CN115929304B - Method for preventing impact of artificial relief layer of stope face - Google Patents
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Abstract
The invention discloses an anti-scour method for an artificial relief layer of a stope face, which comprises the following steps: determining a target rock stratum where an artificial liberation layer is located above a stratum area with rock burst hidden danger; numerical simulation and theoretical analysis are carried out on the artificial liberation layer and the equivalent coal seam exploitation thereof to obtain the stress sigma of the liberation layer under the equivalent coal seam exploitation lib And stress sigma of the released layer under artificial release layer mining art The method comprises the steps of carrying out a first treatment on the surface of the According to sigma lib Sum sigma art Defining an equivalent stress relief coefficient xi, and dividing and judging the artificial relief layer thickness and coverage area in the target rock stratum; establishing an artificial liberation layer judging model according to the division judgment of the thickness and coverage of the artificial liberation layer, arranging a ground fracturing well according to the model, and performing drilling and fracturing operations; the coverage area of the width of the artificial liberation layer correspondingly covers the boundary of each side of the working face by 30-50m, and then the working face stoping operation is carried out. The invention greatly reduces the occurrence probability of rock burst disasters during the stoping of the working face.
Description
Technical Field
The invention relates to the technical field of coal mine safety exploitation, in particular to an anti-impact method for an artificial liberation layer of a stope face.
Background
The roof strata structure, particularly the hard, thick layer sandstone roof above the coal seam, is one of the main factors affecting rock burst occurrence, mainly because hard thick layer sandstone roof tends to accumulate a large amount of elastic energy. During breaking or slipping of the hard roof, a large amount of elastic energy is suddenly released, resulting in rock burst or mine shock.
The mining of the liberation layer is a widely accepted rock burst prevention method, the mining of the liberation layer causes the falling and displacement of rock strata on the top and bottom plates of the goaf, the balance of original ground stress is broken, the ground stress around the stope is redistributed, a certain range of pressure relief zone stress is formed in the top and bottom plate rocks and coal bodies of the stope and is lower than the original stress and the liberation zone, the risk of the impact of a working face is reduced, and the method is the most effective regional prevention measure for fundamentally preventing the rock burst. The principle of the liberation layer mining is to preferentially mine the coal layer with low impact risk.
But not every rock burst mine is provided with conditions for mining a liberation layer, and conditions such as applicable conditions and selection principles for mining the liberation layer, mining design of the liberation layer, protection range, protection effect, pressure relief period and the like need to be achieved. In dynamic disaster mines with rock burst, coal and gas outburst and the like, the mine has no dilemma which can be used as a mining condition of a liberation layer, regional precautions are difficult to implement, the disaster degree in the subsequent mining process is serious, and the safety production is affected very adversely. Based on the relief layer source anti-impact thought, when the relief layer exploitation conditions are not met and the application effect of the traditional anti-impact method is not obvious, the application provides a construction method of the artificial relief layer for realizing the anti-impact effect equivalent to the relief layer exploitation.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems in the related art to some extent.
In order to achieve the above purpose, the invention provides a method for preventing a relief layer of a stope face from being washed, which comprises the following steps:
s1, determining a target rock stratum where an artificial liberation layer is located above a stratum area with rock burst hidden danger, and measuring the thickness of the target rock stratum to obtain the thickness h of the target rock stratum;
s2, carrying out numerical simulation and theoretical analysis on the artificial liberation layer and the equivalent coal seam exploitation thereof to obtain stress sigma of the liberation layer under the equivalent coal seam exploitation lib And stress sigma of the released layer under artificial release layer mining art ；
S3, according to sigma lib Sum sigma art Defining an equivalent stress relief coefficient xi, establishing an artificial relief layer judgment criterion according to the equivalent stress relief coefficient, and carrying out division judgment on the artificial relief layer thickness and coverage area in the target rock stratum according to the judgment criterion;
s4, establishing an artificial liberation layer judging model according to the division judgment of the thickness and coverage area of the artificial liberation layer, arranging a ground fracturing well according to the model, and performing drilling and fracturing operations to enable the target rock to be cracked and depressurized to form the artificial liberation layer;
s5, finishing the operation of the artificial liberation layer covering the working face, so that the coverage of the width of the artificial liberation layer is increased by 30-50m corresponding to each side boundary covering the working face, and after the stress environment during the working face stoping operation is improved, carrying out the working face stoping operation.
According to the invention, the integrity of the upper roof of the impact dangerous area is damaged in advance, so that the load is transferred to a more complete roof area, a low-stress operation large environment is provided for underground tunneling and stoping, the important load condition for starting the rock burst is also lost, the effect equivalent to the mining of a liberation layer is realized, the rock burst disaster during well construction is reduced or avoided, and the occurrence probability of the rock burst disaster during stoping of a working face is greatly reduced.
Optionally, in the step S1, based on geological data of the mine site, the target rock stratum where the artificial liberation layer is located is determined by adopting a main control key layer of coal mining and an analysis method of an energy transfer response and/or a main control key layer of microseism monitoring.
Further, in S2, specifically includes:
s21, simulating by using simulation calculation software or a discrete unit method program, performing numerical simulation and theoretical analysis on the structural form of the target rock stratum and the stress state of the liberated layer, so that the target rock stratum is in a caving zone and a fracture zone of equivalent coal seam exploitation, and is fully destroyed or the energy release of the target rock stratum is effectively reduced;
s22, analyzing stress change, crack development and surrounding rock structure characteristics of the released layer after exploitation of the equivalent coal seamThe method comprises the steps of obtaining stress sigma of a liberated layer under the exploitation of an equivalent coal seam lib ；
S23, analyzing the artificial liberation layer to enable the target rock stratum to be in a caving zone and a fracture zone of equivalent coal seam exploitation, and obtaining stress change, fracture development and surrounding rock structural characteristics of the liberation layer under the condition of sufficient damage or effective reduction of energy release of the target rock stratum, and obtaining stress sigma of the liberation layer under the artificial liberation layer exploitation art 。
Further, in S3, the criterion of the artificial liberation layer is defined as followsThe size of the artificial liberation layer simulation mining planning method is 4 kinds of classification on whether the current artificial liberation layer simulation mining planning is suitable for classification into artificial liberation layers or not, and the method comprises the following steps:
class I, when ζ is less than 0.25, the equivalent stress coefficient ζ is at unsuitable level;
class II, when the zeta is more than or equal to 0.25 and less than 0.5, the equivalent stress coefficient zeta is in a general level;
class III, when the zeta is more than or equal to 0.5 and less than 0.75, the equivalent stress coefficient zeta is at a proper level;
IV, when the value of the equivalent stress coefficient xi is more than or equal to 0.75, the equivalent stress coefficient xi is in a good grade.
Further, in S3, the step of determining the artificial release layer thickness includes:
s31, performing numerical simulation during equivalent coal seam mining by using simulation calculation software or discrete unit method program, respectively simulating mining processes of different coal seam thicknesses, and when the released layer reaches the mining requirement under the obtained equivalent coal seam mining, performing stress sigma of the released layer lib ；
S32, carrying out numerical simulation by using simulation calculation software or discrete unit method program, respectively simulating the mining processes of the artificial liberation layers with different thicknesses, using the caving zone and the fracture zone of the target rock stratum in the equivalent coal seam mining, fully destroying the target rock stratum as the discrimination basis, and simulating the artificial liberation layers to be opened when the same coal seam thickness is mined with the equivalent coal seamAcquiring stress sigma of the released layer under the exploitation of the released layer when the exploitation effect of the discrimination basis is reached in the exploitation process art ；
S33, judging according to the size of the zeta, and determining the mining thickness of the artificial liberation layer when the zeta is in class III and above, wherein the thickness is equivalent thickness, and representing the liberation effect when the artificial liberation layer reaches the determined proper liberation layer thickness mining.
Further, the projection of the coverage area of the artificial liberation layer on the layer where the working surface is located continuously covers all working surfaces between the transport lane and the return air lane;
the projection width direction of the artificial liberation layer coverage area on the working surface is set along the direction from the transportation lane to the return air lane, and the projection width of the artificial liberation layer coverage area on the working surface is larger than the distance between the transportation lane and the return air lane;
the projection length direction of the artificial liberation layer coverage area on the working surface is set along the length direction of the working surface, and the projection length of the artificial liberation layer coverage area on the working surface is larger than the length of the working surface.
Further, in S4, an artificial release layer evaluation model is established for analyzing, calculating and recording the equivalent stress σ of the artificial release layer under the current geological and topographic conditions eq Equivalent height H eq Equivalent thickness h eq To characterize the feasibility of the artificial release layer and to provide design criteria for the determination of the artificial release layer in step S4.
Further, the equivalent stress sigma required for establishing the artificial liberation layer judgment model eq Equivalent height H eq Equivalent thickness h eq The following are provided:
equivalent stress isWherein, xi is more than or equal to 0.5; equivalent height is H eq ＝H+h d Wherein H is the distance between the target layer and the coal seam, H d Distance from the fracturing well position to the bottom of the target layer; equivalent thickness is h eq ＝2h d H is less than or equal to 30m, wherein h is less than or equal to d To fracture the well position distanceDistance of the bottom of the target layer.
Further, in the step S4, performing well layout planning of the fracturing wells according to the coverage area of the artificial liberation layer and the thickness of the rock stratum determined in the step S3, including the number and the positions of the fracturing wells, wherein the fracturing wells include horizontal wells and vertical wells;
the horizontal well comprises a vertically arranged layer penetrating section, a fracturing section horizontally arranged on the target rock stratum and a steering section for connecting the layer penetrating section and the fracturing section, wherein the layer penetrating section, the fracturing section and the steering section are positioned in the same plane and used for performing large-range fracturing operation on the target rock stratum;
the vertical well is arranged on one side of the horizontal well penetrating section, which is away from the fracturing section, and is used for performing fracturing operation on a fracturing blind zone where the fracturing operation cannot be performed by the horizontal well.
Further, when the number of the horizontal wells arranged on the same target rock stratum is 2 or more, two adjacent horizontal wells are in a group, a construction site is shared, the extending directions of the fracturing sections of the two horizontal wells are opposite and are positioned in the same plane, and a vertical well is arranged between the two horizontal wells.
Further, in S4, in order to obtain the artificial liberation layer with the composite requirement, the fracturing well arrangement needs to be comprehensively determined according to the formation lithology, the fracturing property and the joint height, and on this basis, the fracturing operation position of the fracturing well is determined through numerical simulation by combining the artificial liberation layer effect requirement, the rock stratum structure state and the stress state of the liberation layer.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic overall process diagram of an artificial relief layer scour protection method for a stope face according to the present invention;
FIG. 2 is a schematic diagram of the specific steps S2 of an artificial relief layer scour protection method for a stope face according to the present invention;
FIG. 3 is a schematic diagram of the specific step S3 of an artificial relief layer scour protection method for a stope face according to the present invention;
FIG. 4 is a schematic illustration of a surface frac well layout after an artificial relief layer of a stope face artificial relief layer method according to the present invention is determined;
FIG. 5 is a schematic illustration of the fracturing effect of an artificial relief layer of a method of impact protection of an artificial relief layer of a stope face according to the present invention;
FIG. 6 is a schematic illustration of the post-fracturing effect of an artificial relief layer impact protection method for a stope face according to the present invention;
FIGS. 7 (a) and 7 (b) are schematic views showing arrangement modes of a roadway protection artificial relief layer according to an artificial relief layer impact prevention method of a stope face of the present invention;
FIGS. 8 (a) and 8 (b) are schematic diagrams of the layout of the face protection artificial relief layer according to a face relief layer scour protection method of the present invention;
FIG. 9 is a schematic illustration of a construction of a multi-working face artificial relief layer according to a method of mining face artificial relief layer scour protection of the present invention;
FIG. 10 is a schematic illustration of another construction of a multi-working face artificial relief layer according to an embodiment of the present invention;
fig. 11 is a schematic view of working face artificial relief layer construction according to a stope face artificial relief layer scour protection method of the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
The application provides an artificial relief layer anti-impact method for a stope face, and the method is described in detail below with reference to fig. 1 to 11.
An artificial relief layer anti-impact method for a stope face comprises the following steps:
s1, determining a target rock stratum where an artificial liberation layer is located above a stratum area with rock burst hidden danger, and measuring the thickness of the target rock stratum to obtain the thickness h of the target rock stratum;
s2, carrying out numerical simulation and theoretical analysis on the artificial liberation layer and the equivalent coal seam exploitation thereof to obtain stress sigma of the liberation layer under the equivalent coal seam exploitation lib And stress sigma of the released layer under artificial release layer mining art ；
S3, according to sigma lib Sum sigma art Defining an equivalent stress relief coefficient xi, establishing an artificial relief layer judgment criterion according to the equivalent stress relief coefficient, and carrying out division judgment on the artificial relief layer thickness and coverage area in the target rock stratum according to the judgment criterion;
s4, establishing an artificial liberation layer judging model according to the division judgment of the thickness and coverage area of the artificial liberation layer, arranging a ground fracturing well according to the model, and performing drilling and fracturing operations to enable the target rock to be cracked and depressurized to form the artificial liberation layer;
s5, finishing the operation of the artificial liberation layer covering the working face, so that the coverage of the width of the artificial liberation layer is increased by 30-50m corresponding to each side boundary covering the working face, and after the stress environment during the working face stoping operation is improved, carrying out the working face stoping operation.
According to the invention, the integrity of the upper roof of the impact dangerous area is damaged in advance, so that the load is transferred to a more complete roof area, a low-stress operation large environment is provided for underground tunneling and stoping, the important load condition for starting the rock burst is also lost, the effect equivalent to the mining of a liberation layer is further realized, and the occurrence probability of the rock burst disaster during stoping of a working face is greatly reduced.
In S1, determining a target rock stratum where an artificial liberation layer is located generally based on geological data of a mine location and actual mine operation environment conditions, and analyzing rock stratum above a rock burst dangerous area by a physical and mechanical property analysis method, a main control key layer and an energy transfer response analysis method and/or a micro-seismic monitoring main control key rock stratum analysis method, and determining the target rock stratum where the artificial liberation layer is located by combining a key layer theory.
When the main control key layer and the energy transfer response analysis are adopted, firstly, a key layer theory is utilized to determine a plurality of rock stratum key layers above a rock burst hidden danger stratum area, and as the rock stratum key layers of a plurality of different layers have different influences on rock burst degrees of a working surface, bending energy calculation is carried out on the plurality of rock stratum key layers, residual energy from a bottom to a coal layer of the working surface is calculated, energy transfer is determined according to energy release of each rock stratum key layer, and a target rock stratum where a theoretical artificial liberation layer is located is determined according to the residual energy, energy transfer and bending energy transferred from the plurality of rock stratum key layers to the coal layer of the working surface.
If a main control key rock stratum analysis method for microseismic monitoring is adopted, microseismic events of different energy levels for representing surrounding rock activities in the rock stratum are firstly obtained; secondly, analyzing whether surrounding rock activities mainly occur in the roof strata or not according to microseismic events of different energy levels; if so, analyzing the distribution layer positions of the large-energy events in the roof strata, and determining the layer positions where the large-energy events occur intensively as target strata where theoretical artificial liberation layers are located.
In some embodiments, a single analysis method or a plurality of analysis methods are selected according to actual conditions to determine the target rock stratum where the artificial liberation layer is located, and the selection of the plurality of analysis methods can be further mutually evidence, so that the determination of the target rock stratum where the artificial liberation layer is located is more accurate and reliable.
After the determination of the rock stratum where the artificial liberation layer is located is completed, the step S2 is needed to be carried out, and in S2, in order to determine the equivalent stress of the artificial liberation layer, the method specifically comprises the following steps:
s21, simulating by using simulation calculation software or a discrete unit method program, performing numerical simulation and theoretical analysis on the structural form of the target rock stratum and the stress state of the liberated layer, so that the target rock stratum is in a caving zone and a fracture zone of equivalent coal seam exploitation, and is fully destroyed or the energy release of the target rock stratum is effectively reduced;
s22, analyzing stress change, crack development and surrounding rock structural characteristics of the released layer after the equivalent coal seam exploitation to obtain stress sigma of the released layer under the equivalent coal seam exploitation lib ；
S23, analyzing the artificial liberation layer to enable the target rock stratum to be in a caving zone and a fracture zone of equivalent coal seam exploitation, and obtaining stress change, fracture development and surrounding rock structural characteristics of the liberation layer under the condition of sufficient damage or effective reduction of energy release of the target rock stratum, and obtaining stress sigma of the liberation layer under the artificial liberation layer exploitation art 。
Further, accomplish sigma lib Sum sigma art After calculation, the step S3 is carried out, and the stress sigma of the released layer caused by the artificial release layer is determined according to the ratio of the stress sigma and the equivalent stress release coefficient xi art Is converged to the stress sigma of the released layer caused by the exploitation of the equivalent coal seam lib That is to sayThe ratio of the two layers is more similar to 1, which means that the effect of the artificial liberation layer is more similar to the equivalent coal seam exploitation effect, so that the equivalent effect stress liberation coefficient xi is required to be divided, the liberation stress effect in the artificial liberation layer reaches the stress effect of the liberation layer exploitation, and the feasibility of the artificial liberation layer is ensured. In S3, the criterion of the artificial release layer is defined as +.>The size of the artificial liberation layer simulation mining planning method is 4 kinds of classification on whether the current artificial liberation layer simulation mining planning is suitable for classification into artificial liberation layers or not, and the method comprises the following steps:
class I, when ζ is less than 0.25, the equivalent stress coefficient ζ is at unsuitable level;
class II, when the zeta is more than or equal to 0.25 and less than 0.5, the equivalent stress coefficient zeta is in a general level;
class III, when the zeta is more than or equal to 0.5 and less than 0.75, the equivalent stress coefficient zeta is at a proper level;
IV, when the value of the equivalent stress coefficient xi is more than or equal to 0.75, the equivalent stress coefficient xi is in a good grade.
According to the classification of the equivalent stress coefficients, the rock stratum where the artificial liberation layer is located can be analyzed to simulate the rock stratum thickness of the artificial liberation layer, so that a data basis is provided for the establishment of a subsequent artificial liberation layer judgment model. The dividing and judging steps of the artificial liberation layer stratum thickness are as follows:
s31, performing numerical simulation during equivalent coal seam mining by using simulation calculation software or discrete unit method program, respectively simulating mining processes of different coal seam thicknesses, and when the released layer reaches the mining requirement under the obtained equivalent coal seam mining, performing stress sigma of the released layer lib ；
S32, carrying out numerical simulation by using simulation calculation software or discrete unit method program, respectively simulating the mining processes of the artificial liberation layers with different thicknesses, taking the falling zone and the fracture zone of the target rock stratum in equivalent coal seam mining, fully destroying the target rock stratum as the discrimination basis, simulating the mining processes of the artificial liberation layers when the equivalent coal seam mining is equal to each coal seam thickness, and acquiring the stress sigma of the liberation layer under the mining of the liberation layer by people when the mining effect of the discrimination basis is reached art ；
S33, judging according to the size of the zeta, and determining the mining thickness of the artificial liberation layer when the zeta is in class III and above, wherein the thickness is equivalent thickness, and representing the liberation effect when the artificial liberation layer reaches the determined proper liberation layer thickness mining.
After the thickness of the artificial liberation layer is determined through the step S3, planning the area coverage of the artificial liberation layer is required to be planned, and the projection of the coverage of the artificial liberation layer on the layer where the working surface is located continuously covers all working surfaces between the transport roadway and the return air roadway;
the projection width direction of the artificial liberation layer coverage area on the working surface is set along the direction from the transportation lane to the return air lane, and the projection width of the artificial liberation layer coverage area on the working surface is larger than the distance between the transportation lane and the return air lane;
the projection length direction of the coverage of the artificial liberation layer on the working surface is set along the length direction of the working surface, and the projection length of the coverage of the artificial liberation layer on the working surface is larger than the length of the working surface;
when the artificial liberation layer covers a single roadway or a plurality of roadways, the width coverage of the artificial liberation layer needs to span the rock stratum range corresponding to the single roadway or the plurality of roadways, and the width coverage of the artificial liberation layer correspondingly covers each side boundary of the roadway by 30-50m coverage, and the preferred coverage of the artificial liberation layer is 50m;
when the artificial release layer covers a single or multiple working surfaces, the width coverage of the artificial release layer needs to span the range of the rock stratum corresponding to the single or multiple working surfaces, and the width coverage of the artificial release layer correspondingly covers each side boundary of the working surfaces, and the coverage of the artificial release layer is more than 30-50m, and in this embodiment, the preferred range is 50m.
After finishing the area coverage of the artificial liberation layer and the determination of the rock stratum depth, entering into S4, and in S4, establishing an artificial liberation layer judgment model for analyzing, calculating and recording the equivalent stress sigma of the artificial liberation layer under the current geological topography condition eq Equivalent height H eq Equivalent thickness h eq To characterize the feasibility of the artificial release layer and to provide design criteria for the determination of the artificial release layer in step S4. In order to re-check the feasibility of the artificial liberation layer, an artificial liberation layer judging model is established, each data of the above artificial liberation layer is verified and judged, the feasibility of the artificial liberation layer is represented, and design criteria are provided for the determination of the artificial liberation layer. Wherein the equivalent stress sigma required by the artificial liberation layer flat model eq Equivalent height H eq Equivalent thickness h eq The following are provided:
equivalent stress isWherein, xi is more than or equal to 0.5; equivalent height is H eq ＝H+h d Wherein H is the distance between the target layer and the coal seam, H d Distance from the fracturing well position to the bottom of the target layer; equivalent thickness is h eq ＝2h d H is more than or equal to 30m, wherein,h d is the distance of the fracturing well location from the bottom of the target layer.
After the artificial liberation layer judgment model is established, not only the detection judgment is calculated on each data of the artificial liberation layer, but also the equivalent stress sigma can be used for eq Equivalent height H eq Equivalent thickness h eq And (3) calculating results, and giving out design criteria for the fracturing construction of the artificial liberation layer, namely, in the subsequent construction process, carrying out the design of the subsequent artificial liberation layer according to the design criteria given by the artificial liberation layer judgment model.
Specifically, when the protection coverage of the artificial liberation layer is determined, classifying according to the construction site, including protecting the artificial liberation layer of the roadway and protecting the artificial liberation layer of the working face;
the roadway protection artificial liberation layer is mainly used for protecting a dangerous roadway showing mine rock burst, the roadway with better impact risk is selected in a targeted manner, the range of the artificial liberation layer is smaller based on the roadway protection artificial liberation layer, the artificial liberation layer can effectively cover the roadway, and the roadway is in a low-stress area after the arrangement of the artificial liberation layer is completed;
the working surface protects the artificial liberation layer, mainly for the working surface with high risk, the impact risk of the working surface does not have obvious area characteristics, the overall impact risk of the working surface is higher, the risk of occurrence of mineral shock or rock burst is provided, therefore, the working surface needs to be effectively protected for the whole range of the working surface, and the artificial liberation layer has larger range and more embodiments, and referring to fig. 9 to 10, for example: the working face protection artificial liberation layer can be constructed by adopting a construction mode of transversely crossing the working face, so that the large-scale anti-impact effect of the mining area range is realized, and the problem of larger-scale rock burst source management of the mining area is solved; the construction of the artificial liberation layer of the key area can be carried out on the coverage area of the single working face step by step, so that the rock burst source management of each working face scale is solved step by step;
however, in either embodiment, it is desirable to effectively cover the entire working surface, and in some embodiments, the extent of the artificial relief layer may be zoned according to the impact risk such that after placement of the artificial relief layer is completed, the working surface is in a low stress zone, a low energy zone for the release of surrounding rock activity.
After the coverage area and the rock stratum depth of the artificial liberation layer are determined, well layout operation of the ground fracturing well and subsequent fracturing operation can be started after the feasibility of the artificial liberation layer judging model is checked. Therefore, after the artificial liberation layer is subjected to fracturing and pressure relief operation, the stress in the coal bed which is required to be developed, tunneled or extracted at the moment is changed, and the high-pressure area is changed into the low-pressure area, so that the construction operation of the excavation well establishment operation, the excavation collection operation and the extraction working face can be safely carried out.
Thus, in S4, performing a fracturing well layout plan according to the artificial liberation layer coverage and the formation thickness determined in S3, including the number and location of fracturing wells, wherein the fracturing wells include horizontal wells and vertical wells;
the horizontal well comprises a vertically arranged layer penetrating section, a fracturing section horizontally arranged on the target rock stratum and a steering section for connecting the layer penetrating section and the fracturing section, wherein the layer penetrating section, the fracturing section and the steering section are positioned in the same plane and used for performing large-range fracturing operation on the target rock stratum;
the vertical well is arranged on one side of the horizontal well penetrating section, which is away from the fracturing section, and is used for performing fracturing operation on a fracturing blind zone where the fracturing operation cannot be performed by the horizontal well.
When the number of the horizontal wells arranged on the same target rock stratum is 2 or more, two adjacent horizontal wells are in a group, a construction site is shared, the extending directions of the fracturing sections of the two horizontal wells are opposite and are in the same plane, and a vertical well is arranged between the two horizontal wells.
Specifically, determining the type and the number of the adopted fracturing wells according to the occurrence state of the target rock stratum comprises the following steps:
determining the number of horizontal wells according to A= [ target formation length/1500 ] +a, wherein a takes 1 when the remainder of the target formation length/1500 is greater than 500 m; when the remainder of the target rock stratum length/1500 is not more than 500m, a is 0, and A is the number of horizontal wells;
determining the staged fracturing number of the horizontal well in the vertical direction according to B= [ target stratum thickness/100 ], wherein the remainder of the target stratum thickness/100 is 0, and B is the quotient of the target stratum thickness/100; when the remainder of the target rock stratum thickness/100 is not 0, B is an integer quotient +1 of the target rock stratum thickness/100;
determining the number of vertical wells according to C= [ (target formation length-1500.A)/500 ] + [ A/2] +b, wherein the formula is: taking the calculation result when the target stratum length-1500.A only takes the positive value, and taking 1 when the (target stratum length-1500.A)/500 is the positive fraction; when (target formation length-1500. A)/500 is a non-positive fraction, b takes 0.
Determining the position relationship of the fracturing wellhead according to the number of the fracturing wells comprises the following steps:
when the number A of the horizontal wells is equal to 0, the number C of the vertical wells is equal to 1, and the wellhead of the vertical well is positioned on the ground corresponding to the center of the target rock stratum;
when the number A of the horizontal wells is equal to 1, if the number C of the vertical wells is 0 at the moment, adopting the ground corresponding to the wellhead position of the horizontal well outside the boundary of the target rock stratum; if the number C of the vertical wells is 1, adopting the situation that the wellhead positions of the vertical wells and the horizontal wells are positioned on the ground corresponding to the target stratum, and sharing a ground construction site;
when the number A of the horizontal wells is more than or equal to 2, each 2 horizontal wells need to share a ground construction site, a vertical well needs to be arranged in the middle of the 2 horizontal wells, the vertical well and the 2 horizontal wells also share a ground construction site, and the rest 1 vertical well or the horizontal well are separately arranged on the ground construction site.
After well arrangement is completed, constructors can carry out fracturing operation according to fracturing positions obtained through numerical simulation, after the fracturing operation is completed, a thick-layer top plate which is difficult to collapse and easy to release in high energy can be easily crushed in transformation, the transformed thick-layer top plate is changed into a low-energy area from a disaster-causing rock stratum in high energy, the thick-layer top plate is changed into a short-small breaking characteristic from a long-sized and large-sized part, and the mining stress environment below the thick-layer top plate is reduced into a low-pressure area from high stress, so that the releasing layer effect of an artificial releasing layer is realized.
After the setting of the artificial liberation layer is finished, namely the artificial liberation layer is formed on the thick-layer top plate which is difficult to collapse above the working surface, so that the stress environment of the working surface is improved, S5 step can be carried out, and the stoping operation of the working surface is carried out under the condition of low stress, thereby greatly reducing or avoiding the occurrence probability of rock burst disasters during the stoping of the working surface.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the invention, the scope of which is defined by the claims and their equivalents.
Claims (11)
1. The method for preventing the impact of the artificial relief layer of the stope face is characterized by comprising the following steps of:
s1, determining a target rock stratum where an artificial liberation layer is located above a stratum area with rock burst hidden danger, and measuring the thickness of the target rock stratum to obtain the thickness h of the target rock stratum;
s2, carrying out numerical simulation and theoretical analysis on the artificial liberation layer and the equivalent coal seam exploitation thereof to obtain stress sigma of the liberation layer under the equivalent coal seam exploitation lib And stress sigma of the released layer under artificial release layer mining art ；
S3, according to sigma lib Sum sigma art Defining an equivalent stress relief coefficient xi, establishing an artificial relief layer judgment criterion according to the equivalent stress relief coefficient, and carrying out division judgment on the artificial relief layer thickness and coverage area in the target rock stratum according to the judgment criterion;
s4, establishing an artificial liberation layer judging model according to the division judgment of the thickness and coverage area of the artificial liberation layer, arranging a ground fracturing well according to the model, and performing drilling and fracturing operations to enable the target rock to be cracked and depressurized to form the artificial liberation layer;
s5, finishing the operation of the artificial liberation layer covering the working face, so that the coverage of the width of the artificial liberation layer is increased by 30-50m corresponding to each side boundary covering the working face, and after the stress environment during the working face stoping operation is improved, carrying out the working face stoping operation.
2. The method for preventing the artificial liberation layer of the stope face according to claim 1, wherein in the step S1, the target rock stratum where the artificial liberation layer is located is determined by adopting a main control key layer of coal mining and an analysis method of an energy transfer response and/or microseismic monitoring main control key layer based on geological data of a mine location.
3. The method for preventing the impact of an artificial relief layer of a stope face according to claim 1, wherein in S2, specifically comprising:
s21, simulating by using simulation calculation software or a discrete unit method program, performing numerical simulation and theoretical analysis on the structural form of the target rock stratum and the stress state of the liberated layer, so that the target rock stratum is in a caving zone and a fracture zone of equivalent coal seam exploitation, and is fully destroyed or the energy release of the target rock stratum is effectively reduced;
s22, analyzing stress change, crack development and surrounding rock structural characteristics of the released layer after the equivalent coal seam exploitation to obtain stress sigma of the released layer under the equivalent coal seam exploitation lib ；
S23, analyzing the artificial liberation layer to enable the target rock stratum to be in a caving zone and a fracture zone of equivalent coal seam exploitation, and obtaining stress change, fracture development and surrounding rock structural characteristics of the liberation layer under the condition of sufficient damage or effective reduction of energy release of the target rock stratum, and obtaining stress sigma of the liberation layer under the artificial liberation layer exploitation art 。
4. A method of protecting an artificial relief layer of a stope face as claimed in claim 3, wherein in S3 the criterion for said artificial relief layer is defined in terms of ζ asThe size of the artificial liberation layer simulation mining planning method is 4 kinds of classification on whether the current artificial liberation layer simulation mining planning is suitable for classification into artificial liberation layers or not, and the method comprises the following steps:
class I, when ζ is less than 0.25, the equivalent stress coefficient ζ is at unsuitable level;
class II, when the zeta is more than or equal to 0.25 and less than 0.5, the equivalent stress coefficient zeta is in a general level;
class III, when the zeta is more than or equal to 0.5 and less than 0.75, the equivalent stress coefficient zeta is at a proper level;
IV, when the value of the equivalent stress coefficient xi is more than or equal to 0.75, the equivalent stress coefficient xi is in a good grade.
5. The method for preventing a drift of an artificial relief layer of a stope face according to claim 4, wherein in S3, the step of determining the division of the artificial relief layer thickness is:
s31, application imitationNumerical simulation is carried out when equivalent coal seam exploitation is carried out by true calculation software or discrete unit method program, exploitation processes of different coal seam thicknesses are respectively simulated, and under the obtained equivalent coal seam exploitation, when the liberated layer reaches the exploitation requirement, the stress sigma of the liberated layer is reduced lib ；
S32, carrying out numerical simulation by using simulation calculation software or discrete unit method program, respectively simulating the mining processes of the artificial liberation layers with different thicknesses, taking the falling zone and the fracture zone of the target rock stratum in equivalent coal seam mining, fully destroying the target rock stratum as the discrimination basis, simulating the mining processes of the artificial liberation layers when the equivalent coal seam mining is equal to each coal seam thickness, and acquiring the stress sigma of the liberation layer under the mining of the liberation layer by people when the mining effect of the discrimination basis is reached art ；
S33, judging according to the size of the zeta, and determining the mining thickness of the artificial liberation layer when the zeta is in class III and above, wherein the thickness is equivalent thickness, and representing the liberation effect when the artificial liberation layer reaches the determined proper liberation layer thickness mining.
6. The method for preventing impact of an artificial liberation layer of a stope face according to claim 1, wherein the projection of the coverage area of the artificial liberation layer on the layer where the working face is located continuously covers all working faces between a transport roadway and a return roadway;
the projection width direction of the artificial liberation layer coverage area on the working surface is set along the direction from the transportation lane to the return air lane, and the projection width of the artificial liberation layer coverage area on the working surface is larger than the distance between the transportation lane and the return air lane;
the projection length direction of the artificial liberation layer coverage area on the working surface is set along the length direction of the working surface, and the projection length of the artificial liberation layer coverage area on the working surface is larger than the length of the working surface.
7. The method for preventing impact of artificial liberation layer of stope face as claimed in claim 1, wherein in S4, an artificial liberation layer judgment model is built for analyzing, calculating and recording the man-made under the current geological topography conditionEquivalent stress sigma of liberation layer eq Equivalent height H eq Equivalent thickness h eq To characterize the feasibility of the artificial release layer and to provide design criteria for the determination of the artificial release layer in step S4.
8. The method for preventing impact of artificial relief layer of stope face according to claim 7, wherein equivalent stress sigma required for building artificial relief layer evaluation model eq Equivalent height H eq Equivalent thickness h eq The following are provided:
equivalent stress isWherein, xi is more than or equal to 0.5; equivalent height is H eq ＝H+h d Wherein H is the distance between the target layer and the coal seam, H d Distance from the fracturing well position to the bottom of the target layer; equivalent thickness is h eq ＝2h d H is less than or equal to 30m, wherein h is less than or equal to d Is the distance of the fracturing well location from the bottom of the target layer.
9. The method for preventing the flushing of the artificial liberation layer of the stope face according to claim 1, wherein in the step S4, the well layout planning of the fracturing well is carried out according to the coverage range of the artificial liberation layer and the thickness of the rock stratum determined in the step S3, wherein the fracturing well comprises the number and the positions of the fracturing wells, and the fracturing well comprises a horizontal well and a vertical well;
the horizontal well comprises a vertically arranged layer penetrating section, a fracturing section horizontally arranged on the target rock stratum and a steering section for connecting the layer penetrating section and the fracturing section, wherein the layer penetrating section, the fracturing section and the steering section are positioned in the same plane and used for performing large-range fracturing operation on the target rock stratum;
the vertical well is arranged on one side of the horizontal well penetrating section, which is away from the fracturing section, and is used for performing fracturing operation on a fracturing blind zone where the fracturing operation cannot be performed by the horizontal well.
10. The method for preventing a fault in an artificial relief layer of a stope according to claim 9, wherein when the number of horizontal wells provided for the same target rock formation is 2 or more, two adjacent horizontal wells are grouped together, a construction site is shared, the fracturing sections of the two horizontal wells are opposite in extending direction and are located in the same plane, and a vertical well is provided between the two horizontal wells.
11. The method for preventing the flushing of the artificial relief layer of the stope face according to claim 10, wherein in the step S4, in order to obtain the artificial relief layer with composite requirements, the arrangement of the fracturing well is comprehensively determined according to the lithology, the fracking property and the height of the stratum, and the fracturing operation position of the fracturing well is determined through numerical simulation by combining the artificial relief layer effect requirements, the rock stratum structure state and the stress state of the relief layer.
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