A method for determining the width of the filling body beside the gob-side entry retaining with fiber-doped high-water rapid-setting material

Abstract

The present invention discloses a method for determining the width of a roadside filling body of a fiber-doped high-water-hydraulic rapid-setting material along a goaf-retaining lane, including determining a simulation method for the strength-toughness time-varying law of the roadside filling body of the fiber-doped high-water-hydraulic rapid-setting material, correcting parameters of a coal-rock model for a goaf-retaining lane, constructing a 3DEC model for inversely analyzing the evolution of the surrounding rock structure of the roadside filling body of the fiber-doped high-water-hydraulic rapid-setting material along the goaf-retaining lane, determining the relationship between the roadside filling body of the fiber-doped high-water-hydraulic rapid-setting material of different widths and the movement of the roof of the goaf-retaining lane, the deformation of the surrounding rock, and the cracks and damage degree of the roadside filling body of the fiber-doped high-water-hydraulic rapid-setting material, and comprehensively evaluating ... cracks and damage degree of the roadside filling body of the fiber-doped high-water-hydraulic rapid-setting material, and comprehensively evaluating the relationship between the roadside filling body of the fiber-doped high-water-hydraulic rapid-setting material The stability grade of surrounding rock of roadside filling body of fiber high water quick-setting material and the width of roadside filling body of fiber high water quick-setting material along goaf-retaining roadway are determined; the present invention provides a method for determining the width of roadside filling body of fiber high water quick-setting material along goaf-retaining roadway, which solves the problems of increased material cost and severe deformation of roadside filling body of fiber high water quick-setting material caused by unreasonable width of roadside filling body of fiber high water quick-setting material, ensures the stability of surrounding rock of roadside filling body of fiber high water quick-setting material along goaf-retaining roadway, improves the recovery rate of coal resources, and is conducive to promoting the application of roadside filling body of fiber high water quick-setting material along goaf-retaining roadway.

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 roadside filling body of a fiber-doped high-water rapid-setting material along a gob-side roadway retaining. Background Art

[0002] Gob-side entry retaining experiences mining from both the current and lower working faces, resulting in high levels of surrounding rock fracture and significant deformation. Therefore, during the initial construction phase, the entry-side backfill must be capable of shearing off the outer roof of the goaf. Furthermore, during the mid- and late-stage construction phases, it must exhibit a certain degree of shrinkage to gradually accommodate the rotation and subsidence of key blocks above the goaf. Furthermore, it must possess good sealing properties to isolate harmful gases from the goaf. The stability of the entry-side backfill is crucial to its success. High-water-density, fast-setting materials possess excellent plasticity and high strain-bearing properties, along with the shrinkage required for entry-side support in gob-side entry retaining. To reduce entry-side backfill costs, broaden the adaptability of gob-side entry retaining technology to surrounding rock conditions, and enhance the stability of the surrounding rock structure of gob-side entry retaining, existing literature has demonstrated the reinforcing and toughening effects of fibers on high-water-density, fast-setting materials.

