Thick and hard roof slab gob-side entry retaining filling body-gangue combined area-increase filling method

Abstract

A thick and hard roof slab gob-side entry retaining filling body-gangue combined area-increase filling method, comprising the following steps: S1, under the action of a mining stress, a gob-side entry retaining main roof breaking for the first time above a solid coal body side behind a working face; S2, during entry retaining, under superposed effects of an advanced abutment pressure from the working face and lateral abutment pressure generated by a roadway side during tunneling, the main roof breaking for the second time above a gob side, and the main roof and overlying strata of the main roof undergoing grouped and orderly caving; and S3, under the action of the pressure-bearing support resistance of the roadway side filling body during a later stage of the entry retaining, the overlying thick and hard roof slab fully collapsing, and a gangue side with a certain width and bearing performance being formed beside the filling body.

Description

A method for filling thick hard roof gob-side entry retaining filling body-gangue combined reinforcement area Technical Field

[0001] The invention relates to the technical field of underground mechanized construction of roadside filling bodies, in particular to a method for filling a thick hard roof gob-side roadside retaining filling body-gangue combination augmentation area. Background Art

[0002] Due to its special surrounding rock conditions and the influence of tunneling and multiple mining, the mine pressure is severe. With the continuous increase of deep mining intensity and roadway section, the bearing capacity difference of conventional roadway walls (roadside filling and solid coal body walls) on both sides of the gob-side roadway is more significant, and the surrounding rock of the roadway shows a skewed effect as a whole.

[0003] First, in the early stage of gob retention, due to the combined effects of the forward support pressure of the working face and the lateral support pressure generated by the tunneling, the surrounding rock deformation begins to show deviation;

[0004] Second, in the middle and late stages of gob-side entry retention, the overlying roof of the gob gradually rotates and sinks, the supporting pressure of the filling body beside the gob increases, and the lateral supporting pressure gradually shifts to the deep part of the solid coal body. The stress concentration coefficient increases, the floor deformation skewness effect strengthens, and the floor heave is obvious.

[0005] Third, during the stable bearing period of gob-side tunnel retaining, under the combined effect of the advanced support pressure of the secondary working face mining and the tunnel side support pressure, the deformation skewness characteristics of the surrounding rock of the gob-side tunnel retaining are more obvious, and the floor heave is rapid.

[0006] In order to alleviate the skew effect of the surrounding rock of the retained tunnel, the unbalanced bearing capacity of the tunnel sides on both sides of the retained tunnel should be actively studied to make their bearing capacity as relatively consistent as possible, and ultimately ensure the overall stability of the surrounding rock of the retained tunnel.

[0007] Summary of the Invention

[0008] In response to the above technical problems, the present invention proposes a method for increasing the area of ​​filling of a combined wall of thick hard roof and gangue along the goaf, which can obtain a reasonable width of the combined wall and achieve the purpose of jointly increasing the effective area of ​​the wall acting as the bottom plate of the goaf along the goaf near the goaf side by combining the filling body and gangue wall.

[0009] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0010] A method for filling a thick hard roof gob-side entry retaining filling body-gangue combined augmentation area, comprising the following steps:

[0011] S1. Under the action of mining stress, the basic top of the gob-side entry is broken for the first time above the solid coal body behind the working face;

[0012] During the S2 roadway retention period, the supporting resistance of the backfill body beside the roadway and the prefabrication of cracks in the early stage of the roadway retention by the top cutting and pressure relief method achieve a controlled group top cutting effect. Under the combined effect of the advanced support pressure of the working face and the lateral support pressure formed by the roadway side during excavation, the basic roof breaks for the second time at the backfill body, that is, above the goaf. The basic roof and the overlying rock strata of a certain thickness collapse in groups in an orderly manner.

[0013] S3. As the distance from the working face gradually increases, the gangue in the goaf is gradually compacted and plays a higher bearing role. The high stress generated by the movement between key blocks is gradually transferred to the deep part of the solid coal body and the gangue on the side of the goaf. In the later stage of retaining the roadway, the filling body beside the roadway further cuts off the overlying thick hard roof under the action of the bearing support resistance, so that the overlying thick hard roof collapses completely, and a gangue wall with a certain width and bearing performance is formed next to the filling body, so as to achieve the purpose of increasing the effective area of ​​the roadway wall acting as the bottom plate of the roadway retained along the goaf close to the goaf side by the combined filling body-gangue wall.

