Method for determining working resistance of unit bracket at advanced section of mining roadway

Abstract

A method for determining the working resistance of a mining roadway advanced section unit support comprises the following steps that S1, geological parameters of an advanced section overlying strata of a to-be-detected roadway are collected, and the load of the to-be-detected roadway is judged; s2, dividing the to-be-detected roadway into six roadway types according to the lithology of a roadway roof, the structure of the roadway roof and whether the roadway is affected by impact or not and based on whether the roadway is along a gob; s3, super-forepart surrounding rock loads of the six roadways are calculated respectively; s4, respectively calculating the roadway bearing capacity of the six roadways; and S5, respectively calculating the rated working resistance of the unit brackets of the six roadways. According to the method, all load sources possibly borne by the unit supports and the active supporting effect provided by the roadway anchor rod cables are comprehensively considered, the stability of a roadway active supporting system is guaranteed to the maximum extent, and the working resistance of the unit supports in different roadway types and supporting states can be accurately calculated; scientific use of the unit support can be systematically guided in the whole process, it is guaranteed that the operation space is in a safe area, and potential safety hazards are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of safe support for coal mine tunnels, and in particular to a method for determining the working resistance of a unit support in an advanced section of a mining tunnel. Background Art

[0002] The mining tunnel in front of the working face is in the superposition influence area of ​​the working face advance support pressure and lateral support pressure. The support pressure has a great influence on the roof integrity of the tunnel advance section, especially the stress concentration along the side tunnel is obvious, the tunnel maintenance is difficult, and there are safety hazards that threaten the normal production underground. Therefore, in order to ensure the safe mining of the working face, it is necessary to adopt a reinforced support method for the mining tunnel to reduce the damage to the tunnel roof caused by the advance pressure and mining impact, and ensure the stability of the tunnel bearing system.

[0003] The traditional advance-section tunnel reinforcement method of single pillars combined with steel frame top beams has obvious shortcomings such as low strength, low efficiency, high work intensity for workers and great safety hazards, which is difficult to meet the current status of comprehensive mechanized production. In order to solve the above problems, some mines have arranged step-type advance hydraulic supports in groups in the advance section, which repeatedly support and damage the tunnel roof during work, frequently disturb the surrounding rock, and are very unfavorable to the stability of the tunnel. The unit support is an emerging tunnel support reinforcement equipment, which is independent and flexible, easy to carry, and can avoid repeated support and damage to the roof during support work. It is an effective support reinforcement method.

[0004] The geological conditions of the surrounding rock of coal mine tunnels are complex and changeable. The deformation characteristics and failure forms of the surrounding rock of tunnels under different geological and mining conditions are different. In order to better achieve the reinforcement support effect, it is necessary to quantitatively determine the working resistance of the unit support under the optimal working state from the perspective of improving the original surrounding rock stress and deformation state, effectively improving the overall strength of the surrounding rock, and increasing the integrity of the tunnel surrounding rock according to the differences in engineering conditions such as tunnel overburden movement, roof structure, burial depth, and mining layout.

[0005] At present, due to the complex stress conditions of the surrounding rock in the advanced support section and the immaturity of relevant theories, the design and parameter selection of on-site unit support support are still based on experience. A considerable number of tunnel roof accidents are caused by the excessive effect of the unit support on the roof, which destroys the original active support of the anchor cable, or the unit support is too weak to play its due role on the roof, exposing the current lack of scientific calculation and determination methods for the selection of various parameters of the advanced unit support. Therefore, it is urgent to propose a method for determining the working resistance of the unit support in the advanced section of the mining tunnel to standardize the support effectiveness of the unit support on the tunnel roof in different mining tunnel operation areas, and to assist in the selection of unit supports. Summary of the invention

[0006] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a method for determining the working resistance of a unit support in the leading section of a mining tunnel, including the following specific technical solutions:

[0007] A method for determining the working resistance of a unit support in a leading section of a mining tunnel comprises the following steps:

[0008] S1, collecting geological parameters of the overburden of the leading section of the tunnel to be tested, determining the lithology of the tunnel roof, the tunnel roof structure, and whether the tunnel is affected by the impact on the load formed on the tunnel;

[0009] S2, according to the lithology of the roadway roof, the structure of the roadway roof, whether the roadway is affected by impact, and whether the roadway is along the goaf, the roadways to be tested are divided into the following roadway types: Type I roadway: solid coal roadway without impact impact; Type II roadway: solid coal roadway affected by impact; Type III roadway: goaf roadway affected by impact and with the basic roof fracture line located above the solid coal; Type IV roadway: goaf roadway affected by impact and with the basic roof fracture line located above the roadway (coal pillar); Type V roadway: goaf roadway affected by impact and with the basic roof fracture line located above the goaf; Type VI roadway: goaf roadway affected by impact and with the basic roof fractured in advance;

[0010] S3, calculate the surrounding rock load of the leading section of type I to type VI tunnels respectively;

[0011] S4, respectively calculating the tunnel bearing capacity of type I tunnel to type VI tunnel, wherein the tunnel bearing capacity includes the active support bearing capacity of the anchor cable, and / or the coal seam bearing capacity, and / or the coal pillar bearing capacity, and / or the bearing capacity absorbed by the unit support equipment;

[0012] S5, calculate the rated working resistance P of the unit support of type I to type VI lanes by the following formula m :

[0013]

[0014] Furthermore, the geological parameters include the mechanical properties of the surrounding rock of the tunnel, the position of the roof delamination, the spatial occurrence form of the coal seam, the ground stress and the deformation of the surrounding rock of the tunnel; the rock properties of the tunnel roof include the mechanical properties of the surrounding rock of the tunnel and the position of the roof delamination. When the tunnel is excavated, the roof forms a surrounding rock loosening load due to the influence of the rock layer delamination; the tunnel roof structure includes the ground stress. According to the tunnel determination measures, during the mining process of the working face, the leading section of the tunnel forms a mining load due to the influence of mining; whether the tunnel is affected by impact includes the deformation of the surrounding rock of the tunnel. When the leading section of the tunnel is affected by the breaking of the overlying rock layer, a dynamic load is formed; the surrounding rock load of the leading section of the tunnel is calculated by the following formula:

[0015] When the roadway has no impact, including type I roadway:

[0016] Q c无冲击 =Q1+Q2

[0017] When the tunnel is affected by impact, including type II tunnel to type VI tunnel:

[0018] Q c受冲击 =Q1+Q2+Q3

[0019] In the formula, Q c无冲击 is the surrounding rock load of the leading section of the tunnel when there is no impact on the tunnel, kN; Q c受冲击 is the surrounding rock load of the leading section of the tunnel when the tunnel is affected by impact, kN; Q1 is the surrounding rock loosening load, kN; Q2 is the mining load, kN; Q3 is the dynamic load, kN.

