Mining-induced fractured rock mass flow state transition characterization method based on grouting filling rate

Abstract

The invention discloses a mining-induced fractured rock mass flow state transition characterization method based on a grouting filling rate. The method comprises the following steps: defining a nonlinear seepage factor; the quantitative change rule of the porosity of the fractured rock mass along with the filling rate in the grouting process is calculated; correcting the nonlinear seepage factor to obtain a corrected nonlinear seepage factor; performing derivation integration on the corrected nonlinear seepage factors, constructing a judgment index model of the flow state transition of the mining-induced fractured rock mass based on the grouting filling rate, and obtaining nonlinear seepage characteristics of fluid; constructing a mining-induced fractured rock mass flow state transition judgment index based on the grouting filling rate according to the nonlinear seepage characteristics of the fluid; and judging the flow state transition of the mining-induced fractured rock mass in the grouting process according to data measured in engineering practice based on the mining-induced fractured rock mass flow state transition judgment index. According to the method, the flow state transition can be accurately identified in the grouting process, so that reasonable grouting parameters are determined, the grouting engineering design is guided, and the grouting effect is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of grouting filling, and in particular to a method for characterizing flow transition of mining-induced fractured rock mass based on grouting filling rate. Background Art

[0002] During coal mining, the overlying rock strata generate mining cracks under the action of mining, which can easily conduct the aquifer and induce water inrush disasters. In this process, the groundwater flow state gradually changes from linear laminar flow in the aquifer to nonlinear laminar flow in the water-conducting fracture zone, and finally to turbulent flow in the working face area. This flow state transition process has a decisive influence on water inrush disasters. By injecting grouting into the mining fractured rock body, the mining fractures can be effectively closed, the permeability of the overlying rock strata can be significantly reduced, the groundwater flow can be transformed from fracture seepage to pore seepage, and the groundwater flow state can be reversed from high-speed turbulent flow to low-speed linear laminar flow, thereby reducing the amount of water inflow and preventing water inrush disasters.

[0003] Existing patents mostly focus on characterization methods of nonlinear seepage characteristics of fractured rock mass, grouting equipment and methods, etc., but lack a systematic description of the quantitative relationship between flow regime transition and grouting filling rate of fractured rock mass, and there is no analysis method for flow regime transition of fractured rock mass under grouting. Therefore, it is necessary to establish a characterization method for the mechanism of flow regime transition of fractured rock mass during grouting to guide the practice of grouting engineering of fractured rock mass. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a method for characterizing the flow state transition of mined fractured rock mass based on grouting filling rate. By analyzing the changing law of the nonlinear seepage factor of mined fractured rock mass under the condition of grouting filling rate, the flow state transition mechanism in the grouting filling process is revealed to guide the grouting construction design.

[0005] To achieve the above object, the present invention provides a method for characterizing flow transition of mining fractured rock mass based on grouting filling rate, comprising:

[0006] Define the nonlinear seepage factor;

[0007] Calculate the quantitative variation of the porosity of fractured rock mass with filling rate during grouting;

[0008] Correcting the nonlinear seepage factor based on the quantitative change rule to obtain a corrected nonlinear seepage factor;

[0009] Derivatively integrating the corrected nonlinear seepage factor, constructing a discriminant index model for flow state transition of mining fractured rock mass based on grouting filling rate, and obtaining nonlinear seepage characteristics of the fluid;

[0010] By using the nonlinear seepage characteristics of the fluid, a flow state transition discrimination index of mining fractured rock mass based on grouting filling rate is constructed;

[0011] Based on the flow state transition identification index of the mining fractured rock mass and the data measured in the actual project, the flow state transition of the mining fractured rock mass during the grouting process is determined.

[0012] Preferably, the nonlinear percolation factor is defined, including:

[0013] The nonlinear seepage characteristics of mining fractured rock mass satisfy the Forchheimer formula. Based on the viscosity term and inertia term of non-Darcy flow, the nonlinear seepage factor is defined as follows:

[0014]

[0015] Where μ is the fluid dynamic viscosity; k is the permeability of the fractured rock mass; β is the non-Darcy factor; ρ ω is the fluid density; υ is the fluid velocity; F is the nonlinear seepage factor.

