阅读说明：本技术 一种急倾斜煤层水平分段综放开采支架工作阻力计算方法 (Method for calculating working resistance of horizontal subsection fully mechanized caving mining support of steeply inclined coal seam ) 是由 吴锋锋 岳鑫 刘长友 余昌辉 柳启文 李超 于 2021-06-28 设计创作，主要内容包括：本发明公开了一种急倾斜煤层水平分段综放开采支架工作阻力计算方法,包括：确定煤层参数；以铰接岩块结构形成时间为时间界限,将覆岩垮落特征分为开采初期和开采后期两个阶段；构建对应的支架和围岩结构模型；分析两个阶段的液压支架支护强度,计算急倾斜煤层水平分段开采初期阶段和开采后期阶段铰接岩块结构失稳状态下顶板巷一侧和底板巷一侧液压支架的合理工作阻力。本发明提供的计算方法更能准确地表征实际生产中支架的受力状态,该方法对于急倾斜煤层水平分段开采工作面液压支架选型,保证生产高效安全具有重要价值。同时也为该开采条件下回采工作面顶板管理提供了新的理论分析和计算支持。(The invention discloses a method for calculating the working resistance of a horizontal subsection fully mechanized caving mining bracket of a steep coal seam, which comprises the following steps: determining coal bed parameters; taking the formation time of the hinged rock mass structure as a time boundary, and dividing the overlying strata caving characteristic into two stages of an initial mining stage and a later mining stage; constructing corresponding supports and surrounding rock structure models; and analyzing the support strength of the hydraulic supports in the two stages, and calculating the reasonable working resistance of the hydraulic supports on one side of the top plate roadway and one side of the bottom plate roadway in the unstable state of the hinged rock mass structure in the early stage and the later stage of the horizontal sublevel mining of the steeply inclined coal seam. The calculation method provided by the invention can accurately represent the stress state of the support in actual production, and has important value for the type selection of the hydraulic support of the horizontal segmental mining working surface of the steeply inclined coal seam and the guarantee of high efficiency and safety of production. Meanwhile, new theoretical analysis and calculation support is provided for the top plate management of the stope face under the mining condition.)

1. A working resistance calculation method for a horizontal subsection fully mechanized caving mining support of a steep coal seam is characterized by comprising the following steps:

the method comprises the following steps: determining coal bed parameters including a coal bed inclination angle, a coal mining method, a mining height, a top coal caving height, a top rock volume weight and a direct top thickness;

step two: taking the formation time of the hinged rock mass structure as a time boundary, and dividing the overlying strata caving characteristic into two stages of an initial mining stage and a later mining stage;

step three: respectively aiming at the mining initial stage and the mining later stage, constructing corresponding supports and surrounding rock structure models according to the structural characteristics of the coal seam during mining; in the initial mining stage, on one side of a bottom plate roadway, a load borne by a working face hydraulic support comes from the weight of top coal and the weight of coal gangue caving in a goaf; on one side of the roof roadway, the load borne by the working face hydraulic support comes from the weight of the top coal, the weight of coal gangue caving in the goaf and the stress of a roof cantilever beam; in the later stage of mining, when the structure is unstable, the overlying strata caving pressure caused by the unstable structure is increased by the hydraulic support on the top plate lane side and the hydraulic support on the bottom plate lane side on the basis of the original load, and the thickness value of the caving coal gangue in the goaf in the later stage of mining is smaller than that of the caving coal gangue in the goaf in the initial stage of mining;

step four: and analyzing the support strength of the hydraulic supports in the two stages according to the support and surrounding rock structure models in the initial mining stage and the later mining stage respectively, and calculating the reasonable working resistance of the hydraulic supports on one side of the top plate roadway and one side of the bottom plate roadway in the unstable state of the hinged rock block structure in the initial stage of horizontal sublevel mining and the later mining stage of the steeply inclined coal seam.

2. The method for calculating the working resistance of the horizontal subsection fully mechanized caving mining bracket of the steeply inclined coal seam according to claim 1, wherein in the fourth step, the reasonable working resistance of the hydraulic bracket at the top plate tunnel side in the early stage of mining is calculated according to the following formula:

in the formula: p₁The support strength of the hydraulic support at the initial stage of mining; q. q.s_AIs the dead weight stress of the top coal above the working face, q_BThe dead weight stress q of coal gangue caving in the goaf_CStress of the top plate cantilever beam; k is a radical of₁For safety factor, the value is between 1.0 and 1.5; k is a radical of₂The dynamic load coefficient of the top plate is 1.0-1.5; k is a radical of₃The value of the attenuation coefficient is between 0.5 and 0.8; h is₂The unit of the stacking thickness of the coal gangue caving in the goaf is m; k is a radical of₄The cracking and swelling coefficient of the rock is 1.1-1.3; l is the length of the cantilever beam and the unit is m; b is the center distance of the bracket, and the unit is m; lambda [ alpha ]₁Is the volume weight of the top coalIn the unit kN/m³；h₁Is the thickness of the top coal in m; l is the length of the support top beam, and the unit is m; k is a radical of_sSupporting the efficiency for the stent; lambda [ alpha ]₂Is the volume weight of coal gangue, and the unit is kN/m³(ii) a Alpha is the coal bed inclination angle.