[0020] Furthermore, the calculation formula of the surrounding rock loosening load is:

[0021] Q1=B×D×L′×γ

[0022] Where Q1 is the loosening load of surrounding rock, kN; B is the cross-sectional width of the tunnel, m; D is the spacing between unit supports, m; L' is the effective anchoring length of the anchor cable, m; γ is the rock bulk density, kN / m 3 ;

[0023] The calculation formula of the mining load is:

[0024] Type I and Type II lanes:

[0025]

[0026] Type III and Type IV tunnels:

[0027]

[0028] Type V tunnel:

[0029]

[0030] Type VI Lane:

[0031]

[0032] In the above formula,

[0033] B′=B+B m +B s

[0034]

[0035] Q2 is the mining load, kN; η is the roof breaking efficiency; C0 is the basic roof periodic breaking step, m; m is the coal seam thickness, m; mE is the basic roof thickness, m; mz is the direct roof thickness, m; γE is the average bulk density of the basic roof rock layer, kN / m 3 ; γZ is the average bulk density of the immediate top rock layer, kN / m 3 ; B' is the bearing width of the roadway, m; K F is the load distribution factor; K C is the rock weight distribution coefficient; B is the tunnel section width, m; B m is the width of the coal pillar, m; B s is the elastic-plastic boundary length of the coal seam, m; L is the length of the working face, m; L S is the basic roof suspension distance, m; K is the stress concentration factor; μ is the Poisson's ratio of the coal seam; The internal friction angle of the coal seam, °; γ' is the average bulk density of the overlying rock layer of the coal seam, kN / m 3 ; H is the buried depth of the roadway, m; PZ is the support resistance of the coal side of the roadway, MPa; N0 is the cohesion of the coal body, MPa;

[0036] The calculation formula of the dynamic load Q3 is:

[0037] Q3=B×D×ρ×CP×vP

[0038] Where Q3 is the dynamic load, kN; B is the tunnel section width, m; D is the unit support spacing, m; ρ is the medium density, kg / m 3 ; C P is the velocity of the P wave, m / s; v P It is the peak vibration velocity formed above the tunnel after the vibration wave caused by the breaking of the overlying rock is transmitted and attenuated, m / s.

[0039] Furthermore, the bearing capacity of type I and type II roadways includes active support bearing capacity and coal side bearing capacity; the bearing capacity of type III to type VI roadways includes active support bearing capacity, coal side bearing capacity and coal pillar bearing capacity; the active support bearing capacity calculation formula is:

[0040] F 主动 =KZnSQS

[0041] In the formula, F 主动 is the active support bearing capacity of the tunnel; K Z is the influence coefficient of mining or passive support on active support; n S Q is the number of anchor cables within the control top area within the support spacing of the unit support; S is the working load of anchor cable, kN.

[0042] Furthermore, the calculation formula for the rated working resistance of the unit support of the type I tunnel is:

[0043] P m / Ⅰ =(Q c无冲击 -2F s / Ⅰ / Ⅱ -F 主动 ) / n J

[0044] The calculation formula for the rated working resistance of the unit support of the type II tunnel is:

[0045] P m / Ⅱ =(Q c受冲击 -2F s / Ⅰ / Ⅱ -F 主动 ) / n J

[0046] Where P m / Ⅰ is the working resistance of type I tunnel unit support; P m / Ⅱ is the working resistance of type II tunnel unit support; Q c无冲击 is the surrounding rock load of the leading section of the tunnel when there is no impact on the tunnel, kN; Q c受冲击 is the surrounding rock load of the leading section of the tunnel when the tunnel is affected by impact, kN; F s / Ⅰ / Ⅱ is the coal side support load of type I and type II roadways, kN; F 主动 is the active support bearing capacity of the tunnel; n J It is the number of supports within the support spacing of the unit support.

[0047] Furthermore, the calculation formula for the coal side bearing capacity of type I and type II roadways is:

[0048]

[0049] In the formula, F s / Ⅰ / Ⅱ is the coal side support load of type I and type II roadways, kN; m E is the basic top thickness, m; m z is the thickness of the immediate roof, m; γ E is the average bulk density of the basic top rock layer, kN / m 3 ; γ Z is the average bulk density of the immediate top rock layer, kN / m 3 ; D is the spacing between unit supports, m; B is the width of the tunnel section, m; B s is the elastic-plastic boundary length of the coal seam, m.

[0050] Furthermore, for type III to type VI tunnels, the surrounding rock load of the leading tunnel includes surrounding rock loosening load, mining load, and dynamic load. The rated working resistance of the unit support of type III to type VI tunnels is calculated by the following formula:

[0051] P m / x =(Qc受冲击 -F m / x -F S / x -F 主动 ) / n J

[0052] Where P m / x is the working resistance of the unit support of type III-type laneway-type VI laneway; Q c受冲击 is the surrounding rock load of the leading section of the tunnel when the tunnel is affected by impact, kN; F m / x is the coal pillar support force corresponding to type III and type VI roadways, kN; F S / x is the coal support force corresponding to type III and type VI tunnels, kN; F 主动 is the active support bearing capacity of the tunnel; n J It is the number of supports within the support spacing of the unit support.

