CN116756838A - Control method for self-forming roadway roof structure without coal pillar - Google Patents
Control method for self-forming roadway roof structure without coal pillar Download PDFInfo
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Abstract
The application discloses a control method of a self-forming roadway roof structure without coal pillars, which relates to the technical field of mine exploitation and comprises the following steps: acquiring engineering geological parameters in underground mine engineering under the mining condition of self-forming roadway without coal pillars; establishing a mechanical model of a roof structure of the self-forming roadway without coal pillars according to engineering geological parameters, dividing the roof structure into a first structure of the self-forming roadway without coal pillars and a second structure of the self-forming roadway without coal pillars through a discrimination formula, and determining the type of the roof structure of the self-forming roadway without coal pillars; and (3) adopting different roof structure control design methods according to the type of the roof structure of the self-forming roadway without coal pillars, carrying out on-site monitoring on the roof structures adopting the different roof structure control design methods, judging whether the roof structure of the self-forming roadway without coal pillars is stable or not according to the monitoring result, and adopting supplementary control measures on the unstable roof structure. According to the movement characteristics of the roof structure after mining, the roof structure is analyzed, and different roof structure control design methods are adopted to further control the stability of the roof.
Description
Technical Field
The application relates to the technical field of mine exploitation, in particular to a control method for a self-forming roadway roof structure without coal pillars.
Background
The coal mining in China mainly adopts a longwall mining 121 construction method, namely 1 working face is mined, 2 roadways are required to be tunneled in advance, and 1 coal pillar is reserved, so that the construction method makes great contribution to the coal mining industry in China. The method adopts a mode of reserving coal pillars to bear the pressure of the overlying strata, thereby ensuring the stability of surrounding rocks of the roadway. However, the method causes low coal resource extraction rate and concentrated coal pillar stress, and affects the safe and efficient production of the coal mine.
The self-forming roadway mining method without coal pillars is used as a novel coal mining process, and the coal pillar reserving is omitted, so that the stress concentration of surrounding rocks of the roadway can be reduced, and the coal resource mining rate can be improved. However, the structural characteristics and the control mode of the pillar-free self-forming roadway roof after the pillar is cancelled are greatly different from those of the traditional mining method. In order to realize the roof safety control in the mining mode, the application provides a control method for the roof structure of the self-forming roadway without coal pillars, so as to ensure the stability of the roof structure in the mining mode without coal pillars.
Disclosure of Invention
The application aims to provide a control method for a roof structure of a self-forming roadway without coal pillars, which is characterized in that the roof structure of the self-forming roadway without coal pillars is analyzed according to the roof structure and the motion characteristics of the roof structure under the mining mode of the self-forming roadway without coal pillars, and different roof structure control design methods are adopted to further control the stability of the roof.
In order to achieve the above purpose, the application provides a control method of a self-forming roadway roof structure without coal pillars, comprising the following steps:
acquiring engineering geological parameters in underground mine engineering under the mining condition of self-forming roadway without coal pillars;
establishing a mechanical model of a roof structure of the self-forming roadway without coal pillars according to the engineering geological parameters, dividing the roof structure into a first structure of the self-forming roadway without coal pillars and a second structure of the self-forming roadway without coal pillars through a discrimination formula, and determining the type of the roof structure of the self-forming roadway without coal pillars;
and according to the type of the roof structure of the self-forming roadway without the coal pillar, adopting different roof structure control design methods, carrying out field monitoring on roof structures adopting the different roof structure control design methods, judging whether the roof structure of the self-forming roadway without the coal pillar is stable or not according to monitoring results, and adopting supplementary control measures on the unstable roof structure.
Preferably, the discrimination formula includes a discrimination formula for the pillar-free self-lane first structure and a discrimination formula for the pillar-free self-lane second structure.
Preferably, the discrimination formula for the pillar-free self-forming lane first structure is as follows:
wherein ,x 1 ，y 1 is in the range of a first structure of a self-forming roadway without coal pillars,L X in order to articulate the thickness of the rock mass,L A is the width of the rock mass above the coal body,L B is the width of the rock mass above the roadway,L C is the width of the rock mass above the goaf.
Preferably, the discrimination formula for the second structure of the pillar-free self-forming roadway is as follows:
wherein ,x 2 ，y 2 of self-forming lane second construction without coal pillarThe range of the light-emitting diode is within the range,afor the width of the roadway,x 0 the distance from the fracture position of the second structure in the coal seam to the roadway side part is the distance,h f is the cutting top height.