3. The method for calculating the working resistance of the horizontal subsection fully mechanized caving mining bracket of the steeply inclined coal seam according to claim 2, wherein in the fourth step, the reasonable working resistance of the hydraulic bracket at the side of the floor roadway at the early stage of mining is calculated according to the following formula:

4. the method for calculating the working resistance of the horizontal subsection fully mechanized caving mining bracket of the steeply inclined coal seam according to claim 1 or 2, wherein in the fourth step, the reasonable working resistance of the hydraulic bracket at the side of the roof roadway in the unstable state of the hinged rock mass structure at the later stage of mining is calculated according to the following formula:

F_2-2＝F_1-1+Qsin²α

wherein Q is the pressure of the overburden and alpha is the coal bed inclination angle.

5. The method for calculating the working resistance of the horizontal subsection fully mechanized caving mining bracket of the steeply inclined coal seam according to claim 4, wherein in the fourth step, the reasonable working resistance of the hydraulic bracket at one side of the bottom plate roadway in the unstable state of the hinged rock mass structure at the later stage of mining is calculated according to the following formula:

F_2-3＝F_1-2+Qsin²α。

6. the method for calculating the working resistance of the horizontal subsection fully mechanized caving mining bracket of the steeply inclined coal seam according to claim 1, further comprising the following steps:

step five: determining the working resistance variation range of the working face support according to the calculated reasonable working resistance of the hydraulic supports on one side of the top plate lane and one side of the bottom plate lane at the initial stage of mining and the reasonable working resistance of the hydraulic supports on one side of the top plate lane and one side of the bottom plate lane at the unstable state of the hinged rock block structure at the later stage of mining;

step six: and (4) combining the working resistance variation range of the working surface support to perform the type selection and the pressure characteristic analysis of the working surface hydraulic support.

7. A steeply inclined coal seam horizontal subsection fully mechanized caving mining support working resistance calculation device is characterized by comprising:

the coal bed parameter determining module is used for determining coal bed parameters including a coal bed inclination angle, a coal mining method, a mining height, a top coal caving height, a top plate rock volume weight and a direct top thickness;

the stage division module is used for dividing overlying strata caving characteristics into two stages, namely an initial mining stage and a later mining stage by taking the formation time of the hinged rock mass structure as a time boundary;

the structure model building module is used for building corresponding supports and surrounding rock structure models according to the structure characteristics of the coal seam during mining respectively at the early mining stage and the later mining stage; in the initial mining stage, on one side of a bottom plate roadway, a load borne by a working face hydraulic support comes from the weight of top coal and the weight of coal gangue caving in a goaf; on one side of the roof roadway, the load borne by the working face hydraulic support comes from the weight of the top coal, the weight of coal gangue caving in the goaf and the stress of a roof cantilever beam; in the later stage of mining, when the structure is unstable, the pressure of overlying strata collapse caused by the unstable structure is increased by the hydraulic support on the top plate lane side and the hydraulic support on the bottom plate lane side on the basis of the original load, and the thickness value of the coal gangue collapsed in the goaf in the later stage of mining is smaller than that of the coal gangue collapsed in the goaf in the initial stage of mining;

and the working resistance analysis module is used for analyzing the support strength of the hydraulic supports in the two stages according to the supports and the surrounding rock structure models in the initial mining stage and the later mining stage respectively, and calculating the reasonable working resistance of the hydraulic supports on one side of the top plate roadway and one side of the bottom plate roadway under the unstable state of the hinged rock block structures in the initial stage and the later stage of horizontal sublevel mining of the steeply inclined coal seam.

8. The steeply inclined seam horizontal segment fully mechanized caving mining support operational resistance calculation apparatus of claim 7, further comprising:

and the structural model verification module is used for verifying the constructed mining initial stage and mining later stage according to the thickness change of the coal seam.

9. The steeply inclined seam horizontal segment fully mechanized caving mining support operational resistance calculation apparatus of claim 7, further comprising:

the working resistance change range determining module is used for determining the working resistance change range of the working face support according to the calculated reasonable working resistance of the hydraulic supports on one side of the top plate lane and one side of the bottom plate lane at the initial mining stage and the reasonable working resistance of the hydraulic supports on one side of the top plate lane and one side of the bottom plate lane at the unstable state of the hinged rock block structure at the later mining stage;

and the application module is used for carrying out the type selection and the incoming pressure characteristic analysis of the working face hydraulic support in combination with the working resistance variation range of the working face support.

