A floor heave control design method based on maximum allowable floor heave

Abstract

The present invention relates to a floor heave control design method based on the maximum allowable floor heave amount, which belongs to the technical field of tunnel surrounding rock control, and includes: designing the maximum allowable floor heave amount according to the tunnel height, support and construction requirements; determining the maximum allowable horizontal stress of the floor corresponding to the maximum allowable floor heave amount according to the relationship between the floor heave amount and the horizontal force; determining the size of the target horizontal force, and determining the floor heave control measures and designing the construction parameters from the two aspects of the generation and transmission of the horizontal force. The present invention takes the maximum allowable floor heave amount as the foothold, obtains the maximum allowable horizontal force corresponding to the maximum allowable floor heave amount according to the relationship between the tunnel floor heave and the floor horizontal force, and then proposes corresponding control measures from the two aspects of the generation and transmission of the horizontal force, so as to achieve the purpose of effectively controlling the tunnel floor heave.

Description

Technical Field

[0001] The invention relates to a floor heave control design method based on a maximum allowable floor heave amount, and belongs to the technical field of tunnel surrounding rock control. Background Art

[0002] With the decreasing shallow coal resources in my country, most domestic coal mines have entered deep mining, the tunnel burial depth has gradually increased, the geological conditions have become increasingly complex, and the stability of the surrounding rock of deep tunnels has become a key issue that needs to be solved urgently. Especially in deep soft rock broken tunnels, the horizontal stress of the bottom plate is large, the large deformation of the tunnel is very serious, and the tunnel maintenance is very difficult. Floor heave is a common form of damage in deep coal mine tunnels affected by the horizontal force of the bottom plate, and it occupies a major part of the deformation of the tunnel, seriously affecting the safe production of the mine. Currently, the recognized effective methods for controlling floor heave can be roughly divided into two categories: one is prevention, that is, taking measures to reduce the amount of floor heave to the allowable range; the other is to remove the floor heave, remove part of the rock that has already bottom heaved in the tunnel, and restore the cross-sectional area of ​​the tunnel.

[0003] In the prior art, Chinese patent document CN2016108944617 discloses a combined structure of a steel-concrete inverted arch and an anchor rod for controlling the bottom heave of a roadway and a construction method of the combined structure. The method forms a steel arch structure by inserting anchor rods at both ends of an I-beam and connecting them to the surrounding rock of the roadway bottom plate, and finally pouring concrete to form a combined structure of a steel-concrete inverted arch and an anchor rod, thereby achieving the purpose of controlling the bottom heave. However, in the process of forming the steel arch structure, the construction process is relatively cumbersome, the I-beam needs to be roughly equivalent to the arc trend of the bottom plate, and there are certain difficulties in material processing. At the same time, the combined structure of the steel-concrete inverted arch and the anchor rod only restricts the movement of the bottom plate rock layer, and does not consider the bottom heave problem from the perspective of the force source. In addition, there is no specific basis for the design of construction parameters, and it is impossible to achieve effective control of the bottom heave.

[0004] Chinese patent document CN108194097A discloses a convex energy-absorbing bearing structure for preventing and controlling tunnel floor heave, which can effectively release and transfer the high vertical stress transmitted by the two sides and the high horizontal stress of the deep floor, fundamentally cutting off the "force source" of floor heave deformation and achieving control of floor heave. However, this method requires large-scale excavation of the tunnel floor, with a large construction workload and complex construction process. At the same time, the specific design parameters of the convex energy-absorbing bearing structure are not given, and there is no basis for selecting the construction parameters of the floor anchor rods and side anchor rods, which cannot play a good and effective control effect on the tunnel floor heave problem. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention proposes a floor heave control design method based on the maximum allowable floor heave amount. By taking the maximum allowable floor heave amount as the starting point and according to the relationship between the tunnel floor heave and the bottom plate horizontal force, the maximum allowable horizontal force corresponding to the maximum allowable floor heave amount is obtained, and then corresponding control measures are proposed from the two aspects of the generation and transmission of the horizontal force, so as to achieve the purpose of effectively controlling the tunnel floor heave.

[0006] Terminology explanation:

[0007] Plastic zone: refers to the coal body within a certain range from the tunnel on the side of the tunnel that shows plastic damage after the tunnel is excavated. This range or area is called the plastic zone.

