicting water inflow in weakly cemented overburden coal mining faces, relating to the fields of mine safety science and hydrogeology. The method includes: determining the development height of the water-conducting fracture zone in the target working face based on the mining geological conditions; identifying the aquifer (or impermeable) layer affected by mining activities and obtaining its hydrogeological parameters, as well as obtaining the self-healing capacity parameters of the weakly cemented mudstone layer (impermeable layer) under water-rock action; dividing the target working face into at least two sections based on the spatial distribution differences of the mudstone layer and its self-healing capacity parameters, obtaining the average hydrogeological parameters of each section, and calculating the direct water inflow and seepage water inflow of each section; and summing the direct water inflow and seepage water inflow of all sections to obtain the predicted total water inflow of the target working face. This invention effectively improves the accuracy of predicting water inflow in coal mining faces.

Description

Technical Field

[0001] This invention belongs to the fields of mine safety science and hydrogeology, and particularly relates to a method for predicting water inflow in weakly cemented overburden coal mining faces. Background Technology

[0002] As coal resources in eastern China gradually deplete, the focus of coal development has shifted to the northwest. Unlike the high-strength, massive coal seams of the Carboniferous-Permian system mined in central and eastern China, the Jurassic coal seams in the northwest exhibit significantly different engineering geological properties. The strata in this region are dominated by argillaceous sandstone, exhibiting typical characteristics of weakly cemented strata, such as poor cementation, high porosity, low strength, low permeability, and thick aquifers. These poorly cemented strata are prone to weathering and show significant disintegration upon cementing, exhibiting fundamental differences in their hydrophysical properties, mechanical strength, and failure mechanisms compared to conventional strata.

[0003] In weakly cemented strata, accurately predicting the development height of the overlying water-conducting fracture zone and the water inflow at the working face after coal seam mining is a crucial task in coal mine water control. Currently, commonly used methods for predicting coal mine working face water inflow include the large-well method and the water collection gallery method. These methods typically calculate water inflow based on stratigraphic hydrogeological parameters (such as permeability coefficient and aquifer thickness) obtained from exploration boreholes. However, due to the limited number of hydrogeological boreholes in coal mines, the obtained hydrogeological parameters at the working face inherently contain certain errors, leading to significant discrepancies between predicted and actual water inflow.

[0004] More importantly, in weakly cemented strata, water-conducting fractures generated during coal seam mining can penetrate aquitards such as weakly cemented mudstone and enter the overlying aquifer. When groundwater infiltrates into the mudstone aquitard, some of the water-conducting fractures in the rock strata undergo a degree of self-healing under the influence of water and rock, thereby increasing the thickness of the aquitard and improving its water-blocking performance, thus reducing the leakage and inflow of water from the aquifer above the mudstone aquitard. However, existing conventional methods for predicting water inflow do not consider this water-rock healing effect, directly using the original hydrogeological parameters obtained from exploration and testing for calculation. This ignores the dynamic changes in the water conductivity of the aquitard under the influence of water and rock, leading to systematic deviations between the predicted results and the actual situation, making it difficult to meet the practical needs of high-precision prediction of water inflow in coal mine working faces in weakly cemented strata. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for predicting water inflow in weakly cemented overburden coal mining faces, comprising the following steps: Based on the geological conditions of the target working face, determine the development height of the water-conducting fracture zone in the target working face; Based on the development height of the water-conducting fracture zone, the aquifer and impermeable layer affected by mining are determined, and the hydrogeological parameters of the aquifer are obtained, as well as the parameters of the self-healing ability of the impermeable layer under the action of water and rock are obtained. The impermeable layer is a weakly cemented mudstone layer. Based on the spatial distribution differences of the mudstone layer and its fracture self-healing ability parameters, the target working face is divided into at least two sections, and the average hydrogeological parameters of each section are obtained based on the hydrogeological parameters, including the average aquifer thickness and the average permeability coefficient. Based on the average hydrogeological parameters of each section, the direct inflow from the directly filled aquifer in each section is calculated. The directly filled aquifer in each section is the aquifer below the self-healing mudstone layer within the expected water-conducting fracture zone. Based on the average hydrogeological parameters and fissure self-healing capacity parameters of each section, the seepage inflow of each section is calculated after adjusting the thickness of the waterproof protective layer. The total expected water inflow at the target working face is obtained by summing the direct inflow and seepage inflow of all sections.

