Method for preventing and treating mine earthquake in goaf of thick and hard roof by ground super deep hole pre-splitting blasting

Abstract

The application discloses a method for preventing and treating mine earthquake in a goaf of thick and hard roof by ground super-deep hole pre-splitting blasting, and is characterized in that: the method comprises the following steps: determining a target rock stratum of mine earthquake treatment, determining a position of a maximum surface subsidence point according to a surface subsidence curve, optimizing a ground drilling construction area according to a rock stratum structure, determining a first group of drilling construction positions, performing ground drilling construction, charging and blasting a pre-splitting target rock stratum, performing construction of adjacent ground drilling, charging and blasting of adjacent drilling, forming a blasting fissure surface, and performing blasting effect inspection, so that pre-splitting weakening of a key layer of mine earthquake is realized, and the occurrence risk of mine earthquake in the goaf of thick and hard roof is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of coal mine dynamic disaster prevention and treatment, and particularly relates to a method for preventing and treating mine earthquake in a goaf of thick and hard roof by ground super-deep hole pre-splitting blasting. BACKGROUND

[0002] Mine earthquake, also known as mining-induced earthquake, is a vibration phenomenon caused by the rapid release of elastic energy of rock mass disturbed by mining. In a narrow sense, mine earthquake usually refers to the mine earthquake caused by the breaking and sliding of thick and hard rock layer above the goaf. The energy of this kind of mine earthquake is usually greater than 10 5 J, the magnitude is greater than 2.0, and obvious seismic sensation is easily formed on the ground, most of which can be recorded by the seismic network and has vibration and disaster-causing properties.

[0003] In recent years, with the expansion of the mining area and the increase of the mining depth, the frequency of mine earthquake increases year by year. Mine earthquake not only has the risk of inducing coal mine underground rock burst, which seriously threatens the safety production of the mine, but also causes obvious ground seismic sensation, which further deteriorates the ecological environment of the mining area. The main means for treating mine earthquake in the goaf include mining layout optimization, goaf separation grouting and ground hydraulic fracturing, etc. However, the above means have certain limitations in application. For example, mining layout optimization often needs to add new mining area, adjust the mining sequence, and excavate a large number of roadways, the connection adjustment period is long, and the mine production capacity cannot be guaranteed during the adjustment period; the goaf separation grouting has a long construction period, the filling rate is difficult to guarantee, and it lacks timeliness for mine earthquake prevention and treatment; the ground hydraulic fracturing has a long construction period, high construction cost, and the fracturing effect is difficult to directly verify. Therefore, it is an urgent problem to be solved in the current coal mine safety production field to provide a method for preventing and treating mine earthquake in the goaf, which has low cost, high timeliness and verifiable effect. SUMMARY

[0004] The purpose of the present application is to provide a method for preventing and treating mine earthquake in a goaf of thick and hard roof by ground super-deep hole pre-splitting blasting, which solves the problems of long construction period and poor timeliness in the prior art.

[0005] The technical scheme adopted by the present application is that the method for preventing and treating mine earthquake in a goaf of thick and hard roof by ground super-deep hole pre-splitting blasting determines the target rock layer for mine earthquake treatment, determines the position of the maximum ground subsidence point according to the ground subsidence curve, optimizes the ground drilling construction area according to the rock structure, determines the construction position of the first group of drill holes, constructs the ground drill holes, pre-splits the target rock layer by charging and blasting, constructs the adjacent ground drill holes, charges and blasts the adjacent drill holes, forms the blasting fracture surface and verifies the blasting effect, so as to realize the pre-softening of the key layer of mine earthquake and reduce the occurrence risk of mine earthquake in the goaf of thick and hard roof.

[0006] The present application also has the characteristics that,

[0007] The present application is implemented according to the following steps:

[0008] Step 1, determining the target rock stratum of the goaf mine shock treatment;

[0009] Step 2, determining the distance of the maximum subsidence point on the ground surface from the working face and the distance of the maximum subsidence point on the inclination from the middle of the goaf;

[0010] Step 3, determining the ground drilling construction area;

[0011] Step 4, selecting the first group of ground drilling construction positions in the ground drilling construction area;

[0012] Step 5, conducting construction.

[0013] Step 1 is implemented according to the following steps:

[0014] Step 1.1, according to the working face drilling comprehensive columnar chart, determining the target rock stratum of the working face mine shock treatment, the target rock stratum is single or combined thick hard roof rock stratum; when the target horizon is a single rock stratum, the uniaxial compressive strength and thickness respectively exceed σ c and H; when the target horizon is a composite rock stratum, the average uniaxial compressive strength and composite thickness of the rock stratum respectively exceed and ΣH;

[0015] Step 1.2, according to the position of high-energy mine shock occurrence in the working face range, selecting the drilling comprehensive columnar chart closest to the mine shock occurrence position; the main key layer in the rock stratum of the drilling comprehensive columnar chart is determined, and the main key layer is the target rock stratum of the goaf mine shock treatment;

[0016] The discrimination condition of the target rock stratum in Step 1.2 is related to the composite form of the main key layer, when the main key layer is a single rock stratum, the discrimination condition is: σ c ≥ 60 MPa, H ≧ 50 m; when the main key layer is a composite rock stratum, the discrimination condition is: ∑H ≥ 200 m.

[0017] Step 2 is implemented according to the following steps:

[0018] Step 2.1, according to the target working face strike and inclination surface subsidence observation curve, determining the distance P of the maximum subsidence point on the ground surface from the working face and the distance S of the maximum subsidence point on the inclination from the middle of the goaf; according to the target working face surface displacement observation results, drawing the distance from the open-off cut distance-surface subsidence relationship curve along the working face strike, and drawing the distance from the goaf middle distance-surface subsidence relationship curve along the working face inclination;

[0019] Step 2.2, the current advancing degree X1 of the working face, the horizontal coordinate X2 of the maximum subsidence point position in the distance from the open-off cut to the surface subsidence amount relationship curve, the distance P of the maximum subsidence point on the surface trend lagging behind the working face from the middle of the goaf = X1-X2, the vertical coordinate Y of the maximum subsidence point position in the distance from the middle of the goaf to the surface subsidence amount relationship curve, the distance S of the maximum subsidence point deviating from the middle of the goaf = |Y|.

[0020] Step 3 is implemented according to the following steps:

[0021] Step 3.1, when the mine has key stratum thickness distribution contour data, draw a target stratum thickness distribution contour map; when the mine has no key stratum thickness distribution contour data, select all geological drill holes within the range of the target working face, and draw a stratum structure map of the geological drill holes along the working face trend;

[0022] Step 3.2, according to the target stratum thickness distribution contour map, exclude rectangular areas within the range of the working face with single stratum thickness less than H or combined thickness less than ΣH;

[0023] Step 3.3, according to the stratum structure map of the drill holes within the range of the target working face, exclude rectangular areas within the range of the working face with key stratum thickness less than H or combined thickness less than ΣH; when the key stratum is a single key stratum, exclude rectangular areas within the range of the working face with key stratum thickness H<50m; when the key stratum is a composite key stratum, exclude rectangular areas within the range of the working face with key stratum combined thickness ΣH<200m;

[0024] Step 3.4, after excluding the rectangular areas within the range of the working face that do not meet the requirements, the remaining area is the determined ground drill hole construction area.

[0025] Step 4 is implemented according to the following steps:

[0026] Step 4.1, pre-select the first group of drill hole construction positions as the position of the maximum surface subsidence point, deviate from the middle of the goaf S, lag behind the working face distance P, and determine whether the position of the maximum surface subsidence point is within the ground drill hole construction area;

[0027] Step 4.2, if the position of the maximum surface subsidence point is within the ground drill hole construction area, then the first group of drill hole construction positions is determined as the position of the maximum surface subsidence point;

[0028] Step 4.3, if the position of the maximum surface subsidence point is not within the ground drill hole construction area, then draw the distance from the open-off cut, i.e. the surface subsidence rate relationship curve along the working face trend, determine the horizontal coordinate X3 of the maximum subsidence rate point position on the surface trend, and calculate the maximum subsidence rate point lagging behind the working face distance Q = X1-X3;

[0029] Step 4.4, determine whether the maximum point of surface subsidence rate along the working face is in the preferred ground drilling construction area, if yes, determine the specific construction position of the first group of drillings as follows: offset from the middle of the goaf S, lag behind the working face distance Q, continuously repeat steps 4.1 to 4.3 as the working face is continuously mined, and when the maximum subsidence point position or the maximum subsidence rate position is in the ground drilling construction area in step 3, determine the construction position of the first group of ground drillings; if not, it indicates that there is no need to conduct ground super-deep hole presplitting blasting at the current mining stage of the working face.

[0030] Step 5 is implemented according to the following steps:

[0031] Step 5.1, determine the charging, hole sealing and detonation range of the first group of ground drillings;

[0032] Step 5.2, conduct blasting of the first group of ground drillings;

[0033] Step 5.3, sequentially conduct drilling and blasting of each subsequent group;

[0034] Step 5.4, conduct construction inspection drilling and inspect the blasting effect.

[0035] Step 5.1 is specifically:

[0036] Step 5.1.1, drill the first group of ground drillings along the direction perpendicular to the ground until the drillings cover more than 80% of the thickness of the target rock stratum for mine shock control; the construction length L of the ground drilling and the depth H of the main key stratum Z There is a relationship: when the main key stratum is a single rock stratum, L≥H z -0.2H; when the main key stratum is a composite rock stratum, L≥H z -0.2ΣH;

[0037] Step 5.1.2, the charging length of a single group of drillings needs to cover at least 80% of the thickness of the target stratum for mine shock control, the length of the hole sealing section of the drilling is not less than 1 / 5 of the drilling depth, the drilling uses electronic detonators, single-hole single-time detonation, i.e. only one blast hole is detonated each time, and in the drilling structure design, the diameter C1 of the cartridge and the diameter C2 of the drilling hole satisfy the following relationship: 1.3≦C2 / C1≦1.7. Increasing the action time of the blast gas on the hole wall fully expands the blast cracks, which can maximize the cracking effect of the explosive on the mine shock target rock stratum.

[0038] Step 5.1.3, the blast drillings are arranged in a straight line, and the drilling blast forms a crack network perpendicular to the ground and parallel or perpendicular to the direction of the open-off cut, and in the drilling blast scheme, the drilling spacing D satisfies the following condition: 10≦D≦30. This promotes the interpenetration of cracks between the blast drillings, forms a blast crack network, and performs directional cutting on the mine shock target rock stratum in a single direction.

[0039] The water gel explosive with good water resistance is filled to the ground drill hole, the explosive column is placed into the drill hole, the explosive filling height covers all the target rock strata of the mine shock treatment, two detonating cords are fixed along the two sides of the explosive roll and extended to the orifice, the drill hole is sealed by cement mortar, the explosive is initiated after the sealing is completed, the second group of ground drill holes are constructed at the position D apart from the first group of drill holes along the direction parallel or perpendicular to the cut, and the second group of ground super deep hole pre-splitting blasting is sequentially executed, the ground drill hole construction is continuously performed along the original direction, and the charging and blasting are repeatedly performed, so that a row of ground super deep hole pre-splitting blasting drill holes are formed, which are symmetrical to the first group of drill holes and have a distance D.

[0040] Step 5.4 is specifically as follows: a group of ground drill holes are constructed in the middle of two groups of adjacent ground drill holes, the drill hole peeping is performed, and the fracture development of the rock strata in the hole is evaluated; a group of test drill holes are constructed in the middle of the connecting line of the two groups of adjacent blasting drill holes, the distance between the test drill hole and the blasting drill hole is D / 2, wherein D is the blasting drill hole spacing, and the blasting effect is tested.

[0041] The beneficial effects of the present application are as follows:

[0042] 1. The present application comprehensively considers the thickness of the key layer in the goaf, the structure and distribution law of the key layer for the blasting drill hole design, accurately positions the first group of ground blasting drill hole construction positions according to the surface subsidence curve of the target working face, accurately pre-cracks the target rock strata of the mine shock, and avoids blind large-area construction, so that the mine shock treatment is more targeted.

[0043] 2. The present application performs the drill hole peeping and the in-hole television imaging test on the blasting effect, and the test drill hole can be repeatedly blasted, so that the present application has the advantages of short engineering cycle, strong timeliness and testable blasting effect compared with the existing mine shock treatment method, and has strong applicability to the coal mine site. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 is the flow chart of the ground super deep hole pre-splitting blasting method for preventing and treating the mine shock in the thick and hard roof goaf of the present application;

[0045] Figure 2 is the drill hole columnar chart of the target working face in the embodiment 3 of the present application;

[0046] Figure 3 is the determination schematic diagram of the position of the maximum surface subsidence point in the embodiment 3 of the present application;

[0047] Figure 4 is the schematic diagram of the preferred ground drill hole construction area through the rock stratum thickness contour line in the embodiment 3 of the present application.

[0048] Figure 5is a schematic diagram of a ground super-deep hole pre-splitting blasting drilling structure in embodiment 3 of the present application;

[0049] Figure 6 is a schematic diagram of a ground super-deep hole pre-splitting blasting drilling arrangement principle in embodiment 3 of the present application;

[0050] Figure 7 is an I-I sectional view of the stratum in embodiment 3 of the present application;

[0051] Figure 8 is a schematic diagram of a drilling arrangement position inspection in embodiment 3 of the present application. DETAILED DESCRIPTION

[0052] The present application will be described in detail below in combination with the drawings and specific embodiments.

[0053] Embodiment 1

[0054] The present application is a method for preventing and treating goaf mining earthquake of thick and hard roof by ground super-deep hole pre-splitting blasting, which specifically determines the target rock stratum of mining earthquake treatment, determines the position of the maximum surface subsidence point according to the surface subsidence curve, optimizes the ground drilling construction area according to the rock stratum structure, determines the first group of drilling construction positions, constructs the ground drilling, pre-splits the target rock stratum by charging and blasting, constructs the adjacent ground drilling, charges and blasts the adjacent drilling, forms the blasting fracture surface, and inspects the blasting effect, so as to realize the pre-splitting weakening of the key layer of mining earthquake, effectively reduce the occurrence risk of goaf mining earthquake of thick and hard roof, and is suitable for the prevention and treatment of induced felt earthquake in mining activities, especially for the prevention and treatment of mining earthquake induced by coal mining with a buried depth greater than 600m, a large goaf area, and thick and hard roof difficult to collapse in time.

[0055] Embodiment 2

[0056] The flow is shown in Figure 1 , and is specifically implemented according to the following steps:

[0057] Step 1, determine the target rock stratum of goaf mining earthquake treatment, which is specifically implemented according to the following steps:

[0058] Step 1.1, select the target working face, determine the target rock stratum of working face mining earthquake treatment according to the working face drilling comprehensive columnar diagram, and the target rock stratum is single or combined thick and hard roof stratum; when the target layer is a single rock stratum, the uniaxial compressive strength and thickness respectively exceed c and H; when the target layer is a composite rock stratum, the average uniaxial compressive strength and composite thickness respectively exceed and ΣH;

[0059] Step 1.2, according to the position of high-energy mine earthquake occurring in the range of working face, select the drilling comprehensive columnar chart closest to the position of mine earthquake occurring; the main key layer in the drilling comprehensive columnar chart is the target rock stratum of goaf mine earthquake treatment;

[0060] The discrimination condition of target rock stratum in step 1.2 is related to the composite form of main key layer, when the main key layer is single rock stratum, the discrimination condition is: σ c ≥ 60 MPa, H ≧ 50 m; when the main key layer is composite rock stratum, the discrimination condition is: ∑H ≥ 200 m.

[0061] Step 2, determine the distance of surface trend maximum subsidence point lagging behind working face and the distance of surface tendency maximum subsidence point offsetting the middle of goaf;

[0062] Step 2.1, according to the surface subsidence observation curve of target working face trend and tendency, determine the distance P of surface trend maximum subsidence point lagging behind working face and the distance S of surface tendency maximum subsidence point offsetting the middle of goaf; according to the surface rock movement observation results of target working face, draw the distance from open-off cut-distance-surface subsidence relationship curve along the working face trend and the distance from goaf middle-distance-surface subsidence relationship curve along the working face tendency;

[0063] Step 2.2, mark the current working face advance degree X1, the horizontal coordinate X2 of the maximum subsidence point position in the distance from open-off cut-distance-surface subsidence relationship curve, the distance P of surface trend maximum subsidence point lagging behind working face = X1-X2, the vertical coordinate Y of the maximum subsidence point position in the distance from goaf middle-distance-surface subsidence relationship curve, and the distance S of surface tendency maximum subsidence point offsetting the middle of goaf = |Y|.

[0064] Step 3, determine the ground drilling construction area;

[0065] Step 3.1, when the mine has main key layer thickness distribution contour data, draw the target rock stratum thickness distribution contour map; when the mine has no main key layer thickness distribution contour data, select all geological drill holes in the range of target working face and draw the rock stratum structure map of geological drill holes along the working face trend;

[0066] Step 3.2, according to the target rock stratum thickness distribution contour map, exclude the rectangular area with single rock stratum thickness less than H or combined thickness less than ∑H in the range of working face;

[0067] Step 3.3, excluding the rectangular area in which the thickness of the main key stratum is less than H or the combined thickness is less than∑H in the stratum structure diagram of the borehole in the target working face range; when the main key stratum is a single key stratum, excluding the rectangular area in which the thickness of the main key stratum is less than 50 m in the working face range; when the main key stratum is a composite key stratum, excluding the rectangular area in which the combined thickness of the main key stratum is less than 200 m in the working face range;

[0068] Step 3.4, after excluding the rectangular area that does not meet the requirements in the working face range, the remaining area is the determined ground drilling construction area.

[0069] Step 4, selecting a first group of ground drilling construction positions in the ground drilling construction area;

[0070] Step 4.1, pre-selecting the first group of drilling construction positions as the ground surface maximum subsidence point position, offsetting the middle of the goaf S, lagging behind the working face distance P, and determining whether the ground surface maximum subsidence point position is in the ground drilling construction area;

[0071] Step 4.2, if the ground surface maximum subsidence point position is in the ground drilling construction area, then the first group of drilling construction positions is determined as the ground surface maximum subsidence point position;

[0072] Step 4.3, if the ground surface maximum subsidence point position is not in the ground drilling construction area, then a distance curve from the open-off cut is drawn along the working face trend, that is, a ground surface subsidence rate relationship curve, the horizontal coordinate X3 of the ground surface trend subsidence rate maximum point position is determined, and the ground surface trend subsidence rate maximum point lagging behind the working face distance Q=X1-X3 is calculated;

[0073] Step 4.4, determining whether the ground surface trend subsidence rate maximum point is in the preferred ground drilling construction area, if so, determining the specific construction position of the first group of drilling holes as: offsetting the middle of the goaf S, lagging behind the working face distance Q, and continuously repeating the determination steps 4.1 to 4.3 as the working face mining continues, when the trend maximum subsidence point position or the maximum subsidence rate position is in the ground drilling construction area in step 3, the first group of ground drilling construction positions is determined; if not, it indicates that there is no need to perform ground super-deep hole pre-splitting blasting at the current mining stage of the working face.

[0074] Step 5, performing construction;

[0075] Step 5.1, determining the charging, hole sealing, and detonation range of the first group of ground drilling holes;

[0076] Step 5.1.1, drilling the first group of ground drilling holes along the direction perpendicular to the ground until the drilling holes cover more than 80% of the thickness of the target stratum for mine shock control; the construction length L of the ground drilling hole and the depth H of the main key stratum Z There is the following relationship: when the main key stratum is a single stratum, L≥H z-0.2H; when the main key layer is a composite rock layer, L≥H z -0.2∑H;

[0077] Step 5.1.2, the length of the single group of drill hole charge section needs to cover at least 80% of the thickness of the mine shock treatment target layer, the reserved length of the borehole detonating cord at the hole mouth is not less than 1 meter, the length of the drill hole sealing section is not less than 1 / 5 of the drill hole depth, the drill hole uses electronic detonator, single hole single initiation, that is, only one blast hole is initiated at each time of blasting, in the design of the drill hole structure, the diameter C1 of the cartridge and the diameter C2 of the drill hole satisfy the following relationship: 1.3≦C2 / C1≦1.7. The time of the action of the blast gas on the hole wall is increased, and the blast cracks are fully expanded, which can maximize the crack effect of the explosive on the mine shock target rock layer through field verification.

[0078] Step 5.1.3, the blast drill holes are arranged in a straight line, and the blast drill holes form a crack network perpendicular to the ground and parallel or perpendicular to the cut direction after the blast, in the blast drill hole scheme, the drill hole spacing D satisfies the following condition: 10≦D≦30. The cracks between the blast drill holes are promoted to penetrate each other to form a blast crack network, and the mine shock target rock layer is cut in a single direction.

[0079] Step 5.2, first group of ground drill hole blasting is performed;

[0080] The ground drill hole is filled with water gel explosive with good water resistance, the explosive column is placed into the drill hole, the explosive filling height covers all the mine shock treatment target rock layer, and two detonating cords are fixed along the two sides of the explosive column and extended to the hole mouth; the drill hole is sealed with cement mortar, and the explosive is initiated after the sealing is completed;

[0081] Step 5.3, subsequent groups of drill holes and blasting are sequentially performed;

[0082] The second group of ground drill holes are constructed at a distance of D from the first group of drill holes along the parallel or perpendicular direction of the cut, and the process is sequentially performed to complete the second group of ground super deep hole pre-splitting blasting; the ground drill hole construction is continuously performed along the original direction, and the charging and blasting are repeatedly performed to form a row of ground super deep hole pre-splitting blast drill holes symmetrical to the first group of drill holes with a spacing of D;

[0083] Step 5.4, inspection drill hole construction and blasting effect inspection are performed;

[0084] Two groups of adjacent ground drill holes are randomly selected, a group of ground drill holes are constructed in the middle of the drill holes, the drill holes are viewed, and the crack development of the rock layer in the drill hole is evaluated; two groups of adjacent blast drill holes are randomly selected, a group of inspection drill holes are constructed in the middle of the connecting line of the blast drill holes, the distance between the inspection drill hole and the blast drill hole is D / 2, wherein D is the blast drill hole spacing, and the blasting effect is inspected;

[0085] The borehole is inspected using borehole inspection or in-hole television imaging to determine the sufficiency of fracture development. If the fracture development is deemed sufficient, the blasting has achieved the expected effect, and the blasting drilling is stopped. The inspection borehole is then sealed, and the working face can be mined normally. If the fracture development is deemed insufficient, the blasting has not achieved the expected effect. The inspection borehole is then filled with explosives as described in step 5.2, sealed, and blasted. Blasting boreholes are then constructed sequentially in the middle of the original blasting borehole line, and explosives are loaded, sealed, and detonated to form a row of blasting boreholes with a spacing of D / 2, achieving the effect of densifying the blasting boreholes. After this round of drilling and blasting is completed, the working face can be mined normally.

[0086] Example 3

[0087] A method for preventing mine tremors in goaf areas with thick and hard roofs using ground-based ultra-deep hole pre-splitting blasting, as described in this invention, includes the following steps:

[0088] Step 1: Select the target working face as working face B of a certain mine. Based on the borehole columnar section of the working face, determine the target rock strata for mine seismic control as the combined main key strata with a depth of 76.45-307.6m and a cumulative thickness of 259.16m. According to the mine geological data, the average uniaxial compressive strength of the rock strata is... Furthermore, the combined thickness ∑H≥200m, therefore there is a risk of mine seismic activity in the goaf area, requiring surface ultra-deep hole pre-splitting blasting treatment;

[0089] like Figure 2 As shown, the bar chart from top to bottom represents the roof rock strata structure from the surface to the coal seam. It contains 3 sub-critical layers and 1 main critical layer. The main critical layer is closest to the surface and is the target rock strata for mine seismic control. The main critical layer is composed of several rock strata of varying thicknesses, so the main critical layer is a composite critical layer.

[0090] Step 2: Based on the surface rock movement observation results of working face B, plot the relationship curve between the distance from the cut-in point and the surface subsidence along the strike of the working face, and plot the relationship curve between the distance from the center of the goaf and the surface subsidence along the dip of the working face, as follows. Figure 3 As shown, the upper right curve is the working face layout diagram, and the vertical line between working face B and goaf B is the current advancing position of the working face. The lower right curve is a schematic diagram of surface subsidence along the working face. Analysis of the curve shows that the current advancing speed of the working face X1 = 805m, the horizontal coordinate of the maximum subsidence point X2 = 266m, and the distance P = 566m that the maximum subsidence point lags behind the working face. The left curve is a schematic diagram of surface subsidence along the working face. Analysis of the curve shows that the distance S = 114m that the maximum subsidence point is offset from the middle of the goaf. By using the two values ​​P and S, the location of the maximum subsidence point and its relative relationship with the working face can be determined.

[0091] In summary, the current advancing degree of the working face X1 = 805 m, the horizontal coordinate of the maximum subsidence point of the strike X2 = 266 m, the calculation can obtain the surface maximum subsidence point of the strike P = 566 m; the vertical coordinate of the maximum subsidence point of the inclination Y = -114 m, the calculation can obtain the distance S = 114 m of the surface maximum subsidence point of the inclination from the middle of the goaf.

[0092] Step 3, according to the key layer thickness distribution contour map of B working face, as shown in the figure, the thickness distribution contour of the target rock stratum for mine shock control is shown, the numbers represent the thickness of the rock stratum (unit: m), the interval of the contour is 10 m, it can be seen that the combined thickness of the key layer group in the range of B working face is greater than 200 m, the thickness of the target rock stratum in the range of goaf B is at least 210 m, and there is no area with ∑H < 200 m. Therefore, ground drilling construction can be carried out in all areas within the range of goaf B. Figure 4

[0093] Step 4, the first group of ground drilling is constructed at the position of the maximum subsidence point, the specific coordinates are: offset from the middle of the goaf by 114 m, lag behind the current mining position of B working face by 566 m;

[0094] Step 5, the first group of ground drilling is constructed along the direction perpendicular to the ground, as shown in the figure, the length of the drilling is L, the length of the charging section in the drilling is 4 / 5 of the length of the drilling, the length of the hole sealing section is 1 / 5 of the length of the drilling, the diameter of the cartridge needs to be smaller than the diameter of the drilling, the hole sealing section adopts cement mortar sealing, the detonating cord is buried in the drilling and extends to the ground from the hole, and the length of the detonating cord reserved at the hole is not less than 1 meter. Figure 5 Since the main key layer is a composite rock stratum and the buried depth is 307.6 m, the composite thickness is 259.16 m, it can be calculated that the construction depth L of the ground drilling should be greater than 255.77 m, so the design construction depth of the ground drilling is 260 m, which covers at least 80% of the thickness of the target rock stratum for mine shock control.

[0095] The diameter of the ground blasting drilling is designed to be 170 mm, water-resistant water-gel explosive is filled in the hole, the specifications of the explosive are: cartridge diameter 120 mm, length 530 mm, single roll weight 6 kg, and the uncoupling coefficient of the charge is 1.42; the explosive is charged from the bottom of the drilling upward, so that the explosive filling height covers all the target rock stratum for mine shock control, the height of the drilling charging section is 208 m, the length of the charging section covers 80% of the thickness of the target key layer, the single hole charge is 2352 kg, two detonating cords are fixed along the two sides of the cartridge and extend to the hole, and the length of the detonating cord reserved at the hole is 2 meters. As shown in the figure, the blasting drilling is perpendicular to the ground and arranged in a straight line, and the blasting position is behind the working face, which is beneficial to reduce the drilling engineering quantity and reduce the influence of the vibration generated by blasting on the working face.

[0096] Figure 6

[0097] ​​​The cement mortar is used to seal the borehole, the sealing section height is 52 m, and after the sealing is completed, the electronic detonator is used for detonation, single hole and single detonation, and the first group of ground drilling blasting is completed; the second group of ground drilling is constructed along the direction parallel to the cut, and the distance between the first group of drilling is 30 m, the same parameters as the first group of drilling are used for charging, sealing, and blasting, and the second group of ground super deep hole presplitting blasting is completed; 9 groups of ground drilling construction are conducted, and a row of ground super deep hole presplitting blasting drilling is formed with the first group of drilling as the symmetry and the distance of 30 m;

[0098] As shown in Figure 7 , the cracks between the blast holes are mutually penetrated, and a blast crack surface is formed along the arrangement direction of the drilling, which can play a role of directional cutting of the target rock stratum of the mine shock along a single direction. As shown in Figure 8 , the distance between the two blast holes is D, and the test drilling is constructed in the middle of the two blast holes, and the distance from the two blast holes is D / 2, so that the maximum extension range of the blast crack can be obtained.

[0099] The first group and the second group of ground drilling are randomly selected, the tenth group of ground drilling is constructed in the middle of the drilling connecting line, the drilling peeping instrument is used for peeping, it is found that the crack development in the hole is very sufficient, the blasting achieves the expected effect, so the blasting drilling construction is stopped, and the cement mortar is used to seal the test drilling. The high-energy mine shock risk in the goaf is eliminated, and the working face is normally mined.

[0100] The ground super deep hole presplitting blasting method for preventing and controlling the thick and hard roof goaf mine shock in the coal mine in Example 3 is used, the high-energy mine shock risk in the goaf is eliminated, and the working face is normally mined; the construction period is short, the construction cost is low, the method has excellent timeliness for mine shock prevention and control, the fracturing effect is difficult to directly test, and the method has strong applicability to the coal mine site.

Claims

1. A method for preventing and controlling mine earthquake in goaf of thick and hard roof in surface ultra-deep hole presplitting blasting, characterized in that, By determining the target rock stratum of mine earthquake control, determining the position of the maximum surface subsidence point according to the surface subsidence curve, determining the ground drilling construction area according to the rock stratum structure, determining the first group of drilling construction positions, ground drilling construction, pre-splitting target rock stratum by charging and blasting, construction of adjacent ground drillings, charging and blasting of adjacent drillings, formation of blasting fissure surface and blasting effect inspection, the pre-splitting weakening of the key stratum of mine earthquake is realized, and the occurrence risk of mine earthquake in thick and hard roof goaf is reduced. Specifically, the following steps are implemented: Step 1, determining the target rock stratum of mine earthquake control in goaf; Step 2, determining the distance of the maximum surface subsidence point lagging behind the working face along the strike and the distance of the maximum surface subsidence point deviating from the middle of the goaf along the dip; Step 3, determining the ground drilling construction area; Step 4, selecting the first group of ground drilling construction positions in the ground drilling construction area; Step 5, construction; The step 1 is implemented according to the following steps: Step 1.

1. According to the working face drilling comprehensive column chart, the target rock stratum of the working face mine shock control is determined, and the target rock stratum is a single or combined thick hard roof rock stratum; when the target layer is a single rock stratum, the uniaxial compressive strength and thickness respectively exceed and H ; when the target layer is a composite rock stratum, the average uniaxial compressive strength and composite thickness of the rock stratum respectively exceed and ; Step 1.2, according to the position of high-energy mine earthquake occurrence in the working face range, selecting the drilling comprehensive columnar chart closest to the mine earthquake occurrence position; the main key stratum is determined by the rock stratum in the drilling comprehensive columnar chart, which is the target rock stratum of mine earthquake control in goaf; The discriminant condition for the target rock stratum discrimination in step 1.2 is related to the composite form of the main key layer, when the main key layer is a single rock stratum, the discriminant condition is: , H≧50m; when the main key layer is a composite rock stratum, the discriminant condition is: , ; The step 2 is implemented according to the following steps: Step 2.1, according to the target working face strike and dip surface subsidence observation curve, determining the distance of the maximum surface subsidence point lagging behind the working face along the strike P and the distance of the maximum surface subsidence point deviating from the middle of the goaf along the dip S; according to the target working face surface rock movement observation results, the distance from the open-off cut distance-surface subsidence relationship curve along the working face strike is drawn, and the distance from the goaf middle distance-surface subsidence relationship curve along the working face dip is drawn; Step 2.2, calibrate the current advancing degree of the working face X 1, X2, horizontal coordinate of the position of the maximum subsidence point in the distance from the open-off cut-distance-surface subsidence amount relationship curve, distance from the maximum subsidence point on the surface trend to the working face , Y, vertical coordinate of the position of the maximum subsidence point in the distance from the middle of the goaf-distance-surface subsidence amount relationship curve, distance from the middle of the goaf to the maximum subsidence point on the inclination ; The step 3 is implemented according to the following steps: Step 3.1, when the mine has main key stratum thickness distribution contour data, draw the target rock stratum thickness distribution contour map; when the mine has no main key stratum thickness distribution contour data, select all geological drillings in the target working face range, and draw the rock stratum structure diagram along the working face strike; Step 3.2, excluding the rectangular area in which the single rock thickness is less than H or the combined thickness is less than in the working face range according to the target rock thickness distribution contour map. Step 3.3, excluding the rectangular area in which the thickness of the main key stratum in the range of the target working face is less than H or the combined thickness is less than from the stratum structure diagram of the borehole in the range of the target working face; when the main key stratum is a single key stratum, excluding the rectangular area in which the thickness H of the main key stratum in the range of the target working face is less than 50 m; when the main key stratum is a composite key stratum, excluding the rectangular area in which the combined thickness of the main key stratum in the range of the target working face is less than Step 3.4, after excluding the rectangular area that does not meet the requirements in the working face range, the remaining area is the determined ground drilling construction area; The step 4 is implemented according to the following steps: Step 4.1, pre-selecting the first group of drilling construction positions as the position of the maximum surface subsidence point, deviating from the middle of the goaf S, lagging behind the working face distance P, and determining whether the position of the maximum surface subsidence point is in the ground drilling construction area; Step 4.2, if the position of the maximum surface subsidence point is in the ground drilling construction area, the first group of drilling construction positions is determined as the position of the maximum surface subsidence point; Step 4.3, if the position of the maximum subsidence point on the ground surface is not in the ground drilling construction area, draw the distance from the open cut distance, i.e. the relationship curve of the ground surface subsidence rate, to determine the horizontal coordinate X3 of the position of the maximum point of the ground surface subsidence rate along the strike of the working face, and calculate the lag distance of the maximum point of the ground surface subsidence rate from the working face ; Step 4.4, determine whether the maximum point of surface subsidence rate of the working face strike is in the determined ground drilling construction area, if yes, determine the specific construction position of the first group of drillings as: offset from the middle of the goaf S , the distance behind the working face Q , with continuous mining of the working face, steps 4.1 to 4.3 are repeatedly determined, when the maximum subsidence point position or the maximum subsidence rate position of the strike is in the ground drilling construction area in step 3, the construction position of the first group of ground drillings is determined; if not, it indicates that there is no need to carry out ground super-deep hole presplitting blasting at the current mining stage of the working face.

2. The method for preventing and controlling mine earthquake in goaf of thick and hard roof by ground ultra-deep hole presplitting blasting according to claim 1, characterized in that, The step 5 is implemented according to the following steps: Step 5.1, determining the charging, hole sealing and detonation range of the first group of ground drillings; Step 5.2, performing the first group of ground drilling blasting; Step 5.3, sequentially performing drilling and blasting of subsequent groups; Step 5.4, construction inspection drilling and blasting effect.

3. The method for preventing and controlling mine earthquake in goaf of thick and hard roof by ground ultra-deep hole presplitting blasting according to claim 2, characterized in that, The step 5.1 is specifically: Step 5.1.1, drilling the first group of ground boreholes in a direction perpendicular to the ground until the boreholes cover more than 80% of the thickness of the target rock layer for mine shock treatment; the construction length L of the ground boreholes and the depth H of the main key layer Z There is a relationship: when the main key layer is a single rock layer, ; when the main key layer is a composite rock layer, ; Step 5.1.2, the length of the single group of drill hole charge section needs to cover at least 80% of the thickness of the target layer of the mine shock treatment, the reserved length of the borehole detonating cord is not less than 1 meter, the length of the drill hole sealing section is not less than 1 / 5 of the drill hole depth, the drill hole uses electronic detonator, single hole single initiation, that is, each time of blasting only initiates one blast hole, in the design of the drill hole structure, the diameter C1 of the cartridge and the diameter C2 of the drill hole satisfy the following relationship: 1.3 ≦ C2 / C1 ≦ 1.7; the time of the explosion gas acting on the hole wall is increased, the blasting cracks are fully expanded, and the on-site verification can maximize the cracking effect of the explosive on the mine shock target rock layer; Step 5.1.3, the blast drill holes are arranged in a straight line, and the blast drill holes form a crack network perpendicular to the ground and parallel or perpendicular to the cut direction, in the blast drill hole blasting scheme, the drill hole spacing D satisfies the following condition: 10 ≦ D ≦ 30; the cracks between the blast drill holes are promoted to be mutually penetrated to form a blast crack network, and the mine shock target rock layer is cut in a single direction.

4. The method for preventing and controlling mine earthquake in goaf of thick and hard roof by ground super deep hole presplitting blasting according to claim 3, characterized in that, The water-resistant water gel explosive is filled in the ground drill hole, the explosive column is placed in the drill hole, the explosive filling height covers all the target rock layers of the mine shock treatment, two detonating cords are fixed along the two sides of the explosive column and extended to the hole mouth, the drill hole is sealed by cement mortar, the explosive is initiated after the sealing is completed, the second group of ground drill holes are constructed at a distance of D from the first group of drill holes in the direction parallel or perpendicular to the cut direction, and the process is sequentially performed to complete the second group of ground super deep hole pre-splitting blasting, the ground drill hole construction is continued in the original direction, and the charging and blasting are repeatedly performed to form a row of ground super deep hole pre-splitting blasting drill holes symmetrical to the first group of drill holes with a spacing of D.

5. The method for preventing and controlling mine earthquake in goaf of thick and hard roof by ground super deep hole presplitting blasting according to claim 4, characterized in that, The step 5.4 is specifically: two adjacent ground drill holes are randomly selected, a group of ground drill holes are constructed in the middle of the drill holes, the drill hole peeping is performed, and the crack development of the rock layer in the hole is evaluated; two adjacent blast drill holes are randomly selected, a group of test drill holes are constructed in the middle of the connecting line of the blast drill holes, the distance between the test drill hole and the blast drill hole is D / 2, wherein D is the blast drill hole spacing, and the blasting effect is tested.

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