[0008] The present invention adopts the following technical solutions:

[0009] A floor heave control design method based on a maximum allowable floor heave amount comprises:

[0010] Step 1: Design the maximum allowable floor heave w according to the requirements of tunnel height, support and construction. max ;

[0011] Maximum allowable bottom heave w max The determination process is prior art and can be designed with reference to prior art.

[0012] Step 2: According to the relationship between the floor heave and the horizontal force, determine the maximum allowable horizontal stress of the bottom plate corresponding to the maximum allowable floor heave;

[0013] Step 3: Determine the size of the target horizontal force, determine the floor heave control measures and design the construction parameters from the two aspects of the generation and transmission of the horizontal force.

[0014] Preferably, the step 2 is specifically:

[0015] The tunnel floor rock beam is subjected to the extrusion of the floor horizontal force P and bends and deforms. Under the action of the floor horizontal force P, the bending deformation equation of the floor rock beam (the floor rock beam is considered to be horizontal when it is not bent and deformed, and can also be called a horizontal beam) is as follows:

[0016]

[0017] Where: w is the floor heave, m; x is the horizontal distance between the tunnel floor rock beam and the left side of the tunnel, m; E is the elastic modulus of the floor rock beam, GPa; I is the moment of inertia of the cross section of the floor rock beam, m 4 ;

[0018] According to material mechanics, the bending moment equation of the tunnel floor rock beam is (Ⅱ)

[0019] M(x)=-Phω (Ⅱ)

[0020] Where: P is the horizontal force of the bottom plate, N; h is the thickness of the bottom plate rock beam, m;

[0021] From the combined equations (I) and (II), it can be seen that when the tunnel floor reaches the maximum allowable floor heave, the maximum allowable horizontal stress P of the floor is max for:

[0022]

[0023] Where: C is the unknown coefficient, which can be solved according to the elastic surface differential equation of the beam and obtained after entering the boundary conditions.

[0024] Preferably, step 3 comprises:

[0025] Step 3.1: Determine the control target and target horizontal force P according to the actual geological conditions on site. 1 Should meet: P 1 ≤P max ;

[0026] Step 3.2: Take measures to control bottom heave from the two aspects of the generation and transmission of horizontal forces, including setting large-diameter pressure relief boreholes and steel pipe inclined piles.

[0027] Preferably, the design steps of the large diameter pressure relief borehole are as follows:

[0028] (1) Determine the target vertical stress:

[0029] According to the magnitude of the target horizontal force, the magnitude of the target vertical stress σ′ is obtained, where σ′=P 1 (1-μ) / μ, μ is Poisson’s ratio;

[0030] (2) Determine the construction method and design parameters:

[0031] A single row horizontal arrangement is adopted at the side of the tunnel, and a large diameter pressure relief borehole is constructed by a drilling rig. The drilling direction of the large diameter pressure relief borehole is perpendicular to the direction of the tunnel.

[0032] After the construction of large-diameter pressure relief drilling, the plastic zone of the coal body in the tunnel side is expanded, and the stress of the coal body is redistributed. According to the elastic-plastic theory, in the axial direction of the pressure relief drilling hole, the radial stress of the coal body in the elastic zone (radial stress refers to the force acting on the center of the borehole in the axial direction of the borehole) is the unloading stress of the coal body in the tunnel side above the borehole, that is, the radial stress of the coal body in the elastic zone of the borehole is equal to the target vertical stress (target vertical stress refers to the force acting on the tunnel side, vertically downward along the y-axis direction). Therefore, the relationship between the distance between the coal body in the tunnel side and the center of the borehole in the vertical direction and the target horizontal force is obtained as follows:

[0033]

[0034] Wherein, σ is the lateral bearing pressure of the borehole before unloading above the coal body in the axial direction, MPa (which can be obtained by the borehole stress gauge); r is the distance from the side coal body to the center of the borehole in the vertical direction of the side coal body of the roadway, m (this distance can be obtained by knowing the height of the side coal body of the roadway); μ is the Poisson's ratio; R is the radius of the plastic zone of the borehole, Among them, r 0 is the drilling radius, m, σ c is the uniaxial compressive strength of coal, MPa, ξ is the plasticity coefficient; σ rR is the radial stress at the elastic-plastic interface of the borehole, MPa (known, can be calculated using the existing theoretical formula);

[0035] like Figure 3 As shown, the x-axis is the direction of the tunnel, the y-axis is the vertical direction of the tunnel, and the z-axis is the drilling direction of the tunnel side, that is, it intersects perpendicularly with the direction of the tunnel;