[0006] Optionally, the specific determination of the development height of the water-conducting fracture zone at the target working face is as follows: Based on the measured height of the water-conducting fracture zone in adjacent mined working faces, the corresponding mining thickness, working face width, overlying sand and mudstone ratio, and overlying rock quality indicators for each measured point were statistically analyzed. Through a multivariate nonlinear regression method, a regression model was established between the height of the water-conducting fracture zone and the mining thickness, working face width, overlying sand and mudstone ratio, and overlying rock quality indicators. Based on the target working face thickness, working face width, overlying sandstone and mudstone ratio, and overlying rock quality indicators, the height of the water-conducting fracture zone in the target working face is calculated by substituting these into the regression model.

[0007] Optionally, the parameters for obtaining the self-healing ability of weakly cemented rock strata under water-rock action are as follows: Based on the rock cores of the weakly cemented mudstone layer within the expected water-conducting fracture zone in the geological borehole of the target working face, standard rock samples with artificial fractures were prepared. Based on the triaxial test of water-rock interaction on standard rock samples, the change process of the permeability coefficient of rock sample fractures with water-rock interaction time was measured. Based on the test results when the fracture permeability coefficient tends to stabilize, the permeability coefficient for rock sample fracture healing is determined, and the permeability coefficient is determined as the parameter of the self-healing ability of weakly cemented rock strata fractures within the corresponding borehole control range.

[0008] Optionally, the target working face can be divided into at least two sections, specifically: Obtain the self-healing capacity parameters of fractures in the weakly cemented mudstone strata within the control range of each borehole, and divide the areas with similar fracture self-healing capacity parameters and spatial continuity into a segment, thus obtaining at least two independent segments.

[0009] Optionally, the average hydrogeological parameters for each section are obtained as follows: The average thickness of the aquifer within the control range of all boreholes in each section is calculated based on the average thickness of the aquifer. The average permeability coefficient is calculated based on the permeability coefficient of the aquifer within the control range of all boreholes in each section, thus obtaining the average aquifer thickness and average permeability coefficient for each section.

[0010] Optionally, the direct inflow from the directly filled aquifer is calculated in each section as follows: The direct inflow of water in the corresponding section is calculated based on the functional relationship between the average permeability coefficient, average aquifer thickness, hydraulic head, and radius of influence of the corresponding section.

[0011] Optionally, after adjusting for the thickness of the waterproof protective layer, the specific calculation of the leakage inflow for each section is as follows: Based on the functional relationship between the average permeability coefficient, cross-sectional area of ​​water passage, aquifer water level difference, and the corrected thickness of the waterproof protective layer in the corresponding section, the seepage inflow of the corresponding section is calculated. Among them, the thickness of the waterproof protective layer is corrected according to the self-healing ability parameter of the weak cemented rock strata in the corresponding section. The stronger the self-healing ability of the fissures, the larger the thickness value of the waterproof protective layer is adopted.

[0012] On the other hand, the present invention also provides a water inflow prediction system for weakly cemented overburden coal mining faces, used to implement the method, comprising: The parameter acquisition module is used to determine the development height of the water-conducting fracture zone of the target working face based on the mining geological conditions of the target working face, and to determine the aquifer affected by mining based on the development height of the water-conducting fracture zone, and to acquire the hydrogeological parameters of the aquifer and the parameters of the self-healing ability of the fractures of the weakly cemented rock layer under the action of water and rock. The segment division module is used to divide the target working face into at least two segments based on the spatial distribution differences of the fracture self-healing ability parameter, and to obtain the average hydrogeological parameters of each segment based on the hydrogeological parameters, wherein the average hydrogeological parameters include the average aquifer thickness and the average permeability coefficient. The direct inflow calculation module is used to calculate the direct inflow from the directly aquifer in each section based on the average hydrogeological parameters of each section. The leakage and inflow calculation module is used to calculate the leakage and inflow of each section after correcting the thickness of the waterproof protective layer based on the average hydrogeological parameters and crack self-healing ability parameters of each section. The total inflow accumulation module is used to add up the direct inflow and seepage inflow of all sections to obtain the expected total inflow of the target working face.