[0053] Furthermore, the calculation formula for the coal side bearing capacity of type III-VI roadway is:

[0054]

[0055] F S / Ⅳ =B S (m E γ E +m Z γ Z )·D

[0056]

[0057] In the formula, F S / Ⅲ is the coal side support force of type III roadway, kN; F S / Ⅳ is the coal wall support force of type IV roadway, kN; F S / Ⅴ is the coal wall support force of type V tunnel, kN; F s / Ⅵ is the coal support force of type VI roadway, kN; l1 is the lateral fracture span of the key block of type III roadway, m; l3 is the lateral fracture span of the key block of type V roadway, m; L s is the basic top overhang distance, m; θ1 is the key block rotation angle of type III tunnel; θ3 is the key block rotation angle of type V tunnel, °; G Z is the weight of the broken basic top rock block, kN; B is the cross-sectional width of the tunnel, m; B m is the width of the coal pillar, m; G g F is the weight of the top rock layer directly above the tunnel bearing width, kN; C B is the supporting force of the goaf on the key block, kN; s is the elastic-plastic boundary length of the coal seam, m; D is the unit support spacing, m; B P is the distance between the basic top fracture position and the coal pillar, m; m Eis the basic top thickness, m; m z is the thickness of the immediate roof, m; γ E is the average bulk density of the basic top rock layer, kN / m 3 ; γ Z is the average bulk density of the immediate top rock layer, kN / m 3 .

[0058] Furthermore, the calculation formula for the coal pillar bearing capacity of type III-VI roadway is:

[0059]

[0060] In the formula, F m / Ⅲ is the coal pillar support force of type III roadway, kN; F m / Ⅳ is the coal pillar support force of type IV roadway, kN; F m / Ⅴ is the coal pillar support force of type V tunnel, kN; F m / Ⅵ is the coal pillar support force of type VI roadway, kN; l1 is the lateral fracture span of the key block of type III roadway, m; l2 is the lateral fracture span of the key block of type IV roadway, m; l3 is the lateral fracture span of the key block of type V roadway, m; L s is the basic top overhang distance, m; θ1 is the key block rotation angle of type III roadway; θ2 is the key block rotation angle of type IV roadway, °; θ3 is the key block rotation angle of type V roadway, °; G Z is the weight of the broken basic top rock block, kN; B is the cross-sectional width of the tunnel, m; B m is the width of the coal pillar, m; G g F is the weight of the top rock layer directly above the tunnel bearing width, kN; C B is the supporting force of the goaf on the key block, kN; s is the elastic-plastic boundary length of the coal seam, m; D is the unit support spacing, m; B P is the distance between the basic top fracture position and the coal pillar, m; m E is the basic top thickness, m; m z is the thickness of the immediate roof, m; γ E is the average bulk density of the basic top rock layer, kN / m 3 ; γ Z is the average bulk density of the immediate top rock layer, kN / m 3 .

[0061] Furthermore, the rated working resistance P of the unit support of type I to type VI lanes is m The calculation formula is:

[0062]

[0063] Based on the above technical solution, the present invention has the following beneficial effects:

[0064] 1. The present invention records a method for systematically and quantitatively determining the working resistance of a unit support, taking into account all possible load sources of the unit support and the active support provided by the tunnel anchor cable, thereby ensuring the stability of the tunnel active support system to the greatest extent and playing a role in reinforcing support.

[0065] 2. The present invention can accurately calculate the working resistance of unit supports under different tunnel types and support conditions, can systematically and scientifically classify different types of tunnels in the whole process and calculate reasonable working resistance of unit supports, effectively control the sinking of tunnel roof, and guide the scientific use of unit supports.

[0066] 3. The present invention records a quantitative calculation method for the working resistance of the unit support of the mining tunnel at any roof break position, expands the calculation principle of the bearing capacity of the solid coal side and the coal pillar side, and the obtained working resistance can avoid the entire section of the tunnel from being crushed in extreme situations, ensure that the working space is in a safe area, and reduce safety hazards. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 : Schematic diagram of the process of the present invention;

[0068] Figure 2 : Schematic diagram of the relationship between the working resistance of the unit support and the surrounding rock of the tunnel;

[0069] Figure 3 : Schematic diagram of the fault line of the gob-side roadway located above the solid coal;

[0070] Figure 4 : Schematic diagram of the fault line of the gob-side roadway located above the roadway (coal pillar);

[0071] Figure 5 : Schematic diagram of the fault line of the goaf roadway located above the goaf;

[0072] Figure 6 : Schematic diagram of premature roof breaking along gob tunnel;

[0073] Figure 7 : Comparison chart of the working resistance and actual working resistance of the advance unit support at the 2412 working face of a coal mine. DETAILED DESCRIPTION

[0074] It should be noted that:

[0075] Certain words are used in the specification and claims to refer to specific components. It should be understood by those skilled in the art that technicians may use different nouns to refer to the same component. The specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. Unless otherwise defined, technical terms or scientific terms used in this disclosure should be understood by people with ordinary skills in the field to which this disclosure belongs.

[0076] The following is combined with Figure 1 To Attachment Figure 6 , the present invention is described in detail by way of embodiments.

[0077] This embodiment describes a method for determining the working resistance of a unit support in the leading section of a mining tunnel, comprising the following steps:

[0078] S1, collecting geological parameters of the overburden of the advanced section of the tunnel to be tested, the geological parameters include but are not limited to:

[0079] Mechanical properties of the surrounding rock of the tunnel, such as Poisson's ratio μ, bulk density γ, internal friction angle of coal rock wait;

[0080] Top plate separation position;

[0081] Spatial occurrence of coal seams, such as coal seam thickness (m), coal seam immediate top thickness (m) z 、Basic top thickness of coal seam m E wait;

[0082] Ground stress, such as shock waves caused by the breaking of overlying rock layers P , basic top cycle to press step length C0, etc.;

[0083] Deformation of tunnel surrounding rock.

[0084] S2, judging the rock properties of the roadway roof, the roadway roof structure, and whether the roadway is affected by the impact and the load formed on the roadway.

[0085] The tunnel roof lithology includes geological parameters such as the mechanical properties of the tunnel roof rock and the position of the roof delamination. When the tunnel is excavated, the roof is affected by the delamination of the rock layer, forming a loose load on the surrounding rock;

[0086] The tunnel roof structure includes geological parameters such as ground stress and tunnel determination measures. When the working face is mining, the leading section of the tunnel is affected by mining, forming mining load;

[0087] Whether the tunnel is affected by the impact includes geological parameters such as the deformation of the tunnel surrounding rock. When the deformation of the tunnel surrounding rock changes dramatically in a short period of time and is affected by the fracture of the overlying rock strata, dynamic load is generated.