[0036] From formula (IV), the unknown number is R, and R is calculated by formula (IV), thus obtaining the drilling radius r 0 , that is, when the target horizontal force P 1 After determination, the drilling radius r can be obtained 0 At the same time, according to the concept of borehole plastic radius, the borehole spacing S = 2R, the large diameter pressure relief borehole depth L exceeds the peak position of the support pressure, and generally takes a safety factor of 1 to 3, that is, L = (1 to 3) M, M is the distance between the peak of the advance support pressure and the coal seam, m; the value of M can be obtained by installing a borehole stress gauge inside the borehole to monitor the lateral advance support pressure of the tunnel in real time;

[0037] In the present invention, the drilling spacing is the distance between the centers of two adjacent drilling holes in a row of drilling holes. The tunnel side is arranged horizontally in a single row, and the drilling holes are arranged in the middle of the tunnel side. It is only necessary to drill holes in the tunnel side, and the other side is a tunnel side support body or a small coal pillar, and there is no need to set a pressure relief drilling hole.

[0038] Preferably, the design steps of the steel pipe inclined pile are as follows:

[0039] (1) Production of steel pipe inclined piles:

[0040] The steel pipe inclined piles are located at the junction of the tunnel floor and the solid coal seam and coal pillar, and are made of steel pipes, anchor cables and pumping support materials;

[0041] (2) Parameter design of steel pipe inclined piles:

[0042] The horizontal limit load of the steel pipe inclined pile is obtained by calculating the external force acting on the pile and its equilibrium condition, that is, for the transversely loaded steel pipe inclined pile (the steel pipe inclined pile of the present invention belongs to the transversely loaded steel pipe inclined pile), the horizontal limit bearing performance of the rock on the inclined pile side is mainly considered, and the influence of the axial load on the inclined pile is ignored. For the steel pipe inclined pile, under the action of the horizontal load, the total normal stress p on the pile side n and total horizontal friction p r The horizontal ultimate resistance of the steel pipe consists of two parts:

[0043]

[0044] Where, d is the diameter of the steel pipe inclined pile, m; σ m is the maximum normal stress of the rock on the side of the steel pipe inclined pile, MPa; τ m is the maximum tangential shear stress of the rock on the side of the steel pipe inclined pile, MPa; mechanical parameter σ m , τ m All can be obtained through indoor mechanical tests;

[0045] From formula (V), it can be concluded that when the target horizontal force P 1 After determination, the diameter d of the steel pipe inclined pile can be obtained. When the steel pipe inclined pile is installed, one end is inserted into the bottom plate stable rock layer, and the other end is inserted into the junction of the tunnel bottom plate and the solid coal seam / coal pillar. The insertion angle α ranges from 50 to 70°. After the steel pipe inclined pile is inserted, it has a certain length of exposed end, and the length of the exposed end is between 200 and 250 mm. The vertical depth of the inclined pile (the vertical depth of the inclined pile refers to the depth in the vertical direction) should be the depth of the bottom plate stable rock layer, and its value can be determined by observing the damage of the bottom plate rock layer through a borehole peephole.

[0046] Preferably, the manufacturing process of the steel pipe inclined pile is:

[0047] The anchor cable is passed through the steel pipe, and the pumped support material is injected into the gap between the anchor cable and the steel pipe. After the pumped support material solidifies, a certain prestress is applied to the anchor cable. The prestress is applied by a hydraulic jack. The prestress is 30% to 50% of the breaking load of the anchor cable, and the inclined pile can be made.

[0048] Preferably, the pumping support material is a slurry having greater strength after solidification, such as cement-water glass slurry, etc., which is used to fix the steel pipe and the anchor cable.

[0049] Where the present invention is not exhaustive, prior art may be used.

[0050] In the present invention, the large-diameter pressure relief drilling hole can effectively reduce the vertical stress above the coal body on the roadway wall, thereby reducing the horizontal additional stress on the roadway floor and reducing the horizontal force of the floor; the steel pipe inclined pile has strong bending and shear resistance, which can effectively resist the transmission of horizontal force, thereby weakening the horizontal squeezing effect of the horizontal force on both sides of the roadway floor on the floor rock. Both of the above methods have the effect of weakening and resisting the horizontal force of the floor, thereby better controlling the deformation of the floor and preventing the roadway floor from bulging.