[0013] On the other hand, the present invention also provides an electronic device including a memory, a processor, and a computing program stored in the memory and executable on the processor, wherein the processor implements the method when executing the computing program.

[0014] On the other hand, the present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method.

[0015] Compared with the prior art, the present invention has the following advantages and technical effects: This invention fully considers the unique water-rock healing mechanism of weakly cemented overburden strata. First, it accurately determines the development height of the water-conducting fracture zone based on the mining geological conditions of the target working face. Then, it identifies the aquifer affected by mining and obtains its hydrogeological parameters. Simultaneously, it obtains the fracture self-healing capacity parameters of the weakly cemented strata under water-rock action through experiments. Building on this, this invention overcomes the limitations of traditional methods that use a single uniform parameter for overall calculation. It divides the working face into multiple sections based on the actual spatial distribution differences of the fracture self-healing capacity parameters and separately calculates the average hydrogeological parameters for each section. This makes the basic data used in calculating water inflow more closely reflect the actual geological conditions.

[0016] This invention introduces a technique to adjust the thickness of the waterproof protective layer based on the self-healing capacity parameter of the fractures when calculating the seepage inflow. Because water-conducting fractures in weakly cemented mudstone self-heal under the action of water and rock, the actual water-blocking thickness of the waterproof protective layer increases; this dynamic change is completely ignored in conventional methods. This invention, by adjusting the thickness of the waterproof protective layer, makes the calculated seepage inflow more consistent with engineering realities. Finally, by calculating the direct inflow and the adjusted seepage inflow separately for each segment and then summing them, the estimated total inflow for the target working face has higher accuracy compared to traditional methods.

[0017] In summary, this invention, based on the quantitative characterization and segmented refined processing of the water-rock healing effect in weakly cemented strata, significantly reduces the deviation between the predicted and actual water inflow values, providing a more reliable scientific basis for the design of mine drainage systems and the formulation of water control plans, thereby effectively ensuring the safe production of coal mines and improving economic benefits. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the method flow according to an embodiment of the present invention; Figure 2 This diagram shows the total water inflow at the 11601 working face in this embodiment of the invention, regardless of whether the influence of water-rock healing is considered. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0021] Example 1 This embodiment provides a method for predicting water inflow in a weakly cemented overburden coal mining face, including the following steps: Based on the geological conditions of the target working face, determine the development height of the water-conducting fracture zone in the target working face; Based on the development height of the water-conducting fracture zone, the aquifer and impermeable layer affected by mining are determined, and the hydrogeological parameters of the aquifer are obtained, as well as the parameters of the self-healing ability of the impermeable layer under the action of water and rock are obtained. The impermeable layer is a weakly cemented mudstone layer. Based on the spatial distribution differences of the mudstone layer and its fracture self-healing ability parameters, the target working face is divided into at least two sections, and the average hydrogeological parameters of each section are obtained based on the hydrogeological parameters, including the average aquifer thickness and the average permeability coefficient. Based on the average hydrogeological parameters of each section, the direct inflow from the directly filled aquifer in each section is calculated. The directly filled aquifer in each section is the aquifer below the self-healing mudstone layer within the expected water-conducting fracture zone. Based on the average hydrogeological parameters and fissure self-healing capacity parameters of each section, the seepage inflow of each section is calculated after adjusting the thickness of the waterproof protective layer. The total expected water inflow at the target working face is obtained by summing the direct inflow and seepage inflow of all sections.

[0022] As a specific implementation method, such as Figure 1 As shown, the specific steps include: Step 1: Calculate the height and location of water-conducting fractures in coal seam mining using empirical formulas.

[0023] Step 2: Obtain hydrogeological parameters of relevant aquifers (or impermeable strata) near the working face using pumping test data from the study area. Indoor tests are conducted to determine the healing capacity of water-conducting fractures affecting weakly cemented mudstone strata under water-rock interaction.

[0024] Step 3: Based on the hydrogeological parameters obtained in Step 2 and the healing capacity of the weakly cemented mudstone strata under water-rock action, the working face is divided into sections. Specifically, the sections with relatively similar permeability coefficients of directly filled aquifers in the target working face are first divided into sections. Within each section, the working face is further divided into sections based on the distribution of the weakly cemented mudstone aquitard and its healing capacity under water-rock action. The average parameters of each section are calculated using the hydrogeological parameters of the aquifers obtained in Step 2.