Preferably, the method for controlling and designing the roof structure comprises the following steps:
and according to the type of the roof structure of the self-forming roadway without coal pillars, adopting a roof cutting active control method and a crushing expansion bearing control method for the first structure of the self-forming roadway without coal pillars, and adopting an active stress compensation control method and a dynamic pressure bearing control method for the second structure of the self-forming roadway without coal pillars.
Preferably, the active control method for roof cutting comprises the following steps: determining a roof cutting height and a roof cutting angle by adopting theoretical calculation and numerical simulation methods according to engineering geological parameters, and determining roof cutting quality according to a drilling detection method; the roof cutting quality refers to whether the roof is completely cut by a roof directional cutting technology;
the crushing-expanding pressure-bearing control method comprises the following steps: controlling the crushing and expanding height, the crushing and expanding bulk degree and the collapse speed; wherein, the collapse block degree refers to the size block degree of the collapse rock mass, and the crushing expansion height and the crushing expansion block degree are coordinated and controlled through blasting vibration, multidimensional composite roof cutting and bracket extrusion measures, so that the crushing expansion coefficient and the bearing capacity of the collapse rock mass are maximized; the collapse speed refers to the collapse speed of the crushed expanded rock mass, and the rock mass is weakened through blasting vibration, multidimensional composite roof cutting and bracket extrusion measures, so that the roof rock mass collapses at the highest speed.
Preferably, the theoretical calculation method of the truncated height is as follows:
wherein ,h f for the slit height, the slit is formed,Mfor the thickness of the coal to be mined,kto collapse the expansion coefficient of the rock mass,λthe inclination angle influence coefficient is the inclination angle influence coefficient of the coal seam;
the theoretical calculation method of the roof cutting angle comprises the following steps:
wherein θ is the roof-cutting angle; θ' is the optimal roof cutting angle under the horizontal coal seam condition;
the method for determining the topping quality comprises the following steps:
the longitudinal crack rate is more than 80 percent;
the transverse communication rate is more than 80 percent;
wherein the longitudinal crack rate is the crack rate of a single hole; the transverse communication rate is the rate at which the cracks between the two holes communicate.
Preferably, the stress compensation control method comprises the steps of controlling the support strength and the support range of the constant-resistance anchor rod/cable; the dynamic pressure bearing control method comprises the steps of controlling the supporting time, the supporting position and the supporting strength of a roadway in a dynamic pressure bearing stage;
wherein, the supporting strength of constant resistance stock/cable satisfies the condition:
wherein ,Fexternal force is applied to the top plate structure;M 0 bending moment generated on the O point position by the stress of the top plate structure;Gis the gravity of the rock mass;P Z the load is equally and uniformly supported;σ c in order to maintain the residual stress of the coal body at the roadway,σ 0 is the reaction force generated by the fixed end coal body;athe roadway width;x 0 the distance from the fracture position of the second structure in the coal seam to the roadway side part is the distance;βis a roof cutting angle;
the supporting range of the constant-resistance anchor rod/cable meets the following conditions:
Lthe support length of the constant-resistance anchor rod/cable;L m the anchoring length is equal to the anchoring length when the constant-resistance anchor cable anchoring force is equal to the limit breaking force;
the dynamic pressure bearing control support strength meets the following conditions:
wherein ,F t carrying temporary supporting force for dynamic pressure;athe roadway width;γ 1 bulk modulus for the overburden load;γ 2 bulk modulus for the second structure;K 1 is the second structural pressure transmission coefficient;K 2 is an overlying load transfer coefficient;y 2 is the height of the second structure;His the height of the overburden;nthe number of anchor cables in each constant group is equal to that of anchor cables in each constant group;f p the pretightening force of a single constant group anchor cable is adopted;cis the cohesive force of the second structure;φis the internal friction angle of the second structure.