[0003] There has been a lot of research on the stability of surrounding rock of gob-side tunneling with high-water-fast-setting material fillings without fiber addition. However, the research on the reinforcement-toughening effect of fiber-added high-water-fast-setting material fillings is limited to laboratory research. However, there is little research on the influence of fiber-added high-water-fast-setting material fillings on the collapse of gob-side tunneling roof, deformation of surrounding rock of gob-side tunneling, and evolution of cracks and damage degree of tunneling fillings. It is difficult to determine the reasonable width of fiber-added high-water-fast-setting material fillings for gob-side tunneling. The present invention proposes a method for simulating the time-varying law of strength-toughness of roadside fillings made of fiber-doped high-water-hydraulic rapid-setting material, constructs a 3DEC model for inversely analyzing the evolution of the surrounding rock structure of roadside fillings along the goaf of roadside retained by fiber-doped high-water-hydraulic rapid-setting material, obtains the influence law of roadside fillings made of fiber-doped high-water-hydraulic rapid-setting material with different widths on the collapse of the roof of the roadside retained by the goaf, the deformation of the surrounding rock of the roadside retained by the goaf, and the evolution of the cracks and damage degree of the roadside fillings made of fiber-doped high-water-hydraulic rapid-setting material, establishes a model for evaluating the stability grade of the surrounding rock of the roadside retained by the goaf of fiber-doped high-water-hydraulic rapid-setting material, comprehensively evaluates the stability grade of the surrounding rock of the roadside retained by the goaf of roadside filled with fiber-doped high-water-hydraulic rapid-setting material with different widths, determines the width of the roadside filled with fiber-doped high-water-hydraulic rapid-setting material, and ensures the stability of the surrounding rock of the roadside retained by the fiber-doped high-water-hydraulic rapid-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 side filling body of the fiber-doped high-water-fast-setting material in the goaf-retaining tunnel. Through this method, the width of the side filling body of the fiber-doped high-water-fast-setting material in the goaf-retaining tunnel can be determined, which solves the problems of increased material cost and severe deformation of the goaf-retaining tunnel caused by unreasonable width of the side filling body of the fiber-doped high-water-fast-setting material. It ensures the stability of the surrounding rock of the goaf-retaining tunnel of the fiber-doped high-water-fast-setting material side filling body, 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 in the goaf-retaining tunnel.

[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 rapid-setting material for gob-side entry retention, 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, rapid-setting material in a gob-side entry retaining system, characterized by comprising the following steps:

[0008] S1. Use the "block zone generate edge length" and "block zone list poly" commands to obtain the refined tetrahedral joint coordinates, tetrahedral refine the blocks of the fiber-doped high-water rapid-setting material roadside filling, and use the joint slip failure criterion to calculate the mechanical properties of the joint surfaces of the tetrahedrons in contact with each other. According to the actual situation of the working face advancement and the roadway retention site, considering the stage and continuity of the construction process of the roadway retention along the gob, step-by-step excavation and step-by-step timely construction of the fiber-doped high-water rapid-setting material roadside filling are adopted. Then, the mechanical parameters of the reinforced-toughened roadside filling area are set. The mechanical parameters of the filling body of the previous reinforced-toughened roadside filling area are changed to the parameters corresponding to the 2-day age. The cycle is repeated until the excavation of the working face is completed. The 28-day strength is regarded as the final strength of the roadside filling body and the parameters of the coal-rock model of the roadway retention along the gob are corrected.

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

[0010] S3. Relationship between different widths of fiber-reinforced high-water rapid-setting material roadside fillings and roof movement, surrounding rock deformation, and cracks and damage levels of the fiber-reinforced roadside fillings;

[0011] S4. Comprehensively evaluate the stability grade of surrounding rock of gob-retaining tunnels with different widths of fiber-doped, high-water-soluble, and rapid-setting material side fillings, and determine the width of fiber-doped, high-water-soluble, and rapid-setting material side fillings with different widths.

[0012] Preferably, in step S1, combined with actual application conditions of the mine, the fiber volume content in the fiber-doped high-water rapid-setting material roadside filling 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, the blocks of the fiber-doped high-water-fast-setting material roadside filling are tetrahedron-refined, and the mechanical calculation of the joint slip failure criterion of the joint surfaces of the tetrahedrons that contact each other is performed; according to the mechanical parameters of the on-site engineering coal rock mass, the joint surface parameters required to be input into the model: tensile strength, cohesion, internal friction angle, normal stiffness and tangential stiffness, and the 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 the fiber-doped high-water-fast-setting material filling of different ages, thereby ensuring the rationality of the parameter setting in the 3DEC model.

[0014] Preferably, in step S1, considering the stage-by-stage and continuity of the arrangement of the side filling of the gob-side retained entry, step-by-step excavation and step-by-step timely construction of the side filling are adopted. The working face is excavated 3.2m at a time and excavated twice continuously. A 3.2m long side filling is constructed immediately as the working face is mined. Then, the mechanical parameters of the reinforced and toughened side filling in the side filling area are set. Then, 1000 steps are calculated and 3.2m is excavated again. The mechanical parameters of the fiber-doped high-water-soluble rapid-setting material side filling in the previous stage are changed to the parameters corresponding to the 2-day age. The cycle is repeated until the excavation of the working face is completed, and the 28-day strength is regarded as the final strength of the fiber-doped high-water-soluble rapid-setting material side filling.