[0025] Step 4: Calculate and statistically analyze the water inflow at the working face according to the different sections.

[0026] In step 1, which is feasible, the empirical formula for calculating the development height of the water-conducting fracture zone in the working face is as follows: Measured values ​​of the height of the water-conducting fracture zone in this mine and adjacent mines with similar geological conditions were collected. The mining thickness, working face width, proportion of overlying sand and mudstone, and quality index of overlying rock at each measured point were statistically analyzed. A multivariate nonlinear regression analysis method was used to establish a multivariate regression mathematical model between the height of the water-conducting fracture zone and the above-mentioned influencing factors, namely, the prediction formula for the development height of the water-conducting fracture zone in weakly cemented overlying coal seams. The mining thickness, working face width, proportion of overlying sand and mudstone, and quality index of overlying rock of the target working face were predicted by statistical analysis of water inflow. Based on the prediction formula, the development height of the water-conducting fracture zone in the working face was calculated.

[0027] Feasible step 2 involves obtaining the hydrogeological parameters of the aquifers (or impermeable layers) in the overlying strata near the working face, specifically: Based on the location of the working face in the mining area, the water-bearing and aquitard layers affected after mining are determined according to the empirical formula described in step 1. The maximum influence radius is determined based on pumping tests, and the hydrogeological parameters of these related aquifers (and aquitard layers) are obtained through the maximum influence radius. Pumping test boreholes are determined within the maximum influence radius based on the maximum influence radius obtained from the pumping tests. The thickness of the related aquifers (and aquitard layers) under the control range of each borehole is calculated using the pumping test results data conducted in the area. M With permeability coefficient K ; The formulas for calculating the aquifer thickness and permeability coefficient at the working face to be mined are as follows: Thickness of aquifer at the working face to be mined M Calculation formula: ; Permeability coefficient of the working face to be mined K Calculation formula: ; in The thickness of the aquifer in each borehole is in meters (m). The permeability coefficient of the aquifer obtained from each pumping (pressure) test borehole, in m / d; n To count the number of boreholes.

[0028] Furthermore, in step 2, the steps for obtaining the water-rock healing effect of the weakly cemented mudstone waterproof protective layer are as follows: The water-rock healing capacity is quantitatively characterized through laboratory tests. The samples are obtained from geological borehole cores of the target working face; after sampling, standard rock samples are prepared for laboratory testing, mainly using triaxial testing equipment, and the water-rock healing capacity is obtained with the fracture healing permeability coefficient as a reference value.

[0029] Specifically, the healing capacity under water-rock action was obtained through laboratory testing. The test rock samples came from a weakly cemented aquitard in the strata affected by mining activity at the target working face, mainly consisting of mudstone. The retrieved rock cores were cut and ground into φ50mm×100mm cylinders, and samples with abnormal wave velocities were screened using wave velocity testing to remove those. Then, the Brazilian splitting method was used to uniformly split the samples into two halves. During the fracturing process, the sample loss was minimal, and there was no other damage except for the through-crack. Next, an electric grinder was used to grind through-cracks on the surface of the split rock samples and then they were pieced back together.

[0030] After preparation, the water-rock healing strength was tested using a triaxial rock testing apparatus. The same confining pressure was applied to each sample, and the seepage system of the triaxial testing apparatus was activated to simulate water-rock interaction in a real environment. The test duration should be greater than 12 hours to ensure sufficient water-rock interaction time. The test ended when the rock sample fractures essentially stopped shrinking, and the permeability coefficient of fracture healing was determined based on this. This permeability coefficient is then used to represent the water-rock healing capacity of the weakly cemented strata within the control range of the corresponding core borehole.

[0031] In step 3, the sections are divided according to the similarity between the permeability coefficient obtained in step 2 and the water-rock healing capacity. First, sections are divided according to the parts where the water-rock healing capacity of the weakly cemented rock layers is similar, as measured by indoor tests. Then, the arithmetic mean of the aquifer thickness, permeability coefficient, and water-rock healing capacity obtained from rock sample tests in each section is calculated based on the hydrogeological parameters obtained from boreholes.

