CN115046443B - Construction method for breaking blasting in upper section and lower section of roof-cutting entry retaining of thick coal seam - Google Patents
Construction method for breaking blasting in upper section and lower section of roof-cutting entry retaining of thick coal seam Download PDFInfo
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- 238000005422 blasting Methods 0.000 title claims abstract description 126
- 239000003245 coal Substances 0.000 title claims abstract description 69
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
- F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21C—MINING OR QUARRYING
- E21C41/00—Methods of underground or surface mining; Layouts therefor
- E21C41/16—Methods of underground mining; Layouts therefor
- E21C41/18—Methods of underground mining; Layouts therefor for brown or hard coal
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
- F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
- F42D1/08—Tamping methods; Methods for loading boreholes with explosives; Apparatus therefor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42D—BLASTING
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- F42D3/04—Particular applications of blasting techniques for rock blasting
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Abstract
The invention discloses a blasting construction method for cutting a roof of a thick coal seam, retaining a roadway, breaking the roof in a cutting way, cutting the roof in a cutting way, and breaking the roof in a cutting way, wherein the blasting construction method comprises the following steps: the track gate upper broken blasting is to construct ultra-deep hole pre-splitting blasting in the pre-reserved roadway towards the front of the mining coal bed; the track gate undercut blasting is controlled blasting by adopting a bi-directional energy gathering pipe to cut and presplit along the front of a coal seam mined in the reserved roadway; the middle blasting weakening of the track gateway is to implement blasting weakening holes on the lower part of deep hole presplitting blasting and the upper part of undercut blasting in front of the mined coal seam along the inward direction of the reserved tunnel. The blasting construction method can form a smooth and flat roadway side part with good integrity on one side of the goaf of the reserved roadway, can increase the caving height of the top plate of the goaf and the crushed expansion volume of rock mass, weakens the pressure of the top plate of the reserved roadway, and can improve the integral strength and the sealing performance of the roadway side part on one side of the goaf of the reserved roadway by means of mine pressure and utilizing crushed expanded gangue, so that gob-side entry retaining is realized.
Description
Technical Field
The invention relates to a blasting construction method, in particular to a method for breaking blasting construction in upper and lower cutting of a roof-cutting entry retaining of a thick coal seam.
Background
The coal resource is an important basic resource of the country, and particularly for deep well exploitation, the safety of exploitation is the important importance of coal exploitation, and the currently adopted machine roadway, air roadway and open-cut stoping mode has better safety guarantee and is commonly used. Because the coal field area is large, a plurality of areas need to be divided, the length of the open-cut hole cannot be too large, the aspects of supporting pressure, efficiency and the like are mainly considered, a coal seam is mined originally to prevent the influence of adjacent goafs on gas, fire resistance, ground pressure and the like, a section of coal pillar is reserved along the goafs, and then a roadway is re-formed, so that the resource waste is caused, and meanwhile, the construction period is prolonged. In order to recover the protective coal pillar left in the traditional mining mode while reducing the tunneling of a roadway when mining the coal layer each time. And (3) adopting a certain technical means to re-support the roadway of the previous section for the next section. The method of retaining the gob is that the gob is retained at the original roadway along the goaf edge, and is called gob-side entry retaining. The gob-side entry retaining can recover resources to the maximum extent. Avoiding the loss of coal. Reducing the tunneling quantity of the roadway, namely relieving the connection tension; the tunneling team is reduced, and a large amount of tunneling cost is saved; and the section coal pillar is removed, the service life of the mine is prolonged, and the social benefit is improved.
According to the practical experience of China and the current technical level, the pushed coal pillar-free mining roadway is divided into gob-side entry retaining and gob-side entry driving. There are 5 modes of gob-side entry retaining which is a pillar-free entry protection mode. The proper and reasonable scheme should be selected according to the specific situation. In most cases, the mine suitable for the condition should be preferably adopted to carry out the pillar-free mining in the form of a retaining roadway. The successful experience of gob-side entry retaining is available in China from thin coal seam to thick coal seam, and from gently inclined coal seam to steeply inclined coal seam.
The core steps are as follows:
the first step is to strengthen the support of the tunnel roof by using the constant-resistance anchor cable so as to ensure that the quality of the automatically formed tunnel is not affected when the roof is pre-cracked and cut later;
the second step is to use a lancing drill to construct blasting holes, and the energy gathering blasting device pre-cracks the top plate in advance to form cracks on the top plate;
and thirdly, automatically realizing roof cutting along the blank by utilizing mine pressure along the roof crack when the stope period is pressed, cutting down the roof, forming a roadway wall by the cut roof, and simultaneously increasing the volume of crushed rock to be 1.3 times of the original volume by means of the rock crushing expansion coefficient, compacting and isolating the goaf, thereby automatically forming the next stope roadway. The gob-side entry retaining utilizes five utilization modes, namely utilizes mine pressure, utilizes roof rock mass, utilizes original support, utilizes original roadway or utilizes the existing stope space, and utilizes the rock breaking expansion coefficient; three weakening modes are realized, namely period pressure reduction, goaf gas reduction and coal seam spontaneous combustion are realized; two targets are achieved, namely automatic roadway forming and coal pillar-free mining.
However, there are still disadvantages in gob-side entry retaining research and application, so that some mines do not achieve the expected effect, especially in coal mines, in which gob-side entry retaining technology is applied, and the most important is that the roof is controlled to be flat. In order to simply burst through construction joint holes for deep coal seams, particularly for ultra-thick sandstone roof boards, the roof boards are difficult to smoothly collapse by means of mine pressure.
Disclosure of Invention
The invention aims to provide a method for breaking and blasting in upper and lower cutting of a roof-cutting retaining roadway of a thick coal seam, which can form a smooth and flat roadway side part with good integrity on one side of a goaf of a retaining roadway, can increase the falling height of a top plate of the goaf and the broken expansion volume of a rock body, weaken the pressure of the top plate of the retaining roadway, and improve the integral strength and the sealing performance of the roadway side part on one side of the goaf by means of mine pressure and utilizing broken and expanded gangue, so that the gob-side retaining roadway is realized, the self-bearing property of broken and expanded gangue of the goaf and the cooperative supporting effect of surrounding rocks of the roadway are fully utilized, the supporting strength can be effectively reduced, and the roadway stability is enhanced.
The aim of the invention can be achieved by the following technical scheme:
the blasting construction method for the upper-break and lower-break middle-break blasting of the thick coal seam roof-cutting entry retaining comprises the following steps:
s1: broken blasting on track cis-slot
After the roadway support is reserved, the super-deep hole pre-splitting blasting of the thick and hard top plate is constructed, the thick and hard overlying strata are damaged, the forced falling of the overlying strata in the goaf is realized, and the pressure transmission of the overlying strata to the top plate of the reserved roadway is cut off.
S2: track gate undercut blasting
And controlling blasting based on the lancing presplitting of the bidirectional energy collecting pipe.
S3: blasting weakening of middle part of track crossheading
The middle blasting weakening of the track gateway is to implement blasting weakening holes between the lower part of deep hole presplitting blasting and the upper part of undercut blasting in the front of the mining coal seam in advance along the reserved tunnel, so that the rock breaking effect of the upper roof is improved and the upper roof is effectively collapsed.
Further, the scheme of blasting the track cis-slot in S1 is specifically as follows:
starting from the cutting hole, designing a cutting hole, implementing an upper cutting blasting scheme in the range of the coal face, firstly arranging a group of blastholes in the cutting hole, simultaneously arranging a group of blastholes in the 4.4-5.5m top plate in front of the coal face, wherein the group of blastholes comprises A, B, C three blastholes, and then arranging a group of blastholes every 14-16 m.
Further, the track crossheading undercut blasting scheme in S2 is as follows:
step 1: according to geological data of track gateway and transportation gateway tunneling, during the stoping of the coal face, the drilling depth of the pre-splitting joint is related to the mining height, the sinking amount of the top plate and the bottom drum amount, and is determined by the following modes:
H seam(s) ＝(H Coal -ΔH 1 -ΔH 2 )/(k-1)
Wherein: ΔH 1 The sinking amount of the top plate is m; ΔH 2 is The floor heave amount is m; k: the coefficient of expansion is 1.3-1.5.
Step two: design of kerf hole depth to be H Seam(s) ＝16-19m，
Step three: the working face rail entry way vertical direction slitting angle of the designed track entry way undercut blasting scheme is 13-17 degrees.
Step four: the bidirectional energy gathering blasting presplitting technology is adopted, and the distance between the cutting holes is designed to be 550+/-50 mm.
Step five: the explosive roll is a water-permitted explosive with the diameter of phi 35mm multiplied by 330g for three-stage coal mines, the charging length is 7.3-7.9m, the same section of electric detonators are arranged every 2-3m, the detonation is carried out at a time without exceeding 5 blasting holes, 1-5 sections of detonators are sequentially arranged for detonation, the hole sealing is carried out on a bag with the length of 1.3-1.9m, and the detonation is carried out after the hole sealing is carried out for 7-9 hours.
Further, the blasting weakening scheme in the middle of the track cis-slot in the step S3 is specifically as follows:
after the lancing blasting, rock blasting breaking is carried out at the lower part of the presplitting blasting, a breaking belt of a goaf at the lower part is increased, a free face is increased, and a presplitting rock roof covered on the goaf is pushed to fall into a roadway.
Further, the hole opening of the blast hole is plugged by a bag, and the hole in the blast hole is plugged by grouting.
Further, the blast hole grouting adopts the proportion of cement to water of (63-68) (32-37), after being uniformly mixed, the blast hole grouting is pressed into the blast hole through a grouting pipe by a grouting pump until the blast hole is returned to the grouting, the blast hole grouting can be initiated after grouting is solidified for 20-30 hours, and the cement consumption is 7.6-8.3 Kg/m.
When the explosive is charged, the small angle is a low-stage detonator, the large angle is a high-stage detonator, each blast hole is internally provided with two blasting circumferences Duan Leiguan for forward detonation, the gun head of the detonator is firstly wrapped by an insulating adhesive tape, and then is wrapped by self-adhesive glue.
Further, the cement is PC42.5R or PC42.5.
The grouting pump is a 2BQ15/2.0 type pneumatic grouting pump.
Furthermore, the coal seam collection design blast hole spacing is 2.3-2.7m.
The invention has the beneficial effects that:
1. the construction method for breaking the top plate of the roadway in the middle of the upper-break and lower-cut mode can increase the supporting force of the top plate of the roadway, and further reduce the supporting resistance of the roadway. Meanwhile, the caving height of the goaf roof and the crushed expansion volume of the rock mass are increased, and the mine pressure is utilized to protect the roadway, so that gob-side entry retaining is realized;
2. the construction method for breaking the goaf broken and expanded gangue in the upper-break and lower-cut middle-break fully utilizes the self-bearing characteristic of the goaf broken and expanded gangue and the cooperative supporting function of the surrounding rock of the roadway, so that the supporting strength can be effectively reduced, and the stability of the roadway can be enhanced.
Drawings
The invention is further described below with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view of a side blast hole arrangement of a track gate of the present invention;
FIG. 2 is an overall blasthole arrangement and horizontal relative position of the blasting method of the present invention;
FIG. 3 is a plan view of the relative positions of a kerf blasthole D and a broken blasthole E in the blasting construction method of the present invention;
fig. 4 is a flow chart of blasting when the coal seam is not mined according to the invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The coal face is sequentially from top to bottom: sand-mud rock interbedded, medium sand rock, sandy mud rock, fine sand rock, sandy mud rock interbedded, sandy mud layer and track.
The blasting construction method for the upper-break and lower-break middle-break blasting of the thick coal seam roof-cutting entry retaining comprises the following steps as shown in fig. 4:
firstly, aiming at track gate way, transportation gate way and cutting hole, the arrangement of a grinding stope is carried out, the lithology of a roof of a layer to be mined is explored, and a retaining roadway is determined, so that whether the roof is a thick hard roof or not is judged, the non-thick hard roof is determined to be blasted by adopting a conventional 110 work method, if the thick hard roof is subjected to upward breaking, downward cutting and middle breaking blasting, the specific blasting construction method is as follows:
s1: broken blasting on track gate way (reserved tunnel)
After the roadway support is reserved, the super-deep hole pre-splitting blasting of the thick hard roof is constructed, the thick hard rock stratum is damaged, the forced caving of the overlying rock stratum in the goaf is realized, the expansion coefficient of the caving rock is effectively improved, the caving coefficient is further increased, the pressure transmission of the overlying rock stratum to the roof of the reserved roadway is cut off, the roof can fall down, and the broken blasting on the track gateway is the key of roof caving into a roadway.
S2: track gate undercut blasting
Based on bi-directional energy gathering pipe lancing pre-splitting control blasting, the reserved roadway goaf roof pre-splitting blasting is realized, the leveling and falling of the roadway side roof are ensured, the quality of pre-splitting lancing is ensured, meanwhile, the damage to the rock mass of the reserved roadway roof is reduced, the flatness of the roof close to the top surface of the roadway-retaining area is ensured, and convenience is provided for roadway support.
S3: blasting weakening of middle part of track crossheading
The middle blasting weakening of the track gate way is to implement blasting weakening holes E (namely breaking holes E) along the lower part of deep hole presplitting blasting and the upper part of downward cutting blasting in the reserved roadway to ensure that the rock of the upper roof plate effectively collapses, increase the rock breaking volume, implement the blasting weakening holes at the lower part of bidirectional energy collecting pipe lancing presplitting control blasting, ensure that the rock at the lower part of lancing effectively collapses, ensure that the roof plate of the goaf collapses compactly, prevent gas accumulation and prevent goaf fire disasters.
The upper cutting position and the lower cutting position of the coal seam mining roof are broken and collapsed to form a smooth wall, the smooth wall becomes a roadway side part, meanwhile, the volume of broken rock in the middle part is enlarged to form a good support, and the smooth wall is successfully reserved by matching with roadway support.
The scheme of the broken blasting on the track crossheading in S1 is specifically as follows:
starting from the cutting hole, designing a cutting hole front side, implementing an upper cutting blasting scheme, firstly arranging a group of blasting holes on the cutting hole, simultaneously arranging a group of upper cutting blasting holes on a top plate 5m in front of the coal face, and then arranging a group of blasting holes every 15m, wherein each group of upper cutting blasting holes is A, B, C, a specific blasthole plane layout diagram is shown in fig. 1, and specific blasting parameters are shown in table 1.
Table 1 blast parameter table for broken blast hole in roof-cutting entry retaining of broken working face on track gate
Because of the difficulty and unsafe manual charging, the driller is used for feeding the medicine column, namely, the way of drilling, loading and sealing.
Because the manual yellow mud is unreliable in sealing the hole, the hole is sealed by adopting a hole opening bag, grouting and sealing the hole, after the grouting is uniformly mixed by adopting PC42.5R or PC42.5 cement and water in a ratio of 65:35, the grouting is pressed into the hole by using a 2BQ15/2.0 type pneumatic grouting pump through a grouting pipe until the grouting is returned, the grouting can be initiated after the grouting is solidified for 24 hours, and the cement consumption is about 8 Kg/m.
In order to reduce the vibration of the blasting to the top plate, when the blasting is carried out, the blasting is carried out at a small angle by using a low-stage blasting cap, the blasting is carried out at a large angle by using a high-stage blasting cap, and each hole is internally provided with two blasting caps Duan Leiguan for forward blasting. The gun head (explosive filled with detonator) is wrapped by the insulating adhesive tape and then is wrapped by the self-adhesive tape.
The track crossheading undercut blasting scheme in S2 is as follows:
according to geological data of track gateway and transportation gateway tunneling, the coal face stoping period is divided into a first coal layer and a second coal layer, the total of the first coal layer and the second coal layer is 475m, the total of the first coal layer coal top stoping sections is 310m, and the concrete is shown in tables 2 and 3.
TABLE 2 first and second coal seam co-production sections
Table 3 first coal seam roof recovery section
The depth of the pre-split kerf borehole is related to the mining height, roof subsidence and bottom drum, and is determined by:
H seam(s) ＝(H Coal -ΔH 1 -ΔH 2 )/(k-1)
Wherein: ΔH 1 The sinking amount of the top plate is m; ΔH 2 is The floor heave amount is m; k: the coefficient of expansion is 1.3-1.5.
The first coal seam and first coal seam laminated mining section acquisition method comprises the following steps:
the roof is mainly thick-layer fine sandstone, the roof is hard, the total value of the sinking amount of the roof and the bottom drum amount is 0.1m, the expansion coefficient k of the coal gangue in the goaf roof is 1.3, and when the working face adopts 4.0m of high-H coal (tangential direction)Outer 475m section), calculate H Seam(s) =13m, combined with roof lithology and roadway width of 5.5m, kerf height of 13m clearly difficult to support roof pressure of such wide roadway, and considering the above calculation results, kerf hole depth is initially designed to be H Seam(s) ＝18m。
Compared with the working face engineering practice of the mine-collecting 1613A, the result shows that the cutting angle is favorable for roadway stability in the range of 10-20 degrees, the smaller cutting angle can reduce the cantilever beam length of the top plate, and finally the cutting angle of the working face rail along the retained roadway is 15 degrees in the vertical direction of the track along the lower cutting blasting scheme of the track along the trench.
The bidirectional energy gathering blasting presplitting technology is adopted, the distance between the cutting holes is designed to be 550+/-50 mm, the charging parameters are determined through field tests, and the sectional view and the horizontal layout of the cutting energy gathering blasting blasthole are shown in figures 1-2.
And (3) carrying out a single-hole test on the blasting construction method, determining reasonable loading quantity and plugging length, then carrying out interval blasting, observing the crack condition in the empty holes between two adjacent loading holes, if the empty hole crack between two adjacent loading holes does not reach the crack rate requirement standard, carrying out a continuous blasting test again, and finally determining the number of blasting holes, blasting modes and the like.
The invention adopts explosion aperture 50mm, hole depth 18m, angle 75 degree with horizontal direction, two-way energy gathering tube changing outer diameter 32mm, inner diameter 28mm, tube length 1500mm, explosive adopts common three-level coal mine permitted water gel explosive, specification is phi 27 x 430mm x 330 g/volume, parameters are shown in table 4, the continuous charge in tube, charge length is 14m, charge quantity per hole is 10.7Kg, and hole sealing length is 4m. The length of the grouting bag is 1.3m, and the distance between the two bags is 0.7m.
And (3) grouting by using a grouting machine after the mixture ratio of PC42.5R or PC42.5 cement and water is 65:35, and stopping grouting when the grouting pump pressure reaches 1.5 MPa.
Table 4 table top cutting blasting parameter table for track cis-slot undercut blasting scheme working face
The specific charging method of the double energy-gathering medicine tube is as follows: three-stage coal mine water-permitted explosive rolls with phi 27mm multiplied by 430mm multiplied by 330g are all connected and placed in the energy collecting pipes at intervals, and each energy collecting pipe is provided with a positioning block or 1 anti-skid device along the joint cutting direction so as to ensure that the joint cutting direction is a connecting line of two holes. And 5 electric detonators which are allowed to be used in the coal mine and are in the same section are arranged every 3m, and the leg wires of the 5 electric detonators are only reserved for 20cm and are connected in parallel with the pattern wires.
Because the explosive loading is large, the disturbance of blasting vibration to the top plate is prevented, the same section of detonator is sequentially loaded into every two holes along the sequence, the number of blasting holes cannot be more than 6 at one time, the specific sections of the detonators are shown in the table 5, the next group of blasting holes are required to be drilled after drilling and blasting, and the purpose that the next group of blasting holes are blasted after the last group of blasting and cannot be charged is achieved.
TABLE 5 truncated blasting Kong Lei tube section
| Gun hole number | 1 | 2 | 3 | 4 | 5 | 6 |
| Lightning tube section | 1 | 1 | 3 | 3 | 5 | 5 |
The blasting weakening scheme of the middle part of the track crossheading in the S3 is specifically as follows:
after the lancing blasting, the rock at the lower part of the lancing is a complete rock stratum and cannot be broken within the range of 50m before gob-side entry retaining, rock blasting breaking is required to be carried out at the lower part of presplitting blasting, a lower goaf breaking belt is increased, a free surface is increased, presplitting rock roof is pushed to cover the goaf to be ejected and fall into a lane, the blast hole design is shown in a table 6, the relation profile and the plane layout of specific blasting breaking holes and presplitting blastholes are shown in figures 1-3, the blasthole spacing is 2.5m, the explosive roll is a water gel explosive allowed by phi 35mm multiplied by 330g of a three-level coal mine, the charging length is 7.5m, an identical section of electric detonator is filled every 2.5m, no more than 5 blastholes are blasted at one time, and 1-5 sections of detonators are sequentially filled for detonation. And the hole sealing is carried out on the bag with the length of 1.5m, and the detonation is carried out after 8 hours of hole sealing.
Table 6 table working face roof cutting entry retaining lower broken hole blasting parameter table for middle blasting weakening scheme of track gate way
In the description of the present specification, the descriptions of the terms "one embodiment," "example," "specific example," and the like, mean 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 do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims.
Claims (5)
1. The construction method for breaking and blasting in the upper section and the lower section of a thick coal seam roof-cutting entry retaining is characterized by comprising the following steps of:
s1: broken blasting on track cis-slot
After the reserved roadway support is carried out, the super-deep hole pre-splitting blasting of the thick and hard roof is constructed, the thick and hard overlying strata are damaged, the forced falling of the overlying strata in the goaf is realized, and the pressure transmission of the overlying strata to the roof of the reserved roadway is cut off;
starting from cutting holes, designing a cutting blasting scheme in the range of a coal face, firstly arranging a group of blastholes in the cutting holes, simultaneously arranging a group of blastholes in a top plate 4.4-5.5m in front of the coal face, wherein the group of blastholes comprises A, B, C three blastholes, and then arranging a group of blastholes every 14-16 m;
s2: track gate undercut blasting
Controlling blasting based on the lancing pre-splitting of the bidirectional energy collecting pipe;
s3: blasting weakening of middle part of track crossheading
The middle blasting weakening of the track gateway is to implement blasting weakening holes between the upper blasting lower part and the lower cutting blasting upper part in front of the mining coal seam in advance along the reserved roadway, so that the rock breaking effect of the upper covering plate and the effective collapse are ensured; after kerf blasting, rock blasting breaking is carried out at the lower part of upper broken blasting, a lower goaf breaking belt is increased, a free surface is increased, and a pre-broken rock roof covered on a goaf is pushed to fall into a roadway;
the length of the blasthole of the blasting weakening hole is 10 meters, the elevation angle is 40 degrees, the included angle between the blasthole and the reserved roadway is 90 degrees, the aperture is 50mm, the charging length is 7.5m, the charging quantity is 7.5kg, the hole sealing length is 2.5m, and the blasthole distance is 2.5m; the explosive roll is phi 35mm multiplied by 330mm multiplied by 330g of three-stage permitted water gel explosive for coal mines, an identical-stage electric detonator is arranged every 2.5m, no more than 5 blasting holes are detonated at one time, and 1-5 sections of detonators are sequentially arranged for detonation.
2. The method for broken blasting construction in upper-break and lower-cut of a thick coal seam roof-cutting entry retaining according to claim 1, wherein the scheme of track gate undercut blasting in S2 is as follows:
step one: according to geological data of track gateway and transportation gateway tunneling, during the stoping of the coal face, the drilling depth of the pre-splitting joint is related to the mining height, the sinking amount of the top plate and the bottom drum amount, and is determined by the following modes:
H seam(s) =(H Coal -ΔH 1 -ΔH 2 )/(k-1)
Wherein: ΔH 1 The sinking amount of the top plate is m; ΔH 2 The unit is m; k: the coefficient of expansion is 1.3-1.5;
step two: design of kerf hole depth to be H Seam(s) =16-19m；
Step three: the working face rail entry way vertical direction slitting angle of the designed track entry way undercut blasting scheme is 13-17 degrees;
step four: adopting a bidirectional energy gathering blasting presplitting technology, and designing the distance between joint cutting holes to be 550+/-50 mm;
step five: the explosive roll is a water-permitted explosive of a three-stage coal mine with the diameter of phi 35mm multiplied by 330mm multiplied by 330g, the charging length is 7.3-7.9m, an identical section of electric detonator is arranged every 2-3m, no more than 5 blasting holes are detonated at one time, 1-5 sections of detonators are sequentially arranged for detonating, the hole sealing is a bag with the length of 1.3-1.9m, and the detonation is performed after the hole sealing is performed for 7-9 hours.
3. The construction method for breaking and blasting in upper-break and lower-break in a thick coal seam roof-cutting entry retaining way according to claim 1, wherein the orifice of the blasthole is plugged by a bag, and the blasthole is plugged by grouting.
4. The construction method for breaking and blasting in the upper-break and lower-break roadway retention and in the middle-break of the thick coal seam roof-cutting according to claim 1, wherein the blast hole grouting adopts the cement and water ratio of (63-68) (32-37) to be uniformly mixed, and then the grouting is pressed into the blast hole through a grouting pipe by using a grouting pump until the grouting is performed after the grouting is returned, the blasting can be performed after the grouting is solidified for 20-30 hours, and the cement consumption is 7.6-8.3 Kg/m;
when the explosive is charged, the small angle is a low-stage detonator, the large angle is a high-stage detonator, each blast hole is internally provided with two blasting circumferences Duan Leiguan for forward detonation, the gun head of the detonator is firstly wrapped by an insulating adhesive tape, and then is wrapped by self-adhesive glue.
5. The method for the construction of the thick coal seam roof-cutting entry retaining upper-break lower-break middle-break blasting according to claim 4, wherein the cement is PC42.5R or PC42.5;
the grouting pump is a 2BQ15/2.0 type pneumatic grouting pump.
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