Technical Field

The invention relates to the technical field, in particular to a method for calculating the working resistance of a horizontal subsection fully mechanized caving mining bracket of a steep coal seam.

Background

The steeply inclined coal seam is a coal seam with a buried dip angle of more than 45 degrees, is concentrated in western regions and accounts for 10 percent of the coal reserves in China, and the coal seam is usually mined in a horizontal sectional mode. The horizontal sectional mining greatly improves the mining efficiency of the steeply inclined coal seam, but along with the fact that the mining space at the upper part of the sectional mining is larger and larger, the roof rock stratum can collapse towards the offset of the mining area side, the rock stratum control difficulty is increased, and the safety production of a mine is affected.

The conventional working face support working resistance calculation method comprises an empirical formula estimation method, a rock weight method and an engineering comparison method, but the calculation methods are usually suitable for horizontal or near-horizontal coal seams with small coal seam occurrence angles. The steep coal seam has a special structure, particularly, the overburden rock structure has different characteristics in different mining subsections under the horizontal subsection mining condition, the traditional support working resistance calculation method is applied to the defects that the steep coal seam mining has larger error and does not consider structural change, and the applicability is not strong. Therefore, a reasonable support working resistance calculation method based on overburden structure change during horizontal subsection mining of the steeply inclined coal seam has important significance for guiding support model selection under the mining condition to control rock stratum stability so as to guarantee safe mining.

The invention with the patent number of CN107220470A discloses a method for determining the support load of a large-dip-angle coal seam working face, which analyzes the distribution characteristics of the inclined caving roof structure and the support load by considering the difference of the large-dip-angle coal seam working face and the caving roof structure of a nearly horizontal coal seam working face and converts the inclined caving roof structure and the support load into uniformly distributed loads in the direction of trend; and combining the top plate inclination structure with the trend structure, analyzing the direct top, the key layer and a force transmission mechanism of the direct top and the key layer to the support, and determining the reasonable support load of the working surface. At present, no mining support working resistance calculation method which only aims at the working face of the coal seam with a large inclination angle and simultaneously considers the coal seam change in the mining process exists.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the method for calculating the working resistance of the horizontal subsection fully mechanized caving mining bracket of the steeply inclined coal seam, which can more accurately represent the stress state of the bracket in actual production, has important value for the type selection of the hydraulic bracket of the horizontal subsection mining working face of the steeply inclined coal seam, ensures the high-efficiency and safe production, and simultaneously provides new theoretical analysis and calculation support for the roof management of the stoping working face under the mining condition.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the embodiment of the invention provides a method for calculating the working resistance of a horizontal subsection fully mechanized caving mining bracket of a steep coal seam, which comprises the following steps:

the method comprises the following steps: determining coal bed parameters including a coal bed inclination angle, a coal mining method, a mining height, a top coal caving height, a top rock volume weight and a direct top thickness;

step two: taking the formation time of the hinged rock mass structure as a time boundary, and dividing the overlying strata caving characteristic into two stages of an initial mining stage and a later mining stage;

step three: respectively aiming at the mining initial stage and the mining later stage, constructing corresponding supports and surrounding rock structure models according to the structural characteristics of the coal seam during mining; in the initial mining stage, on one side of a bottom plate roadway, a load borne by a working face hydraulic support comes from the weight of top coal and the weight of coal gangue caving in a goaf; on one side of the roof roadway, the load borne by the working face hydraulic support comes from the weight of the top coal, the weight of coal gangue caving in the goaf and the stress of a roof cantilever beam; in the later stage of mining, when the structure is unstable, the pressure of overlying strata collapse caused by the unstable structure is increased by the hydraulic support on the top plate lane side and the hydraulic support on the bottom plate lane side on the basis of the original load, and the thickness value of the coal gangue collapsed in the goaf in the later stage of mining is smaller than that of the coal gangue collapsed in the goaf in the initial stage of mining;

step four: and analyzing the support strength of the hydraulic supports in the two stages according to the support and surrounding rock structure models in the initial mining stage and the later mining stage respectively, and calculating the reasonable working resistance of the hydraulic supports on one side of the top plate roadway and one side of the bottom plate roadway in the unstable state of the hinged rock block structure in the initial mining stage and the later mining stage of the horizontal subsection mining of the steeply inclined coal seam.