[0051] The beneficial effects of the present invention are:

[0052] 1) The present invention takes the maximum allowable floor heave as the starting point, obtains the maximum allowable horizontal force corresponding to the maximum allowable floor heave according to the relationship between the tunnel floor heave and the bottom plate horizontal force, and then proposes corresponding control measures from the two aspects of the generation and transmission of the horizontal force, so as to achieve the purpose of effectively controlling the tunnel floor heave.

[0053] 2) The present invention obtains the main parameter design method of large-diameter pressure relief drilling and steel pipe inclined piles by taking the target horizontal force as the theoretical calculation basis. The selection of construction parameters has a theoretical basis, which effectively avoids the problem of unsatisfactory control effect or excessive waste of resources due to inappropriate parameter selection.

[0054] 3) The present invention establishes the relationship between the maximum allowable bottom heave and the maximum allowable horizontal force, proposes corresponding control measures for the generation and transmission of the bottom plate horizontal force, and provides a basis for parameter selection. The construction process is simple, stable, and reliable, and will not affect the normal use of the tunnel. The control method can effectively control the tunnel bottom heave problem, which is of great significance for the control of the tunnel bottom heave problem caused by deep high horizontal stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A flow chart of a floor heave control design method based on a maximum allowable floor heave amount of the present invention;

[0056] Figure 2 It is a schematic diagram of the tunnel floor rock beam being squeezed by horizontal force in the present invention;

[0057] Figure 3 It is a three-dimensional schematic diagram of a large-diameter pressure relief borehole in the middle lane of the present invention and the surrounding coal body;

[0058] Figure 4 It is a schematic diagram of the cross section of the steel pipe inclined pile in the present invention;

[0059] Figure 5 A schematic diagram of a floor heave control measure based on a maximum allowable floor heave amount according to an embodiment of the present invention;

[0060] In the figure, 1-tunnel, 2-coal body, 3-coal pillar, 4-bottom plate rock beam, 5-lateral support pressure before pressure relief above the coal body, 6-large diameter pressure relief borehole, 7-steel pipe, 8-anchor cable, 9-pumping support material, 10-steel pipe inclined pile, 11-bottom plate stable rock layer. DETAILED DESCRIPTION

[0061] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, they will be described in detail with reference to the accompanying drawings and specific embodiments, but are not limited to these. Anything not fully described in the present invention shall be based on conventional techniques in the art.

[0062] Embodiment 1:

[0063] A floor heave control design method based on the maximum allowable floor heave, such as Figure 1-5 As shown, including:

[0064] Step 1: Design the maximum allowable floor heave w according to the requirements of tunnel 1 height, support and construction. max ;

[0065] Maximum allowable bottom heave w max The determination process is prior art and can be designed with reference to prior art.

[0066] Step 2: According to the relationship between the floor heave and the horizontal force, determine the maximum allowable horizontal stress of the bottom plate corresponding to the maximum allowable floor heave;

[0067] Step 3: Determine the size of the target horizontal force, determine the floor heave control measures and design the construction parameters from the two aspects of the generation and transmission of the horizontal force.

[0068] Embodiment 2:

[0069] A floor heave control design method based on a maximum allowable floor heave amount, the structure of which is as shown in Example 1, except that step 2 is specifically as follows:

[0070] The bottom rock beam 4 of the tunnel is subjected to the extrusion of the bottom horizontal force P and is bent and deformed. According to the relevant mechanical analysis, under the action of the bottom horizontal force P, the bending deformation equation of the bottom rock beam 4 (the bottom rock beam is considered to be horizontal when it is not bent and deformed, and can also be called a horizontal beam) is as follows:

[0071]

[0072] Where: w is the floor heave, m; x is the horizontal distance between the tunnel floor rock beam and the left side of the tunnel, m; E is the elastic modulus of the floor rock beam 4, GPa; I is the moment of inertia of the cross section of the floor rock beam, m 4 ;

[0073] According to material mechanics, the bending moment equation of tunnel floor rock beam 4 is (Ⅱ)

[0074] M(x)=-Phω (Ⅱ)

[0075] Where: P is the horizontal force of the bottom plate, N; h is the thickness of the bottom plate rock beam, m;

[0076] From the combined equations (I) and (II), it can be seen that when the floor of tunnel 1 reaches the maximum allowable floor heave, the maximum allowable horizontal stress P of the floor is max for:

[0077]

[0078] Where: C is the unknown coefficient, which can be solved according to the elastic surface differential equation of the beam and obtained after entering the boundary conditions.