[0016] Preferably, calculating the quantitative variation law of the porosity of the fractured rock with the filling rate during the grouting process includes:

[0017] Based on the changes in the porosity and grouting filling rate of the fractured rock mass, the slope φ0 of the relationship curve between the two is obtained, that is, the quantitative change law;

[0018] The changes in the porosity and grouting filling rate of the fractured rock mass are obtained as follows:

[0019] Before grouting begins, calculate the initial porosity of the broken rock mass;

[0020] When grouting starts, the relationship between the grouting filling rate and the slurry filling volume of the fractured rock mass is obtained;

[0021] During the grouting process, the porosity of the fractured rock mass gradually decreases as the slurry is filled, and the porosity at this time is obtained;

[0022] Based on the initial porosity of the broken rock mass, the relationship between the grouting filling rate and the slurry filling volume of the fractured rock mass and the porosity during the grouting process, the relationship between the porosity of the fractured rock mass and the grouting filling rate is obtained.

[0023] Preferably, the method for calculating the initial porosity of the broken rock mass is:

[0024]

[0025] Where V s is the solid phase volume; V r is the volume of broken rock mass; o is the initial porosity of the broken rock mass;

[0026] The relationship between the grouting filling rate of the fractured rock mass and the slurry filling volume is:

[0027]

[0028] Where V j is the volume of slurry in the fracture; η is the grouting filling rate of the fractured rock mass;

[0029] The calculation method of the porosity of fractured rock mass is:

[0030]

[0031] Where φ is the porosity.

[0032] Preferably, the porosity of the fractured rock mass and the grouting filling rate satisfy the following relationship:

[0033] φ=φ0(1-η).

[0034] Preferably, the nonlinear seepage factor is corrected, including:

[0035] According to the empirical formula of the non-Darcy factor and the relationship between the porosity of the fractured rock mass and the grouting filling rate, the nonlinear seepage factor is corrected. The corrected nonlinear seepage factor is:

[0036]

[0037] In the formula, F a is the corrected nonlinear seepage factor; ρ ω is the fluid density; υ is the fluid velocity; φ o is the initial porosity of the broken rock mass; η is the grouting filling rate of the fractured rock mass; a, b, c are all constants related to the medium; μ is the dynamic viscosity of the fluid.

[0038] Preferably, the modified nonlinear percolation factor is derived to obtain:

[0039]

[0040] In the formula, in the formula, F′ t is the discriminant index model for flow transition of mining fractured rock mass based on grouting filling rate; ν t ′、η t ′ are the partial derivatives of fluid velocity and grouting filling rate with respect to time t; ρ ω is the fluid density; φ o is the initial porosity of the fractured rock mass; η is the grouting filling rate of the fractured rock mass; μ is the fluid dynamic viscosity; v is the fluid flow rate;

[0041] Among them, the fluid velocity is positively correlated with the nonlinear seepage characteristics of the fluid, the influence of the time gradient of the permeability of the fractured rock mass on the nonlinear seepage characteristics of the fluid is related to the coefficient a, and the influence of the time gradient of the grouting filling rate on the nonlinear seepage characteristics of the fluid is related to the coefficient b, including:

[0042] If a<1, the permeability time gradient is positively correlated with the growth of the nonlinear seepage factor F; if a>1, the permeability time gradient is negatively correlated with the growth of the nonlinear seepage factor F; if a=1, the effect of the permeability time gradient on the nonlinear seepage factor F is ignored;

[0043] If b>0, the time gradient of filling rate is positively correlated with the growth of nonlinear seepage factor F; if b<0, the time gradient of filling rate is negatively correlated with the growth of nonlinear seepage factor F; if b=0, the influence of time gradient of filling rate on nonlinear seepage factor F is ignored.

[0044] Preferably, the discriminant index model for flow transition of mining fractured rock mass based on grouting filling rate is:

[0045]

[0046] Preferably, a flow state transition identification index of mining fractured rock mass based on grouting filling rate is constructed, including:

[0047] The change of the nonlinear seepage factor F is determined by the relative change rate of fluid velocity υ R Relative change rate of grouting filling rate σ R Determine, based on the relative rate of change of the fluid velocity υ R The relative change rate of the grouting filling rate σ R The relationship between the size of , the flow state transition discrimination index of the mining fractured rock mass based on the grouting filling rate is established, which is specifically:

[0048] If the relative change rate of fluid velocity is greater than the relative change rate of grouting filling rate, that is, F t '>0, the nonlinear seepage factor F tends to increase, and the flow form tends to be turbulent; if the relative change rate of the grouting filling rate is higher than the relative change rate of the fluid flow rate, that is, F t '<0, the nonlinear seepage factor F shows a downward trend and the flow form tends to laminar flow.