Optionally, in step four, the reasonable working resistance of the hydraulic support at the roof roadway side in the early mining stage is calculated according to the following formula:

in the formula: p₁The support strength of the hydraulic support at the initial stage of mining; q. q.s_AIs the dead weight stress of the top coal above the working face, q_BThe dead weight stress q of coal gangue caving in the goaf_CStress of the top plate cantilever beam; k is a radical of₁For safety factor, the value is between 1.0 and 1.5; k is a radical of₂The dynamic load coefficient of the top plate is 1.0-1.5; k is a radical of₃The value of the attenuation coefficient is between 0.5 and 0.8; h is₂The unit of the stacking thickness of the coal gangue caving in the goaf is m; k is a radical of₄The cracking and swelling coefficient of the rock is 1.1-1.3; l is the length of the cantilever beam and the unit is m; b is the center distance of the bracket, and the unit is m; lambda [ alpha ]₁Is the top coal volume weight, and the unit is kN/m³；h₁Is the thickness of the top coal in m; l is the length of the support top beam, and the unit is m; k is a radical of_sSupporting the efficiency for the stent; lambda [ alpha ]₂Is the volume weight of coal gangue, and the unit is kN/m³(ii) a Alpha is the coal bed inclination angle.

Optionally, in step four, the reasonable working resistance of the hydraulic support at the side of the floor roadway at the early mining stage is calculated according to the following formula:

optionally, in the fourth step, the reasonable working resistance of the hydraulic support at the side of the roof roadway in the unstable state of the hinged rock mass structure at the later stage of mining is calculated according to the following formula:

F_2-2＝F_1-1+Qsin²α

wherein Q is the pressure of the overburden and alpha is the coal bed inclination angle.

Optionally, in the fourth step, the reasonable working resistance of the hydraulic support at the side of the bottom plate roadway in the unstable state of the hinged rock mass structure at the later stage of mining is calculated according to the following formula:

F_2-3＝F_1-2+Qsin²α。

optionally, the working resistance calculation method further comprises the steps of:

step five: determining the working resistance variation range of the working face support according to the calculated reasonable working resistance of the hydraulic supports on one side of the top plate lane and one side of the bottom plate lane at the initial stage of mining and the reasonable working resistance of the hydraulic supports on one side of the top plate lane and one side of the bottom plate lane at the unstable state of the hinged rock block structure at the later stage of mining;

step six: and (4) combining the working resistance variation range of the working surface support to perform the type selection and the pressure characteristic analysis of the working surface hydraulic support.

In a second aspect, an embodiment of the present invention provides a working resistance calculation device for a horizontal sectioned fully mechanized caving mining support of a steeply inclined coal seam, where the working resistance calculation device includes:

the coal bed parameter determining module is used for determining coal bed parameters including a coal bed inclination angle, a coal mining method, a mining height, a top coal caving height, a top plate rock volume weight and a direct top thickness;

the stage division module is used for dividing overlying strata caving characteristics into two stages, namely an initial mining stage and a later mining stage by taking the formation time of the hinged rock mass structure as a time boundary;

the structure model building module is used for building corresponding support and surrounding rock structure models according to the structure characteristics of the coal seam during mining respectively at the early mining stage and the later mining stage; in the initial mining stage, on one side of a bottom plate roadway, a load borne by a working face hydraulic support comes from the weight of top coal and the weight of coal gangue caving in a goaf; on one side of the roof roadway, the load borne by the working face hydraulic support comes from the weight of the top coal, the weight of coal gangue caving in the goaf and the stress of a roof cantilever beam; in the later stage of mining, when the structure is unstable, the pressure of overlying strata collapse caused by the unstable structure is increased by the hydraulic support on the top plate lane side and the hydraulic support on the bottom plate lane side on the basis of the original load, and the thickness value of the coal gangue collapsed in the goaf in the later stage of mining is smaller than that of the coal gangue collapsed in the goaf in the initial stage of mining;

and the working resistance analysis module is used for analyzing the support strength of the hydraulic supports in the two stages according to the supports in the initial mining stage and the later mining stage and the structural models of the surrounding rocks respectively, and calculating the reasonable working resistance of the hydraulic supports on one side of the top plate roadway and one side of the bottom plate roadway under the unstable state of the hinged rock mass structure in the initial mining stage and the later mining stage of the horizontal sublevel mining of the steeply inclined coal seam.

Optionally, the working resistance calculation means further comprises:

and the structural model verification module is used for verifying the constructed mining initial stage and mining later stage according to the coal seam change.

Optionally, the working resistance calculation means further comprises:

the working resistance change range determining module is used for determining the working resistance change range of the working face support according to the calculated reasonable working resistance of the hydraulic supports on one side of the top plate lane and one side of the bottom plate lane in the initial mining stage and the reasonable working resistance of the hydraulic supports on one side of the top plate lane and one side of the bottom plate lane in the unstable state of the hinged rock block structure in the later mining stage;

and the application module is used for carrying out the type selection and the incoming pressure characteristic analysis of the working face hydraulic support in combination with the working resistance variation range of the working face support.