[0079] Embodiment 3:

[0080] A floor heave control design method based on a maximum allowable floor heave amount, the structure of which is as shown in Example 1, except that step 3 comprises:

[0081] Step 3.1: Determine the control target and target horizontal force P according to the actual geological conditions on site. 1 Should meet: P 1 ≤P max ;

[0082] Step 3.2: measures for controlling the bottom heave from the two aspects of the generation and transmission of horizontal force, including setting large-diameter pressure relief boreholes 6 and steel pipe inclined piles 10.

[0083] Embodiment 4:

[0084] A method for controlling the heave based on the maximum allowable heave amount is described. The structure is as shown in Example 3. The difference is that the design steps of the large-diameter pressure relief borehole 6 are as follows:

[0085] (1) Determine the target vertical stress:

[0086] According to the magnitude of the target horizontal force, the magnitude of the target vertical stress σ′ is obtained, where σ′=P 1 (1-μ) / μ, μ is Poisson’s ratio;

[0087] (2) Determine the construction method and design parameters:

[0088] A single row horizontal arrangement is adopted in the side of the tunnel 1, and a large diameter pressure relief borehole 6 is constructed by a drilling rig, and the drilling direction of the large diameter pressure relief borehole 6 is perpendicular to the direction of the tunnel;

[0089] After the construction of large-diameter pressure relief drilling, the plastic zone of the coal body in the side of tunnel 1 is expanded, and the stress of coal body 2 is redistributed. According to the elastic-plastic theory, in the axial direction of the pressure relief drilling hole, the radial stress of coal body 2 in the elastic zone (radial stress refers to the force acting on the center of the borehole in the axial direction of the borehole) is the unloading stress of the coal body on the side of the tunnel above the borehole, that is, the radial stress of the coal body in the elastic zone of the borehole is equal to the target vertical stress (target vertical stress refers to the force acting on the side of the tunnel, vertically downward along the y-axis direction). Therefore, the relationship between the distance between the coal body on the side of the tunnel and the center of the borehole in the vertical direction and the target horizontal force is obtained as follows:

[0090]

[0091] Wherein, σ is the lateral bearing pressure 5 of the large-diameter pressure relief borehole 6 before pressure relief above the coal body in the axial direction, MPa (which can be obtained by the borehole stress gauge); r is the distance from the side coal body to the center of the large-diameter pressure relief borehole 6 in the vertical direction of the side coal body of the roadway, m (this distance can be obtained by knowing the height of the side coal body of the roadway); μ is the Poisson's ratio; R is the radius of the plastic zone of the borehole, Among them, r 0 Radius of large diameter pressure relief drilling hole 6, m, σ c is the uniaxial compressive strength of coal, MPa, ξ is the plasticity coefficient; σ rR is the radial stress at the elastic-plastic interface of the large-diameter pressure relief borehole 6, MPa (known and can be calculated using the existing theoretical formula);

[0092] like Figure 3 As shown, the x-axis is the direction of the tunnel, the y-axis is the vertical direction of the tunnel, and the z-axis is the drilling direction of the tunnel side, that is, it intersects perpendicularly with the direction of the tunnel;

[0093] From formula (IV), the unknown number is R, and R is calculated by formula (IV), thus obtaining the drilling radius r 0 , that is, when the target horizontal force P 1 After determination, the radius r of the large-diameter pressure relief drilling hole 6 can be obtained 0 At the same time, according to the concept of borehole plastic radius, it is known that the spacing S of the large-diameter pressure relief borehole 6 is 2R, and the depth L of the large-diameter pressure relief borehole exceeds the peak position of the support pressure. Generally, a safety factor of 1 to 3 is taken, that is, L = (1 to 3) M, where M is the distance between the peak of the advance support pressure and the coal seam, m; the value of M can be obtained by installing a borehole stress gauge inside the borehole to monitor the lateral advance support pressure of the tunnel in real time;

[0094] In the present invention, the drilling spacing is the distance between the centers of two adjacent drilling holes in a row of drilling holes. The tunnel side is arranged horizontally in a single row, and the drilling holes are arranged in the middle of the tunnel side. It is only necessary to drill holes in the tunnel side, and the other side is a tunnel side support body or a small coal pillar, and there is no need to set a pressure relief drilling hole.

[0095] Embodiment 5:

[0096] A method for controlling the heave of the floor based on the maximum allowable heave amount is described in detail in Example 3. The difference is that the design steps of the steel pipe inclined pile 10 are as follows:

[0097] (1) Production of steel pipe inclined piles:

[0098] The steel pipe inclined piles are located at the junction of the bottom plate of the tunnel 1 and the solid coal seam (i.e., the media 2) and the coal pillar 3, and are made of steel pipes 7, anchor cables 8, and pumping support materials 9. Figure 4 As shown;

[0099] The manufacturing process of the steel pipe inclined pile 10 is:

[0100] The anchor cable 8 is passed through the steel pipe 7, and the pumping support material 9 is injected into the gap between the anchor cable 8 and the steel pipe 7. After the pumping support material 9 solidifies, a certain prestress is applied to the anchor cable. The prestress is applied by a hydraulic jack, and the prestress is 40% of the breaking load of the anchor cable, so that the inclined pile can be made;

[0101] The pumping support material is a slurry with greater strength after solidification, such as cement-water glass slurry, which is used to fix steel pipes and anchor cables.

[0102] (2) Parameter design of steel pipe inclined pile 10:

[0103] The horizontal limit load borne by the steel pipe inclined pile 10 is obtained by calculating the external force acting on the pile and its equilibrium condition, that is, for the transversely loaded steel pipe inclined pile 10 (the steel pipe inclined pile of the present invention belongs to the transversely loaded steel pipe inclined pile), the horizontal limit bearing performance of the rock on the inclined pile side is mainly considered, and the influence of the axial load on the steel pipe inclined pile 10 is ignored. For the steel pipe inclined pile, under the action of the horizontal load, the total normal stress p on the pile side n and total horizontal friction p r The horizontal ultimate resistance of the steel pipe inclined pile 10 is composed of two parts, wherein:

[0104]

[0105] Where, d is the diameter of the steel pipe inclined pile 10, m; σ m is the maximum normal stress of the rock on the 10th side of the steel pipe inclined pile, MPa; τ m is the maximum tangential shear stress of the rock on the side of the steel pipe inclined pile, MPa; mechanical parameter σ m , τ m All can be obtained through indoor mechanical tests;

[0106] From formula (V), it can be concluded that when the target horizontal force P 1After determination, the diameter d of the steel pipe inclined pile 10 can be obtained. When the steel pipe inclined pile 10 is installed, one end is inserted into the bottom plate stable rock layer 11, and the other end is inserted into the junction of the tunnel bottom plate and the solid coal seam / coal pillar. The insertion angle α ranges from 60°. After the steel pipe inclined pile 10 is inserted, it has an exposed end of a certain length, and the length of the exposed end is between 200 and 250 mm. The vertical depth of the inclined pile (the vertical depth of the inclined pile refers to the depth in the vertical direction) should be the depth of the bottom plate stable rock layer, and its value can be determined by observing the damage of the bottom plate rock layer through a borehole peephole.