[0049] Compared with the prior art, the present invention has the following advantages and technical effects:

[0050] The present invention proposes a method for calculating the nonlinear seepage factor taking into account the grouting filling rate, which is beneficial to characterizing the nonlinear hydraulic characteristics of the fractured rock mass during the grouting process; a quantitative relationship between the grouting filling rate and the nonlinear seepage factor is constructed, and the influence of the grouting filling rate on the nonlinear seepage characteristics of the fractured rock mass under mining is accurately evaluated; a discrimination index for the flow state transition of the fractured rock mass under the action of grouting is formed, which is beneficial to the accurate identification of the flow state transition during the grouting process, the determination of reasonable grouting parameters, the guidance of the grouting engineering design, and the guarantee of the grouting effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0052] Figure 1 A flow chart of a method for characterizing flow transition of a mining fractured rock mass based on grouting filling rate according to an embodiment of the present invention;

[0053] Figure 2 A graph showing the relationship between the porosity of a fractured rock mass and the grouting filling rate in an embodiment of the present invention;

[0054] Figure 3 Schematic diagram of the influence of the relative growth rate of fluid flow rate and the relative growth rate of grouting filling rate on the nonlinear seepage factor in an embodiment of the present invention. DETAILED DESCRIPTION

[0055] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0056] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0057] The present invention proposes a method for characterizing flow transition of mining fractured rock mass based on grouting filling rate, such as Figure 1 ,include:

[0058] Define the nonlinear seepage factor;

[0059] Calculate the quantitative variation of the porosity of fractured rock mass with filling rate during grouting;

[0060] Correcting the nonlinear seepage factor based on the quantitative change rule to obtain a corrected nonlinear seepage factor;

[0061] Derivatively integrating the corrected nonlinear seepage factor, constructing a discriminant index model for flow state transition of mining fractured rock mass based on grouting filling rate, and obtaining nonlinear seepage characteristics of the fluid;

[0062] By using the nonlinear seepage characteristics of the fluid, a flow state transition discrimination index of mining fractured rock mass based on grouting filling rate is constructed;

[0063] Based on the flow state transition identification index of the mining fractured rock mass and the data measured in the actual project, the flow state transition of the mining fractured rock mass during the grouting process is determined.

[0064] This embodiment uses a nonlinear seepage factor calculation method that takes into account the grouting filling rate, which is beneficial to characterizing the nonlinear hydraulic characteristics of the fractured rock mass during the grouting process; constructs a quantitative relationship between the grouting filling rate and the nonlinear seepage factor, and accurately evaluates the influence of the grouting filling rate on the nonlinear seepage characteristics of the mined fractured rock mass; forms a flow transition analysis method for the mined fractured rock mass under the action of grouting, which is beneficial to the accurate identification of the flow transition during the grouting process, determines reasonable grouting parameters, guides the grouting engineering design, and ensures the grouting effect.

[0065] Furthermore, the nonlinear seepage factor is defined, including:

[0066] The nonlinear seepage characteristics of mining-induced fractured rock mass satisfy the Forchheimer formula:

[0067]

[0068] Where ▽p is the pressure gradient; μ is the fluid dynamic viscosity; k is the permeability of the fractured rock mass; β is the non-Darcy factor; ρ ω is the fluid density; υ is the fluid velocity; F is the nonlinear seepage factor.

[0069] Based on the non-Darcy flow viscosity and inertia terms, the nonlinear seepage factor is defined as follows:

[0070]

[0071] Where μ is the fluid dynamic viscosity; k is the permeability of the fractured rock mass; β is the non-Darcy factor; ρ ω is the fluid density; υ is the fluid velocity; F is the nonlinear seepage factor.