The invention has the beneficial effects that:

the invention provides a method for calculating the working resistance of a overburden rock structure change support during horizontal sublevel mining based on a steep coal seam. Compared with the prior art, the method disclosed by the invention has the advantages that the time limit is formed by the hinged rock mass of the top plate in the horizontal sectional mining of the steeply inclined coal seam, and the working resistance of the support is calculated in the early stage and the later stage of the mining. In the initial stage of mining, a pressure arch structure exists in the overlying strata, the load of the overlying strata is transferred to the upper side and the lower side of the goaf by the pressure arch, and the balance and stability of the overlying strata are maintained. The load borne by the bracket of the working face comes from the load of the top coal, the caving coal gangue and the top plate. And respectively giving calculation formulas of the working resistance of the top plate side bracket and the bottom plate side bracket. In the later stage of mining, the overburden rock collapse is always broken in a rotary mode in a cantilever beam mode, the larger the overburden rock load is, the longer the cantilever is, the larger the bending deformation energy accumulated by the cantilever beam is, and the larger the influence caused in the breaking process is. Under the stable state of the hinged rock block structure, the working face hydraulic support is only under the load action of the top coal, the coal gangue in the goaf and the top plate. Under the unstable state of the hinged rock block structure, the working face support still needs to bear the pressure of overlying strata collapse after the structure is unstable. And respectively providing calculation formulas of the working resistance of the support during the stabilization and the instability of the hinged rock mass. The calculation method provided by the invention can accurately represent the stress state of the support in actual production, and has important value for the type selection of the hydraulic support of the horizontal segmental mining working surface of the steeply inclined coal seam and the guarantee of high efficiency and safety of production. Meanwhile, new theoretical analysis and calculation support is provided for the top plate management of the stope face under the mining condition.

Drawings

Fig. 1 is a schematic flow chart of a method for calculating the working resistance of a fully mechanized caving mining support based on a horizontal subsection of a steeply dipping coal seam according to an embodiment of the invention.

FIG. 2 is a diagram of a pressure arch structure model at the beginning of mining according to an embodiment of the present invention.

FIG. 3 illustrates the interaction of the support and the surrounding rock at the early stage of mining according to an embodiment of the invention.

FIG. 4 is an analysis diagram of the pressure applied to the top plate at the initial stage of mining according to the embodiment of the present invention.

FIG. 5 is a diagram of a model of a hinged rock mass structure at a later stage of mining in accordance with an embodiment of the present invention.

FIG. 6 is a diagram of analysis of local stress of the hinged rock mass at the later stage of mining according to the embodiment of the invention.

FIG. 7 is a stress analysis diagram of the hinged rock mass structure destabilization at the later mining stage in the embodiment of the invention.

Detailed Description

The present invention will now be described in further detail with reference to the accompanying drawings.

It should be noted that the terms "upper", "lower", "left", "right", "front", "back", etc. used in the present invention are for clarity of description only, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not limited by the technical contents of the essential changes.

Example one

Fig. 1 is a schematic flow chart of a method for calculating the working resistance of a fully mechanized caving mining support based on a horizontal subsection of a steeply inclined coal seam according to an embodiment of the invention. The embodiment is applicable to the situation that the working resistance of the horizontal subsection mining bracket of the steeply inclined coal seam is calculated through equipment such as a server, and the method can be executed by a device for calculating the working resistance of the fully mechanized caving mining bracket based on the horizontal subsection of the steeply inclined coal seam, and the device can be realized in a software and/or hardware mode and can be integrated in electronic equipment, such as integrated server equipment.

Referring to fig. 1, the working resistance calculation method includes the steps of:

the method comprises the following steps: and determining coal bed parameters including coal bed inclination angle, coal mining method, mining height, top coal caving height, top rock volume weight and direct top thickness.

Step two: the formation time of the hinged rock mass structure is used as a time boundary, and overlying strata caving characteristics are divided into two stages, namely an exploitation initial stage and an exploitation later stage.

Step three: respectively aiming at the mining initial stage and the mining later stage, constructing corresponding supports and surrounding rock structure models according to the structural characteristics of the coal seam during mining; in the initial mining stage, on one side of a bottom plate roadway, a load borne by a working face hydraulic support comes from the weight of top coal and the weight of coal gangue caving in a goaf; on one side of the roof roadway, the load borne by the working face hydraulic support comes from the weight of the top coal, the weight of coal gangue caving in the goaf and the stress of a roof cantilever beam; in the later stage of mining, when the structure is unstable, the pressure of overlying strata collapse caused by the unstable structure is increased by the hydraulic support on the top plate lane side and the hydraulic support on the bottom plate lane side on the basis of the original load, and the thickness value of the coal gangue collapsing in the goaf in the later stage of mining is smaller than that of the coal gangue collapsing in the goaf in the initial stage of mining.

Step four: and analyzing the support strength of the hydraulic supports in the two stages according to the support and surrounding rock structure models in the initial mining stage and the later mining stage respectively, and calculating the reasonable working resistance of the hydraulic supports on one side of the top plate roadway and one side of the bottom plate roadway in the unstable state of the hinged rock block structure in the initial mining stage and the later mining stage of the horizontal subsection mining of the steeply inclined coal seam.