Preferably, the on-site monitoring of the roof structure adopting the different roof structure control design method includes:
monitoring the coal pillar-free self-forming first structure, wherein the monitoring content is the microseismic energy, acoustic emission and earth sound signals in the rock stratum above the working surface, when the continuous change of the microseismic energy, acoustic emission and earth sound signals in the rock stratum above the working surface is monitored, the coal pillar-free self-forming first structure is unstable, and when the change of the microseismic energy, acoustic emission and earth sound signals in the rock stratum above the working surface is monitored, the coal pillar-free self-forming first structure is stable;
and monitoring the self-forming roadway second structure without coal pillars, wherein the monitoring content is monitoring roadway deformation conditions, surrounding rock stress conditions and supporting structure stress conditions, when the sum of the energy generated by roadway deformation and surrounding rock stress concentration minus the energy absorbed by the supporting structure is larger than the maximum damage energy born by surrounding rocks of the roadway, or the roadway deformation and surrounding rock stress is continuously increased, the self-forming roadway second structure without coal pillars is unstable, and when the sum of the energy generated by roadway deformation and surrounding rock stress concentration minus the energy absorbed by the supporting structure is smaller than the maximum damage energy born by surrounding rocks of the roadway, or the roadway deformation and surrounding rock stress are not changed any more, the self-forming roadway second structure without coal pillars is stable.
Preferably, the method for calculating the maximum damage energy which can be born by the roadway surrounding rock is as follows:
wherein ,E wy is the maximum energy which can be born by the surrounding rock of the roadway,E rd for the energy generated by the deformation of the roadway,E rs for energy generated by stress concentration of surrounding rock,E ss in order to support the energy absorbed by the structure,ρis an influence coefficient of the deformation energy of the roadway,εas an influence coefficient of the stress energy of the surrounding rock,ζan influence coefficient for absorbing energy for the support structure;
if the first structure of the self-forming roadway without the coal pillar is unstable, taking further measures on the first structure of the self-forming roadway without the coal pillar, including measures of increasing the roof cutting height, secondary roof cutting and the like;
if the coal pillar-free self-forming roadway second structure is unstable, the coal pillar-free self-forming roadway second structure is further reinforced, including measures such as anchor cable repairing and anchor cable adding and temporary support adding to a roadway roof.
Compared with the prior art, the application has the following advantages and technical effects:
according to the application, different targeted control countermeasures are provided for the special structure of the self-forming roadway roof without coal pillars, so that the roof structure and the stability of roadway surrounding rock can be accurately controlled;
the control method can adapt to the structural characteristics of the top plate in a new mining mode, so that the aims of maintaining tunnel stability and guaranteeing production safety are fulfilled.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:
FIG. 1 is a flow chart of a method for controlling a self-forming roadway roof structure without coal pillars in an embodiment of the application;
FIG. 2 is a block diagram of specific design steps of a control method for a pillar-free self-forming roof structure in an embodiment of the application;
FIG. 3 is a schematic diagram of a self-forming roadway roof strata structure without coal pillars according to an embodiment of the application;
the mining goaf comprises a goaf, a roof slab joint cutting structure, a gangue blocking structure, a roadway, a coal seam, a coal pillar-free self-forming roadway second structure, a constant-resistance anchor cable, a coal pillar-free self-forming roadway first structure, a coal body upper rock block, a roadway upper rock block and a goaf upper rock block, wherein the goaf comprises a goaf 1, a roof slab joint cutting structure, a gangue blocking structure, a roadway 4, a roadway 5, a coal seam 6, a coal pillar-free self-forming roadway second structure, a constant-resistance anchor cable, a coal pillar-free self-forming roadway first structure, a coal pillar-free self-forming roadway 9 and a goaf upper rock block.
Detailed Description
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described in detail below with reference to the drawings in connection with embodiments.
It should be noted that the steps illustrated in the flowcharts of the figures may be performed in a computer system such as a set of computer executable instructions, and that although a logical order is illustrated in the flowcharts, in some cases the steps illustrated or described may be performed in an order other than that illustrated herein.
The application provides a control method of a self-forming roadway roof structure without coal pillars, as shown in fig. 1, comprising the following steps:
firstly, acquiring engineering geological parameters in underground mine engineering under the mining condition of self-forming roadway without coal pillars;
secondly, establishing a mechanical model of the self-forming roadway roof structure without coal pillars according to engineering geological parameters in underground mine engineering, and dividing the roof structure into a first structure and a second structure according to a judging formula so as to judge the type of the self-forming roadway roof structure without coal pillars;
thirdly, adopting a roof cutting active control method and a crushing expansion bearing control method for a first structure and adopting an active stress compensation control method and a dynamic pressure bearing control method for a second structure according to the type of the coal pillar-free self-forming roadway roof structure;
and fourthly, on-site monitoring is carried out on the roof structures adopting different roof structure control methods, and if the first structure and the second structure reach a stable state, the control effect is good. If the first structure is unstable, further reinforcement of the first structure is required; if the second structure is unstable, further reinforcement of the second structure is required.