[0015] Preferably, in step S2, the overall size of the 3DEC model is determined based on the layout overview of the gob-side entry retaining working face, 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 normal displacement is limited on all sides.

[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 rapid-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.

[0017] Preferably, in step S3, in order to obtain the changing relationship between the movement of the roof of the gob-side entry retaining and the deformation of the surrounding rock of the fiber-doped high-water rapid-setting material roadside filling bodies of different widths and the gob-side entry retaining, a measuring station is set up to monitor the subsidence of the key block B at the end position of the basic top of the gob-side entry retaining of the fiber-doped high-water rapid-setting material roadside filling bodies of different widths and the deformation of the surrounding rock of the gob-side entry retaining, 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 the fiber-doped high-water-soluble rapid-setting material and the roadside filling body of the gob-side reserved entry with different widths, the FISH language is compiled to monitor and record the normal stress of the joint surface of the current time step and the previous time step, the tangential stress of the joint surface of the current time step and the previous time step, the maximum shear stress when the moor slip condition is reached, the number of joints and the calculation time step of the roadside filling body of the fiber-doped high-water-soluble 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 the fiber-doped high-water-soluble rapid-setting material are proposed. S and tensile damage factor D T Evaluation of damage degree of roadside filling body made of fiber-doped high-water rapid-setting material:

[0019]

[0020] Where U jt is the shear strain energy, U jf is the slip strain energy, U js is the tensile strain energy, U jc is the compressive strain energy, U cj is the strain energy stored in the joints.

[0021]

[0022] Where: is the normal stress on 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. Where, f n For the power of Dharma, is the internal friction angle, c0 is the cohesion, nc is the number of joints, and nt is the calculation time step.

[0023] Preferably, in step S4, the hierarchical analysis method and the matter-element analysis method are comprehensively used to establish a stability grade evaluation model for the surrounding rock of the roadside filling body of the fiber-doped high-water-fast-setting material along the gob retaining lane, and the value of the evaluation index of the stability grade of the surrounding rock of the roadside filling body of the fiber-doped high-water-fast-setting material along the gob retaining lane is determined according to the simulation results of the 3DEC model and the on-site mine pressure observation data. The comprehensive evaluation system is used to obtain the evaluation results of the stability grade of the surrounding rock of the roadside filling body of the fiber-doped high-water-fast-setting material along the gob retaining lane of different widths, and the reasonable width of the roadside filling body of the fiber-doped high-water-fast-setting material along the gob retaining lane 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 fillings made of fiber-doped high-water-hydraulic rapid-setting materials, constructs a 3DEC model for inversely analyzing the evolution of the surrounding rock structure of roadside fillings along the goaf of roadside retained by fiber-doped high-water-hydraulic rapid-setting materials, and visualizes the influence of the width of roadside fillings made of fiber-doped high-water-hydraulic rapid-setting materials on the collapse of the roof of the goaf-retained roadside retained by fiber-doped high-water-hydraulic rapid-setting materials, the deformation along the surrounding rock, and the evolution of cracks and damage degree of roadside fillings. Based on the evaluation model of the surrounding rock stability of roadside fillings made of fiber-doped high-water-hydraulic rapid-setting materials, the roadside fillings made of fiber-doped high-water-hydraulic rapid-setting materials are evaluated. The stability of the surrounding rock of the gob-side entry retained by the fiber-doped high-water rapid-setting material is comprehensively evaluated, which fills the gap in the current determination of the width of the fiber-doped high-water rapid-setting material roadside filling body for gob-side entry retained, in which the structural evolution of the surrounding rock of the gob-side entry retained by the fiber-doped high-water rapid-setting material roadside filling body cannot be visualized and the stability of the surrounding rock cannot be comprehensively evaluated. This method can determine the reasonable width of the fiber-doped high-water rapid-setting material roadside filling body for gob-side entry retained by the fiber-doped high-water rapid-setting material roadside filling body, ensure the stability of the surrounding rock of the gob-side entry retained by the fiber-doped high-water rapid-setting material roadside filling body, 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 for gob-side entry retained by the fiber-doped high-water rapid-setting material roadside filling body. 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 following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