[0014] The width of the filler-gangue combination is obtained by the following method:

[0015] S31 establishes a structural mechanics model of the composite short-arm beam with cooperative bearing capacity, specifically:

[0016] Considering the immediate roof, backfill, gangue side, and solid coal side as deformable bodies with different stiffnesses, the given deformation of the basic roof at the backfill-gangue combined side is composed of the compression of the immediate roof and the compression of the backfill-gangue combined side. The compression of the backfill-gangue combined side includes the compression of the backfill and the gangue side. When the basic roof key block B1 rotates and sinks to stability during the gob-side entry retention stage, the sinking amount of the end of the basic roof key block B1 above the gangue side is, y2 = ηh - h z (k z -1) (1)

[0017] Where, η is the coal recovery rate of the working face;

[0018] h is the thickness of the coal seam, in m;

[0019] h z is the thickness of the immediate roof, in m;

[0020] k z is the direct top expansion coefficient;

[0021] The amount of subsidence of the basic top above the middle of the roadside filling is:

[0022] Where b is the tunnel width, unit is m;

[0023] a is the width of the roadside filling, in m.

[0024] xp The distance between the fracture line of the basic top key block B1 in the solid coal body and the surface of the solid coal body side of the roadway, that is, the width of the plastic zone of the solid coal body side, in meters;

[0025] The subsidence y1 of the basic top above the middle of the roadway filling is regarded as the compression of the filling-gangue combination. Therefore, the compression of the filling itself is:

[0026] Where y1 is the subsidence of the basic top above the middle of the roadside filling body, unit is m;

[0027] y2 is the subsidence of the end of the key block B1 above the gangue wall, in m;

[0028] E a is the elastic modulus of the roadside filling, unit: MPa;

[0029] E sz is the direct top elastic modulus, unit: MPa;

[0030] μ is the Poisson's ratio of the immediate top rock layer, in MPa;

[0031] L1 is the length of the key block B1, in meters;

[0032] S32. Simplify the backfill and overburden bearing system of gob-side entry retaining into ES energy system, where the vertical displacement of the backfill is less than the displacement v at which the backfill reaches the peak stress. sp When , the total energy accumulated in the ES energy system in the gob-side entry is,

[0033] Where:

[0034] S is the filling material;

[0035] E is overlying rock;

[0036] U s is the energy of the filling body, unit is J;

[0037] U e is the energy of the overburden, unit is J;

[0038] v s is the vertical displacement of the filling body, unit, m;

[0039] v e is the vertical displacement of the overburden, unit, m;

[0040] v sp is the displacement at which the filling body reaches the peak stress;

[0041] v epIt is the displacement when the overburden reaches the same stress as the peak stress of the filling body;

[0042] When the vertical displacement of the filling body is greater than the displacement v at which the filling body reaches the peak stress, sp When dU=dU, the increase in displacement will cause further development of primary and secondary cracks inside the filling body and consume energy. As the filling body enters the strain softening stage, the overburden rock undergoes stress unloading as the bearing capacity of the filling body decreases, and its deformation rebounds and releases energy. s +dU e When <0, the energy consumed by the filling body is less than the energy released by the overburden, and the excess energy will be released in the form of kinetic energy. In addition, the additional work done by the gravitational potential energy of the overburden on the filling body will eventually lead to the destruction and instability of the filling body.

[0043] By continuously reducing the width of the filling body, the vertical displacement v of the filling body in the filling body-gangue combination is obtained. s and top cutting resistance, vertical displacement of filling body v s At the intersection of the curve and the top cutting resistance curve, the filling body width corresponding to the vertical displacement of the filling body here is taken as the optimal width of the filling body. Beneficial effects:

[0044] The present invention discloses a method for filling a combined sidewall augmentation of a gob-retaining entry with a thick hard roof and gangue. By analyzing the energy bearing system of the gob-retaining entry filling body and the overburden, the invention reduces the width of the filling body on the basis of controlled top cutting and pressure relief technology to form a combined sidewall bearing structure of a narrow filling body + a wide gangue sidewall, determines the optimal width of the filling body, achieves the purpose of balanced bearing of the two sides of the gob-retaining entry, mitigates large deformation of the gob-retaining entry, and exerts an inhibitory effect on the floor heave of the gob-retaining entry. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a diagram showing the asymmetric stress and deformation evolution characteristics of the surrounding rock of a gob-side entry retaining;

[0046] Figure 2 is the structural mechanics model of the interaction between the combined sidewall and the basic roof in the gob-side entry retaining;

[0047] p is the overburden load, unit is kN;

[0048] L1 is the length of the key block B1, in meters;

[0049] L2 is the length of key block B2, in meters;

[0050] q1 and q2 are the loads of overburden acting on key blocks B1 and B2, in kN;

[0051] x p is the width of the plastic zone of the solid coal body, in m;

[0052] b is the width of the lane, in m;

[0053] a is the width of the filling body, in m;

[0054] x s is the width of the waste rock bank, in m;

[0055] Figure 3 shows the energy conversion relationship of the ES system in gob-side entry retention;

[0056] Vs is the displacement value of body s, unit is m;

[0057] Ve is the displacement value of body e, unit is m;

[0058] Ve1 and Ve2 are the displacement values ​​of body e at points 1 and 2 respectively, in m;

[0059] Vs1 and Vs2 are the displacement values ​​of the s body at points 1 and 2 respectively, in m. DETAILED DESCRIPTION

[0060] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and the accompanying drawings to enable those skilled in the art to have a clearer understanding of the technical solution of the present invention.

[0061] The present invention provides a method for filling a thick hard roof gob-side entry retaining filling body-gangue combined augmentation area, comprising the following steps:

[0062] S1. Under the action of mining stress, the basic top of the gob-side entryway breaks for the first time above the solid coal body behind the working face;

[0063] During the tunneling period, the supporting resistance of the backfill body beside the tunnel and the prefabrication of cracks in the early stage of tunneling by the pressure relief method achieve a controlled group roof cutting effect. Under the combined effect of the advanced support pressure of the working face and the lateral support pressure formed by the tunnel side during excavation, the basic roof breaks for the second time above the goaf of the backfill body, and the overlying rock layer of a certain thickness collapses in groups in an orderly manner.

[0064] S3. As the distance from the working face gradually increases, the gangue in the goaf is gradually compacted and plays a higher bearing role. The high stress generated by the movement between key blocks is gradually transferred to the deep part of the solid coal body and the gangue on the side of the goaf. In the later stage of retaining the roadway, under the action of the bearing support resistance of the roadway side filling body, the overlying thick hard roof is further cut off, causing it to collapse fully, and forming a gangue wall with a certain width and bearing performance next to the filling body, so as to achieve the purpose of increasing the effective area of ​​the roadway wall acting as the bottom plate of the roadway retained along the goaf close to the goaf side by combining the filling body and the gangue wall.

[0065] S4. In order to analyze the load-bearing mechanism of the combined sidewall in detail and obtain the reasonable width of the combined sidewall, the structural mechanics model of the combined short-arm beam cooperative load-bearing structure as shown in Figure 2 and the energy conversion relationship of the ES system in the gob-side entry retention as shown in Figure 3 are established.

[0066] Combined with the mechanical model of the interaction between the combined rib and the basic roof established in Figure 2, the immediate roof, backfill, gangue rib, and solid coal rib are considered deformable bodies with varying stiffnesses. The given deformation of the basic roof at the combined rib is composed of the compression of the immediate roof and the combined rib, which in turn includes the compression of the backfill and the gangue rib. When the basic roof key block B1 rotates and sinks to stability during the gob-side entry retention phase, the amount of sinking at the end of the key block B1 above the gangue rib is y2 = ηh - h z (k z -1) (1)

[0067] Where η is the coal recovery rate of the working face; h is the thickness of the coal seam, m; h z is the thickness of the immediate roof, m; k z is the direct top expansion coefficient.