[0032] In step 4, which is feasible, the formula for calculating the estimated water inflow of the working face segment by segment based on the hydrogeological parameters of the working face is as follows: The water inflow in each section originates from the direct inflow brought about by water-conducting fractures penetrating the aquifer (the aquifer below the healed mudstone layer within the water-conducting fracture zone). Q直 The water-conducting fractures affect the weakly cemented strata (mudstone), leading to a simple leakage of water from the overlying aquifer. Q 渗 .

[0033] Direct water filling aquifer inflow Q 直 Expected formula: ; in, The direct water inflow at the working face is expressed in m. 3 / d; The aquifer permeability coefficient is given in m / d. H The water head height is in meters (m). M The thickness of the aquifer is in meters (m). R 0 represents the radius of influence of the reference, in meters; Let m be the reference radius.

[0034] Water leakage of waterproof protective layer Q 渗 Expected formula: ; In the formula, The leakage rate is expressed in m. 3 / d; The permeability coefficient of the impermeable layer after the cracks in the section have healed, in m / d; hydraulic gradient ( ); The water head height is in meters (m). — The distance from the bottom interface of the self-healing mudstone layer to the aquifer above, i.e. the thickness of the waterproof protective layer, in meters; —Water flow section, m 2 .

[0035] Total water inflow in each section Q 总 Expected formula: .

[0036] The following section uses the 11601 working face of a coal mine as an example to describe the invention in detail.

[0037] Based on step 1, the empirical formula for calculating the development height of water-conducting fractures in this area is first obtained: The relevant parameters are shown in Table 1: Table 1 Using regression analysis, the empirical formula for calculating the development height of water-conducting fractures using a multivariate nonlinear regression mathematical model is determined as follows: ; In the formula, y The height of the water-conducting fracture zone, in meters; x 1 represents the mining thickness, in meters (m). x 2 represents the mining depth, in meters (m). x 3 represents the working surface width, in meters (m). x 4 represents the proportion of sandstone and mudstone; x 5 represents the quality index of the overlying rock, %.

[0038] Calculations show that the average height of water-conducting fractures in the 11601 working face after coal seam mining is approximately 59.1m.

[0039] Within a 59.1m range overlying the working face, there are two aquifers: the inter-coal seam fissure aquifer in the middle section of the Xishanyao Formation (between coal seams 3 and 7) and the aquifer above coal seam 3 in the upper section of the Xishanyao Formation. The inter-coal seam fissure aquifer between coal seams 3 and 7 is well-developed, with good permeability and water-bearing capacity, and is a weakly water-rich aquifer directly filling the roof of coal seam 6. The aquifers above coal seam 3 are mainly composed of fine sandstone, coarse sandstone, and gravelly coarse sandstone. A weakly cemented mudstone aquitard overlying coal seam 3 exists between the two aquifers; therefore, the aquifers above coal seam 3 serve as indirect seepage aquifers filling the roof of the coal seam.

[0040] According to step 2, the hydrogeological parameters of the 11601 working face and the water-rock healing capacity of the weakly cemented rock strata are obtained.

[0041] The water-rock healing capacity was assessed using outdoor sampling and indoor testing. In the laboratory, the retrieved rock cores were cut and ground into φ50mm×100mm cylinders, and samples with abnormal wave velocities were screened using wave velocity testing. Then, the Brazilian splitting method was used to uniformly split the samples into two halves. The mass loss during the fracturing process was minimal, and the samples suffered almost no damage other than the through-fracture. A power grinder was used to grind the split rock core surface to create a through-fracture, and the two halves were then reassembled to prepare fractured samples. Because the two fractured surfaces are convex and concave, they couple with each other after reassembly, resulting in a large contact area and a very small actual hydraulic aperture. Compared to manually ground and cut fractures with a certain aperture, the water conductivity of the fractured surface is negligible in the experiment. This method allows for the rapid, efficient, and high-success-rate preparation of a batch of fractured samples.