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

[0028] Figure 2 A comprehensive drilling histogram of the gob-side entry retaining working face of the fiber-doped high-water quick-setting material roadside filling 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 Flowchart of the method for simulating the time-varying law of strength and toughness of the roadside filling body made of fiber-doped high-water rapid-setting material provided in this embodiment;

[0031] Figure 5 This is a graph showing the stress-strain characteristic results of the fiber-doped, high-water-density rapid-setting material roadside filling model after correction of the joint surface parameters and block parameters in the 3DEC model provided in this embodiment;

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

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

[0034] Figure 8 The variation law of the end subsidence of the key block B of the gob-side entry retaining body of the fiber-doped high-water quick-setting material with different widths provided in this embodiment;

[0035] Figure 9 The total damage degree variation law of the roadside filling body of the gob-side entry retaining material with fiber-doped high-water rapid-setting material of different widths provided in this embodiment;

[0036] Figure 10 The variation law of the top and bottom plate movement of the roadside filling body with different widths of fiber-doped high-water quick-setting materials provided in this embodiment;

[0037] Figure 11 The variation law of the amount of the two sides of the gob-side entry retaining filling body of fiber-doped high-water quick-setting material with different widths provided in this embodiment;

[0038] Figure 12 The crack evolution law of the 2.0m wide fiber-doped high-water rapid-setting material roadside filling provided in this embodiment;

[0039] Figure 13 The evolution laws of tensile damage, shear damage and total damage of the 2.0m wide fiber-doped high-water rapid-setting material roadside filling provided in this embodiment;

[0040] Figure 14 A diagram showing the stability evaluation model of surrounding rock of the gob-side entry retaining structure of the fiber-doped high-water rapid-setting material roadside filling provided in this embodiment;

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

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts 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, which has 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 tunneling rate, improve the coal recovery rate, optimize the working face ventilation method, and ensure safe and efficient mining of the mine, the 120307 working face return air chute is used to retain the goaf. The 120307 working face has a ground elevation of 900 to 1000 meters and an underground elevation of 705 to 745 meters. The mineable strike length is 1200 meters and the dip length is 240 meters. The plan layout diagram of the 120307 working face is as follows: Figure 1 As shown, the coal seam conditions and coal seam roof and floor conditions are as follows Figure 2 shown.

[0045] See also Figures 1 to 15 This embodiment provides a method for determining the width of a gob-side entry retaining backfill made of fiber-doped, high-water, and rapid-setting materials, specifically comprising the following steps:

[0046] Step 1: Determine the simulation method for the time-varying law of strength and 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 gob-side roadway retention.

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

[0048] In the 3DEC simulation of the fiber-doped high-water rapid-setting material roadside filling, the "block zone generateedge length" and "block zone listpoly" commands are used to obtain the refined tetrahedral joint coordinates. The blocks of the fiber-doped high-water rapid-setting material roadside filling are tetrahedron-refined. The interaction force between adjacent blocks is controlled by the joint surface cohesion, 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 of time-varying strength-toughness law of roadside filling with fiber-doped high-water rapid-setting material

[0050] According to the actual situation of working face advancement and roadway retention, considering the stage and continuity of the construction process of roadway retention along the gob, it was determined that the return air chute of the 120307 working face should be retained along the gob during coal seam mining, 3.2m behind the working face end. The width and height of the retained roadway were 3.5 and 2.8m respectively. Step-by-step excavation and timely construction of fiber-doped high-water rapid-setting material roadway filling were adopted. The working face was excavated 3.2m and excavated twice continuously. A 3.2m long roadway filling was immediately constructed as the working face was mined. Then, the mechanical parameters of the reinforced-toughened roadway filling area were set. Then, 1000 steps were calculated and 3.2m was excavated again. The mechanical parameters of the filling body in the previous reinforced-toughened roadway filling area became the parameters corresponding to the 2-day age. The cycle was repeated until the excavation of the 120307 and 120308 working faces was completed. The 28-day strength was regarded as the final strength of the fiber-doped high-water rapid-setting material roadway filling. Figure 4 shown.