[0088] S3, according to the lithology of the tunnel roof, the structure of the tunnel roof, whether the tunnel is affected by impact, and whether the tunnel is along the goaf, the tunnel to be tested is divided into the following tunnel types:

[0089] Type I roadway: solid coal roadway without impact influence;

[0090] Type II roadway: solid coal roadway affected by impact;

[0091] Type III roadway: a roadway along the goaf that is affected by impact and whose basic top fracture line is located above the solid coal;

[0092] Type IV roadway: a roadway along the goaf that is affected by impact and has the basic top fracture line located above the roadway (coal pillar);

[0093] Type V tunnel: a tunnel along the goaf that is affected by impact and whose basic top fault line is located above the goaf;

[0094] Type VI tunnel: a tunnel along the goaf that is affected by impact and whose basic roof breaks prematurely.

[0095] S4, calculate the surrounding rock load of the leading section of the tunnel by the following formula:

[0096] When the tunnel has no impact, Q c =Q1+Q2;

[0097] When the tunnel is affected by impact, Q c =Q1+Q2+Q3;

[0098] In the formula,

[0099] Q c is the surrounding rock load of the advanced section of the tunnel, kN; Q1 is the surrounding rock loosening load, kN; Q2 is the mining load, kN; Q3 is the dynamic load, kN.

[0100] The surrounding rock loosening load Q1, mining load Q2 and dynamic load Q3 are calculated respectively through the following steps.

[0101] S401, surrounding rock loosening load Q1 is determined based on the lithology and structure of the tunnel roof, and is applied to type I to type VI tunnels. The calculation formula is:

[0102] Q1=B×D×L′×γ

[0103] In the formula,

[0104] Q1 is the loosening load of surrounding rock, kN; B is the cross-sectional width of the tunnel, m; D is the spacing between unit supports, m; L' is the effective anchoring length of the anchor cable, m; γ is the rock bulk density, kN / m 3 .

[0105] S402, mining load Q2 is determined based on whether the tunnel roof is along the void:

[0106] For type I and type II lanes, the calculation formula is:

[0107]

[0108] For type III and type IV lanes, the calculation formula is:

[0109]

[0110] For type V tunnel, the calculation formula is:

[0111]

[0112] For type VI tunnel, the calculation formula is:

[0113]

[0114] In the above formula,

[0115] B′=B+B m +B s

[0116]

[0117] Q2 is the mining load, kN; η is the roof breaking efficiency; C0 is the basic roof cycle breaking step, m; m is the coal seam thickness, m; m E is the basic top thickness, m; m z is the thickness of the immediate roof, m; γ E is the average bulk density of the basic top rock layer, kN / m 3 ; γ Z is the average bulk density of the immediate top rock layer, kN / m 3 ; B' is the bearing width of the roadway, m; KF is the load distribution coefficient; KC is the rock weight distribution coefficient; B is the cross-sectional width of the roadway, m; B m is the width of the coal pillar, m; B s is the elastic-plastic boundary length of the coal seam, m; L is the length of the working face, m; L S is the basic roof suspension distance, m; K is the stress concentration factor; μ is the Poisson's ratio of the coal seam; The internal friction angle of the coal seam, °; γ' is the average bulk density of the overlying rock layer of the coal seam, kN / m 3 ; H is the tunnel depth, m; P Z is the support resistance of coal wall in roadway, MPa; N0 is the cohesion of coal body, MPa.

[0118] S403, dynamic load Q3 is determined according to the impact condition of the tunnel, and is applied to type II to type VI tunnels. The calculation formula is:

[0119] Q3=B×D×ρ×CP ×v P

[0120] In the formula,

[0121] Q3 is the dynamic load, kN; B is the tunnel section width, m; D is the unit support spacing, m; ρ is the medium density, kg / m 3 ; C P is the velocity of the P wave, m / s; v P It is the peak vibration velocity formed above the tunnel after the vibration wave caused by the breaking of the overlying rock is transmitted and attenuated, m / s.

[0122] S5, calculating the bearing capacity of the tunnel, including the active support bearing capacity of the anchor cable, and / or the coal bank bearing capacity, and / or the coal pillar bearing capacity, and / or the bearing capacity absorbed by the unit support equipment.

[0123] S501, calculate the active support bearing capacity of the anchor cable in the leading section of Type I to Type VI tunnels by the following formula:

[0124] F 主动 =K Z n S Q S

[0125] In the formula,

[0126] F 主动 is the active support bearing capacity of the tunnel; K Z is the influence coefficient of mining or passive support on active support; n S Q is the number of anchor cables within the control top area within the support spacing of the unit support; S is the working load of anchor cable, kN.

[0127] S502, for Type I and Type II roadways, i.e., solid coal roadways without impact influence and solid coal roadways affected by impact, the roadway bearing capacity includes active support bearing capacity and coal side bearing capacity.

[0128] The calculation formula of the coal seam bearing capacity is:

[0129]

[0130] In the formula,

[0131] F s / Ⅰ / Ⅱ is the coal side support load of type I and type II roadways, kN; m E is the basic top thickness, m; m z is the thickness of the immediate roof, m; γ E is the average bulk density of the basic top rock layer, kN / m 3 ; γ Z is the average bulk density of the immediate top rock layer, kN / m3 ; D is the spacing between unit supports, m; B is the width of the tunnel section, m; B s is the elastic-plastic boundary length of the coal seam, m.

[0132] S503, for Type III tunnels, that is, tunnels along the goaf that are affected by impact and whose basic top fault line is located above the solid coal, the tunnel bearing capacity includes the active support bearing capacity, coal side bearing capacity and coal pillar bearing capacity.