[0042] After the fractured specimens were prepared, triaxial tests were conducted. After loading the specimens, both the confining pressure and axial pressure were simultaneously increased to 1 MPa. The seepage system was then opened, and timing began when water flowed out from the bottom of the specimen. The system automatically recorded the flow rate changes in real time during the test. The test was terminated when the permeability coefficient of the fractured mudstone specimen remained almost constant. The time it took for the permeability coefficient to no longer change was recorded as the criterion for assessing healing ability. During the test, the permeability coefficient was calculated using the steady-state method, with the following formula: ; In the formula: Q For flow rate, m 3 ; L The sample length is indicated in meters (m). m The viscosity coefficient of water is 1.01 × 10⁻⁶ at a temperature of 25°C. -3 Pa·s; A m is the cross-sectional area of ​​the sample. 2 ; P The pressure difference between the upstream and downstream sides during the test, in Pa; For time, s.

[0043] Based on the water-rock healing capacity obtained from the experiment, the 11601 working face was divided into four sections according to the distribution of the water-rock healed mudstone and its permeability coefficient. The average permeability coefficient of the weakly cemented mudstone aquitard under undisturbed conditions was measured to be approximately 0.003 m / s.

[0044] Determination of hydrogeological parameters: Drainage boreholes were drilled at the 11601 roof working face. After dividing the working face into sections based on the water-rock healing capacity, the water inflow of each borehole in each section was obtained through water release tests. With the drop in water level .

[0045] Based on the final drilling test of the working face, the average permeability coefficient of the main directly filled aquifer in the 11601 working face was 0.1115 m / s.

[0046] Table 2 The working face is divided into sections as shown in Table 2. Substituting the parameters of each section into the aforementioned formulas for predicting the inflow of water from directly filled aquifers and predicting the inflow of water from indirect seepage, the aquifer water level difference is used in the prediction of the inflow of water from seepage. =51m.

[0047] (1) Expected water inflow in section I: ① Estimated water inflow from the directly filled aquifer in Section I: Calculate parameter values: a= 570m b= 220m r 0 =η(a+b) / 4 , R=10S , S=H= 103.4m R 0 =r 0 +R= 468.6mM= 34m; ; ② Estimated seepage and inflow volume of the water-filled aquifer in section I: Calculate parameter values: A= 125400m 2 , I= / l , ， When water-rock interaction is not considered, l= 31m, after considering the interaction between water and rock, l= 41m 。

[0048] When water-rock healing is not considered: Q=KIA= 27.15m 3 / h; When considering the water-rock healing effect: Q=KIA= 19.48m 3 / h; (2) Expected inflow of water in section II: ① Estimated water inflow from the directly filled aquifer in Section II: Calculate parameter values: a= 450m b= 220m r 0 =η(a+b) / 4, R=10S , S=H= 103.4m ，R 0 =r 0 +R= 432.3m M= 30m; ; ② Estimated seepage and inflow volume of the water-filled aquifer in section I: Calculate parameter values: A= 99000m 2 , I= / l , ， When water-rock interaction is not considered, l= 16m ， Since the rock strata in this section do not contain weak cemented layers, the water-rock healing effect is minimal and is not considered.

[0049] The leakage and inflow volume statistics are as follows: Q=KIA= 37.3m 3 / h.

[0050] (3) Estimated inflow of water in section III: ① Estimated water inflow from the directly filled aquifer in Section III: Calculate parameter values: a= 600m b= 220m r 0 =η(a+b) / 4,R=10S , S=H= 103.4m R 0 =r 0 +R= 476.55m M= 28m; ; ② Estimated leakage and inflow volume of the water-filled aquifer in section III: Calculate parameter values: A= 132000m 2 , I= / l , When water-rock interaction is not considered, l= 33m, after considering the interaction between water and rock, l= 43m 。

[0051] When water-rock healing is not considered: Q=KIA= 25.5m 3 / h; When considering the water-rock healing effect: Q=KIA= 19.57m 3 / h; (4) Expected inflow of water in section IV: ① Estimated water inflow from the directly filled aquifer in section IV: Calculate parameter values: a= 300m b= 220m r 0 =η(a+b) / 4 , R=10S , S=H= 103.4m ，R 0 =r 0 +R= 388.05m ，M= 26m; ; ② Estimated seepage and inflow volume of the water-filled aquifer in section IV: Calculate parameter values:A= 125400m 2 , I= / l , When water-rock interaction is not considered ，l= 35m, after considering the interaction between water and rock, l= 45m 。

[0052] When water-rock healing is not considered: Q=KIA= 11.69m 3 / h; When considering the water-rock healing effect: Q=KIA= 9.15m 3 / h; The water inflow rates of the 11601 working face in different sections are shown in Table 3: Table 3 In summary, the total water inflow at the 11601 working face is as follows: Figure 2 As shown, without considering the water-rock healing effect, the total water inflow at the working face is... Q 总 =198.7m 3 / h; after the water-rock healing effect takes effect, the total water inflow at the working face Q 总 =182.56m 3 / h, the total inflow is expected to decrease by about 10%.