[0051] (3) Parameter correction of coal rock mass and fiber-doped high-water rapid-setting material roadside filling model

[0052] In the 3DEC model, the five model parameters that need to be input are: tensile strength of the 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 mechanical parameters. The stress distribution characteristics of the 7-day fiber-doped high-water rapid-setting material roadside filling model at different stages are as follows: Figure 5 As shown in Figure 3, the results are consistent with the stress-strain curves measured in the laboratory, verifying the rationality of the parameter settings in the 3DEC model.

[0053] Step 2: Construct a 3DEC model to inversely analyze the evolution of the surrounding rock structure of the gob-side entry retaining structure of the fiber-doped high-water rapid-setting material roadside filling

[0054] The establishment of 3DEC model consists of three parts: block construction and meshing, constitutive relationship and material assignment, and boundary and initial condition setting. Based on 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 roadway with fiber-doped high-water rapid-setting material roadway filling was constructed. Considering the model's operation rate and the model's boundary effect, the overall dimensions of the model were determined to be 400m in length, 200m in width, and 61.6m in height. Figure 6As shown, the model includes the 120307 working face, the 120307 working face return air chute, and the 120308 working face. The Mohr-Coulomb model is used for interblock relationships, and the interblock joint parameters are calculated using the Coulomb slip model. The working face advances along the y-axis, the bottom boundary of the model has a fixed displacement, and the surrounding normal displacements are constrained. The model has a lateral pressure coefficient of 1.2, and an equivalent load of 5.0 MPa, representing the deadweight of the overlying strata, is applied to the upper portion of the model. Typical in-situ rock stresses are selected: a vertical stress of 5.8 MPa, a maximum horizontal stress of 7.1 MPa, and a minimum horizontal stress of 3.2 MPa.

[0055] Step 3: Relationship between different widths of fiber-reinforced high-water rapid-setting material roadside fillings and roof movement, surrounding rock deformation, and cracks and damage degree of fiber-reinforced roadside fillings

[0056] Based on the production geological conditions of the return air chute along the goaf of the 120307 working face of a mine, the goaf width is 3.5m, the width of the fiber-doped high-water rapid-setting material roadside filling is 2.0m, and four cases with the width of the fiber-doped high-water rapid-setting material roadside filling are selected, namely 1.5, 2.0, 2.5 and 3.0m respectively. Other stress and rock parameters and other occurrence conditions remain the same. The partial diagram of the model is shown below. 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 the figure. Figures 8-11 shown.

[0057] As the width increases, the bearing capacity of the fiber-doped high-water-fast-setting material roadside filling becomes stronger, the roof rock layer outside the fiber-doped high-water-fast-setting material roadside filling collapses more completely, the activity duration of the roof becomes shorter, and the overall damage degree of the fiber-doped high-water-fast-setting material roadside filling 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 12-13 As shown, from Figures 12-13It 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 had tiny cracks, and the crack in the upper left corner extended to the middle and lower parts, but no obvious main cracks appeared. The tensile damage, shear damage and total damage of the 2.0 m wide fiber-doped high-water rapid-setting material roadside filling body increased 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 had smaller cracks distributed around the middle crack, and the cracks were not completely connected. The 2.0 m wide fiber-doped high-water rapid-setting material roadside filling body had smaller cracks distributed around the middle crack, and the cracks were not completely connected. The tensile damage, shear damage and total damage of the roadway filling 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 2.0 m wide fiber-doped high-water rapid-setting material roadway filling further expanded and penetrated, but due to the bonding and friction of the fibers, the internal fibers broke, slipped and pulled out. Therefore, the 2.0 m wide fiber-doped high-water rapid-setting material roadway filling was not completely damaged. The fiber-doped high-water rapid-setting material roadway filling in the post-peak state still had a certain bearing capacity, ensuring the stability of the surrounding rock of the gob-side retained roadway during the mining process of the 120308 working face.