Exemplarily, the working resistance calculation method further comprises the steps of:

step five: and determining the working resistance variation range of the working face support according to the calculated reasonable working resistance of the hydraulic supports on one side of the top plate lane and one side of the bottom plate lane at the initial stage of mining and the calculated reasonable working resistance of the hydraulic supports on one side of the top plate lane and one side of the bottom plate lane at the later stage of mining under the unstable state of the hinged rock mass structure.

Step six: and (4) combining the working resistance variation range of the working surface support to perform the type selection and the pressure characteristic analysis of the working surface hydraulic support.

In the horizontal sectional mining process of the steeply inclined coal seam, a time limit is formed by a hinged rock block structure, and overlying strata caving characteristics are divided into two stages of a mining initial stage and a mining later stage to be explained respectively.

1) Calculation of support working resistance at early mining

In the initial stage of horizontal sectional mining of the steeply inclined extra-thick coal seam, the load borne by the hydraulic support on the working face mainly comes from the weight of top coal and the weight of coal gangue caving in a goaf, but on one side of a roof roadway, the support is also under the action of the roof load, and the structural model of the support and surrounding rocks is continuously simplified to obtain the calculation formula (1) of the support strength of the hydraulic support in the initial stage of mining:

P₁＝k₁(q_A+q_B)+k₂q_C (1)

in the formula: q. q.s_AIs the dead weight stress of the top coal above the working face, q_BThe dead weight stress q of coal gangue caving in the goaf_CStress of the top plate cantilever beam, k₁For safety reasons, the value is usually between 1.0 and 1.5，k₂The dynamic load coefficient of the top plate is 1.0-1.5.

The dead weight of the coal gangue can not completely act on the hydraulic support of the working face, and the dead weight stress can be gradually attenuated when being transmitted downwards, so that the dead weight stress of the broken coal gangue collapsing in the goaf can be expressed as:

q_B＝k₃λ₂h₂/k₄ (2)

in the formula: k is a radical of₃The attenuation coefficient is usually between 0.5 and 0.8, lambda₂The unit of volume weight of coal gangue in the goaf is kN/m³，h₂The stacking thickness of coal gangue caving in the goaf is m, k₄The breaking and swelling coefficient of the rock is usually 1.1-1.3.

Except top coal and caving coal gangue, the load that the support of working face receives still partly comes from the roof cantilever beam, does the stress analysis with the support of roof lane one side and the structure of country rock interact, can obtain from it:

in the formula: l is the length of the cantilever beam in m, b is the center distance of the bracket in m.

By the formula (3), when other conditions are fixed, the influence of the top plate cantilever beam on the support is smaller and smaller along with the increase of the coal seam inclination angle, when the coal seam inclination angle is 45 degrees, the support strength of the hydraulic support on one side of the top plate roadway is about 0.28MPa, and when the coal seam inclination angle is increased to 90 degrees, the top plate cantilever beam has no influence on the support and accords with the actual situation.

Substituting the formulas (3) and (2) into the formula (1) at the same time, and obtaining a calculation formula of the support strength of the hydraulic support on one side of the roof roadway at the early stage of the horizontal sublevel mining of the steeply inclined coal seam, wherein the calculation formula is as follows:

in the formula: lambda [ alpha ]₁Is a roofCoal unit weight in kN/m₃，h₁Is the thickness of the top coal in m.

Therefore, a calculation formula of the reasonable working resistance of the hydraulic support on one side of the roof roadway at the initial stage of the horizontal sublevel mining of the steeply inclined coal seam can be obtained:

in the formula: l is the length of the support top beam and the unit is m; k is a radical of_sSupporting the efficiency for the stent.

The calculation formula of the reasonable working resistance of the hydraulic support on one side of the bottom plate roadway at the initial stage of the horizontal sublevel mining of the steeply inclined coal seam is as follows:

2) calculation of support working resistance in later period of mining

In the later stage of mining, the top plate broken rock blocks can be hinged with each other in the inclined direction to form a hinged rock block structure. Under the stable state of the hinged rock block structure, like a protective umbrella transmits the load of an overlying rock stratum to the top and bottom plates, the hydraulic support of the working face is protected, and under the state, the load borne by the hydraulic support of the working face is similar to that of the initial stage of excavation and is only under the load of top coal, coal gangue in a goaf and a top plate. Thus, at this point, the reasonable working resistance F of the stent_2-1＝F_1-1：

Under the action of the normal component force of the hinged rock blocks C, broken coal gangue which collapses between the goaf rock blocks C and the bottom plate is compacted, meanwhile, the hinged rock blocks also prevent the overlying strata from collapsing and continuing to slide to the lower part of the goaf, only a few broken coal gangue can slide to the upper part of the top coal of the working face, and therefore the value of the thickness h2 of the coal gangue which collapses in the goaf is much smaller than that in the early stage of mining.