[0053] In summary, this invention primarily aims to predict the water inflow in coal mine working faces with weakly cemented strata in western China. By acquiring the water-rock healing capacity of the weakly cemented strata, the working face is divided into sections. Based on hydrogeological parameters obtained from borehole pumping tests, the water inflow of directly aquifers is predicted according to these sections. Q 直 With leakage and inflow volume Q 渗 Compared to existing methods, this method considers that weakly cemented strata, under the influence of water and rock, will cause existing water-conducting fractures to close, thereby reducing the height of these fractures and increasing the thickness of the protective layer beneath the aquifer, thus reducing seepage and inflow. This method improves the accuracy of inflow prediction, provides a theoretical basis for mine water control systems, and ensures safe production in coal mines.

[0054] On the other hand, the present invention also provides a water inflow prediction system for weakly cemented overburden coal mining faces, used to implement the method, comprising: The parameter acquisition module is used to determine the development height of the water-conducting fracture zone of the target working face based on the mining geological conditions of the target working face, and to determine the aquifer affected by mining based on the development height of the water-conducting fracture zone, and to acquire the hydrogeological parameters of the aquifer and the parameters of the self-healing ability of the fractures of the weakly cemented rock layer under the action of water and rock. The segment division module is used to divide the target working face into at least two segments based on the spatial distribution differences of the fracture self-healing ability parameter, and to obtain the average hydrogeological parameters of each segment based on the hydrogeological parameters, wherein the average hydrogeological parameters include the average aquifer thickness and the average permeability coefficient. The direct inflow calculation module is used to calculate the direct inflow from the directly aquifer in each section based on the average hydrogeological parameters of each section. The leakage and inflow calculation module is used to calculate the leakage and inflow of each section after correcting the thickness of the waterproof protective layer based on the average hydrogeological parameters and crack self-healing ability parameters of each section. The total inflow accumulation module is used to add up the direct inflow and seepage inflow of all sections to obtain the expected total inflow of the target working face.

[0055] On the other hand, this embodiment also provides an electronic device, including a memory, a processor, and a computing program stored in the memory and executable on the processor, wherein the processor implements the method when executing the computing program.

[0056] On the other hand, this embodiment also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method.

[0057] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for predicting water inflow in a weakly cemented overburden coal face, characterized in that, Includes the following steps: Based on the geological conditions of the target working face, determine the development height of the water-conducting fracture zone in the target working face; Based on the development height of the water-conducting fracture zone, the aquifer and impermeable layer affected by mining are determined, and the hydrogeological parameters of the aquifer are obtained, as well as the parameters of the self-healing ability of the impermeable layer under the action of water and rock are obtained. The impermeable layer is a weakly cemented mudstone layer. Based on the spatial distribution differences of the fractured mudstone layer and its self-healing ability parameters, the target working face is divided into at least two sections, and the average hydrogeological parameters of each section are obtained based on the hydrogeological parameters, including the average aquifer thickness and the average permeability coefficient. Based on the average hydrogeological parameters of each section, the direct inflow from the directly filled aquifer in each section is calculated. The directly filled aquifer in each section is the aquifer below the self-healing mudstone layer within the expected water-conducting fracture zone. Based on the average hydrogeological parameters and fissure self-healing capacity parameters of each section, the seepage inflow of each section is calculated after adjusting the thickness of the waterproof protective layer. The total expected water inflow at the target working face is obtained by summing the direct inflow and seepage inflow of all sections.