[0072] Specifically, due to the change in porosity of the mined fractured rock mass during the grouting process, it is difficult to describe the non-Darcy flow characteristics of the fluid in the fracture using a single permeability and non-Darcy factor change rule. In this regard, in order to analyze the nonlinear characteristics of the mined fractured rock mass under the influence of the grouting project, this embodiment proposes a flow state analysis method with the nonlinear seepage factor as the core indicator.

[0073] In this embodiment, when the nonlinear seepage factor F is less than 0.1, that is, the viscous resistance is ten times greater than the inertial resistance, the influence of the inertial resistance on the seepage can be ignored, and the seepage form of the fluid is laminar flow. When the nonlinear seepage factor F is greater than 10, the inertial resistance far exceeds the influence of the viscous resistance, and the seepage form of the fluid is turbulent flow.

[0074] Furthermore, the quantitative variation law of the porosity of the fractured rock mass with the filling rate during the grouting process is calculated, including:

[0075]

[0076] Among them, V j is the volume of slurry in the fracture, V k is the fracture volume of the fractured rock mass.

[0077] Porosity refers to the ratio of the total volume of all pores in the mining fractured rock mass to the volume of the rock mass. The formula is as follows:

[0078]

[0079] Among them, V s is the solid phase volume; V r is the volume of broken rock mass.

[0080] Based on the changes in the porosity and grouting filling rate of the fractured rock mass, the slope of the relationship curve between the two, φ0, is obtained, that is, the quantitative change law;

[0081] The changes of porosity and grouting filling rate of fractured rock mass are obtained, specifically:

[0082] Before grouting begins, calculate the initial porosity of the broken rock mass;

[0083]

[0084] Where V s is the solid phase volume; V r is the volume of the broken rock mass; φ0 is the initial porosity of the broken rock mass;

[0085] When grouting starts, the relationship between the grouting filling rate and the slurry filling volume of the fractured rock mass is obtained;

[0086]

[0087] Where V j is the volume of slurry in the fracture; η is the grouting filling rate of the fractured rock mass.

[0088] During the grouting process, the porosity of the fractured rock mass gradually decreases as the slurry is filled. The porosity at this time is obtained:

[0089]

[0090] Where φ is the porosity of fractured rock mass.

[0091] Based on the initial porosity of the broken rock mass, the relationship between the grouting filling rate of the fractured rock mass and the slurry filling volume, and the porosity during the grouting process, the porosity of the fractured rock mass and the grouting filling rate satisfy the relationship. As the grouting project progresses, the porosity of the rock mass gradually decreases, and the porosity of the fractured rock mass and the grouting filling rate satisfy the relationship as follows:

[0092] φ=φ0(1-η);

[0093] Among them, φ0 is the initial porosity of the fractured rock mass, and η is the grouting filling rate.

[0094] like Figure 2 As shown in the figure, the porosity of the fractured rock mass is negatively correlated with the change of the grouting filling rate, and the slope of the relationship curve between the two is φ0.

[0095] Furthermore, the nonlinear seepage factor is corrected, including:

[0096] Permeability and porosity are key parameters for predicting non-Darcy coefficients. According to a large number of experiments and literature, the non-Darcy factor satisfies the following empirical equation:

[0097]

[0098] Among them, a, b, and c are constants related to the medium.

[0099] According to the empirical formula of the non-Darcy factor and the relationship between the porosity of the fractured rock mass and the grouting filling rate, the nonlinear seepage factor is corrected. The corrected nonlinear seepage factor is:

[0100]

[0101] In the formula, F a is the corrected nonlinear seepage factor; ρ ω is the fluid density; υ is the fluid velocity; φ0 is the initial porosity of the fractured rock mass; η is the grouting filling rate of the fractured rock mass; μ is the fluid dynamic viscosity; k is the permeability of the fractured rock mass.

[0102] Specifically, during the grouting process, the fluid dynamic viscosity μ and fluid density ρ ω , the initial porosity φ0 of the rock mass is deterministic and does not change with time. The nonlinear seepage factor model is derived with respect to time t to obtain a discriminant index model for the transition of flow state in mining fractured rock mass based on the grouting filling rate.

[0103] Furthermore, the discriminant index model of flow transition of mining fractured rock mass based on grouting filling rate is:

[0104]

[0105] Where, ν t ′, k t ′、η t ′ are the partial derivatives of fluid velocity, permeability and grouting filling rate with respect to time t; F′ t is the discriminant index model for flow transition of mining fractured rock mass based on grouting filling rate; ρ ω is the fluid density; φ o is the initial porosity of the broken rock mass; η is the grouting filling rate of the fractured rock mass; μ is the fluid dynamic viscosity; k is the permeability of the fractured rock mass; and v is the fluid flow rate.

[0106] From the above formula, it can be seen that the effect of permeability time gradient on the nonlinear seepage characteristics of fluid is related to coefficient a. If a < 1, the permeability time gradient is positively correlated with the growth of nonlinear seepage factor F; if a > 1, the permeability time gradient is negatively correlated with the growth of nonlinear seepage factor F; if a = 1, the effect of permeability time gradient on nonlinear seepage factor F is ignored.

[0107] The influence of the time gradient of grouting filling rate on the nonlinear seepage characteristics of the fluid is related to the coefficient b. If b>0, the time gradient of the filling rate is positively correlated with the growth of the nonlinear seepage factor F; if b<0, the time gradient of the filling rate is negatively correlated with the growth of the nonlinear seepage factor F; if b=0, the influence of the time gradient of the filling rate on the nonlinear seepage factor F is ignored.

[0108] According to a large number of test and simulation results, the parameters of the non-Darcy factor empirical formula can be obtained to satisfy the following relationship:

[0109]

[0110] That is, a=1, b=1, c=1.15×10 -6 , (k is in m 2 ; The unit of β is m -1 ) can further obtain the discriminant index model:

[0111]

[0112] Due to the fluid dynamic viscosity μ and fluid density ρ ω , the non-negativity of the initial porosity φ0 of the rock mass, and the grouting filling rate η<1 always hold true. t '(1-η)+υη t ']>0, F t '>0 holds, otherwise [υ t '(1-η)+υη t ']<0, F t '<0 holds.

[0113] Furthermore, the flow transition identification index of mining fractured rock mass based on grouting filling rate is constructed, including:

[0114] If F t '>0, that is, when the fluid tends to seepage and stabilizes, it satisfies the following inequality:

[0115]

[0116] Integrate both sides of the inequality in the time domain and slightly rearrange to obtain the following inequality:

[0117]

[0118] make

[0119] In the above formula, υ R Expressed as the relative rate of change of fluid velocity, σ R It is expressed as the relative change rate of grouting filling rate within the same time interval, are the fluid flow rate and grouting filling rate at time T1 and T2 respectively.

[0120] The change of nonlinear seepage factor F is determined by the change rate of fluid velocity υ R The change rate of grouting filling rate σ R Determine, based on the relative rate of change of the fluid velocity υ R The relative change rate of the grouting filling rate σ R The nonlinear seepage characteristics of the fluid are determined by the magnitude relationship between the relative change rate of the fluid velocity and the relative change rate of the grouting filling rate, specifically:

[0121] If the relative change rate of fluid velocity is greater than the relative change rate of grouting filling rate, F t '>0, the nonlinear seepage factor F tends to increase, and the flow form tends to be turbulent; if the relative change rate of the grouting filling rate is higher than the relative change rate of the fluid flow rate, F t '<0, the nonlinear seepage factor F shows a downward trend, and the flow form tends to laminar flow. t ′=0, the nonlinear seepage factor remains unchanged, and the fluid flow state remains in the original flow form.

[0122] Specifically, based on the revised discrimination index (i.e., the discrimination index of flow state transition of mining fractured rock mass based on grouting filling rate), the flow state transition in the grouting process is accurately identified by closely combining various data measured during the actual operation of the project. During the grouting process, it is feasible and achievable to measure the flow velocity of the fluid, the flow rate of the slurry, the spatial volume of the mining fractured rock mass, etc. in real time through instruments and equipment. After the data is processed, the relative growth rate of the fluid flow velocity and the relative growth rate of the grouting filling rate are calculated, and the flow state transition in the grouting process is accurately judged based on the relationship between the two.

[0123] In order to more clearly express the technical solution of the present invention, the following specific embodiments are provided to introduce the solution:

[0124] Step 1: Define the nonlinear seepage factor;

[0125] The nonlinear seepage characteristics of mining fractured rock mass satisfy the Forchheimer formula. Based on the viscosity and inertia terms of non-Darcy flow, the nonlinear seepage factor is defined as:

[0126]

[0127] Where μ is the fluid dynamic viscosity; k is the permeability of the fractured rock mass; β is the non-Darcy factor; ρ ω is the fluid density; υ is the fluid velocity.

[0128] Step 2: Calculate the quantitative variation law of the porosity of the fractured rock mass with the filling rate during the grouting process;

[0129] Before grouting begins, the calculation formula for the initial porosity of the broken rock mass is as follows:

[0130]

[0131] Among them, V s is the solid phase volume; V r is the volume of broken rock mass.

[0132] When grouting starts, the relationship between the grouting filling rate of the fractured rock mass and the slurry filling volume is:

[0133]

[0134] From the above, we can know that:

[0135]

[0136] Among them, V j is the volume of slurry in the fracture.

[0137] During the grouting process, the porosity of the fractured rock mass gradually decreases as the slurry is filled. The porosity calculation formula is as follows:

[0138]

[0139] From the above, it can be seen that the porosity of the fractured rock mass and the grouting filling rate satisfy the following relationship:

[0140] φ=φ0(1-η);

[0141] like Figure 2 As shown in the figure, the porosity of the fractured rock mass is negatively correlated with the change of the grouting filling rate, and the slope of the relationship curve between the two is φ0.

[0142] Step 3: Correct the nonlinear seepage factor based on the quantitative change law to obtain a corrected nonlinear seepage factor;

[0143] Based on a large number of test and simulation results, the empirical formula of non-Darcy factor is as follows:

[0144]

[0145] According to the empirical formula of non-Darcy factor, the relationship between the porosity of fractured rock mass and the grouting filling rate, the corrected nonlinear seepage factor model is obtained after a little arrangement as follows:

[0146]

[0147] Step 4: Derivatively integrate the corrected nonlinear seepage factor, construct a discriminant index model for flow transition of mining fractured rock mass based on grouting filling rate, and obtain the nonlinear seepage characteristics of the fluid;

[0148] According to the time-varying characteristics of the flow state of the fractured rock mass during the grouting process, the nonlinear seepage factor model is derived with respect to time t. The derived formula is as follows:

[0149]

[0150] It can be seen from the above formula that the influence of the permeability time gradient on the nonlinear seepage characteristics of the fluid is related to the coefficient a, and the influence of the grouting filling rate time gradient on the nonlinear seepage characteristics of the fluid is related to the coefficient b, specifically:

[0151] If a < 1, the time gradient of permeability is positively correlated with the growth of F; if a > 1, the time gradient of permeability is negatively correlated with the growth of F; if a = 1, the effect of the time gradient of permeability on F is ignored. If b > 0, the time gradient of filling rate is positively correlated with the growth of F; if b < 0, the time gradient of filling rate is negatively correlated with the growth of F; if b = 0, the effect of the time gradient of filling rate on F is ignored.

[0152] According to a large number of test and simulation results, the parameters of the non-Darcy factor empirical formula can be obtained to satisfy the following relationship:

[0153]

[0154] That is, a=1, b=1, c=1.15×10 -6 (The unit of k is m 2 ; The unit of β is m -1 ), and further obtain the discriminant index model:

[0155]

[0156] If t '(1-η)+υη t ']>0, F t '>0 holds, otherwise [υ t '(1-η)+υη t ']<0, F t '<0 is established;

[0157] Step 5: Through the nonlinear seepage characteristics of the fluid, construct an index to identify the flow transition of the mining-induced fractured rock mass based on the grouting filling rate.

[0158] If [υ t '(1-η)+υη t ']>0, then the following equivalent formula is satisfied:

[0159]

[0160] Integrate the above equivalent formula in the time range T1~T2 to obtain the following formula:

[0161]

[0162] Right now:

[0163]

[0164] In the above formula, are the fluid flow rate and grouting filling rate at time T1 and T2 respectively. Slightly rearranging the above equation, we can obtain the following inequality:

[0165]

[0166] make

[0167] In the formula, υ R Expressed as the relative rate of change of fluid velocity, σ R It is expressed as the relative rate of change of the grouting filling rate within the same time interval.

[0168] From the above, we can see that the nonlinear seepage characteristics of the fluid are determined by the relationship between the relative change rate of the fluid velocity and the relative change rate of the grouting filling rate. If the relative change rate of the fluid velocity is greater than the relative change rate of the grouting filling rate, F t '>0, F increases, and the flow tends to be turbulent; if the relative change rate of grouting filling rate is higher than the relative change rate of fluid velocity, F t '<0, F shows a downward trend, and the flow form tends to be laminar flow. Based on the relative change rate of the fluid flow velocity υ R The relative change rate of the grouting filling rate σ R The relationship between the size of the flow state transition of the mining-induced fractured rock mass based on the grouting filling rate is established.

[0169] Step 5: Based on the flow state transition identification index of the mining fractured rock mass, the flow state transition of the mining fractured rock mass during the grouting process is determined according to the data measured in the actual project.

[0170] like Figure 3 As shown in Figure 2, the influence of the relative change rate of fluid velocity and the relative change rate of grouting filling rate on the nonlinear seepage factor. In this embodiment, the analysis is carried out from four stages: the first stage is the development stage, the relative change rate of grouting filling rate is large, but the influence of slurry on fluid velocity in the initial stage of grouting is small, υ R Greater than σ R , the nonlinear hydraulic characteristics of the fluid increase. The second stage is the transition period, the relative change rate of the fluid velocity is at the same level as the relative change rate of the grouting filling rate, and the fluid flow pattern changes slightly. The third stage is the decline period, the fluid velocity decreases rapidly, but due to the decrease in the porosity of the fractured rock mass, σ R The fourth stage is the stable period. As the grouting process continues, υ R With σ R They all decreased continuously to a stable state.

[0171] from Figure 3 It can be found that the fluid velocity decreases with the grouting process, but it is not a linear change process. F generally shows a trend of increasing first and then decreasing, that is, the nonlinear seepage factor F increases significantly in the early stage, and the possibility of water inrush is high. At this stage, it should be controlled by adjusting the grouting parameters and grouting scheme.

[0172] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for characterizing flow transition of mining fractured rock mass based on grouting filling rate, characterized in that: include: Define the nonlinear seepage factor; Calculate the quantitative variation of the porosity of fractured rock mass with filling rate during grouting; Correcting the nonlinear seepage factor based on the quantitative change rule to obtain a corrected nonlinear seepage factor; Derivatively integrating the corrected nonlinear seepage factor, constructing a discriminant index model for flow state transition of mining fractured rock mass based on grouting filling rate, and obtaining nonlinear seepage characteristics of the fluid; By using the nonlinear seepage characteristics of the fluid, a flow state transition discrimination index of mining fractured rock mass based on grouting filling rate is constructed; Based on the flow state transition identification index of the mining fractured rock mass and the data measured in the actual project, the flow state transition of the mining fractured rock mass during the grouting process is determined.

2. The method for characterizing flow transition of mining fractured rock mass based on grouting filling rate according to claim 1 is characterized in that: Define nonlinear seepage factors, including: The nonlinear seepage characteristics of mining fractured rock mass satisfy the Forchheimer formula. Based on the viscosity term and inertia term of non-Darcy flow, the nonlinear seepage factor is defined as follows: Where μ is the fluid dynamic viscosity; k is the permeability of the fractured rock mass; β is the non-Darcy factor; ρ ω is the fluid density; υ is the fluid velocity; F is the nonlinear seepage factor.

3. The method for characterizing flow transition of mining fractured rock mass based on grouting filling rate according to claim 1, characterized in that: Calculating the quantitative variation law of the porosity of the fractured rock with the filling rate during the grouting process includes: Based on the changes in the porosity and grouting filling rate of the fractured rock mass, the slope φ0 of the relationship curve between the two is obtained, that is, the quantitative change law; The changes in the porosity and grouting filling rate of the fractured rock mass are obtained as follows: Before grouting begins, calculate the initial porosity of the broken rock mass; When grouting starts, the relationship between the grouting filling rate and the slurry filling volume of the fractured rock mass is obtained; During the grouting process, the porosity of the fractured rock mass gradually decreases as the slurry is filled, and the porosity at this time is obtained; Based on the initial porosity of the broken rock mass, the relationship between the grouting filling rate and the slurry filling volume of the fractured rock mass and the porosity during the grouting process, the relationship between the porosity of the fractured rock mass and the grouting filling rate is obtained.

4. The method for characterizing flow transition of mining fractured rock mass based on grouting filling rate according to claim 3 is characterized in that: The method for calculating the initial porosity of the broken rock mass is: Where V s is the solid phase volume; V r is the volume of broken rock mass; o is the initial porosity of the broken rock mass; The relationship between the grouting filling rate of the fractured rock mass and the slurry filling volume is: Where V j is the volume of slurry in the fracture; η is the grouting filling rate of the fractured rock mass; The calculation method of the porosity of fractured rock mass is: Where φ is the porosity.

5. The method for characterizing flow transition of mining fractured rock mass based on grouting filling rate according to claim 4 is characterized in that: The porosity of the fractured rock mass and the grouting filling rate satisfy the following relationship: φ=φ0(1-η).

6. The method for characterizing flow transition of mining fractured rock mass based on grouting filling rate according to claim 1, characterized in that: The nonlinear seepage factor is corrected, including: According to the empirical formula of the non-Darcy factor and the relationship between the porosity of the fractured rock mass and the grouting filling rate, the nonlinear seepage factor is corrected. The corrected nonlinear seepage factor is: In the formula, F a is the corrected nonlinear seepage factor; ρ ω is the fluid density; υ is the fluid velocity; φ o is the initial porosity of the broken rock mass; η is the grouting filling rate of the fractured rock mass; a, b, c are all constants related to the medium; μ is the dynamic viscosity of the fluid.

7. The method for characterizing flow transition of mining fractured rock mass based on grouting filling rate according to claim 6 is characterized in that: The modified nonlinear seepage factor is derived to obtain: In the formula, in the formula, F′ t is the discriminant index model for flow transition of mining fractured rock mass based on grouting filling rate; ν t ′、η t ′ are the partial derivatives of fluid velocity and grouting filling rate with respect to time t; ρ ω is the fluid density; φ o is the initial porosity of the fractured rock mass; η is the grouting filling rate of the fractured rock mass; μ is the fluid dynamic viscosity; v is the fluid flow rate; Among them, the fluid velocity is positively correlated with the nonlinear seepage characteristics of the fluid, the influence of the time gradient of the permeability of the fractured rock mass on the nonlinear seepage characteristics of the fluid is related to the coefficient a, and the influence of the time gradient of the grouting filling rate on the nonlinear seepage characteristics of the fluid is related to the coefficient b, including: If a<1, the permeability time gradient is positively correlated with the growth of the nonlinear seepage factor F; if a>1, the permeability time gradient is negatively correlated with the growth of the nonlinear seepage factor F; if a=1, the effect of the permeability time gradient on the nonlinear seepage factor F is ignored; If b>0, the time gradient of filling rate is positively correlated with the growth of nonlinear seepage factor F; if b<0, the time gradient of filling rate is negatively correlated with the growth of nonlinear seepage factor F; if b=0, the influence of time gradient of filling rate on nonlinear seepage factor F is ignored.

8. The method for characterizing flow transition of mining fractured rock mass based on grouting filling rate according to claim 7, characterized in that: The discriminant index model for flow transition of mining fractured rock mass based on grouting filling rate is:

9. The method for characterizing flow transition of mining fractured rock mass based on grouting filling rate according to claim 8, characterized in that: Construct the flow transition identification index of mining fractured rock mass based on grouting filling rate, including: The change of the nonlinear seepage factor F is determined by the relative change rate of fluid velocity υ R Relative change rate of grouting filling rate σ R Determine, based on the relative rate of change of the fluid velocity υ R The relative change rate of the grouting filling rate σ R The relationship between the size of , the flow state transition discrimination index of the mining fractured rock mass based on the grouting filling rate is established, which is specifically: If the relative change rate of fluid velocity is greater than the relative change rate of grouting filling rate, that is, F t '>0, the nonlinear seepage factor F tends to increase, and the flow form tends to be turbulent; if the relative change rate of the grouting filling rate is higher than the relative change rate of the fluid flow rate, that is, F t '<0, the nonlinear seepage factor F shows a downward trend and the flow form tends to laminar flow.

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