Method for determining width of gob-side entry retaining fiber-doped high-water quick-setting material roadside filling body

Abstract

The invention discloses a method for determining the width of a gob-side entry retaining fiber-doped high-water quick-setting material roadside filling body. Comprising the following steps: determining a strength-toughness time-varying rule simulation method of the roadside filling body doped with the fiber-doped high-water quick-setting material; correcting parameters of a gob-side entry retaining coal rock mass model; and constructing a 3DEC model for inverting the evolution of a surrounding rock structure of the gob-side entry retaining of the roadside filling body doped with the fiber-doped high-water quick-setting material. Comprehensively judging the stability level of the surrounding rock of the gob-side entry retaining of the roadside filling bodies with the different widths and the fiber-doped high-water quick-setting material roadside filling bodies according to the change relation of the movement of the roadside filling bodies with the different widths and the gob-side entry retaining roof, the deformation of the surrounding rock and the crack and damage degree of the roadside filling bodies with the fiber-doped high-water quick-setting material roadside filling bodies. Determining the width of a gob-side entry retaining fiber-doped high-water quick-setting material roadside filling body; the invention provides a method for determining the width of a fiber-doped high-water quick-setting material roadside filling body for gob-side entry retaining, solves the problems of material cost increase, severe deformation of the gob-side entry retaining and the like caused by unreasonable width of the fiber-doped high-water quick-setting material roadside filling body, ensures the stability of surrounding rock of the fiber-doped high-water quick-setting material roadside filling body in the gob-side entry retaining, and improves the construction quality of the gob-side entry retaining body. The recovery rate of coal resources is increased, and the application of the gob-side entry retaining of the roadside filling body doped with the fiber-doped high-water quick-setting material is favorably popularized.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, and in particular to a method for determining the width of a filling body beside a gob-side tunnel retaining tunnel made of fiber-doped high-water quick-setting material. Background Art

[0002] The side filling body of the goaf-retained roadway has been affected by the mining of the working face of this section and the lower section. The surrounding rock has a high degree of fracture and is prone to large deformation. Therefore, in the early stage of the construction of the side filling body, it must have the ability to cut off the outer roof of the goaf area, and at the same time, it must have a certain degree of shrinkage in the middle and late stages of construction to gradually adapt to the rotation and sinking of the key blocks above the goaf area. In addition, it is also necessary to have good sealing performance to isolate the harmful gases in the goaf. The stability of the side filling body of the goaf-retained roadway is the key to the success of the goaf-retained roadway. High-water quick-setting materials have good plasticity and high strain bearing properties, and have the shrinkage required for the side support of the goaf-retained roadway. In order to reduce the cost of side filling, broaden the adaptability of the goaf-retained roadway technology to the surrounding rock conditions, and improve the stability of the surrounding rock structure of the goaf-retained roadway, existing literature has demonstrated that fibers have a reinforcing and toughening effect on the side filling body of high-water quick-setting materials.

[0003] There have been a lot of research on the stability of surrounding rock of gob-retaining tunnels with high-water rapid-setting material fillings without fiber, while the research on the reinforcement-toughening effect of high-water rapid-setting material fillings with fiber is limited to laboratory research. However, there are few studies on the influence of high-water rapid-setting material fillings with fiber on the collapse of the roof of gob-retaining tunnels, the deformation of the surrounding rock of gob-retaining tunnels, and the evolution of cracks and damage degree of the fillings. It is difficult to determine the reasonable width of high-water rapid-setting material fillings with fiber. The present invention proposes a method for simulating the time-varying law of strength-toughness of roadside filling bodies made of fiber-doped high-water-fast-setting material, constructs a 3DEC model for inversely analyzing the evolution of surrounding rock structure of roadside filling bodies made of fiber-doped high-water-fast-setting material along goaf-retaining, obtains the influence law of roadside filling bodies made of fiber-doped high-water-fast-setting material with different widths on the collapse of roof of goaf-retaining, deformation of surrounding rock along goaf-retaining and evolution of cracks and damage degree of roadside filling bodies made of fiber-doped high-water-fast-setting material, establishes an evaluation model for the stability grade of surrounding rock along goaf-retaining of roadside filling bodies made of fiber-doped high-water-fast-setting material, comprehensively evaluates the stability grade of surrounding rock along goaf-retaining of roadside filling bodies made of fiber-doped high-water-fast-setting material with different widths, determines the width of roadside filling bodies made of fiber-doped high-water-fast-setting material along goaf-retaining, and ensures the stability of surrounding rock along goaf-retaining of roadside filling bodies made of fiber-doped high-water-fast-setting material. Summary of the invention