Specifically, as shown in fig. 2, the method comprises the following steps:
firstly, acquiring geological parameters in a mine underground project under a non-coal pillar self-lane mining condition, wherein the geological parameters comprise data such as a rock stratum structure, rock stratum properties, mining conditions and the like in the mine underground project;
in the implementation, according to geological exploration data of field engineering, the rock stratum structure, the rock stratum property, the mining condition and the like of a mine under the mining condition of the self-forming roadway without coal pillars are collected, so that preparation is made for building a mechanical model of the roof structure of the self-forming roadway without coal pillars.
Secondly, establishing a mechanical model of the self-forming roadway roof structure without coal pillars according to geological parameters in underground mine engineering, and dividing the roof structure into a first structure and a second structure according to a judging formula so as to judge the type of the self-forming roadway roof structure without coal pillars;
in implementation, according to geological parameters in underground engineering of a mine under the mining condition of the self-forming roadway without coal pillars, a mechanical model of the roof structure of the self-forming roadway without coal pillars shown in fig. 3 is established, and the roof structure is divided into a first structure and a second structure according to a discrimination formula, so that the type of the roof structure of the self-forming roadway without coal pillars is discriminated.
The method comprises the following steps: the hinged structure formed by the coal body upper rock 9, the roadway upper rock 10 and the goaf upper rock 11 and the balance structure formed by the interaction of the caving gangue are called a coal pillar-free self-forming roadway first structure 8;
the discrimination formula for the range of the first structure 8 without the coal pillar self-forming lane is as follows:
wherein ,x 1 ，y 1 to the extent that there are no pillar self-forming first structures 8,L X in order to articulate the thickness of the rock mass,L A for the width of the rock mass 9 above the coal body,L B for the width of the rock mass 10 above the roadway,L C the width of the rock mass 11 above the goaf;
the stable structure of forming an inner ring by the combined action of a roadway top plate and an intra-roadway support and the like of a short arm beam structure formed below the top plate cutting joint 2 is called a self-forming roadway second structure 6 without coal pillars;
the judgment formula for the range of the second structure 6 without the coal pillar self-forming roadway is as follows:
wherein ,x 2 ，y 2 is in the range of a second structure without coal pillar self-forming lane,afor the width of the roadway,x 0 the distance from the fracture position of the second structure in the coal seam to the roadway side part is the distance,h f is the cutting top height.
In the implementation, according to the established mechanical model of the self-forming roadway roof structure without coal pillars, the method of drilling detection, theoretical calculation, numerical simulation and the like is comprehensively utilized to judge the type of the self-forming roadway roof structure without coal pillars;
the drilling detection means that the position of the basic roof and the actual lancing range are detected, and then the range of the first self-forming structure 8 without coal pillar and the second self-forming structure 6 without coal pillar is judged;
the theoretical calculation refers to the range of judging the self-forming first structure 8 without coal pillars and the self-forming second structure 6 without coal pillars by calculating the roof cutting height by using the crushing expansion coefficient of the caving rock mass, and the specific calculation formula is as follows:
wherein ,h f for the slit height, the slit is formed,Mfor the thickness of the coal to be mined,kto collapse the expansion coefficient of the rock mass,λas the coal seam inclination angle influence coefficient, when the roadway is positioned at the upper part of the inclined coal seam,λ> 1; when the roadway is positioned at the lower part of the inclined coal seam,λ＜1。
thirdly, adopting a roof cutting active control method and a crushing expansion pressure bearing control method for the first structure 8 of the self-forming roadway without coal pillars according to the type of the roof structure of the self-forming roadway without coal pillars, and adopting an active stress compensation control method and a dynamic pressure bearing control method for the second structure 6 of the self-forming roadway without coal pillars;
in the implementation, the control design method for the first structure 8 without the coal pillar self-forming roadway is a roof cutting active control method and a crushing expansion pressure-bearing control method;
the active control method for roof cutting mainly comprises the steps of controlling the roof cutting height, the roof cutting angle and the roof cutting quality;
roof slitting quality refers to whether the roof is completely slit by the roof slitting technique.
The theoretical calculation method of the roof cutting angle comprises the following steps:
wherein θ is the roof-cutting angle; θ 'is the optimal roof cutting angle under the condition of a horizontal coal seam, and the value of θ' is 10-15 degrees; when the roof cutting roadway is positioned at the upper part of the inclined coal seam,λ< 1; when the roof cutting roadway is positioned at the lower part of the inclined coal seam,λ＞1。
further, the method for actively controlling the roof cutting of the first structure 8 without the coal pillar self-forming roadway is to determine the roof cutting height and the roof cutting angle by adopting a theoretical calculation and numerical simulation method according to geological parameters in underground mine engineering, and determine the roof cutting quality according to a drilling detection method.
The method for determining the topping quality comprises the following steps:
the longitudinal crack rate is more than 80 percent;
the transverse communication rate is more than 80 percent;
the longitudinal crack rate is the crack rate of a single hole; the transverse communication rate is the rate at which the cracks between the two holes communicate.
The crushing-expanding pressure-bearing control method mainly comprises the steps of controlling the crushing-expanding height, crushing-expanding bulk and collapse speed;
the collapse block degree refers to the size block degree of the collapsed rock mass, and the collapse speed refers to the speed of the collapse of the crushed expanded rock mass.
The crushing-expanding pressure-bearing control method comprises the following steps: controlling the crushing and expanding height, the crushing and expanding bulk degree and the collapse speed; wherein, the collapse block degree refers to the size block degree of the collapse rock mass, and the crushing expansion height and the crushing expansion block degree are coordinated and controlled through measures such as blasting vibration, multidimensional composite roof cutting, bracket extrusion and the like, so that the crushing expansion coefficient and the bearing capacity of the collapse rock mass are maximized; the collapse speed refers to the collapse speed of the crushed expanded rock mass, and the rock mass is weakened through measures such as blasting vibration, multidimensional composite roof cutting, bracket extrusion and the like, so that the roof rock mass collapses at the highest speed.
The crushing expansion pressure-bearing control method for the non-coal pillar self-forming first structure 8 is a method for controlling the caving gangue to fill a goaf by using an active roof cutting control method, and supporting the non-coal pillar self-forming first structure 8 under the lateral blocking protection effect of the gangue blocking structure 3 to control the movement of the non-coal pillar self-forming first structure 8.
In the implementation, the control method of the non-pillar self-forming roadway second structure 6 is an active stress compensation control method and a dynamic pressure bearing control method;
further, the active stress compensation control method comprises the step of controlling the support strength and the support range of the constant-resistance anchor rod/cable.
For an active stress compensation method of the coal pillar-free self-forming roadway second structure 6, calculating the supporting strength and supporting range of the constant-resistance anchor rod/rope according to the stratum structure, stratum property and exploitation conditions;
further, the dynamic pressure bearing control method mainly comprises the steps of controlling the supporting time, the supporting position and the supporting strength of the roadway 4 in the dynamic pressure bearing stage; the control method for the non-coal pillar self-forming second structure 6 mainly prevents breakage, separation and other damages of the non-coal pillar self-forming second structure 6 and keeps the balance and stability of the non-coal pillar self-forming second structure 6.
The supporting strength of the constant-resistance anchor rod/cable meets the following conditions:
wherein ,Gthe gravity of the rock mass is vertically downward, and the gravity acts on the centroid position of the structure equivalently;P Z is equivalent toUniformly supporting the load;σ c in order to maintain the residual stress of the coal body at the roadway,σ 0 is the reaction force generated by the fixed end coal body;athe roadway width;x 0 the distance from the fracture position of the second structure in the coal seam to the roadway side part is the distance;βis a truncated angle.
The supporting range of the constant-resistance anchor rod/cable meets the following conditions:
wherein ,L m the anchoring force of the constant-resistance anchor cable 7 is equal to the anchoring length when the ultimate breaking force is equal.
The dynamic pressure bearing control support strength meets the following conditions:
wherein ,F t carrying temporary supporting force for dynamic pressure;athe roadway width;γ 1 bulk modulus for the overburden load;γ 2 bulk modulus for the second structure;K 1 is the second structural pressure transmission coefficient;K 2 is an overlying load transfer coefficient;y 2 is the height of the second structure;His the height of the overburden;nthe number of anchor cables in each constant group is equal to that of anchor cables in each constant group;f p the pretightening force of a single constant group anchor cable is adopted;cis the cohesive force of the second structure;φis the internal friction angle of the second structure.
And fourthly, on-site monitoring is carried out on the roof structures adopting different roof structure control methods, and if the first structure 8 without coal pillar self-forming lane and the second structure 6 without coal pillar self-forming lane reach a stable state, the control effect is good. If the self-forming first structure 8 without the coal pillar is unstable, further reinforcement of the self-forming first structure 8 without the coal pillar is needed; if the pillar-free self-forming second structure 6 is unstable, further reinforcement of the pillar-free self-forming second structure 6 is required.
In the implementation, the roof after the control method of the self-forming roadway roof structure without coal pillars is adopted is monitored, and the self-forming roadway roof structure without coal pillars is monitored on site by means of micro-vibration, ground sound, acoustic emission, drilling and the like;
the site monitoring part mainly monitors the first self-forming structure 8 without coal pillar and the second self-forming structure 6 without coal pillar on site by using the means of micro-vibration, ground sound, acoustic emission, drilling and the like;
monitoring a coal pillar-free self-forming first structure, wherein the monitoring content is microseismic energy, acoustic emission and earth sound signals in a rock stratum above a working surface, when the microseismic energy, acoustic emission and earth sound signals in the rock stratum above the working surface are continuously changed, the coal pillar-free self-forming first structure is unstable, and when the microseismic energy, acoustic emission and earth sound signals in the rock stratum above the working surface are not changed any more, the coal pillar-free self-forming first structure is stable;
further, further measures to be taken for the pillar-free self-forming first structure 8 include measures to increase the roof-cutting height and secondary roof cutting.
The second structure 6 of the self-forming roadway without coal pillar is monitored on site to monitor the deformation condition of the roadway, the stress condition of surrounding rock and the stress condition of the supporting structure;
and monitoring the self-forming roadway second structure without coal pillars, wherein the monitoring content is monitoring roadway deformation conditions, surrounding rock stress conditions and supporting structure stress conditions, when the sum of the energy generated by roadway deformation and surrounding rock stress concentration minus the energy absorbed by the supporting structure is larger than the maximum damage energy born by surrounding rocks of the roadway, or the roadway deformation and surrounding rock stress is continuously increased, the self-forming roadway second structure without coal pillars is unstable, and when the sum of the energy generated by roadway deformation and surrounding rock stress concentration minus the energy absorbed by the supporting structure is smaller than the maximum damage energy born by surrounding rocks of the roadway, or the roadway deformation and surrounding rock stress is not obviously increased any more, the self-forming roadway second structure without coal pillars is stable.
Further, if the second structure of the self-forming roadway without the coal pillar is unstable, further reinforcing the second structure comprises the measures of repairing anchor cables on a roadway top plate, adding temporary support and the like.
The method for the maximum damage energy which can be born by the surrounding rock of the roadway comprises the following steps:
wherein ,E wy is the maximum energy which can be born by the surrounding rock of the roadway,E rd for the energy generated by the deformation of the roadway,E rs for energy generated by stress concentration of surrounding rock,E ss in order to support the energy absorbed by the structure,ρis an influence coefficient of the deformation energy of the roadway,εas an influence coefficient of the stress energy of the surrounding rock,ζthe influence coefficient of energy absorption for the support structure.
The self-forming roadway without coal pillars has essential difference from the traditional roof structure of the coal pillar mining roadway, the roof structure of the coal pillar mining roadway is a long-arm beam, and the roof structure is mainly kept stable by virtue of the reserved coal pillars and supports in the roadway. The self-forming roadway roof structure without coal pillars is a short-arm beam, and is not supported by the coal pillars, the requirement cannot be met by adopting the prior supporting form, and the bearing capacity of the caving gangue of the goaf needs to be exerted to be kept stable.
According to the control method provided by the application, a mechanical model of the self-forming roadway roof structure without coal pillars is established, and the roof structure is divided into a first structure and a second structure according to a judging formula, so that the type of the self-forming roadway roof structure without coal pillars is judged. According to different types of the self-forming roadway roof structures without coal pillars, a roof cutting active control method and a crushing expansion pressure bearing control method are adopted for the first structure, and an active stress compensation control method and a dynamic pressure bearing control method are adopted for the second structure. The roof structures adopting different roof structure control methods are monitored on site, and if the first structure and the second structure reach a stable state, the control effect is good; if the first structure is unstable, further measures need to be taken for the first structure; if the second structure is unstable, further measures need to be taken with respect to the second structure.
The application provides different targeted control countermeasures aiming at the special structure of the self-forming roadway roof without coal pillars, and can accurately control the roof structure and the stability of roadway surrounding rocks. The control method can adapt to the structural characteristics of the top plate in a new mining mode, so that the aims of maintaining tunnel stability and guaranteeing production safety are fulfilled.
The present application is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present application are intended to be included in the scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims (10)
1. The control method of the self-forming roadway roof structure without the coal pillar is characterized by comprising the following steps of:
acquiring engineering geological parameters in underground mine engineering under the mining condition of self-forming roadway without coal pillars;
establishing a mechanical model of a roof structure of the self-forming roadway without coal pillars according to the engineering geological parameters, dividing the roof structure into a first structure of the self-forming roadway without coal pillars and a second structure of the self-forming roadway without coal pillars through a discrimination formula, and determining the type of the roof structure of the self-forming roadway without coal pillars;
and according to the type of the roof structure of the self-forming roadway without the coal pillar, adopting different roof structure control design methods, carrying out field monitoring on roof structures adopting the different roof structure control design methods, judging whether the roof structure of the self-forming roadway without the coal pillar is stable or not according to monitoring results, and adopting supplementary control measures on the unstable roof structure.
2. The method for controlling a pillar-free self-forming roof structure according to claim 1, wherein the discrimination formula includes a discrimination formula for the pillar-free self-forming first structure and a discrimination formula for the pillar-free self-forming second structure.
3. The method for controlling a pillar-free self-forming roof structure according to claim 2, wherein the discrimination formula for the pillar-free self-forming first structure is:
wherein ,x 1 ，y 1 is in the range of a first structure of a self-forming roadway without coal pillars,L X in order to articulate the thickness of the rock mass,L A is the width of the rock mass above the coal body,L B is the width of the rock mass above the roadway,L C is the width of the rock mass above the goaf.
4. The method for controlling a self-forming roadway roof structure without coal pillars according to claim 2, wherein the discrimination formula for the self-forming roadway roof structure without coal pillars is:
wherein ,x 2 ，y 2 is in the range of a second structure without coal pillar self-forming lane,afor the width of the roadway,x 0 the distance from the fracture position of the second structure in the coal seam to the roadway side part is the distance,h f is the cutting top height.
5. The method for controlling a roof structure of a pillar-free self-forming roadway according to claim 1, wherein the method for controlling and designing the roof structure comprises the steps of:
and according to the type of the roof structure of the self-forming roadway without coal pillars, adopting a roof cutting active control method and a crushing expansion bearing control method for the first structure of the self-forming roadway without coal pillars, and adopting an active stress compensation control method and a dynamic pressure bearing control method for the second structure of the self-forming roadway without coal pillars.
6. The method for controlling a pillar-free self-forming roof structure according to claim 5, wherein the method for actively controlling roof cutting comprises: determining a roof cutting height and a roof cutting angle by adopting theoretical calculation and numerical simulation methods according to engineering geological parameters, and determining roof cutting quality according to a drilling detection method; the roof cutting quality refers to whether the roof is completely cut by a roof directional cutting technology;
the crushing-expanding pressure-bearing control method comprises the following steps: controlling the crushing and expanding height, the crushing and expanding bulk degree and the collapse speed; wherein, the collapse block degree refers to the size block degree of the collapse rock mass, and the crushing expansion height and the crushing expansion block degree are coordinated and controlled through blasting vibration, multidimensional composite roof cutting and bracket extrusion measures, so that the crushing expansion coefficient and the bearing capacity of the collapse rock mass are maximized; the collapse speed refers to the collapse speed of the crushed expanded rock mass, and the rock mass is weakened through blasting vibration, multidimensional composite roof cutting and bracket extrusion measures, so that the roof rock mass collapses at the highest speed.
7. The method for controlling a self-forming roadway roof structure without coal pillars according to claim 6, wherein the theoretical calculation method of the roof cutting height is as follows:
wherein ,h f for the slit height, the slit is formed,Mfor the thickness of the coal to be mined,kto collapse the expansion coefficient of the rock mass,λthe inclination angle influence coefficient is the inclination angle influence coefficient of the coal seam;
the theoretical calculation method of the roof cutting angle comprises the following steps:
wherein θ is the roof-cutting angle; θ' is the optimal roof cutting angle under the horizontal coal seam condition;
the method for determining the topping quality comprises the following steps:
the longitudinal crack rate is more than 80 percent;
the transverse communication rate is more than 80 percent;
wherein the longitudinal crack rate is the crack rate of a single hole; the transverse communication rate is the rate at which the cracks between the two holes communicate.
8. The method for controlling a pillar-free self-forming roof structure according to claim 6, wherein the stress compensation control method comprises controlling the support strength and the support range of a constant-resistance anchor rod/cable; the dynamic pressure bearing control method comprises the steps of controlling the supporting time, the supporting position and the supporting strength of a roadway in a dynamic pressure bearing stage;
wherein, the supporting strength of constant resistance stock/cable satisfies the condition:
wherein ,Fexternal force is applied to the top plate structure;M 0 bending moment generated on the O point position by the stress of the top plate structure;Gis the gravity of the rock mass;P Z the load is equally and uniformly supported;σ c in order to maintain the residual stress of the coal body at the roadway,σ 0 is the reaction force generated by the fixed end coal body;athe roadway width;x 0 the distance from the fracture position of the second structure in the coal seam to the roadway side part is the distance;βis a roof cutting angle;
the supporting range of the constant-resistance anchor rod/cable meets the following conditions:
Lthe support length of the constant-resistance anchor rod/cable;L m the anchoring length is equal to the anchoring length when the constant-resistance anchor cable anchoring force is equal to the limit breaking force;
the dynamic pressure bearing control support strength meets the following conditions:
wherein ,F t carrying temporary supporting force for dynamic pressure;athe roadway width;γ 1 bulk modulus for the overburden load;γ 2 bulk modulus for the second structure;K 1 is the second structural pressure transmission coefficient;K 2 is an overlying load transfer coefficient;y 2 is the height of the second structure;His the height of the overburden;nthe number of anchor cables in each constant group is equal to that of anchor cables in each constant group;f p the pretightening force of a single constant group anchor cable is adopted;cis the cohesive force of the second structure;φis the internal friction angle of the second structure.
9. The method for controlling a roof structure of a pillar-less self-forming roadway of claim 1, wherein the on-site monitoring of the roof structure by the different roof structure control design methods comprises:
monitoring the coal pillar-free self-forming first structure, wherein the monitoring content is the microseismic energy, acoustic emission and earth sound signals in the rock stratum above the working surface, when the continuous change of the microseismic energy, acoustic emission and earth sound signals in the rock stratum above the working surface is monitored, the coal pillar-free self-forming first structure is unstable, and when the change of the microseismic energy, acoustic emission and earth sound signals in the rock stratum above the working surface is monitored, the coal pillar-free self-forming first structure is stable;
and monitoring the self-forming roadway second structure without coal pillars, wherein the monitoring content is monitoring roadway deformation conditions, surrounding rock stress conditions and supporting structure stress conditions, when the sum of the energy generated by roadway deformation and surrounding rock stress concentration minus the energy absorbed by the supporting structure is larger than the maximum damage energy born by surrounding rocks of the roadway, or the roadway deformation and surrounding rock stress is continuously increased, the self-forming roadway second structure without coal pillars is unstable, and when the sum of the energy generated by roadway deformation and surrounding rock stress concentration minus the energy absorbed by the supporting structure is smaller than the maximum damage energy born by surrounding rocks of the roadway, or the roadway deformation and surrounding rock stress are not changed any more, the self-forming roadway second structure without coal pillars is stable.
10. The method for controlling a self-forming roadway roof structure without coal pillars according to claim 9, wherein the method for calculating the maximum damage energy which can be born by the roadway surrounding rock is as follows:
wherein ,E wy is the maximum energy which can be born by the surrounding rock of the roadway,E rd for the energy generated by the deformation of the roadway,E rs for energy generated by stress concentration of surrounding rock,E ss in order to support the energy absorbed by the structure,ρis an influence coefficient of the deformation energy of the roadway,εas an influence coefficient of the stress energy of the surrounding rock,ζan influence coefficient for absorbing energy for the support structure;
if the first structure of the self-forming roadway without the coal pillar is unstable, taking further measures on the first structure of the self-forming roadway without the coal pillar, including measures of increasing the roof cutting height, secondary roof cutting and the like;
if the coal pillar-free self-forming roadway second structure is unstable, the coal pillar-free self-forming roadway second structure is further reinforced, including measures such as anchor cable repairing and anchor cable adding and temporary support adding to a roadway roof.
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