When the structure is unstable, the hinged rock block structure formed by overlying rock collapse disappears, the rock block randomly collapses in a goaf to form a new structure, at the moment, the collapsed rock block is taken out independently for stress analysis, it can be seen that after the hinged rock block structure is unstable, the overlying rock originally acting on the hinged rock block structure can slide to the upper side of the working face top coal of a mining area along with the instability of the structure, at the moment, the hydraulic support of the working face loses the protection of the structure, at the moment, the support not only bears the pressure of the top coal, coal gangue and a top plate, but also bears the pressure of the overlying rock collapse after the structure is unstable. The stress analysis can know that after the pressure Q of the rock block and the overlying strata is decomposed along the normal direction and the inclination, the component force of the pressure of the overlying strata along the normal direction is directly acted on the bottom plate and has no influence on the working face, the component force along the inclination direction is just acted above the top coal of the working face along the direction parallel to the top plate and the bottom plate, and the calculation formula of the reasonable working resistance of the bracket at one side of the top plate roadway of the working face under the unstable state of the hinged rock block structure at the later stage of excavation can be expressed as follows:

the formula for calculating the reasonable working resistance of the hydraulic support on one side of the bottom plate roadway in the unstable state of the hinged rock mass structure at the later stage of horizontal sublevel mining of the steeply inclined coal seam:

the invention provides a novel support working resistance calculation method based on overburden structure change during horizontal sublevel mining of a steep coal seam. Compared with the prior art, the method disclosed by the invention has the advantages that the time limit is formed by the hinged rock mass of the top plate in the horizontal sectional mining of the steeply inclined coal seam, and the working resistance of the support is calculated in the early stage and the later stage of the mining.

In the initial stage of mining, a pressure arch structure exists in the overlying strata, the load of the overlying strata is transferred to the upper side and the lower side of the goaf by the pressure arch, and the balance and stability of the overlying strata are maintained. The load borne by the bracket of the working face comes from the load of the top coal, the caving coal gangue and the top plate. And respectively giving calculation formulas of the working resistance of the top plate side bracket and the bottom plate side bracket.

In the later stage of mining, the overburden rock collapse is always broken in a rotary mode in a cantilever beam mode, the larger the overburden rock load is, the longer the cantilever is, the larger the bending deformation energy accumulated by the cantilever beam is, and the larger the influence caused in the breaking process is. Under the stable state of the hinged rock block structure, the working face hydraulic support is only under the load action of the top coal, the coal gangue in the goaf and the top plate. Under the unstable state of the hinged rock block structure, the working face support still needs to bear the pressure of overlying strata collapse after the structure is unstable. And respectively providing calculation formulas of the working resistance of the support during the stabilization and the instability of the hinged rock mass.

The calculation method provided by the invention can accurately represent the stress state of the support in actual production, and has important value for the type selection of the hydraulic support of the horizontal segmental mining working surface of the steeply inclined coal seam and the guarantee of high efficiency and safety of production. Meanwhile, new theoretical analysis and calculation support is provided for the top plate management of the stope face under the mining condition.

The Yimen coal mine is used as an engineering background, the coal face of the Yimen coal mine adopts horizontal subsection caving coal mining, and parameter determination, model selection and support working resistance field monitoring are carried out on a 1212 working face support.

1) Support strength calculation and support model selection

(1) Support strength

According to the analysis, the support strength and the working resistance of the support can be influenced by the working face in different mining stages and different positions of the hydraulic support, and the support strength and the working resistance of the support are calculated respectively according to different working conditions.

Working condition one, the support intensity and the working resistance of the hydraulic support in the initial stage of excavation are as follows:

F＝P×3.4×1÷0.85

according to the formula, the support strength is a decreasing function of the coal seam inclination angle, the lean coal mine coal seam inclination angle is at least 30 degrees, at the moment, the support strength can be calculated to be 0.35MPa, and the working resistance is 1400 kN.

And working condition II, the support strength and the working resistance of the hydraulic support on one side of the excavated initial stage bottom plate roadway are as follows:

P＝1.1×(15×10³×12.5+0.6×25×10³×20÷1.2)＝0.48MPa

F＝P×3.4×1÷0.85＝1920KN

working condition three, the support intensity and the working resistance of roof lane one side support are when excavation later stage articulated rock mass structure unstability:

F＝P×3.4×1÷0.85＝1800KN

working condition four, when the articulated rock mass structure of excavation later stage is unstable, the support intensity and the working resistance of bottom plate lane one side support are:

F＝P×3.4×1÷0.85＝1720KN

(2) rack height determination

The mining height H of the working face is 2.5m, and the maximum structural height H of the support_maxTaking 2.6m and the minimum structure height H_min1.6m is taken.

(3) Hydraulic support model selection

According to the calculation, the hydraulic support is a ZF2600/16/26 type low-position caving coal hydraulic support. The scaffold parameters are shown in table 1.