[0107] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A floor heave control design method based on a maximum allowable floor heave amount, characterized in that: include: Step 1: Design the maximum allowable floor heave w according to the tunnel height, support and construction requirements max ; Step 2: According to the relationship between the floor heave and the horizontal force, determine the maximum allowable horizontal stress of the bottom plate corresponding to the maximum allowable floor heave; Step 3: Determine the size of the target horizontal force, determine the floor heave control measures and design the construction parameters from the two aspects of the generation and transmission of the horizontal force; Step 3 includes: Step 3.1: Determine the control target according to the actual geological conditions on site. The target horizontal force P1 should satisfy: P1≤P max ; Step 3.2: Take measures to control the bottom heave from the aspects of the generation and transmission of horizontal forces, including setting large-diameter pressure relief boreholes and steel pipe inclined piles; The design steps for large diameter pressure relief drilling are as follows: (1) Determine the target vertical stress: According to the magnitude of the target horizontal force, the magnitude of the target vertical stress σ′ is obtained, where σ′=P1(1-μ) / μ, μ is the Poisson's ratio; (2) Determine the construction method and design parameters: A single-row horizontal arrangement is adopted at the side of the tunnel, and a large-diameter pressure relief borehole is constructed by a drilling rig. The drilling direction of the large-diameter pressure relief borehole is perpendicular to the direction of the tunnel. After the construction of large-diameter pressure relief drilling, the plastic zone of the coal body in the tunnel side is expanded, and the stress of the coal body is redistributed. According to the elastic-plastic theory, in the axial direction of the pressure relief drilling hole, the radial stress of the coal body in the elastic zone is the unloading stress of the coal body in the tunnel side above the drilling hole, that is, the radial stress of the coal body in the elastic zone of the drilling hole is equal to the target vertical stress. Therefore, the relationship between the distance between the coal body in the tunnel side and the center of the drilling hole in the vertical direction and the target horizontal force is obtained as follows: Wherein, σ is the lateral bearing pressure of the borehole before unloading the coal body in the axial direction, MPa; r is the distance from the side coal body to the center of the borehole in the vertical direction of the side coal body of the roadway, m; μ is the Poisson's ratio; R is the radius of the plastic zone of the borehole, Among them, r0 is the drilling radius, m, σ c is the uniaxial compressive strength of coal, MPa, ξ is the plasticity coefficient; σ rR is the radial stress at the elastic-plastic interface of the borehole, MPa; From formula (IV), it can be seen that when the target horizontal force P1 is determined, the value of the borehole radius r0 can be obtained. At the same time, according to the concept of the borehole plastic radius, the borehole spacing S = 2R is known. The depth L of the large-diameter pressure relief borehole exceeds the peak position of the support pressure, and a safety factor of 1 to 3 is taken, that is, L = (1 to 3) M, where M is the distance between the peak of the advance support pressure and the coal seam, m; The design steps of steel pipe inclined piles are as follows: (1) Production of steel pipe inclined piles: The steel pipe inclined piles are located at the junction of the tunnel floor and the solid coal seam and coal pillar, and are made of steel pipes, anchor cables and pumping support materials; (2) Parameter design of steel pipe inclined piles: The horizontal limit load of the steel pipe inclined pile is obtained by calculating the external force acting on the pile and its equilibrium condition, that is, for the transversely loaded steel pipe inclined pile, the horizontal limit bearing capacity of the rock on the inclined pile side is considered, and the influence of the axial load on the inclined pile is ignored, where: Where, d is the diameter of the steel pipe inclined pile, m; σ m is the maximum normal stress of the rock on the side of the steel pipe inclined pile, MPa; τ m is the maximum tangential shear stress of the rock on the side of the steel pipe inclined pile, MPa; It can be concluded from formula (V) that when the target horizontal force P1 is determined, the diameter d of the steel pipe inclined pile can be obtained. When the steel pipe inclined pile is installed, one end is inserted into the bottom plate stable rock layer, and the other end is inserted into the junction of the tunnel bottom plate and the solid coal seam / coal pillar. The insertion angle α ranges from 50 to 70°. After the steel pipe inclined pile is inserted, it has an exposed end of a certain length, and the length of the exposed end is between 200 and 250 mm. The production process of steel pipe inclined piles is: The anchor cable is passed through the steel pipe, and the pumped support material is injected into the gap between the anchor cable and the steel pipe. After the pumped support material solidifies, a certain prestressing force is applied to the anchor cable. The prestressing force is 30% to 50% of the breaking load of the anchor cable, and the inclined pile production can be realized.

2. The floor heave control design method based on the maximum allowable floor heave amount according to claim 1, characterized in that: The step 2 is specifically as follows: The tunnel floor rock beam is subjected to the extrusion of the floor horizontal force P and bends and deforms. Under the action of the floor horizontal force P, the bending deformation equation of the floor rock beam is as follows: Where: w is the floor heave, m; x is the horizontal distance between the tunnel floor rock beam and the left side of the tunnel, m; E is the elastic modulus of the floor rock beam, GPa; I is the moment of inertia of the cross section of the floor rock beam, m 4 ; According to material mechanics, the bending moment equation of the tunnel floor rock beam is (Ⅱ) M(x)=-Phω(Ⅱ) Where: P is the horizontal force of the bottom plate, N; h is the thickness of the bottom plate rock beam, m; From the combined equations (I) and (II), it can be seen that when the tunnel floor reaches the maximum allowable floor heave, the maximum allowable horizontal stress P of the floor is max for: Where: C is the unknown coefficient, obtained from the boundary conditions.

3. The floor heave control design method based on the maximum allowable floor heave amount according to claim 1, characterized in that: The pumping support material is a slurry that has a certain strength after solidification.

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