[0133] in,

[0134] The calculation formula of coal pillar bearing capacity is:

[0135]

[0136] The calculation formula of the coal seam bearing capacity is:

[0137]

[0138] In the formula,

[0139] F m / Ⅲ is the coal pillar support force of type III roadway, kN; F S / Ⅲ is the coal side support force of type III roadway, kN; G Z is the weight of the broken basic top rock block, kN; B is the cross-sectional width of the tunnel, m; B m is the width of the coal pillar, m; G g F is the weight of the top rock layer directly above the tunnel bearing width, kN; C is the supporting force of the goaf on the key block, kN; l1 is the lateral fracture span of the key block of the type III roadway, m; θ1 is the rotation angle of the key block of the type III roadway; B s is the elastic-plastic boundary length of the coal seam, m; D is the unit support spacing, m.

[0140] S504, for Type IV tunnels, that is, tunnels along the goaf that are affected by impact and whose basic top fault line is located above the tunnel (coal pillar), the tunnel bearing capacity includes the active support bearing capacity, coal side bearing capacity and coal pillar bearing capacity.

[0141] in,

[0142] The calculation formula of coal pillar bearing capacity is:

[0143]

[0144] The calculation formula of the coal seam bearing capacity is:

[0145] F S / Ⅳ =B S (m E γ E +m Z γ Z )·D

[0146] In the formula,

[0147] F m / Ⅳ is the coal pillar support force of type IV roadway, kN; F S / Ⅳ is the coal side support force of type IV roadway, kN; G Z is the weight of the broken basic top rock block, kN; B P is the distance between the basic top fracture position and the coal pillar, m; B m is the width of the coal pillar, m; G g F is the weight of the top rock layer directly above the tunnel bearing width, kN; C is the supporting force of the goaf on the key block, kN; l2 is the lateral fracture span of the key block of the type IV roadway, m; θ2 is the rotation angle of the key block of the type IV roadway, °; B s is the elastic-plastic boundary length of the coal seam, m; m E is the basic top thickness, m; m z is the thickness of the immediate roof, m; γ E is the average bulk density of the basic top rock layer, kN / m 3 ; γ Z is the average bulk density of the immediate top rock layer, kN / m 3 ; D is the spacing between unit brackets, m;

[0148] S505, for Type V tunnels, that is, tunnels along the goaf that are affected by impact and whose basic top fault line is located above the goaf, the tunnel bearing capacity includes the active support bearing capacity, coal side bearing capacity and coal pillar bearing capacity.

[0149] in,

[0150] The calculation formula of coal pillar bearing capacity is:

[0151]

[0152] The calculation formula of the coal seam bearing capacity is:

[0153]

[0154] In the formula,

[0155] F m / Ⅴ is the coal pillar support force of type V tunnel, kN; F S / Ⅴ is the coal wall support force of type V roadway, kN; m E is the basic top thickness, m; m z is the thickness of the immediate roof, m; γ E is the average bulk density of the basic top rock layer, kN / m 3 ; γ Z is the average bulk density of the immediate top rock layer, kN / m 3; l3 is the lateral fracture span of the key block of the V-type tunnel, m; G Z is the weight of the broken basic top rock block, kN; θ3 is the key block rotation angle of the V-type tunnel, °; B s is the length of the elastic-plastic boundary of the coal seam, m; B is the cross-sectional width of the tunnel, m; B m is the width of the coal pillar, m; L s is the basic top-to-top distance, m.

[0156] S506, for Type VI tunnels, i.e., tunnels along the goaf that are affected by impact and whose basic roof breaks prematurely, the tunnel bearing capacity includes the active support bearing capacity, the coal side bearing capacity and the coal pillar bearing capacity.

[0157] in,

[0158] The calculation formula of coal pillar bearing capacity is:

[0159]

[0160] The calculation formula of the coal seam bearing capacity is:

[0161]

[0162] In the formula,

[0163] F m / Ⅵ is the coal pillar support force of type VI roadway, kN; F S / Ⅵ is the coal wall support force of type VI roadway, kN; m E is the basic top thickness, m; m z is the thickness of the immediate roof, m; γ E is the average bulk density of the basic top rock layer, kN / m 3 ; γ Z is the average bulk density of the immediate top rock layer, kN / m 3 ; B s is the length of the elastic-plastic boundary of the coal seam, m; B is the cross-sectional width of the tunnel, m; B m is the width of the coal pillar, m; D is the spacing between unit supports, m.

[0164] S6, calculate the rated working resistance of the unit support of type I to type VI lanes respectively through the following steps:

[0165] S601, for Type I roadway, the surrounding rock load of the leading section of the roadway includes surrounding rock loosening load and mining load. The rated working resistance of the unit support of Type I roadway, i.e., solid coal roadway without impact influence, is calculated by the following formula:

[0166] P m / Ⅰ =(Q1+Q2-2F s / Ⅰ / Ⅱ -K Z n S Q S) / n J

[0167] In the formula,

[0168] P m / Ⅰ is the working resistance of the type I tunnel unit support; Q1 is the surrounding rock loosening load; Q2 is the mining load; F s / Ⅰ / Ⅱ is the coal side support load of type I and type II tunnels, kN; K Z is the influence coefficient of mining or passive support on active support; n S Q is the number of anchor cables within the control top area within the support spacing of the unit support; S is the working load of the anchor cable, kN; n J It is the number of supports within the support spacing of the unit support.

[0169] S602, for Type II roadway, the surrounding rock load of the leading section roadway includes surrounding rock loosening load, mining load and dynamic load. The rated working resistance of the unit support of Type II roadway, i.e. the solid coal roadway affected by impact, is calculated by the following formula:

[0170] P m / Ⅱ =(Q1+Q2+Q3-2F s / Ⅰ / Ⅱ -Q 卸 -K Z n S Q S ) / n J

[0171] Considering the most dangerous situation, Q 卸 Due to various reasons of failure or instantaneous pressure damage, for the sake of support safety, Q is taken in the calculation 卸 is 0, therefore,

[0172] P m / Ⅱ =(Q1+Q2+Q3-2F s / Ⅰ / Ⅱ -K Z n S Q S ) / n J

[0173] In the formula,

[0174] P m / Ⅱ is the working resistance of the type II tunnel unit support; Q1 is the surrounding rock loosening load; Q2 is the mining load; Q3 is the dynamic load; Q 卸 Fs is the load capacity absorbed by the unit support equipment; / Ⅰ / Ⅱ is the coal side support load of type I and type II tunnels, kN; K Z is the influence coefficient of mining or passive support on active support; n S Q is the number of anchor cables within the control top area within the support spacing of the unit support; Sis the working load of the anchor cable, kN; n J It is the number of supports within the support spacing of the unit support.

[0175] S603, for Type III to Type VI tunnels, the surrounding rock loads of the leading tunnels include surrounding rock loosening load, mining load, and dynamic load. The rated working resistance of the unit support of Type III to Type VI tunnels is calculated by the following formula:

[0176] P m / x =(Q1+Q2+Q3-F m / x -F S / x -Q 卸 -K Z n S Q S ) / n J

[0177] Considering the most dangerous situation, Q 卸 Due to various reasons of failure or instantaneous pressure damage, for the sake of support safety, Q is taken in the calculation 卸 is 0, so

[0178] P m / x =(Q1+Q2+Q3-F m / x -F S / x -K Z n S Q S ) / n J

[0179] In the formula,

[0180] P m / x is the working resistance of the unit support of type III-VI tunnel; Q1 is the surrounding rock loosening load; Q2 is the mining load; Q3 is the dynamic load; Q 卸 F is the load capacity absorbed by the unit support equipment; m / x is the coal pillar support force corresponding to type III and type VI roadways, kN; F S / x K is the coal support force corresponding to type III and type VI tunnels, kN; Z is the influence coefficient of mining or passive support on active support; n S Q is the number of anchor cables within the control top area within the support spacing of the unit support; S is the working load of the anchor cable, kN; n J It is the number of supports within the support spacing of the unit support.

[0181] The following is a specific construction site case of the 2412 working face of a coal mine to verify the method of the rated working resistance of the advance unit support of the above-mentioned tunnel working face:

[0182] 1. Basic situation of tunnel support

[0183] 1. The active support anchor cable adopts a steel strand anchor cable with a model of Φ21.8×8500mm, uses MSK2850 resin anchoring agent, and the drilling diameter is Φ32mm.

[0184] Spacing between roof anchor cables: transport lane, 1600×2700mm; return air lane, 2000×1800mm.

[0185] The effective anchoring section length L′ of the anchor cable, i.e. “anchor cable length - anchor cable anchoring end length - anchor cable exposed end length”: the length for both the transport lane and the return air lane is 6.45m.

[0186] 2. Tunnel section width B: 6m for transport tunnel and 5.2m for return air tunnel; coal pillar width B m =6m, width of plastic zone of solid coal seam B S =8.15m, tunnel burial depth H=600m.

[0187] 3. Unit support layout spacing D: 5m for both lanes; coal seam thickness m = 11.3m; direct roof thickness m Z =2.4m, basic top thickness m E =1.3m; basic top period breaking step C0 = 4.89m; solid coal bulk density γ: 13kN / m 3 , basic top average density γ E =25kN / m 3 , average bulk density of direct top γ Z =25kN / m 3 ; Average bulk density of overlying rock γ'=25kN / m 3 ; Coal seam Poisson's ratio μ = 0.25; Coal seam internal friction angle Coal seam cohesion N0 = 1.87 MPa; tunnel coal support resistance P Z =0.

[0188] 4. The energy of mine earthquake is 1.62×10 4 J, medium density ρ = 25kg / m 3 , P wave velocity C P =5.8×10 3 m / s, vibration speed v P =1.32m / s.

[0189] In the above 2412 working face:

[0190] The return air chute is a goaf-side tunnel, and the basic top is broken in advance under the impact of the unit support support, that is, the return air chute is a type VI tunnel, and the calculation formula of the unit support rated resistance is:

[0191] P m / x =(Q1+Q2+Q3-F m / x-F S / x -K Z n S Q S ) / n J

[0192] Right now:

[0193] P m / Ⅵ =(Q1+Q2+Q3-F m / Ⅵ -F S / Ⅵ -K Z n S Q S ) / n J

[0194]

[0195] The transport chute is a solid coal tunnel and is supported by unit supports under the impact, that is, the transport chute is a type II tunnel, and the calculation formula for the rated resistance of the unit support is:

[0196] P m / Ⅱ =(Q1+Q2+Q3-2F s / Ⅰ / Ⅱ -K Z n S Q S ) / n J

[0197]

[0198] 2. Calculation of rated working resistance of leading unit bracket

[0199] 1. Return air chute

[0200] ① Loose load of surrounding rock

[0201] Q1=B×D×L′×γ=2180KN

[0202] ② Mining load

[0203]

[0204] Where η is the top breaking efficiency, which is 1.45; B' is the bearing width of the roadway, B' = B + B m +B S =19.35m; K F is the load distribution coefficient, D / 0.5C0.

[0205] ③ Dynamic load

[0206] Q3=B×D×ρ×CP×vP=4976KN

[0207] ④ Active support strength

[0208] K Z n S Q S =0.9×8×553.07=3982KN

[0209] In the formula, K Z is the influence coefficient of mining or passive support on active support, which is taken as 0.9; n S is the number of anchor cables within the control top area within the support spacing of the unit support, 8; Q S is the working load of the anchor cable, 553.07kN.

[0210] ⑤ Coal pillar support force F m

[0211]

[0212] ⑥ Coal side support force F S

[0213]

[0214] Therefore, the working resistance of the unit support of the return air chute in the 2412 working face is

[0215] P m =(Q1+Q2+Q3-F m -F s -K Z n S Q S ) / n J =3601KN

[0216] Among them, n J The number of supports within the unit support spacing is 2.

[0217] The calculated result 3601kN refers to the rated working resistance of the unit support when the unit support is arranged in double rows on site.

[0218] 2. Transport chute

[0219] ① Loose load of surrounding rock

[0220] Q1=B×D×L′×γ=2516KN

[0221] ② Mining load

[0222]

[0223] Where B' is the roadway inclination width, B' = B + 2B S =22.3m; K F is the load distribution coefficient, D / 0.5C0.

[0224] ③ Dynamic load

[0225] Q3=B×D×ρ×CP×vP=5742KN

[0226] ④ Active support strength

[0227] K Z n S Q S =0.9×9×553.07=4480KN

[0228] In the formula, K Z is the influence coefficient of mining or passive support on active support, which is taken as 0.9; n S is the number of anchor cables within the control top area within the unit support spacing, 9; Q S is the working load of the anchor cable, 553.07kN.

[0229] ⑤ Coal side support

[0230]

[0231] Therefore, the working resistance of the unit support of the transport chute of the 2412 working face is

[0232] P m =(Q1+Q2+Q3-2F s -K Z n S Q S ) / n J =3778KN

[0233] Where n J The number of supports within the unit support spacing is 1.

[0234] The calculated result of 3778kN refers to the rated working resistance of the unit support when the unit support is arranged in a single row on site.

[0235] Attached Figure 7 A comparison chart of the working resistance of the two leading unit supports of the 2412 working face and the actual working resistance is shown. From the comparison chart, it can be seen that different unit support layout spacings require different unit support working resistances, and different working resistances should be selected according to the actual situation on site.

[0236] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A method for determining the working resistance of a unit support in the leading section of a mining tunnel, characterized in that: The following steps are involved: S1, collecting geological parameters of the overburden of the leading section of the tunnel to be tested, determining the lithology of the tunnel roof, the tunnel roof structure, and whether the tunnel is affected by the impact on the load formed on the tunnel; S2, according to the lithology of the roadway roof, the structure of the roadway roof, whether the roadway is affected by impact, and whether the roadway is along the goaf, the roadways to be tested are divided into the following roadway types: Type I roadway: solid coal roadway without impact impact; Type II roadway: solid coal roadway affected by impact; Type III roadway: goaf roadway affected by impact and with the basic roof fracture line located above the solid coal; Type IV roadway: goaf roadway affected by impact and with the basic roof fracture line located above the roadway (coal pillar); Type V roadway: goaf roadway affected by impact and with the basic roof fracture line located above the goaf; Type VI roadway: goaf roadway affected by impact and with the basic roof fractured in advance; S3, calculate the surrounding rock load of the leading section of type I to type VI tunnels respectively; S4, respectively calculating the tunnel bearing capacity of type I tunnel to type VI tunnel, wherein the tunnel bearing capacity includes the active support bearing capacity of the anchor cable, and / or the coal seam bearing capacity, and / or the coal pillar bearing capacity, and / or the bearing capacity absorbed by the unit support equipment; S5, calculate the rated working resistance P of the unit support of type I to type VI lanes by the following formula m :

2. A method for determining the working resistance of a unit support in the leading section of a mining tunnel according to claim 1, characterized in that: The geological parameters include mechanical properties of the surrounding rock of the tunnel, the position of the roof separation, the spatial occurrence of the coal seam, the ground stress and the deformation of the surrounding rock of the tunnel; The tunnel roof lithology includes the mechanical properties of the tunnel surrounding rock and the position of the roof delamination. When the tunnel is excavated, the roof forms a surrounding rock loosening load due to the delamination of the rock layer; The roadway roof structure includes ground stress. According to the roadway determination measures, during the mining process of the working face, the leading section of the roadway forms mining load due to mining influence; Whether the tunnel is affected by the impact includes the deformation of the tunnel surrounding rock. When the leading section of the tunnel is affected by the breaking of the overlying rock layer, a dynamic load is formed; The surrounding rock load of the tunnel leading section is calculated by the following formula: When the roadway has no impact, including type I roadway: Q c无冲击 =Q1+Q2 When the tunnel is affected by impact, including type II tunnel to type VI tunnel: <h2 style=";text-align:left;direction:ltr">Q<h2 style=";text-align:left;direction:ltr"> c受冲击 <h2 style=";text-align:left;direction:ltr"> =Q1+Q2+Q3 In the formula, Q c无冲击 is the surrounding rock load of the leading section of the tunnel when there is no impact on the tunnel, kN; Q c受冲击 is the surrounding rock load of the leading section of the tunnel when the tunnel is affected by impact, kN; Q1 is the surrounding rock loosening load, kN; Q2 is the mining load, kN; Q3 is the dynamic load, kN.

3. A method for determining the working resistance of a unit support in the leading section of a mining tunnel according to claim 2, characterized in that: The calculation formula of the surrounding rock loosening load is: Q1=B×D×L′×γ Where Q1 is the loosening load of surrounding rock, kN; B is the cross-sectional width of the tunnel, m; D is the spacing between unit supports, m; L' is the effective anchoring length of the anchor cable, m; γ is the rock bulk density, kN / m 3 ; The calculation formula of the mining load is: Type I and Type II lanes: Type III and Type IV tunnels: Type V tunnel: Type VI Lane: In the above formula, B′=B+B m +B s Q2 is the mining load, kN; η is the roof breaking efficiency; C0 is the basic roof cycle breaking step, m; m is the coal seam thickness, m; m E is the basic top thickness, m; m z is the thickness of the immediate roof, m; γ E is the average bulk density of the basic top rock layer, kN / m 3 ; γ Z is the average bulk density of the immediate top rock layer, kN / m 3 ; B' is the bearing width of the roadway, m; K F is the load distribution factor; K C is the rock weight distribution coefficient; B is the tunnel section width, m; B m is the width of the coal pillar, m; B s is the elastic-plastic boundary length of the coal seam, m; L is the length of the working face, m; L S is the basic roof suspension distance, m; K is the stress concentration factor; μ is the Poisson's ratio of the coal seam; The internal friction angle of the coal seam, °; γ' is the average bulk density of the overlying rock layer of the coal seam, kN / m 3 ; H is the tunnel depth, m; P Z is the support resistance of the coal wall in the roadway, MPa; N0 is the cohesion of the coal body, MPa; The calculation formula of the dynamic load Q3 is: Q3=B×D×ρ×C P ×v P Where, Q3 is the dynamic load, kN; B is the tunnel section width, m; D is the unit support spacing, m; ρ is the medium density, kg / m 3 ; C P is the velocity of the P wave, m / s; v P It is the peak vibration velocity formed above the tunnel after the vibration wave caused by the breaking of the overlying rock is transmitted and attenuated, m / s.

4. A method for determining the working resistance of a unit support in the leading section of a mining tunnel according to claim 3, characterized in that: Type I and Type II tunnels, their tunnel bearing capacity includes active support bearing capacity and coal wall bearing capacity; Type III to Type VI tunnels, whose tunnel bearing capacity includes active support bearing capacity, coal side bearing capacity and coal pillar bearing capacity; The active support bearing capacity calculation formula is: F 主动 =K Z n S Q S In the formula, F 主动 is the active support bearing capacity of the tunnel; K Z is the influence coefficient of mining or passive support on active support; n S Q is the number of anchor cables within the control top area within the support spacing of the unit support; S is the working load of anchor cable, kN.

5. A method for determining the working resistance of a unit support in the leading section of a mining tunnel according to claim 4, characterized in that: The calculation formula for the rated working resistance of the unit support of the type I lane is: P m / Ⅰ =(Q c无冲击 -2F s / Ⅰ / Ⅱ -F 主动 ) / n J The calculation formula for the rated working resistance of the unit support of the type II tunnel is: P m / Ⅱ =(Q c受冲击 -2F s / Ⅰ / Ⅱ -F 主动 ) / n J In the formula, P m / Ⅰ is the working resistance of type I tunnel unit support; P m / Ⅱ is the working resistance of type II tunnel unit support; Q c无冲击 is the surrounding rock load of the leading section of the tunnel when there is no impact on the tunnel, kN; Q c受冲击 is the surrounding rock load of the leading section of the tunnel when the tunnel is affected by impact, kN; F s / Ⅰ / Ⅱ is the coal side support load of type I and type II roadways, kN; F 主动 is the active support bearing capacity of the tunnel; n J It is the number of supports within the support spacing of the unit support.

6. A method for determining the working resistance of a unit support in the leading section of a mining tunnel according to claim 5, characterized in that: The calculation formula for the coal side bearing capacity of type I and type II roadways is: In the formula, F s / Ⅰ / Ⅱ is the coal side support load of type I and type II roadways, kN; m E is the basic top thickness, m; m z is the thickness of the immediate roof, m; γ E is the average bulk density of the basic top rock layer, kN / m 3 ; γ Z is the average bulk density of the immediate top rock layer, kN / m 3 ; D is the spacing between unit supports, m; B is the width of the tunnel section, m; B s is the elastic-plastic boundary length of the coal seam, m.

7. A method for determining the working resistance of a unit support in the leading section of a mining tunnel according to claim 4, characterized in that: For Type III to Type VI tunnels, the surrounding rock loads of the leading tunnels include loosening loads, mining loads, and dynamic loads. The rated working resistance of the unit support for Type III to Type VI tunnels is calculated using the following formula: P m / x =(Q c受冲击 -F m / x -F S / x -F 主动 ) / n J In the formula, P m / x is the working resistance of the unit support of type III-type laneway-type VI laneway; Q c受冲击 is the surrounding rock load of the leading section of the tunnel when the tunnel is affected by impact, kN; F m / x is the coal pillar support force corresponding to type III and type VI roadways, kN; F S / x is the coal support force corresponding to type III and type VI tunnels, kN; F 主动 is the active support bearing capacity of the tunnel; n J It is the number of supports within the support spacing of the unit support.

8. A method for determining the working resistance of a unit support in the leading section of a mining tunnel according to claim 7, characterized in that: The calculation formula for the coal side bearing capacity of type III to type VI roadway is: F S / Ⅳ =B S (m E c E +m Z c Z )·D In the formula, F S / Ⅲ is the coal side support force of type III roadway, kN; F S / Ⅳ is the coal wall support force of type IV roadway, kN; F S / Ⅴ is the coal wall support force of type V tunnel, kN; F S / Ⅵ is the coal wall support force of type VI roadway, kN; l1 is the lateral fracture span of the key block of type III tunnel, m; l3 is the lateral fracture span of the key block of type V tunnel, m; L s is the basic top overhang distance, m; θ1 is the key block rotation angle of type III roadway; θ3 is the key block rotation angle of type V roadway, °; G Z is the weight of the broken basic top rock block, kN; B is the cross-sectional width of the tunnel, m; B m is the width of the coal pillar, m; G g F is the weight of the top rock layer directly above the tunnel bearing width, kN; C B is the supporting force of the goaf on the key block, kN; s is the elastic-plastic boundary length of the coal seam, m; D is the unit support spacing, m; B P is the distance between the basic top fracture position and the coal pillar, m; m E is the basic top thickness, m; m z is the thickness of the immediate roof, m; γ E is the average bulk density of the basic top rock layer, kN / m 3 ; γ Z is the average bulk density of the immediate top rock layer, kN / m 3 .

9. A method for determining the working resistance of a unit support in the leading section of a mining tunnel according to claim 7, characterized in that: The calculation formula for the coal pillar bearing capacity of type III-VI roadway is: In the formula, F m / Ⅲ is the coal pillar support force of type III roadway, kN; F m / Ⅳ is the coal pillar support force of type IV roadway, kN; F m / Ⅴ is the coal pillar support force of type V tunnel, kN; F m / Ⅵ is the coal pillar support force of type VI roadway, kN; l1 is the lateral fracture span of the key block of type III tunnel, m; l2 is the lateral fracture span of the key block of type IV tunnel, m; l3 is the lateral fracture span of the key block of type V tunnel, m; L s is the basic top overhang distance, m; θ1 is the key block rotation angle of type III roadway; θ2 is the key block rotation angle of type IV roadway, °; θ3 is the key block rotation angle of type V roadway, °; G Z is the weight of the broken basic top rock block, kN; B is the cross-sectional width of the tunnel, m; B m is the width of the coal pillar, m; G g F is the weight of the top rock layer directly above the tunnel bearing width, kN; C B is the supporting force of the goaf on the key block, kN; s is the elastic-plastic boundary length of the coal seam, m; D is the unit support spacing, m; B P is the distance between the basic top fracture position and the coal pillar, m; m E is the basic top thickness, m; m z is the thickness of the immediate roof, m; γ E is the average bulk density of the basic top rock layer, kN / m 3 ; γ Z is the average bulk density of the immediate top rock layer, kN / m 3 .

10. A method for determining the working resistance of a unit support in the leading section of a mining tunnel according to claim 1, characterized in that: Rated working resistance P of unit support for type I to type VI lanes m The calculation formula is:

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