[0068] The amount of subsidence of the basic top above the middle of the roadside filling is:

[0069] Where η is the coal recovery rate of the working face; h is the thickness of the coal seam, m; h z is the thickness of the immediate roof, m; k z is the direct top expansion coefficient; b is the roadway width, m; a is the width of the roadside filling, m, x p It is the distance between the fracture line of the basic top key block B1 in the solid coal body and the surface of the solid coal body side of the roadway, that is, the width of the plastic zone of the solid coal body side, m.

[0070] Since there is generally no direct roof above the gangue wall, its own compression is approximately equal to the sinking amount y2 of the end of the key block B1 above it. At the same time, for the convenience of calculation, the sinking amount y1 of the basic roof above the middle of the roadside filling body is regarded as the compression amount of the combined wall. Therefore, the compression amount of the filling body itself is,

[0071] Where y1 is the subsidence of the basic top above the middle of the roadside filling body, unit is m;

[0072] y2 is the subsidence of the end of the key block B1 above the gangue wall, in m;

[0073] η is the coal recovery rate of the working face;

[0074] h is the thickness of the coal seam, in m;

[0075] h z is the thickness of the immediate roof, in m;

[0076] k z is the direct top expansion coefficient;

[0077] b is the width of the lane, in m;

[0078] a is the width of the roadside filling, in m,

[0079] x p The distance between the fracture line of the basic top key block B1 in the solid coal body and the surface of the solid coal body side of the roadway (i.e., the width of the plastic zone of the solid coal body side), unit: m;

[0080] E a is the elastic modulus of the roadside filling, unit: MPa;

[0081] E sz is the direct top elastic modulus, unit: MPa;

[0082] μ is the Poisson's ratio of the immediate top rock layer, in MPa;

[0083] L1 is the length of the key block B1, in meters;

[0084] The premise of ensuring the stable bearing capacity of the filling-gangue combination is to ensure that the deformation of the narrow filling does not exceed a certain threshold. The filling and overburden bearing system along the gob-side entry is simplified to the ES energy system. Assuming that the displacement of the filling to reach the stress peak is v sp , the displacement v when the overburden reaches the same stress ep ; When the displacement of the filling body is less than the displacement v at which the filling body reaches the stress peak sp When , the total energy accumulated in the ES system in the gob-side entry is,

[0085] Where:

[0086] S is the filling material;

[0087] E is overlying rock;

[0088] U s is the energy of the filling body, unit is J;

[0089] U e is the energy of the overburden, unit is J;

[0090] v s is the vertical displacement of the filling body, unit, m;

[0091] v e is the vertical displacement of the overburden, unit, m;

[0092] v sp is the displacement at which the filling body reaches the peak stress;

[0093] v ep It is the displacement when the overburden reaches the same stress as the peak stress of the filling body;

[0094] When the vertical displacement of the filling body is greater than the displacement v at which the filling body reaches the peak stress, sp When dU=dU, the increase in displacement will cause further development of primary and secondary cracks inside the filling body and consume energy. As the filling body enters the strain softening stage, the overburden rock undergoes stress unloading as the bearing capacity of the filling body decreases, and its deformation rebounds and releases energy. s +dU e When <0, the energy consumed by the filling body is less than the energy released by the overburden, and the excess energy will be released in the form of kinetic energy. In addition, the additional work done by the gravitational potential energy of the overburden on the filling body will eventually lead to the destruction and instability of the filling body.

[0095] By continuously reducing the width of the filling body, the vertical displacement v of the filling body in the filling body-gangue combination is obtained. s and top cutting resistance, vertical displacement of filling body v s At the intersection of the curve and the top cutting resistance curve, the filling body width corresponding to the vertical displacement of the filling body here is taken as the optimal width of the filling body.

Claims

1. A method for filling a thick hard roof gob-side entry retaining filling body-gangue combination reinforcement area, characterized in that: The following steps are involved: S1. Under the action of mining stress, the top of the gob-side retained roadway breaks for the first time above the solid coal body behind the working face; S2. During the tunnel retention period, the supporting resistance of the backfill body beside the tunnel and the prefabrication of cracks in the early stage of the tunnel retention by the top cutting pressure relief method achieve the effect of controlled group top cutting. Under the superposition of the advanced support pressure of the working face and the lateral support pressure formed by the tunnel side during excavation, the basic top is broken for the second time at the backfill body, that is, above the side of the goaf, and the basic top and the overlying rock layer of a certain thickness collapse in groups in an orderly manner. S3. As the distance from the working face gradually increases, the gangue in the goaf is gradually compacted and exerts a higher bearing capacity. The high stress generated by the movement between key blocks is gradually transferred to the deep part of the solid coal body and the gangue on the side of the goaf. In the later stage of retaining the roadway, the filling body beside the roadway further cuts off the overlying thick hard roof under the action of the pressure support resistance, so that the overlying thick hard roof collapses fully, and a gangue wall with bearing capacity of a certain width is formed beside the filling body, so as to achieve the purpose of increasing the effective area of ​​the roadway wall acting on the side of the goaf near the goaf by the combined filling body-gangue wall.

2. The thick hard roof gob-side entry retaining filling body-gangue combined augmentation area filling method according to claim 1 is characterized in that: The width of the filler-gangue combination is obtained by the following method: S31 establishes a structural mechanics model of composite short arm beams with cooperative bearing capacity, specifically: The direct roof, backfill, gangue wall and solid coal wall are regarded as deformable bodies with different stiffness. The given deformation of the basic roof at the backfill-gangue combination wall is composed of the compression of the direct roof and the compression of the backfill-gangue combination wall. The compression of the backfill-gangue combination wall includes the compression of the backfill and the compression of the gangue wall. When the basic roof key block B1 rotates and sinks to stability in the gob-side entry retention stage, the sinking amount of the end of the basic roof key block B1 above the gangue wall is, y2=ηh-h z (k z -1) (1) Where, η is the coal recovery rate of the working face; h is the thickness of the coal seam, in m; h z is the thickness of the immediate roof, in m; k z is the direct top crushing expansion coefficient; The amount of subsidence of the basic top above the middle of the roadside filling is: Where, b is the width of the lane, in m; a is the width of the backfill beside the roadway, in m. x p is the distance between the fracture line of the basic top key block B1 in the solid coal body and the surface of the solid coal body wall of the roadway, that is, the width of the plastic zone of the solid coal body wall, in meters; The sinking amount y1 of the basic top above the middle of the roadside filling body is regarded as the compression amount of the filling body-gangue combination wall. Therefore, the compression amount of the filling body itself is: Where y1 is the subsidence of the basic top above the middle of the roadside filling body, unit: m; y2 is the sinking amount of the end of the key block B1 above the gangue wall, in m; E a is the elastic modulus of the roadside filling, unit: MPa; E sz is the direct top elastic modulus, unit: MPa; μ is: Poisson's ratio of the immediate top rock layer, unit: MPa; L1 is the length of the key block B1, in m; S32. Simplify the backfill and overburden bearing system of gob-side entry retention into an ES energy system, where the vertical displacement of the backfill is less than the displacement v at which the backfill reaches the peak stress. sp When , the total energy accumulated in the ES energy system in the gob-side entry is: Where: S is the filling body; E is the overlying rock; U s is the energy of the filling body, in J; U e is the energy of the overburden, unit is J; v s is the vertical displacement of the filling body, unit, m; v e is the vertical displacement of the overburden, unit, m; v sp is the displacement of the filling body reaching the peak stress; v ep It is the displacement when the overburden reaches the same stress as the peak stress of the filling body; When the vertical displacement of the filling body is greater than the displacement v at which the filling body reaches the peak stress sp When dU=dU, the increase in displacement will cause further development of primary and secondary cracks inside the filling body and consume energy. As the filling body enters the strain softening stage, the overburden rock undergoes stress unloading as the bearing capacity of the filling body decreases, and its deformation also rebounds and releases energy. s +dU e When <0, the energy consumed by the filling body is less than the energy released by the overburden, and the excess energy will be released in the form of kinetic energy. In addition, the additional work done by the gravitational potential energy of the overburden on the filling body will eventually lead to the destruction and instability of the filling body. By continuously reducing the width of the filling body, the vertical displacement v of the filling body in the filling body-gangue combination is obtained. s and top cutting resistance, vertical displacement of filling body v s At the intersection of the curve and the top cutting resistance curve, the filling body width corresponding to the vertical displacement of the filling body here is taken as the optimal width of the filling body.

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