2. The method according to claim 1, characterized in that, The specific height of the water-conducting fracture zone development at the target working face is determined as follows: Based on the measured height of the water-conducting fracture zone in adjacent mined working faces, the corresponding mining thickness, working face width, overlying sand and mudstone ratio, and overlying rock quality indicators for each measured point were statistically analyzed. Through a multivariate nonlinear regression method, a regression model was established between the height of the water-conducting fracture zone and the mining thickness, working face width, overlying sand and mudstone ratio, and overlying rock quality indicators. Based on the target working face thickness, working face width, overlying sandstone and mudstone ratio, and overlying rock quality indicators, the height of the water-conducting fracture zone in the target working face is calculated by substituting these into the regression model.

3. The method according to claim 1, characterized in that, The parameters for obtaining the self-healing ability of weakly cemented mudstone strata under water-rock action are as follows: Based on the rock cores of the weakly cemented mudstone layer within the expected water-conducting fracture zone in the geological borehole of the target working face, standard rock samples with artificial fractures were prepared. Based on the triaxial test of water-rock interaction on standard rock samples, the change process of the permeability coefficient of rock sample fractures with water-rock interaction time was measured. Based on the test results when the fracture permeability coefficient tends to stabilize, the permeability coefficient for rock sample fracture healing is determined, and the permeability coefficient is determined as the parameter of the self-healing ability of weakly cemented rock strata fractures within the corresponding borehole control range.

4. The method according to claim 1, characterized in that, The target working face is divided into at least two sections, specifically: Obtain the self-healing capacity parameters of fractures in the weakly cemented mudstone strata within the control range of each borehole, and divide the areas with similar fracture self-healing capacity parameters and spatial continuity into a segment, thus obtaining at least two independent segments.

5. The method according to claim 1, characterized in that, The average hydrogeological parameters for each section are as follows: The average thickness of the aquifer within the control range of all boreholes in each section is calculated based on the average thickness of the aquifer. The average permeability coefficient is calculated based on the permeability coefficient of the aquifer within the control range of all boreholes in each section, thus obtaining the average aquifer thickness and average permeability coefficient for each section.

6. The method according to claim 1, characterized in that, The specific calculation of the direct inflow from the directly filled aquifer in each section is as follows: The direct inflow of water in the corresponding section is calculated based on the functional relationship between the average permeability coefficient, average aquifer thickness, hydraulic head, and radius of influence of the corresponding section.

7. The method according to claim 1, characterized in that, After adjusting for the thickness of the waterproof protective layer, the specific leakage inflow volume for each section is calculated as follows: Based on the functional relationship between the average permeability coefficient, cross-sectional area of ​​water passage, aquifer water level difference, and the corrected thickness of the waterproof protective layer in the corresponding section, the seepage inflow of the corresponding section is calculated. Among them, the thickness of the waterproof protective layer is corrected according to the self-healing ability parameter of the weak cemented rock strata in the corresponding section. The stronger the self-healing ability of the fissures, the larger the thickness value of the waterproof protective layer is adopted.

8. A system for predicting water inflow in weakly cemented overburden coal mining faces, characterized in that, For implementing the method according to any one of claims 1-7, comprising: The parameter acquisition module is used to determine the development height of the water-conducting fracture zone of the target working face based on the mining geological conditions of the target working face, and to determine the aquifer affected by mining based on the development height of the water-conducting fracture zone, and to acquire the hydrogeological parameters of the aquifer and the parameters of the self-healing ability of the fractures of the weakly cemented rock layer under the action of water and rock. The segment division module is used to divide the target working face into at least two segments based on the spatial distribution differences of the fracture self-healing ability parameter, and to obtain the average hydrogeological parameters of each segment based on the hydrogeological parameters, wherein the average hydrogeological parameters include the average aquifer thickness and the average permeability coefficient. The direct inflow calculation module is used to calculate the direct inflow from the directly aquifer in each section based on the average hydrogeological parameters of each section. The leakage and inflow calculation module is used to calculate the leakage and inflow of each section after correcting the thickness of the waterproof protective layer based on the average hydrogeological parameters and crack self-healing ability parameters of each section. The total inflow accumulation module is used to add up the direct inflow and seepage inflow of all sections to obtain the expected total inflow of the target working face.

9. An electronic device comprising a memory, a processor, and a computing program stored in the memory and executable on the processor, characterized in that, When the processor executes the computing program, it implements the method of any one of claims 1-7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 1-7.

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