[0004] In view of the above-mentioned technical deficiencies, the purpose of the present invention is to provide a method for determining the width of the fiber-doped high-water-fast-setting material side filling body along the goaf-retaining lane. Through this method, the width of the fiber-doped high-water-fast-setting material side filling body along the goaf-retaining lane can be determined, which solves the problems of increased material cost and severe deformation of the goaf-retaining lane caused by unreasonable width of the fiber-doped high-water-fast-setting material side filling body, ensures the stability of the surrounding rock of the fiber-doped high-water-fast-setting material side filling body along the goaf-retaining lane, improves the coal resource recovery rate, and is conducive to promoting the application of the fiber-doped high-water-fast-setting material side filling body along the goaf-retaining lane.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for determining the width of a roadside filling body of a fiber-doped high-water quick-setting material for gob-side road retaining, which specifically comprises the following steps:

[0007] 1. A method for determining the width of a roadside filling body of a fiber-doped high-water quick-setting material for gob-side entry retention, characterized in that it specifically comprises the following steps:

[0008] S1. Determine the simulation method of the time-varying law of strength and toughness of the roadside filling body made of fiber-doped high-water rapid-setting materials, and calibrate the parameters of the coal-rock model of the roadway retained along the gob;

[0009] S2. Construction of 3DEC model for inverse analysis of the surrounding rock structure evolution of the roadside filling body along the gob retaining roadway of fiber-doped high-water rapid-setting material;

[0010] S3. Relationship between the roadside filling bodies with fiber-doped high-water rapid-setting materials of different widths and the roof movement of the gob-side retained roadway, surrounding rock deformation, and cracks and damage degree of the fiber-doped roadside filling bodies;

[0011] S4. Comprehensively evaluate the stability grade of surrounding rock of roadside filling bodies with fiber-doped high-water rapid-setting materials of different widths along the gob-retaining roadway, and determine the width of roadside filling bodies with fiber-doped high-water rapid-setting materials along the gob-retaining roadway.

[0012] Preferably, in step S1, combined with actual application conditions of the mine, the fiber volume content in the fiber-doped high-water quick-setting material roadside filling body is 0.3%, the fiber length is 6 mm, the fiber diameter is 18 μm, and the fiber type is polypropylene fiber.

[0013] Preferably, in step S1, the "block zone generate edge length" and "block zonelist poly" commands are used to obtain the refined tetrahedral joint coordinates, and the blocks of the fiber-doped high-water rapid-setting material roadside filling body are tetrahedron-refined, and the mechanical calculation joint slip failure criterion of the joint surfaces of the tetrahedrons in contact with each other is performed. According to the mechanical parameters of the coal and rock mass in the on-site engineering, the joint surface parameters required to be input into the model: tensile strength, cohesion, internal friction angle, normal stiffness and tangential stiffness, block parameters: elastic modulus, density and Poisson's ratio are corrected to obtain the joint surface parameters and block parameters that can simulate the laboratory uniaxial compression stress-strain characteristics of fiber-doped high-water rapid-setting material filling bodies of different ages, so as to ensure the rationality of the parameter setting in the 3DEC model.

[0014] Preferably, in step S1, the stages and continuity of the arrangement of the roadside filling bodies along the gob-retained roadway are taken into consideration, and step-by-step excavation and step-by-step timely construction of the roadside filling bodies are adopted. The working face is excavated 3.2 m and excavated twice continuously. A 3.2 m long roadside filling body is immediately constructed as the working face is mined. Then, the mechanical parameters of the reinforced and toughened roadside filling body in the roadside filling area are set, and then 1000 steps are calculated and 3.2 m of excavation is continued. The mechanical parameters of the roadside filling body of the fiber-doped high-water-soluble quick-setting material in the previous stage become the parameters corresponding to the 2-day age, and the cycle is repeated until the excavation of the working face is completed (the 28d strength is regarded as the final strength of the roadside filling body of the fiber-doped high-water-soluble quick-setting material).

[0015] Preferably, in step S2, the overall size of the 3DEC model is determined based on the layout profile of the gob-side tunnel retaining working face, taking into account the model's operation rate and the model's boundary effect, the model's bottom boundary is fixedly displaced, and the surrounding normal displacements are limited.

[0016] Preferably, in step S3, the 3DEC model excavates the return air chute of the working face after initial balance, and then excavates the working face in steps, and sets fiber-doped high-water quick-setting material laneside filling bodies with widths of 1.5, 2.0, 2.5, and 3.0 m respectively 3.2 m behind the working face.

[0017] Preferably, in step S3, in order to obtain the changing relationship between the movement of the roof and the deformation of the surrounding rock of the roadside filling bodies with fiber-doped high-water quick-setting materials of different widths and the goaf-retaining roadway, a measuring station is set up to monitor the settlement of the end position of the key block B of the basic top of the goaf-retaining roadway of the roadside filling bodies with fiber-doped high-water quick-setting materials of different widths and the deformation of the surrounding rock of the goaf-retaining roadway, and the results are output.

[0018] Preferably, in step S3, in order to obtain the relationship between the damage degree of the roadside filling body of fiber-doped high-water-precipitated quick-setting material and the roadside filling body of the gob-retained roadway with different widths, the FISH language is compiled to monitor and record the normal stress of the joint surface at the current time step and the previous time step, the tangential stress of the joint surface at the current time step and the previous time step, the maximum shear stress when the molar slip condition is reached, the number of joints and the calculation time step of the roadside filling body of fiber-doped high-water-precipitated quick-setting material with different widths in the model, and the total damage factor D and the shear damage factor D of the roadside filling body of fiber-doped high-water-precipitated quick-setting material are proposed according to the standard of formula (1). S and tensile damage factor D T Evaluation of the damage degree of the roadside filling body of fiber-doped high-water rapid-setting material:

[0019]

[0020] U jt , U jf , U js , U jc are the compressive strain energy, tensile strain energy, shear strain energy and slip dissipation energy of the joint surface, respectively, and are calculated by the following formula (2):

[0021]

[0022] Where: is the normal stress of the joint surface at the current time step and the previous time step; The tangential stress of the joint surface at the time step and the previous time step; are the increments of tangential displacement and normal displacement respectively; f smax To achieve the maximum shear stress when the molar slip condition is met, the formula is satisfied nc is the number of joints; nt is the calculation time step.

[0023] Preferably, in step S4, a hierarchical analysis method and a matter-element analysis method are comprehensively used to establish a model for evaluating the stability grade of surrounding rock of roadside filling bodies along goaf-retaining lanes of fiber-doped high-water-fast-setting material roadside filling bodies; according to the simulation results of the 3DEC model, on-site mine pressure observation data, etc., the values ​​of evaluation indicators for the stability grade of surrounding rock of roadside filling bodies along goaf-retaining lanes of fiber-doped high-water-fast-setting material roadside filling bodies are determined; a comprehensive evaluation system is used to obtain evaluation results for the stability grade of surrounding rock of roadside filling bodies along goaf-retaining lanes of fiber-doped high-water-fast-setting material roadside filling bodies of different widths, and a reasonable width of the fiber-doped high-water-fast-setting material roadside filling bodies along goaf-retaining lanes is determined.

[0024] The beneficial effects of the present invention are:

[0025] The present invention proposes a simulation method for the time-varying law of strength-toughness of roadside filling bodies of fiber-doped high-water-water rapid-setting materials, constructs a 3DEC model for inversely analyzing the evolution of surrounding rock structure of roadside filling bodies of fiber-doped high-water-water rapid-setting materials along the goaf-retaining roadway, and visualizes the influence of the width of roadside filling bodies of fiber-doped high-water-water rapid-setting materials on the collapse of the roof of the goaf-retaining roadway, the deformation of the surrounding rock, and the evolution of cracks and damage degree of the roadside filling bodies. Based on the surrounding rock stability evaluation model of roadside filling bodies of fiber-doped high-water-water rapid-setting materials along the goaf-retaining roadway, the roadside filling bodies of fiber-doped high-water-water rapid-setting materials are simulated. The method can be used to comprehensively judge the stability of the surrounding rock of the goaf-retaining roadway, fill the gap in the current determination of the width of the fiber-doped high-water rapid-setting material roadside filling body along the goaf-retaining roadway, and cannot visualize the structural evolution of the surrounding rock of the goaf-retaining roadway and comprehensively judge the stability of the surrounding rock. This method can determine the reasonable width of the fiber-doped high-water rapid-setting material roadside filling body along the goaf-retaining roadway, ensure the stability of the surrounding rock of the fiber-doped high-water rapid-setting material roadside filling body along the goaf-retaining roadway, improve the coal resource recovery rate, and is conducive to the promotion and application of the fiber-doped high-water rapid-setting material roadside filling body along the goaf-retaining roadway. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram of the plan layout of the mining engineering of the roadside filling body along the gob retaining working face of the fiber-doped high-water quick-setting material provided in this embodiment;

[0028] Figure 2 A comprehensive drilling column diagram of the working face of the gob-side retaining roadway of the fiber-doped high-water quick-setting material roadway filling body provided in this embodiment;

[0029] Figure 3 The local area joint refinement model and joint slip failure criterion provided for this embodiment;

[0030] Figure 4 A flow chart of a method for simulating the time-varying law of strength and toughness of a roadside filling body made of fiber-doped high-water rapid-setting material provided in this embodiment;

[0031] Figure 5 A stress-strain characteristic result diagram of a roadside filling body model of fiber-doped high-water rapid-setting material after correction of joint surface parameters and block parameters in the 3DEC model provided in this embodiment;

[0032] Figure 6 A 3DEC model diagram for inversion of the surrounding rock structure evolution of the gob-side entry retaining of the fiber-doped high-water quick-setting material roadside filling provided in this embodiment;

[0033] Figure 7 A partial schematic diagram of the width of the roadside filling body of fiber-doped high-water quick-setting material with different widths in the 3DEC model provided in this embodiment;

[0034] Figure 8 The variation law of the end settlement of the key block B of the gob-side entry retaining body provided by the embodiment of the invention for the fiber-doped high-water quick-setting material roadside filling body with different widths;

[0035] Fig. 9 The total damage degree variation law of the roadside filling body of the fiber-doped high-water quick-setting material roadside filling body with different widths provided in this embodiment;

[0036] Fig.10 The variation law of the top and bottom plates of the roadside filling bodies with fiber-doped high-water quick-setting materials of different widths provided in this embodiment;

[0037] Fig.11 The variation law of the amount of movement of the two sides of the roadway retaining along the gob provided by the fiber-doped high-water quick-setting material roadway filling body with different widths provided in this embodiment;

[0038] Fig.12 The crack evolution law of the roadside filling body of fiber-doped high-water rapid-setting material with a width of 2.0m provided in this embodiment;

[0039] Fig.13 The evolution law of tensile damage, shear damage and total damage of the fiber-doped high-water rapid-setting material roadside filling with a width of 2.0m provided in this embodiment;

[0040] Fig.14 A diagram of the surrounding rock stability evaluation model for the roadside filling body of fiber-doped high-water rapid-setting material provided in this embodiment;

[0041] Fig.15 This is a flow chart of the analysis method provided in this embodiment. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Engineering background of this embodiment:

[0044] The coal seam currently being mined is the No. 12 coal seam, with a thickness of 4.6 to 5.8 meters, an average thickness of 5.2 meters, and an average inclination of 8 degrees. In order to solve the tension in mining and excavation, reduce the tunnel excavation rate, improve the coal recovery rate, optimize the ventilation method of the working face, and ensure safe and efficient mining of the mine, the return air chute of the 120307 working face is left along the empty space. The ground elevation of the 120307 working face is 900 to 1000 meters, the underground elevation is 705 to 745 meters, the mineable strike length is 1200 meters, the dip length is 240 meters, and the plan layout diagram of the 120307 working face is as follows: Figure 1 As shown in the figure, the coal seam conditions and the coal seam roof and floor conditions are as follows Figure 2 shown.

[0045] See also Figures 1 to 15 The present embodiment provides a method for determining the reinforcement parameters of coal pillars under disturbance of double-tunnel arrangement system, which specifically includes the following steps:

[0046] Step 1: Determine the simulation method for the time-varying law of strength-toughness of the roadside filling body of fiber-doped high-water rapid-setting material, and calibrate the parameters of the coal-rock model of the roadway retained along the gob.

[0047] (1) Modeling method of roadside filling body with fiber-doped high-water rapid-setting material

[0048] In the 3DEC simulation of the fiber-doped high-water rapid-setting material roadside filling body, the "block zone generateedge length" and "block zone list poly" commands are used to obtain the refined tetrahedral joint coordinates, and the blocks of the fiber-doped high-water rapid-setting material roadside filling body are tetrahedron-refined. The interaction force between adjacent blocks is controlled by the joint surface bonding force, tensile strength, etc. The mechanical calculation criteria for the joint surfaces of the tetrahedrons in contact with each other are as follows: Figure 3 shown.

[0049] (2) Simulation method for the time-varying law of strength and toughness of roadside fillings made of fiber-doped high-water rapid-setting materials

[0050] According to the actual situation of working face advancement and lane retention on site, considering the stage and continuity of the construction process of lane retention along the goaf, it is determined that in the process of coal seam mining, the return air chute of the 120307 working face is left along the goaf by 3.2m behind the end of the working face. The width and height of the left lane are 3.5 and 2.8m respectively. Step-by-step excavation and timely construction of the lane side filling body of fiber-doped high-water quick-setting material are adopted. The working face is excavated 3.2m and excavated twice continuously. A 3.2m long lane side filling body is immediately constructed as the working face is mined. Then, the mechanical parameters of the reinforced-toughened lane side filling body in the lane side filling area are set, and then 1000 steps are calculated. The excavation continues for 3.2m. The mechanical parameters of the filling body in the previous reinforced-toughened lane side filling area become the parameters corresponding to the 2-day age. The cycle is repeated until the excavation of the 120307 and 120308 working faces is completed (the 28-day strength is regarded as the final strength of the lane side filling body). Figure 4 shown.

[0051] (3) Correction of model parameters of coal-rock mass and roadside filling body with fiber-doped high-water rapid-setting material

[0052] In the 3DEC model, the five model parameters that need to be input are: tensile strength of joint surface, cohesion, internal friction angle, normal stiffness and tangential stiffness. The mechanical parameters in the model are corrected according to the on-site engineering mechanics parameters. The stress distribution characteristics of the 7-day fiber-doped high-water rapid-setting material roadside filling model at different stages are shown in the figure. Figure 5 As shown in Figure 3, the results are consistent with the stress-strain curve measured in the laboratory, verifying the rationality of the parameter settings in the 3DEC model.

[0053] Step 2: Construct a 3DEC model for inverse analysis of the surrounding rock structure evolution of the gob-side entry retaining body with fiber-doped high-water rapid-setting material

[0054] The establishment of 3DEC model includes three parts: block construction and meshing, constitutive relationship and material assignment, and boundary and initial condition setting. Combined with the actual production geological conditions of the 120307 working face of a certain mine, a 3DEC model for inverse analysis of the evolution of the surrounding rock structure of the gob-retained laneway with fiber-doped high-water rapid-setting material laneway filling body was constructed. Considering the model's operation rate and the model's boundary effect, the overall dimensions of the model were determined to be 400, 200, and 61.6 meters in length, width, and height, respectively. Figure 6 As shown, the model includes 120307 working face, 120307 working face return air chute, and 120308 working face. The Moore Coulomb model is used between blocks, and the Coulomb slip model is used for the joint parameters between blocks. The working face advances along the y-axis direction, the bottom boundary of the model is fixedly displaced, the normal displacement is limited around, the lateral pressure coefficient of the model is 1.2, and the equivalent load of the deadweight of the overlying rock layer is applied to the upper part of the model. The typical original rock stresses are selected as 5.8MPa of vertical stress, 7.1MPa of maximum horizontal stress, and 3.2MPa of minimum horizontal stress.

[0055] Step 3: Relationship between the roadside filling bodies with fiber-doped high-water rapid-setting materials of different widths and the roof movement of the gob-side retained roadway, surrounding rock deformation, and cracks and damage degree of the fiber-doped roadside filling bodies

[0056] Based on the production geological conditions of the return air chute along the goaf of the 120307 working face of a certain mine (2.0m, the width of the goaf is 3.5m), four cases are selected, namely, the width of the fiber-doped high-water rapid-setting material goaf filling body is 1.5, 2.0, 2.5 and 3.0m respectively. Other stress and rock formation parameters and other occurrence conditions remain the same. The partial schematic diagram of the model is as follows Figure 7 The relationship between the roof collapse, surrounding rock deformation, cracks and damage degree of the roadside filling body of fiber-doped high-water rapid-setting material with different widths and the gob-side retained roadway is analyzed. The results are shown in Figures 8 to 10 shown.

[0057] As the width increases, the bearing capacity of the fiber-doped high-water rapid-setting material tunnel side filling body becomes stronger, the roof rock layer outside the fiber-doped high-water rapid-setting material tunnel side filling body collapses more completely, the activity duration of the roof becomes shorter, and the overall damage degree of the fiber-doped high-water rapid-setting material tunnel side filling body is also significantly reduced.

[0058] The evolution laws of cracks, shear damage, tensile damage and total damage of the 2.0m wide fiber-doped high-water rapid-setting material roadside filling are as follows: Figures 11-12 As shown, from Figures 11-12It can be seen from the figure that ① in the range of 0 to 30 m behind the 120307 working face, the 2.0 m wide fiber-doped high-water rapid-setting material roadside filling body has tiny cracks, and the crack in the upper left corner extends to the middle and lower parts, but no obvious main control cracks appear. The tensile damage, shear damage and total damage of the 2.0 m wide fiber-doped high-water rapid-setting material roadside filling body increase from 0 to 30.9%, 13.9% and 44.8%, respectively; ② in the range of 30 to 100 m behind the 120307 working face, the 2.0 m wide fiber-doped high-water rapid-setting material roadside filling body has smaller cracks distributed around the middle crack, and the cracks are not completely connected. The 2.0 m wide fiber-doped high-water rapid-setting material roadside filling body has smaller cracks distributed around the middle crack, and the cracks are not completely connected. The tensile damage, shear damage and total damage of the roadway filling body increased from 30.9%, 13.9% and 44.8% to 46.1%, 18.9% and 65.0%, respectively; ③ In the range of 0 to 40 m in front of the 120308 working face, the cracks inside the roadway filling body of fiber-doped high-water rapid-setting material with a width of 2.0 m further expanded and penetrated, but due to the bonding and friction of the fibers, the internal fibers broke, slipped and pulled out, so the roadway filling body of fiber-doped high-water rapid-setting material with a width of 2.0 m was not completely damaged. The roadway filling body of fiber-doped high-water rapid-setting material in the post-peak state still has a certain bearing capacity, ensuring the stability of the surrounding rock of the roadway retained along the goaf during the mining process of the 120308 working face.

[0059] In summary, the fiber-doped high-water quick-setting material roadside filling body with a width of 2.0 m can not only cut off the roof rock layer of a certain height, but also adapt well to the rotation and sinking of the roof.

[0060] Step 4: Comprehensive evaluation of the stability grade of surrounding rock of the roadside filling body of fiber-doped high-water rapid-setting material and determination of the width of the roadside filling body of fiber-doped high-water rapid-setting material

[0061] (1) Establishment of a stability evaluation model for surrounding rock mass of roadside filling bodies with fiber-doped high-water rapid-setting materials

[0062] The hierarchical analysis method and matter-element analysis method are used to establish a stability evaluation model for the surrounding rock of the gob-side retaining roadway with fiber-doped high-water rapid-setting material roadway filling. Fig.14 The stability grade of surrounding rock of gob-retaining tunnel with fiber-doped high-water quick-setting material tunnel filling body is divided into five levels, namely very stable I, stable II, moderately stable III, unstable IV, and extremely unstable V.

[0063] (2) Comprehensive evaluation of the stability grade of surrounding rock of the roadway retaining structure with fiber-doped high-water rapid-setting material

[0064] Taking the gob retaining lane along the return air chute of the 120307 working face of a mine as an example, according to the output results of the 3DEC model and the on-site mine pressure observation data, the values ​​of the evaluation index of the stability grade of the surrounding rock of the gob retaining lane along the fiber-doped high-water rapid-setting material lane side filling body are obtained. The evaluation results of the surrounding rock stability of the gob retaining lane along the fiber-doped high-water rapid-setting material lane side filling body with different widths are obtained by using a comprehensive evaluation system. The surrounding rock stability grade of the gob retaining lane along the fiber-doped high-water rapid-setting material lane side filling body with a width of 2.0m is III, and the eigenvalue of the level variable is 3.1.

[0065] (3) Determination of the width of the roadside filling body with fiber-doped high-water rapid-setting material

[0066] Combined with the evolution law of surrounding rock structure of gob-retaining tunnels with fiber-doped high-water rapid-setting material tunnel side fillings of different widths and the comprehensive evaluation results of surrounding rock stability grade of gob-retaining tunnels with fiber-doped high-water rapid-setting material tunnel side fillings of different widths, the reasonable width of fiber-doped high-water rapid-setting material tunnel side fillings is determined to be 2.0m.

[0067] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for determining the width of the filling body beside the gob-side entry retaining with fiber-doped high-water rapid-setting material, characterized in that: The specific steps include: S1. Determine the simulation method of the time-varying law of strength and toughness of the roadside filling body made of fiber-doped high-water rapid-setting materials, and calibrate the parameters of the coal-rock model of the roadway retained along the gob; S2. Construction of 3DEC model for inverse analysis of the surrounding rock structure evolution of the roadside filling body along the gob retaining roadway of fiber-doped high-water rapid-setting material; S3. Relationship between the roadside filling bodies with fiber-doped high-water rapid-setting materials of different widths and the roof movement of the gob-side retained roadway, surrounding rock deformation, and cracks and damage degree of the fiber-doped roadside filling bodies; S4. Comprehensively evaluate the stability grade of surrounding rock of roadside filling bodies with fiber-doped high-water rapid-setting materials of different widths along the gob-retaining roadway, and determine the width of roadside filling bodies with fiber-doped high-water rapid-setting materials along the gob-retaining roadway.

2. The method for determining the width of the roadside filling body of fiber-doped high-water rapid-setting material in gob-side entry retention as claimed in claim 1, characterized in that: In step S1, in combination with the actual application conditions of the mine, the fiber volume content in the fiber-doped high-water quick-setting material roadside filling body is 0.3%, the fiber length is 6 mm, the fiber diameter is 18 μm, and the fiber type is polypropylene fiber.

3. The method for determining the width of the roadside filling body of fiber-doped high-water rapid-setting material in gob-side entry retention as claimed in claim 1, characterized in that: In step S1, the "block zone generate edge length" and "block zonelist poly" commands are used to obtain the refined tetrahedral joint coordinates, and the blocks of the fiber-doped high-water rapid-setting material roadside filling body are tetrahedron-refined, and the mechanical calculation of the joint sliding failure criterion of the joint surfaces that contact each other between the tetrahedrons is performed. According to the mechanical parameters of the coal rock mass in the field engineering, the joint surface parameters required to be input into the model: tensile strength, cohesion, internal friction angle, normal stiffness and tangential stiffness, block parameters: elastic modulus, density and Poisson's ratio are corrected to obtain the joint surface parameters and block parameters that can simulate the laboratory uniaxial compression stress-strain characteristics of fiber-doped high-water rapid-setting material filling bodies of different ages, ensuring the rationality of the parameter settings in the 3DEC model.

4. The method for determining the width of the roadside filling body of fiber-doped high-water rapid-setting material in gob-side entry retention as claimed in claim 1, characterized in that: In step S1, considering the stage and continuity of the arrangement of the roadside filling body of the gob-retained roadway, step-by-step excavation and step-by-step timely construction of the roadside filling body are adopted. The working face is excavated 3.2m and excavated twice continuously. A 3.2m long roadside filling body is immediately constructed as the working face is mined. Then, the mechanical parameters of the reinforced and toughened roadside filling body in the roadside filling area are set. After 1000 steps, the excavation continues for 3.2m. The mechanical parameters of the roadside filling body of the fiber-doped high-water rapid-setting material in the previous stage become the parameters corresponding to the 2-day age, and the cycle is repeated until the excavation of the working face is completed (the 28d strength is regarded as the final strength of the roadside filling body of the fiber-doped high-water rapid-setting material).

5. The method for determining the width of the roadside filling body of fiber-doped high-water rapid-setting material in gob-side entry retention as claimed in claim 1, characterized in that: In step S2, according to the layout of the gob-side tunneling working face, the overall size of the 3DEC model is determined taking into account the model's operation rate and the model's boundary effect, the bottom boundary of the model is fixed with a displacement, and the surrounding normal displacements are limited.

6. The method for determining the width of the roadside filling body of fiber-doped high-water rapid-setting material in gob-side entry retention as claimed in claim 1, characterized in that: In step S3, the 3DEC model excavates the return air chute of the working face after initial balance, and then excavates the working face in steps, and sets the fiber-doped high-water quick-setting material lane side filling bodies with widths of 1.5, 2.0, 2.5, and 3.0 m respectively 3.2 m behind the working face.

7. The method for determining the width of the roadside filling body of fiber-doped high-water rapid-setting material in gob-side entry retention as claimed in claim 1, characterized in that: In step S3, in order to obtain the changing relationship between the movement of the roof and the deformation of the surrounding rock of the roadside filling bodies with fiber-doped high-water quick-setting materials of different widths and the gob-retaining roadway, the settlement of the end position of the key block B of the basic top of the gob-retaining roadway with fiber-doped high-water quick-setting materials of different widths and the deformation of the surrounding rock of the gob-retaining roadway are monitored by measuring stations and the results are output.

8. The method for determining the width of the roadside filling body of fiber-doped high-water rapid-setting material in gob-side entry retention as claimed in claim 1, characterized in that: In step S3, in order to obtain the relationship between the damage degree of the roadside filling body of fiber-doped high-water rapid-setting material with different widths and the roadside filling body of gob-retaining roadside, a FISH program is compiled to monitor and record the normal stress of the joint surface at the current time step and the previous time step, the tangential stress of the joint surface at the current time step and the previous time step, the maximum shear stress when the molar slip condition is reached, the number of joints and the calculation time step of the roadside filling body of fiber-doped high-water rapid-setting material with different widths in the model. According to the standard of formula (1), the total damage factor D and the shear damage factor D of the roadside filling body of fiber-doped high-water rapid-setting material are proposed. S and tensile damage factor D T Evaluation of the damage degree of the roadside filling body of fiber-doped high-water rapid-setting material: U jt , U jf , U js , U jc are the compressive strain energy, tensile strain energy, shear strain energy and slip dissipation energy of the joint surface, respectively, and are calculated by the following formula (2): Where: is the normal stress of the joint surface at the current time step and the previous time step; The tangential stress of the joint surface at the time step and the previous time step; are the increments of tangential displacement and normal displacement respectively; f smax To achieve the maximum shear stress when the molar slip condition is met, the formula is satisfied nc is the number of joints; nt is the calculation time step.

9. The method for determining the width of the roadside filling body of fiber-doped high-water rapid-setting material in gob-side entry retaining as claimed in claim 1, characterized in that: In step S4, a hierarchical analysis method and a matter-element analysis method are comprehensively used to establish a model for evaluating the stability grade of surrounding rock of roadside filling bodies along goaf-retaining lanes of fiber-doped high-water-fast-setting material roadside filling bodies. According to the simulation results of the 3DEC model and the on-site mine pressure observation data, the values ​​of the evaluation indexes of the stability grade of surrounding rock of roadside filling bodies along goaf-retaining lanes of fiber-doped high-water-fast-setting material roadside filling bodies are determined. The evaluation results of the stability grade of surrounding rock of roadside filling bodies along goaf-retaining lanes of fiber-doped high-water-fast-setting material roadside filling bodies of different widths are obtained by using a comprehensive evaluation system, and a reasonable width of the fiber-doped high-water-fast-setting material roadside filling bodies along goaf-retaining lanes is determined.

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