[0059] In summary, the 2.0m-wide fiber-doped high-water rapid-setting material tunnel filling can not only cut off the roof rock layer at 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 the surrounding rock of the gob-side retaining tunnel filling body of fiber-doped high-water rapid-setting material and determination of the width of the fiber-doped high-water rapid-setting material tunnel filling body

[0061] (1) Establish a model for evaluating the stability grade of surrounding rock of gob-side fillings with fiber-doped high-water rapid-setting materials

[0062] type

[0063] The hierarchical analysis method and matter-element analysis method are comprehensively used to establish a stability evaluation model for the surrounding rock of the gob-side entry retaining filling body of fiber-doped high-water rapid-setting materials. Figure 14 The stability grade of surrounding rock of gob-side entry retaining with fiber-doped high-water rapid-setting material filling is divided into five levels, namely very stable I, stable II, moderately stable III, unstable IV, and extremely unstable V.

[0064] (2) Comprehensive evaluation of the stability grade of surrounding rock of the roadway retaining structure with fiber-doped high-water rapid-setting material filling

[0065] Taking the gob-side entry retaining of the return air chute of the 120307 working face in a certain mine as an example, the values of the evaluation index of the stability grade of the surrounding rock of the gob-side entry retaining of the fiber-doped high-water rapid-setting material roadside filling body are obtained according to the output results of the 3DEC model and the on-site mine pressure observation data. The evaluation results of the surrounding rock stability of the gob-side entry retaining of the fiber-doped high-water rapid-setting material roadside filling body with different widths are obtained by using a comprehensive evaluation system. The surrounding rock stability grade of the gob-side entry retaining of the fiber-doped high-water rapid-setting material roadside filling body with a width of 2.0 m is obtained as III, and the eigenvalue of the grade variable is 3.1.

[0066] (3) Determination of the width of the roadside filling body with fiber-doped high-water rapid-setting material

[0067] Combined with the evolution law of surrounding rock structure of gob-retaining tunnels with fiber-doped high-water-precipitated rapid-setting material side fillings of different widths and the comprehensive evaluation results of surrounding rock stability grade of gob-retaining tunnels with fiber-doped high-water-precipitated rapid-setting material side fillings of different widths, the reasonable width of the fiber-doped high-water-precipitated rapid-setting material side filling is determined to be 2.0m.

[0068] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for determining the width of the roadside filling body of fiber-doped high-water rapid-setting material in gob-side entry retention, characterized in that: The specific steps include: S1. Use the "block zone generate edge length" and "block zone list poly" commands to obtain the refined tetrahedral joint coordinates, tetrahedral refine the blocks of the fiber-doped high-water rapid-setting material roadside filling, and use the joint slip failure criterion to calculate the mechanical properties of the joint surfaces of the tetrahedrons in contact with each other. According to the actual situation of the working face advancement and the roadway retention site, considering the stage and continuity of the gob-side roadway retention construction process, step-by-step excavation and step-by-step timely construction of the fiber-doped high-water rapid-setting material roadside filling are adopted. Then, the mechanical parameters of the reinforced-toughened roadside filling area are set. The mechanical parameters of the previous reinforced-toughened roadside filling area are changed to the parameters corresponding to the 2-day age. The cycle is repeated until the working face excavation is completed. The 28-day strength is regarded as the final strength of the roadside filling body and the parameters of the coal-rock model of the gob-side roadway retention are corrected. S2. Construction of a 3DEC model for inverse analysis of the surrounding rock structure evolution of the gob-side entry retaining filling body of fiber-doped high-water rapid-setting material; S3. Relationship between different widths of fiber-reinforced high-water rapid-setting material roadside fillings and roof movement, surrounding rock deformation, and cracks and damage levels of the fiber-reinforced roadside fillings; S4. Comprehensively evaluate the stability grade of surrounding rock of gob-retaining tunnels with different widths of fiber-doped, high-water-soluble, and rapid-setting material side fillings, and determine the width of fiber-doped, high-water-soluble, and rapid-setting material side fillings with different widths.

2. The method for determining the width of the roadside filling body of fiber-doped high-water rapid-setting material in a gob-side entry retaining according to claim 1, characterized in that: In step S1, based on the actual application conditions of the mine, the fiber volume content in the fiber-doped high-water rapid-setting material roadside filling 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 a gob-side entry retaining 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-precipitation rapid-setting material roadside filling are tetrahedron-refined. The mechanical calculation of the joint slip failure criterion of the joint surfaces of the contacting tetrahedrons is performed. The joint surface parameters required for the model input: tensile strength, cohesion, internal friction angle, normal stiffness and tangential stiffness; and the block parameters: elastic modulus, density and Poisson's ratio are corrected based on the mechanical parameters of the coal and rock mass in the on-site engineering project. The joint surface parameters and block parameters that can simulate the laboratory uniaxial compression stress-strain characteristics of fiber-doped high-water-precipitation rapid-setting material filling at different ages are obtained to ensure 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 a gob-side entry retaining as claimed in claim 1, characterized in that: In step S1, considering the stage-by-stage and continuity of the arrangement of the side filling of the gob-side retained entry, step-by-step excavation and step-by-step timely construction of the side filling are adopted. The working face is excavated 3.2m at a time and excavated twice continuously. A 3.2m long side filling is constructed immediately as the working face is mined. Then, the mechanical parameters of the reinforced and toughened side filling in the side filling area are set. After 1000 steps, the excavation is continued for 3.2m. The mechanical parameters of the fiber-doped high-water-soluble rapid-setting material side filling in the previous stage are changed to the parameters corresponding to the 2-day age. The cycle is repeated until the excavation of the working face is completed. The 28-day strength is regarded as the final strength of the fiber-doped high-water-soluble rapid-setting material side filling.

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

6. The method for determining the width of the roadside filling body of fiber-doped high-water rapid-setting material in a gob-side entry retaining as claimed in claim 1, characterized in that: In step S3, after initial balancing, the 3DEC model excavates the return air chute of the working face, and then excavates the working face in steps. Fiber-doped high-water rapid-setting material roadside filling bodies with widths of 1.5, 2.0, 2.5, and 3.0 m are set 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 a gob-side entry retaining as claimed in claim 1, characterized in that: In step S3, in order to obtain the changing relationship between the roadside filling bodies of fiber-doped high-water-precipitated quick-setting materials of different widths and the movement of the roof and surrounding rock deformation along the gob-side entry, measuring stations are set up to monitor the subsidence of the key block B at the end position of the basic top of the gob-side entry retaining bodies of fiber-doped high-water-precipitated quick-setting materials of different widths and the deformation of the surrounding rock along the gob-side entry retaining, 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 a gob-side entry retaining 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 and the roadside filling body of the gob-side entry with different widths of fiber-doped high-water-soluble rapid-setting material, a FISH program is compiled to monitor and record the normal stress of the joint surface between the current time step and the previous time step, the tangential stress of the joint surface between the current time step and the previous time step, the maximum shear stress when the moor slip condition is reached, the number of joints and the calculation time step of the roadside filling body with fiber-doped high-water-soluble rapid-setting material 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 with fiber-doped high-water-soluble rapid-setting material are proposed. S and tensile damage factor D T Evaluation of damage degree of roadside filling body made of fiber-doped high-water rapid-setting material: Where U jt is the shear strain energy, U jf is the slip strain energy, U js is the tensile strain energy, U jc is the compressive strain energy, U cj The strain energy stored in the joints; Where: is the normal stress on 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. Where, f n For the power of Dharma, internal friction angle, c0 is the cohesion; 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 a gob-side entry retaining as claimed in claim 1, characterized in that: In step S4, the hierarchical analysis method and the matter-element analysis method are comprehensively used to establish a stability grade evaluation model for the surrounding rock of the fiber-doped high-water-fast-setting material roadside filling body along the gob retaining lane. The value of the evaluation index of the stability grade of the surrounding rock of the fiber-doped high-water-fast-setting material roadside filling body along the gob retaining lane is determined according to the 3DEC model simulation results and the on-site mine pressure observation data. The comprehensive evaluation system is used to obtain the evaluation results of the stability grade of the surrounding rock of the fiber-doped high-water-fast-setting material roadside filling body along the gob retaining lane of different widths, and the reasonable width of the fiber-doped high-water-fast-setting material roadside filling body along the gob retaining lane is determined.

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