TABLE 1 major parameters of ZF2600/16/26 Hydraulic Stent

2) Measured working face pressure characteristic analysis

The 1212 working face hydraulic support selects ZF2600/16/26 type low level caving coal hydraulic support. The working face top plate pressure step distance is analyzed and determined by observing the support resistance of the working face hydraulic support, and further the working face mine pressure display rule, the bearing characteristic of the hydraulic support and the support quality are mastered.

According to the actual situation of the site, measuring areas are arranged at two ends and the middle part of the working surface along the surface length direction. The GPD60(A) type mining intrinsic safety type pressure sensor is adopted to automatically acquire pressure, and the initial supporting force and the working resistance of the hydraulic support pillar on the working face of the Yimen coal mine 1212 are observed

The actual measurement result shows that the initial supporting force of the No. 1 measuring line of the working surface is 54.05% on average above 500 KN; the initial supporting force of the No. 2 measuring line of the working surface accounts for 68.47 percent above 500 KN; the number 3 measuring line initial supporting force of the working surface accounts for 72.73 percent when being more than 500 KN. Therefore, the initial supporting force of the hydraulic support can meet the supporting requirement of a working face.

The average support strength of the actually measured support is as follows: the initial supporting strength p0 is 0.16MPa, the cycle end supporting strength pm is 0.28MPa, the time weighted average supporting strength pt is 0.22MPa, and the supporting strength meets the requirement of supporting a top plate on a working face; the average maximum support strength of the measured support is as follows: the maximum initial support strength p0max is 0.32MPa, the maximum cycle end support strength pmmax is 0.45MPa, the maximum time weighted average support strength ptmax is 0.31MPa, the designed average value of the support strength of the hydraulic support is 0.49MPa, the actual measurement result of the maximum support strength has small deviation from the theoretical calculation, and the support strength of the hydraulic support is fully applied and is not out of limit.

Example two

The embodiment of the invention provides a working resistance calculation device for a horizontal subsection fully mechanized caving mining support of a steep coal seam.

And the coal bed parameter determining module is used for determining coal bed parameters including a coal bed inclination angle, a coal mining method, a mining height, a top coal caving height, a top plate rock volume weight and a direct top thickness.

And the stage division module is used for dividing the overburden caving characteristics into two stages, namely an initial mining stage and a later mining stage by taking the formation time of the hinged rock mass structure as a time boundary.

The structure model building module is used for building corresponding support and surrounding rock structure models according to the structure characteristics of the coal seam during mining respectively at the early mining stage and the later mining stage; in the initial mining stage, on one side of a bottom plate roadway, a load borne by a working face hydraulic support comes from the weight of top coal and the weight of coal gangue caving in a goaf; on one side of the roof roadway, the load borne by the working face hydraulic support comes from the weight of the top coal, the weight of coal gangue caving in the goaf and the stress of a roof cantilever beam; in the later stage of mining, when the structure is unstable, the pressure of overlying strata collapse caused by the unstable structure is increased by the hydraulic support on the top plate lane side and the hydraulic support on the bottom plate lane side on the basis of the original load, and the thickness value of the coal gangue collapsed in the goaf in the later stage of mining is smaller than that of the coal gangue collapsed in the goaf in the initial stage of mining.

And the working resistance analysis module is used for analyzing the support strength of the hydraulic supports in the two stages according to the supports in the initial mining stage and the later mining stage and the structural models of the surrounding rocks respectively, and calculating the reasonable working resistance of the hydraulic supports on one side of the top plate roadway and one side of the bottom plate roadway under the unstable state of the hinged rock mass structure in the initial mining stage and the later mining stage of the horizontal sublevel mining of the steeply inclined coal seam.

Optionally, the working resistance calculation means further comprises a structural model verification module; the structural model verification module is used for verifying the constructed mining initial stage and mining later stage according to coal seam change.

Optionally, the working resistance calculation device further comprises a resistance variation range determination module and an application module.

And the resistance change range determining module is used for determining the working resistance change range of the working face support according to the calculated reasonable working resistance of the hydraulic supports on one side of the top plate roadway and one side of the bottom plate roadway at the initial stage of mining and the reasonable working resistance of the hydraulic supports on one side of the top plate roadway and one side of the bottom plate roadway at the later stage of mining in the unstable state of the hinged rock mass structure.

And the application module is used for carrying out the type selection and the incoming pressure characteristic analysis of the working face hydraulic support in combination with the working resistance variation range of the working face support.

Through the working resistance calculation device provided by the embodiment of the invention, the transmission object is determined by establishing the data containing relation of the whole application, so that the aim of calculating the working resistance of the horizontal sectional mining support of the steeply inclined coal seam is achieved. The calculation device provided by the embodiment of the invention can execute the calculation method for the working resistance of the horizontal sublevel mining bracket of the steeply inclined coal seam provided by any embodiment of the invention, and has corresponding functional modules and beneficial effects of the execution method.

The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention.