CN112923821A - Drilling and blasting tunneling method for reducing and fixing rock resistance - Google Patents
Drilling and blasting tunneling method for reducing and fixing rock resistance Download PDFInfo
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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
- F42D3/00—Particular applications of blasting techniques
- F42D3/04—Particular applications of blasting techniques for rock blasting
Abstract
The invention relates to a drilling and blasting tunneling method for reducing and fixing rock resistance. In order to overcome the defects of the prior art, the burst hole is divided into a front section and a rear section which are respectively called a front section and a rear section of the burst hole, the front section and the rear section of the burst hole are respectively filled with a group of explosive rolls, all peripheral holes and bottom holes are respectively filled with a group of explosive rolls, each group of explosive rolls is respectively inserted with a detonator, the detonators are respectively connected with a leg wire, the other end of each leg wire is respectively connected with a corresponding connection terminal of a matched detonator, the detonators are millisecond delay detonators, and the delay time of the detonator in the explosive roll at the front section of the burst hole is less than the delay time of the detonator in the explosive roll at the rear section of the burst hole is less than the delay time of the detonator in the explosive roll at the peripheral holes, namely the delay time of the detonator in the explosive roll at the bottom hole. The invention can not only give full play to the explosive force of the explosive, reduce the explosive and detonator consumption, but also keep the strength of the roadway and the roof to the maximum extent, and is suitable for blasting mining and tunneling processes of various mines.
Description
Technical Field
The invention relates to a drilling and blasting tunneling method for reducing and fixing rock resistance, in particular to a novel medium-length hole smooth blasting method based on in-hole subsection differential blasting, which is suitable for drilling and blasting tunneling under various rocks and section conditions and promotes reasonable matching of blasting force of safety blasting equipment allowed for a coal mine and rock resistance.
Background
The tunneling engineering amount accounts for a large proportion (45% or 25%) in mine construction and production, and drilling and blasting operation is an important method for tunneling mine tunnels and accounts for a certain proportion: in China, coal mine construction and production need to consume tens of thousands of tons of various explosives every year, and about five hundred million detonators are generated. Therefore, the operation efficiency is directly related to the coal mine production, construction efficiency and safety condition. In China mines, particularly in coal mine tunnels, drilling, blasting and tunneling have various restriction conditions, and the rock breaking effect is limited to be fully exerted. The method is limited by surrounding rock characteristics, most of coal mine roadways are distributed in sedimentary rock layers, mainly comprise 5 sedimentary rocks such as ash, mud, sand, shale, coal and the like, have anisotropic and heterogeneous brittleness characteristics, are rich in joints and cracks, and increase the blasting control difficulty; secondly, flammable and explosive toxic gases such as gas exist, so that the use of high-performance equipment and equipment is limited; and only one free surface is provided, which is similar to funnel blasting in infinite value, the clamping effect is large, and the rock breaking efficiency is greatly influenced. In addition, the underground roadway has a narrow space, so that the application of high-power and high-efficiency rock drilling, loading and supporting equipment is limited, and the tunneling speed of the coal mine rock roadway is also limited.
Disclosure of Invention
The invention provides a drilling and blasting tunneling method for an underground tunnel, in particular to a medium-length hole smooth blasting method for reducing and fixing the resistance of a tunnel section rock, and particularly relates to a novel medium-length hole smooth blasting method based on in-hole subsection differential blasting, which is suitable for drilling and blasting tunneling under various rocks and section conditions and promotes reasonable matching of the blasting force of allowable safe blasting equipment of a coal mine and the resistance of the rocks.
The drilling and blasting tunneling method for reducing and fixing the rock resistance comprises the following steps:
planning a tunneling full section on a rock wall to be tunneled, drilling a plurality of blast holes on the tunneling full section, wherein the blast hole at the bottommost layer is a bottom hole, the blast holes at the two sides and the outermost layer at the top are peripheral holes, the blast holes between the bottom hole and the peripheral holes are caving holes,
secondly, all the caving holes are divided into a front section and a rear section which are respectively called as a front section and a rear section of the caving hole, the front section and the rear section of the caving hole are respectively filled with a group of explosive rolls, all the peripheral holes and the bottom holes are respectively filled with a group of explosive rolls, each group of explosive rolls is respectively inserted with a detonator, the detonators are respectively connected with a leg wire, the other end of each leg wire is respectively connected with a corresponding connecting terminal of a matched detonator,
the detonators are all millisecond delay detonators, the delay time of the detonators in the explosive roll at the front section of the bursting hole is less than the delay time of the detonators in the explosive roll at the rear section of the bursting hole and less than the delay time of the detonators in the explosive roll at the peripheral hole, namely the delay time of the detonators in the explosive roll at the bottom hole,
withdrawing the equipment and personnel outside the safety alert area according to the conventional regulations, adding necessary protection for the cable and the lighting equipment, starting the detonator to explode, and sequentially exploding after each detonator receives the trigger signal. (the blasting sequence is front caving eye segment → rear caving eye segment → peripheral eye and bottom eye, the inspection along the line can be carried out after 30 minutes, if the conditions of refusal blasting and residual blasting occur, special measures are taken according to the relevant regulations of coal mine safety regulations and the like for processing, and the rest safety matters still follow the existing safety regulations of coal mine blasting).
And fourthly, removing broken stone and crushed coal generated by blasting and float coal and float gangue on the side wall, the top plate and the bottom plate of the roadway.
Supporting the newly formed roadway, including roof supporting and side protecting supporting;
and returning to the first step, and repeatedly performing circulating operation until all tunneling operations are completed.
Due to the design, when in detonation, the detonator simultaneously sends out a detonation signal, and because the delay time of the detonator is different, the explosive cartridge at the front section of the caving hole is always detonated first, then the explosive cartridge at the rear section of the caving hole is detonated, and finally the explosive cartridges in the peripheral holes and the bottom holes are detonated.
The impact and the crack generated by the explosion of the front section of the caving hole develop to the periphery and the depth, the impact and the crack generated by the explosion of the rear section of the caving hole further develop to the periphery and the depth, and the explosive force of the explosive can be fully exerted, so that the rock resistance is reduced, and the explosive cartridge and the detonator are saved.
And finally, when explosive cartridges in the peripheral holes and the bottom holes explode, because the rock wall or the coal wall around the original caving hole is already exploded, the impact waves and cracks generated by the explosion of the explosive cartridges are mainly developed and released to the broken rock wall or the coal wall around the original caving hole, the rock wall or the coal wall outside the peripheral holes and the bottom holes is kept, the side wall and the top plate of the roadway to be formed are not damaged, the resistance of rocks is fixed and kept, and the strength and the resistance of the side wall and the top plate of the roadway are improved.
And (4) optimizing, wherein the drilling depth of all blastholes in the first step is 2-2.2 meters. Practice proves that the design has high tunneling efficiency and high tunneling speed.
As optimization, in the second step, the requirements for filling detonators and explosive cartridges are as follows:
a. the peripheral hole is provided with an explosive cartridge provided with a 5-section millisecond detonator, and water stemming is blocked, wherein the stemming blocking length is not less than 500 mm;
b. eye collapse: 1 explosive cartridge is arranged at the rear section of the collapse hole, an explosive cartridge provided with a 4-section millisecond detonator is closely arranged, the water plugging blister and the stemming are 400mm long (note that the plugging length of each collapse blast hole is consistent),
then continuously installing an explosive cartridge with a 2-section millisecond detonator in the blast hole at the front section of the burst hole, filling water stemming after the explosive loading is finished, and then using the stemming to plug the hole opening;
c. bottom eye: 1 explosive cartridge is arranged at the bottom layer of the bottom hole, a 5-section millisecond detonator explosive cartridge is arranged next to the explosive cartridge, water stemming is filled after the explosive cartridge is filled, and then the stemming is used for plugging the hole;
the explosive rolls in the peripheral holes, the front section of the caving hole, the rear section of the caving hole and the bottom hole are all explosive rolls with the diameter of 32mm, the length of 300mm and the weight of 300 g.
By the design, sectional differential blasting is carried out inside the blast holes, all the blast holes except the peripheral blast holes in the full section are uniformly distributed, the sectional lengths are equal, the same-section blasting of the columnar explosive packages is carried out among the holes, and the blasting is carried out in the holes according to a certain differential interval sectional sequence by utilizing the differential blasting principle.
Preferably, colored paper scraps or colored ribbons are filled between the stemming and the explosive cartridge. After the detonation, if the corresponding colored paper scraps or colored belts appear on the periphery of the corresponding blasthole, the corresponding explosive cartridge is detonated, otherwise, the corresponding explosive cartridge is not detonated. The design facilitates the gun inspection.
Preferably, when stemming is blocked, the tail wire of the detonator at the rear section of the caving hole is straightened and squeezed between the upper wall of the blasting hole and the stemming. By the design, the broken-hole rear section detonator leg wire can be prevented from being damaged when stemming is carried out.
The drilling and blasting tunneling method for reducing and fixing rock resistance of the coal mine can not only fully exert the explosive force of the explosive in blasting tunneling, improve blasting and tunneling efficiency, reduce the using amount of the explosive and the detonator, but also keep the strength of a roadway and a roof to the greatest extent, and is suitable for blasting mining and tunneling processes of the coal mine and other mines.
Drawings
FIG. 1 is a schematic diagram of a blast hole arrangement of a drilling and blasting tunneling method for reducing and fixing rock resistance of a coal mine;
FIG. 2 is a schematic diagram of the charges of the peripheral holes, the bottom holes and the cut holes (cut along a vertical plane passing through the axial lead of the blast hole) of the drilling and blasting tunneling method for reducing and fixing the rock resistance of the coal mine;
fig. 3 is a schematic diagram of the charge of the breakout hole (sectioned along a vertical plane passing through the axis of the blasthole) of the drilling and blasting excavation method for reducing and fixing rock resistance of a coal mine.
In the figure: 1 bottom hole, 2 peripheral holes, 3 collapse holes, 31 front collapse hole, 32 rear collapse hole, 4 cut, 5 cut holes, 6 bottom plate, 7 explosive cartridge, 8 detonator, 9 foot line, 10 blister mud, 11 stemming and 12 ribbon.
Detailed Description
Example 1: as shown in fig. 1-3, the drilling and blasting tunneling method for reducing and fixing rock resistance comprises the following steps:
firstly, planning a tunneling full section on a rock wall to be tunneled, drilling a plurality of blast holes on the tunneling full section, wherein the blast hole at the bottommost layer is a bottom hole 1, the blast holes at the two sides and the top outermost layer are peripheral holes 2, and the blast hole between the bottom hole 1 and the peripheral holes 2 is a caving hole 3.
(note: on the full section of the excavation to be cut, the cutting 4 needs to be dug on the bottom plate, and then the cutting hole 5 needs to be drilled.
Secondly, all the caving holes 3 are divided into a front section and a rear section which are respectively called as a front section 31 and a rear section 32 of the caving hole, the front section 31 and the rear section 32 of the caving hole are respectively filled with a group of explosive cartridges 7, all the peripheral holes 2 and the bottom holes 1 are respectively filled with a group of explosive cartridges 7, each group of explosive cartridges 7 is respectively inserted with a detonator 8, the detonators 8 are respectively connected with a leg wire 9, the other end of each leg wire 9 is respectively connected with a corresponding connecting terminal of an initiator (not shown in the figure),
the detonators 8 are all millisecond delay detonators, the delay time of the detonators in the explosive roll 7 of the front bursting hole section 31 is less than the delay time of the detonators 8 in the explosive roll 7 of the rear bursting hole section 32 is less than the delay time of the detonators 8 in the explosive roll 7 of the peripheral hole 2, namely the delay time of the detonators 8 in the explosive roll 7 of the bottom hole 1,
withdrawing the equipment and personnel outside the safety alert area according to the conventional regulations, adding necessary protection for the cable and the lighting equipment, starting the detonator to explode, and sequentially exploding after each detonator 8 receives the trigger signal.
(the blasting sequence is front broken down eye 31 → back broken down eye 32 → peripheral eye 2 and bottom eye 1, can be checked along the line after 30min, if the conditions of refusal blasting and residual blasting appear, special measures are taken according to the relevant regulations of coal mine safety regulations, and the other safety matters still follow the current safety regulations of coal mine blasting)
Fourthly, the broken stone and crushed coal generated by blasting and the float coal and float gangue on the side wall, the top plate and the bottom plate of the roadway are removed,
supporting the newly formed roadway, including roof supporting and side protecting supporting;
and returning to the first step, and repeatedly performing circulating operation until all tunneling operations are completed.
And firstly, drilling the holes of all blastholes to the depth of 2-2.2 meters. Secondly, the requirements for filling the detonator 8 and the explosive cartridge 7 are as follows:
a. the peripheral hole 2 is provided with an explosive cartridge 7 provided with a 5-section millisecond detonator 8, water plugging stemming 10 and stemming 11 with the plugging length not less than 500 mm;
b. eye collapse 3: the rear section 32 of the collapse hole is provided with 1 explosive cartridge 7, and is closely provided with the explosive cartridge 7 provided with a 4-section millisecond detonator 8, the water plugging blister 10 and the stemming 11 are 400mm long (the plugging length of each collapse hole 3 is kept consistent),
then continuously installing an explosive roll 7 with a 2-section millisecond detonator 8 in the blast hole of the front section 31 of the burst hole, filling water stemming 10 after the explosive is filled, and then using stemming 11 to seal the hole;
c. bottom eye 1: 1 explosive cartridge 7 is arranged in a bottom hole 1, the explosive cartridge 7 provided with a 5-section millisecond detonator 8 is closely attached to the bottom hole, and after the explosive charging is finished, water stemming 10 is filled, and then stemming 11 is used for plugging the hole;
the explosive cartridges 7 in the peripheral hole 2, the front end 31 of the caving hole, the rear end 32 of the caving hole and the bottom hole 1 are all explosive cartridges with the diameter of 32mm, the length of 300mm and the weight of 300 g.
A colored ribbon 12 (or colored paper scraps) is filled between the stemming 11 and the explosive stick 7.
When the stemming 11 is plugged, the leg wire 9 of the blasting hole rear section detonator 8 is straightened and squeezed between the upper wall of the blasting hole and the stemming 11.
The purpose of the invention is realized by the following technical scheme:
1. the rock resistance of the drilling and blasting tunneling section is reduced and fixed. The method is to carry out sectional differential blasting inside blast holes, uniformly distribute holes on all blast holes except peripheral holes and cut holes on the full section, have equal sectional length, carry out group column shaped explosive charge same section blasting among the holes, and carry out blasting according to a certain differential interval sectional sequence by utilizing the differential blasting principle in the holes. Thereby carrying out sectional rock breaking and throwing on the whole blasting rock body. The cracks of the blast hole are not larger than the resistance line of the rock, so that the clamping force is reduced, the effective destructive power is increased, and the problem that the resistance line is enlarged and difficult to blast after the blast hole is lengthened is solved.
2. The most effective destructive power of the blasting material to the rock body is improved by increasing the pressure of the blasting gas. The friction force is increased by increasing the number n of the blocking bodies of each blast hole, so that the pressure of the explosive gas is enlarged by n times, and the most effective destructive power of the rock mass is increased.
3. The maximum anti-explosion force of the bottom of the hole is reasonably matched with the rock breaking capacity of the equipment through reasonable hole depth, so that the anti-explosion force of the rock at the bottom of the blast hole is changed. Because the front-section charging blasting can create a new free surface for the rear-section charging blasting, the rock antiknock force is redistributed, and the maximum antiknock of the hole bottomThe force is reduced, and the maximum anti-explosion force f of the hole bottom is obtained through reasonable hole depthcThe capacity of rock breaking is basically close to the capacity F of rock breaking, so that the best blasting effect is achieved.
4. The clamping coefficient of the working section is changed and reduced, so that the clamping effect of the working face is reduced, and the blasting effect is improved. The whole section rock mass is divided into a front section and a rear section, and the rock mass is damaged and thrown by the explosive charge firstly, so that the rock is displaced in space, and a new free surface and more or smaller fracture auxiliary free surfaces are created for the rear section blasting. Although the number of the free surfaces is not increased, the single-time blasting free surface is expanded to the whole working surface, so that the rock clamping effect is greatly reduced (L/B is defined by K, and when L is definite, B is increased, and K is reduced), and the rock blasting is facilitated.
5. The combination of the cut blasting technology and the hole subsection differential blasting method makes up the limitation of the small-diameter explosive cartridge, and obtains good adaptability of the field blasting of domestic mines, especially coal mine tunnels.
1. General overview of coal mine roadway
And designing and implementing a drilling and blasting tunneling method for reducing and fixing rock resistance in a total return air duct roadway of a certain 103 mining area of a coal mine. The roadway condition is as follows: the roadway is designed into a straight wall semicircular arch shape, the net section area is 5000mm multiplied by 4000mm, the design length is 1710.4m, the design gradient is 8 degrees for descending, 18 degrees for descending, and 0 per mill and 3 per mill for descending; the bottom of the tunnel is connected with the parking lot, and no other tunnel is constructed around the tunnel; the roadway is positioned on a 10-seam floor with a simple structure, the thickness is 2.0-3.85 m, and the average thickness is 2.9 m; the lithology of the roadway is mainly siltstone and fine sandstone, the siltstone is inferior, the mudstone is dark grey to grey black, the inclination angle of the layer is changed between 5 degrees and 21 degrees, the average is 12 degrees, the siltstone is directly supported, the lithology is characterized by dark grey, block shape, compactness, little sand in local part, staggered fracture, the siltstone is also directly supported at the bottom, the lithology is characterized by light grey yellow, grey, local dark grey, block shape, compactness, and plant fossil fragments; the normal water inflow for tunneling is about 12m3H, maximum water inflow of 78m3The water pressure of the grey rock on the bottom plate of the train yard is 2.0-2.2 MPa, q is 0.110L/(s.m), the water-rich property is medium, the minimum water-resisting rock pillar of the roadway is 16.7-25.1 m, and water control measures of geophysical prospecting and drilling are adopted during constructionWhen abnormal conditions are found, the head is stopped in time for treatment, and the drainage capacity of the drainage system is more than or equal to 150m3H; coal (mine) dust has explosion danger, coal is easy to be self-burning coal, and the influence of rock burst is avoided in the process of tunneling a roadway. The lithology of the construction area is the interbed of siltstone and mudstone, and the hardness of the Purchase is 6-10.
2. Drilling and blasting tunneling method design for reducing and fixing rock resistance
2.1 ratio of segmental length to segmental dose
KL represents the upper and lower segment length ratio, KQ represents the upper and lower segment charge ratio, L1 and L2 represent the upper and lower segment blast hole lengths, and Q1 and Q2 represent the upper and lower segment charge. Namely, KL is L1/L2, and K is Q1/Q2.
According to the Lee's blasting funnel theory, when the explosive is blasted in the medium, the explosive dose is unchanged, the burial depth is reduced and the burial depth is unchanged, the explosive dose is increased within the optimal burial depth range, and the blasting effect is similar. Therefore, the ratio of the length of the segments and the ratio of the amount of the drug to be segmented are mutually restricted. The relationship between KL and KQ is:
in the formula: kqIs the ratio of the unit drug consumption of the upper and lower sections, and the application of the higher unit drug consumption can generally select K due to the high clamping strength of the lower sectionq0.8 to 1.0; λ is a parameter related to the charge coefficient of the blast hole, and when the charge coefficient is 0.5-0.8, λ can be approximately considered to be 0.8. During the test, take Kq＝0.8，KQWhen it is 0.6, K is calculatedL1.0, i.e., up and down, etc.
2.2 hole depth L
The extension depth (L) of the free surface reflection as tensile wave energy is proportional to the single detonation zone width (B) (i.e., the area of the detonation zone excluding the perimeter holes), i.e.: l is KB and K is the clamping coefficient. The larger K is, the larger the rock clamping effect is, and the poorer the blasting effect is; conversely, the smaller K, the smaller the rock clamping effect, and the better the blasting effect. It is also critical to choose which is the best value. The data show that the K value is reasonable between 0.5 and 1.2, and the clamping coefficient is basically between 0.4 and 0.5 due to the large section of the experimental roadway of the project. And theoretically calculating the L to be 2.5-6 m according to the section situation of 5 multiplied by 4m, considering that the explosive force of the safety explosive is small and the safety explosive is small-diameter explosive, and determining the depth of the blast hole to be less than 2.5 m.
2.3 delay time and charging Structure
The delay time is denoted by τ. According to the principle of sectional charging differential blasting, in order to ensure that the lower section can fully utilize the new free surface created by the upper section, the method is provided with the following steps: tau is not less than t0+tc+tp. In the formula: t is t0Is the time from initiation to fracture initiation; t is tcIs the time at which the crack begins to propagate to form a funnel-shaped crack with a vertex angle of 2 alpha, tc＝L1/(cosα.VC)，VCIs the average velocity of fracture propagation; t is tpIs the time from the formation of a leakage hopper fracture to the time when the broken rock is separated from the original rock mass and a fracture with a certain width is generated, tp＝L1/Vp；VpIs the average velocity of movement of the rock fragment. During the test, tau is taken to be 20ms and is controlled by a two-stage detonator. The upper section of the caving hole uses a first section of electric detonator, and the lower section uses two to four sections of electric detonators; five-section electric detonators are used for the peripheral holes.
2.4 charging structure
Different blasting types need to adopt different charging structures, so that corresponding blasting effects and purposes can be achieved. After the sectional blasting in the hole is determined, in order to ensure that the explosive energy is distributed more uniformly to improve the blasting quality, tests of equivalent charging and unequal charging are carried out to determine the optimal charging structure. The data show that the explosive quantity in the lower section of the hole is large, and the blasting effect is better.
2.5 pitch a, row pitch b
The pitch and row span value range phi 14 to phi 20 (phi is the diameter of a drilled hole) is reasonable and is determined to be 500mm to 600 mm.
3. Drilling and blasting tunneling method construction key point for reducing and fixing rock resistance
3.1 points of drilling
(1) The peripheral eyes are processed according to the original process;
(2) eye collapse: and punching a first row of collapse holes at a position 460mm upwards from the bottom of the roadway, wherein each row is longitudinally spaced by 520mm, the holes are uniformly and alternately punched, and the distance between the holes is 600 mm. The distance between eyes in the middle row is adjusted as shown in the blasting chart 3, the distance between eyes is 550mm at the periphery, and the distance between eyes is 500mm at the breakout.
(3) Bottom eye: the eye distance is 470 mm.
3.2 essential point of charging at lower part of section
(1) Peripheral holes, 1 block of explosive, water plugging stemming and stemming;
(2) eye collapse, 3 pieces of drug:
firstly, continuously preparing 2 explosive blocks at the bottom layer of a hole as a gun head, then plugging water bubble mud and gun mud with the length of 400mm (paying attention to the consistent plugging length of each burst gun hole), loading a colored tape when plugging the gun mud so as to facilitate gun inspection, then using yellow mud with appropriate hardness to perform first layer plugging, and straightening a detonator foot line to the upper wall of the gun hole when plugging the gun mud so as to prevent the detonator foot line from being damaged when plugging the gun mud;
secondly, charging 1 piece of powder into the upper layer hole section, filling water stemming after the powder charging is finished, and then using yellow mud to plug the hole;
thirdly, the blast head on the bottom layer of the hole is a 4-section millisecond detonator, and the blast head on the upper layer of the hole is a 3-section millisecond detonator;
fourthly, 5-section millisecond detonators are arranged in the peripheral holes and the bottom holes.
(3) Bottom hole charging: 2, charging the medicines according to the old process.
3.3 blasting the network. And the series connection and the parallel connection are carried out.
3.4 one-time drilling, one-time charging and one-time blasting.
3.5, improving the energy directional strength of the explosive in the peripheral holes and adopting a portable energy directional light explosion technology.
4 safety measures
(1) The distance between the blasting point and the blasting warning position is 120-200 m from the blasting place.
(2) The throwing effect is strong, and when the blasting is implemented, the blasting vibration condition is observed, and the water inflow change condition before and after blasting is observed.
(3) After blasting for 30min, the blasting personnel, the gas inspector and the shift captain enter the field inspection after blasting smoke is blown out. After the normal safety is confirmed, other personnel can enter the system. And if the inspection result meets the specification, the power supply of the explosion area can be recovered, and the next production is carried out.
(4) The drilling, charging and blasting personnel must be explained and trained on site by Nanjing institute technicians, and can work on duty.
(5) And conducting test is carried out on the detonator, and the detonator which is possibly unqualified is removed.
(6) Preparation work to be done before construction:
firstly, reinforcing and checking the roadway support within the range of 50m behind the working surface.
Secondly, before blasting, mechanical equipment is moved outside a safety warning area, and cables, lighting equipment and the like are strictly protected by bamboo fences, wood boards and the like.
(7) Before charging, during charging and before and after blasting, a professional gas inspector needs to inspect the gas concentration in the blasting place and the return air flow, and the operation cannot be carried out when the gas concentration exceeds 0.1 percent.
(8) Prevent the individual interruption of the blasting network from causing the misfire measure. The drilling and blasting tunneling method for reducing and fixing the rock resistance is generally suitable for full-face one-time blasting, so that blasting network connection needs to be reliable for blasting reliability, network resistance measurement is carried out before blasting, network reliability is guaranteed, and phenomena such as blasting missing are prevented.
(9) When the explosion is refused after the electrification, a blasting person must firstly take off the key of the initiator, remove the blasting bus from the power supply and twist the blasting bus into a short circuit, and the inspection along the line can be carried out at least after 30 min.
(10) If the conditions of explosion rejection and residual explosion occur, special measures are taken for processing according to relevant regulations such as coal mine safety regulations and the like.
(11) The other safety items still follow the current safety regulations of coal mine blasting.
Compared with the conventional blasting, the drilling and blasting tunneling method for reducing and fixing the rock resistance has the potential safety hazard and the precautionary measures that:
(1) the blasting network is individually interrupted, causing a misfire. The drilling and blasting tunneling method for reducing and fixing the rock resistance can reduce the number of blast holes by a considerable amount, so that the blasting network can adopt a parallel connection mode, and the electric detonator can obtain electric initiation energy at the same time.
(2) The explosive columns in the staged blastholes are sympathetic explosive, so that the drilling and blasting tunneling method for reducing and fixing the rock resistance fails. Mining explosives such as emulsion explosive, water-gel explosive all have the biggest sympathetic detonation distance, when designing loaded constitution, through reasonable in design's interval distance, guarantee to block up the quality and avoid. If necessary, a standardized blocking body can be used for protection.
(3) In the sectional charging in the hole, the low-section detonator is not exploded and is pushed into the exploded gangue by the post-explosion charge, so that unsafe factors are increased. The low-section detonator is not exploded, and three conditions exist, namely, the millisecond detonator has insufficient precision, so that the jump section explosion is caused; secondly, the detonator per se fails to detonate; and thirdly, blasting network quality.
For the first case, a skip charge may be employed in the in-hole staging. Such as 1, 4, etc.; the second case, generally, does not occur. Because the qualification rate of the mine detonators in China basically reaches one thousandth of qualification rate at present, even if the one thousandth of qualification rate is not completely rejected. And thus the misfire rate is lower. Secondly, conducting test can be carried out through the detonator, and possible unqualified detonators are removed. And thirdly, even if the drilling and blasting tunneling method is used for preventing the blasting, the hole distance of the drilling and blasting tunneling method for reducing and fixing the rock resistance is large, the influence of adjacent blast holes is small, the blasting is difficult to throw out due to the bottom charge, and the bottom charge is continuously left on the rock surface and is easy to find and process. And aiming at the third situation, the quality of the blasting network is ensured, and a qualified blasting machine and the like are adopted.
5. Blasting conditions and parameters
5.1 blasting conditions
The equipment and machines such as explosives, detonators, exploders, rock drills, drill bits and the like are completely the same as the drilling and blasting tunneling operation of a common coal mine, only the blasting process adopts a drilling and blasting tunneling method for reducing and fixing the resistance of rocks to tunnel, the actual one-time blasting capability of the exploder for the common coal mine is considered, the section is large, and in order to achieve the reliable blasting effect, the drilling and blasting tunneling method test for reducing and fixing the resistance of the rocks is only carried out at the lower part of the section of the roadway.
2. Blasting equipment
PT-473 model mining water gel explosive or three-level allowable emulsion explosive for coal mines with the specification of phi 27 multiplied by 400mm and 8# millisecond delay electric detonator are adopted; the blasting network adopts series-parallel connection. The FD-200Z capacitance type exploder is used for explosion (the explosion capacity is 200, the maximum external load is 1220 omega, and the peak voltage is more than or equal to 2800V).
3. Parameters of blasting
(1) The number of blast holes is still 46, but no slotted holes are arranged, the cross section is uniformly distributed, the horizontal spacing of the blast holes is 600mm, the row spacing is 500mm, and the depth of the blast holes is 2 m-2.2 m;
(2) two sections of explosive are filled in each blast hole, and two detonators are detonated; each section is charged with powder continuously and positively, yellow mud and water stemming are used as plugging materials, the total plugging length follows the regulation, and the plugging length of the middle stemming is 300-400 mm according to the situation;
4. blasting network
The left and right symmetrical series connection and the parallel connection are adopted; the blasting network calculation is as follows:
when blasting with a normal low voltage copper core cable: i string is U/(R1+ R2)
In the formula: i-string-total current (a) through the series line; u-blasting power supply voltage U is 2800V; r1 — bus resistance R1 ═ 0.075 × 150/1.5 ═ 7.5 Ω; r2-series detonator resistance R2 ═ R0 × n; r0-single detonator resistance (3.2-4.9 omega), R0 is 4.9 omega; n-the number of the detonators connected in series, wherein n is 54; r2 ═ 54 × 4.9 ═ 264.6 Ω; i0-minimum quasi-explosion current of series detonator, I0 is 1.2A I series-2800/(7.5 +264.6) 10.29A. The I string is more than 2I0, so that the blasting material selection meets the blasting requirement.
5. The charge structure design is shown in figures 1 and 2.
The layered charge structure is adopted, each layer charges continuously and positively, yellow mud and water stemming are used as plugging materials, and the total plugging length follows the regulation. The intermediate stemming is 300mm-400mm according to the condition.
6. Drilling and blasting tunneling method for reducing and fixing rock resistance of coal mine tunnel and field test effect and analysis
The drilling and blasting tunneling method for reducing and fixing the rock resistance obtains good comprehensive blasting indexes such as circulation footage, blasthole utilization rate, rock breaking lumpiness, light blasting effect and the like under the condition of small equipment increment, and reduces the number of using sections of the tunneling blasting detonators. The actual footage is 1.8 m-2.0 m, the explosive circulation consumption is 30.2kg, and the detonator circulation consumption is 63. Compared with the prior blast shaft blasting scheme, the circulating footage is increased by 20 percent, the utilization rate of blastholes is increased by 8 percent, the smooth blasting effect is better than that of the prior scheme, and the blasting rock has small and uniform lumpiness and is convenient to transport.
Technical parameters of drilling and blasting tunneling method for reducing and fixing rock resistance and general drilling and blasting tunneling method applied to coal mine tunnel and comparison table 1 thereof
The above embodiments are merely illustrative, and the protection scope of the present invention includes but is not limited to the above embodiments, and any technical solutions according to the description of the patent claims fall within the protection scope of the present invention.
Claims (5)
1. A drilling and blasting tunneling method for reducing and fixing rock resistance comprises the following steps:
planning a tunneling full section on a rock wall to be tunneled, drilling a plurality of blast holes on the tunneling full section, wherein the blast hole at the bottommost layer is a bottom hole, the blast holes at the two sides and the outermost layer at the top are peripheral holes, the blast holes between the bottom hole and the peripheral holes are caving holes,
secondly, all the caving holes are divided into a front section and a rear section which are respectively called as a front section and a rear section of the caving hole, the front section and the rear section of the caving hole are respectively filled with a group of explosive rolls, all the peripheral holes and the bottom holes are respectively filled with a group of explosive rolls, each group of explosive rolls is respectively inserted with a detonator, the detonators are respectively connected with a leg wire, the other end of each leg wire is respectively connected with a corresponding connecting terminal of a matched detonator,
the detonators are all millisecond delay detonators, the delay time of the detonators in the explosive roll at the front section of the bursting hole is less than the delay time of the detonators in the explosive roll at the rear section of the bursting hole and less than the delay time of the detonators in the explosive roll at the peripheral hole, namely the delay time of the detonators in the explosive roll at the bottom hole,
withdrawing the equipment and personnel outside the safety alert area according to the conventional regulations, adding necessary protection for the cable and the lighting equipment, starting the detonator for blasting, sequentially detonating after each detonator receives the trigger signal,
fourthly, the broken stone and crushed coal generated by blasting and the float coal and float gangue on the side wall, the top plate and the bottom plate of the roadway are removed,
supporting the newly formed roadway, including roof supporting and side protecting supporting;
and returning to the first step, and repeatedly performing circulating operation until all tunneling operations are completed.
2. The method of drill blast tunneling with reduced and fixed rock resistance according to claim 1, wherein: and firstly, drilling the holes of all blastholes to the depth of 2-2.2 meters.
3. The method of drill blast tunneling with reduced and fixed rock resistance according to claim 1, wherein: secondly, the requirements for filling detonators and explosive cartridges are as follows:
a. the peripheral hole is provided with an explosive cartridge provided with a 5-section millisecond detonator, and water stemming is blocked, wherein the stemming blocking length is not less than 500 mm;
b. eye collapse: 1 explosive cartridge is arranged at the rear section of the collapse hole, an explosive cartridge provided with a 4-section millisecond detonator is closely arranged, the length of the water plugging mud and the stemming is 400mm,
then continuously installing an explosive cartridge with a 2-section millisecond detonator in the blast hole at the front section of the burst hole, filling water stemming after the explosive loading is finished, and then using the stemming to plug the hole opening;
c. bottom eye: 1 explosive cartridge is arranged at the bottom layer of the bottom hole, a 5-section millisecond detonator explosive cartridge is arranged next to the explosive cartridge, water stemming is filled after the explosive cartridge is filled, and then the stemming is used for plugging the hole;
the explosive rolls in the peripheral holes, the front section of the caving hole, the rear section of the caving hole and the bottom hole are all explosive rolls with the diameter of 32mm, the length of 300mm and the weight of 300 g.
4. A method of drill and blast tunneling with reduced and fixed rock resistance as claimed in claim 3, wherein: and a colored ribbon or colored paper scraps are filled between the stemming and the explosive roll.
5. A method of drill and blast tunneling with reduced and fixed rock resistance as claimed in claim 3, wherein: when stemming is blocked, the foot line of the detonator at the rear section of the caving hole is straightened and squeezed between the upper wall of the blast hole and the stemming.
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