A method of energy-gathering smooth surface blasting with multiple wedge straight cuts in deep holes in rock roadways

Abstract

A method of energy-gathering smooth surface blasting with multiple wedge straight cuts in deep holes in rock roadways. The method adopts multiple wedge straight cutting technology to realize a large cavity with a cavity opening of 3.2-3.4m and a deep hole cavity with a depth of more than 3.0m, which improves the single-cycle footage of rock roadway excavation; adopts peripheral T-shaped energy-concentrating blasting technology, realize the small diameter and low explosive density of peripheral blasting, and the two-way full-hole deep slits along the tangential direction on both sides form a smooth surface, and the gravel is cut along the radial direction. Small super-under-excavation, reducing gangue lumpiness, good smooth surface formation, and stable support effects; on the basis of these two key technical solutions, the full-section blasting process and parameters are set to achieve the expected rock roadway blasting depth of 3.0m as a whole Deep hole glossy blasting effect.

Description

technical field [0001] The invention belongs to the technical field of smooth blasting, in particular to a method for energy-gathering smooth blasting of deep holes in rock roadways with multiple straight wedge cuts. Background technique [0002] In recent years, the annual excavation volume of rock roadway in my country's coal industry has reached more than 3000km, and rock roadway excavation generally accounts for 30% of the total mine excavation volume. It is the throat project of coal mine construction and development extension. Accelerate the speed of rock roadway excavation. Among them, the rapid excavation of soft to medium hard rock roadways has been solved by fully mechanized excavators, with an average monthly footage of more than 300m. Hard rock roadway excavation mainly relies on the drilling and blasting method. Newly developed equipment such as rock drilling rigs, backhoe loaders, and rock roadway drilling units have basically solved the main processes of drill...

AI Technical Summary

Problems solved by technology

Hard rock roadway excavation mainly relies on the drilling and blasting method. Newly developed equipment such as rock drilling rigs, backhoe loaders, and rock roadway drilling units have basically solved the main processes of drilling and gangue extraction. However, the blasting process has always been It is the bottleneck that restricts the level of single entry, mainly as follows: (1) The cutting cavity is small, generally the width of the cavity opening is 0.8m ~ 1.2m, and the width of the bottom of the cavity is 0.2 ~ 0.4m. Generally, single wedge, double wedge, wedge Direct hybrid cutting method, the actual depth of the cavity after cutting blasting is less than 2.5m (belonging to medium and deep hole blasting), the actual blasthole utilization is 70% to 80% (drilling 3m, the actual utilization hole depth is 2.2m), resulting in cyclic footage Generally, it is 2-2.5m, and the monthly single entry level is generally 60m-70m; (2) 32mm large-diameter drug rolls are used, and the peripheral spacing is controlled at 300mm-400mm, resulting in high drug density. Serious over- and under-excavation, poor roadway formation, large amount of secondary renovation works around, time-consuming, large amount of shotcrete, high cost, and unfavorable for surrounding rock stability, low roadway support efficiency, and difficulty in increasing the excavation speed; (3) When the rock is hard, it is generally solved by increasing the number of blastholes and loading more explosives, resulting in a large number of gouges in the whole section, a long time for gouging holes, a large amount of charge, large blasting vibration, and a long throwing distance. There are many gangue in the back, and the gangue needs to be crushed twice, which seriously restricts the excavation speed

[0003] In terms of rock roadway cutting methods, multi-wedge cutting has been adopted in recent years, wherein (1) multi-wedge cutting adopts two-stage wedge-shaped or three-stage wedge-shaped compound Fewer advantages, using the wedge-shaped one-time + two-time + three times to increase the cutting depth step by step, but in the coal mine roadway, the roadway section is generally 4 ~ 5.7m, the roadway width is limited, and the cutting cavity mouth can meet 0.8 ~1.2m, and the hole depth meets the design requirements of 2.4~3.0m, the rock drilling rig used for drilling is limited by the length of the drill arm (3.5m~4.7m), resulting in the wedge angle of the main cut generally being 78~ 84°, 60-75° beyond the reasonable cutting angle of squint eyes, resulting in increased clamping effect of the bottom, thicker bulging phenomenon at the bottom, and reduced blasthole utilization rate to 80%. The actual cutting depth is only 2.2-2.4m, and it is difficult to reach 3m above deep hole cut

(2) Straight-wedge mixed cutting adopts primary wedge + secondary wedge-straight hybrid enhanced cutting, and primary wedge-straight mixed enhanced cut. Generally, the width of the primary groove is 0.8-1.5m, and the small groove causes the secondary groove to be free. The surface is small, and the utilization rate of the straight hole is low under the action of deep clamping. The actual depth is only 2.4-2.6m. At the same time, the rate of large pieces of gangue is high, and the rate of excessive broken pieces is also high

In terms of peripheral smooth blasting, the conventional method adopts a large diameter of 32mm without coupled light blasting, with a spacing of 300-400mm. Due to the large diameter of the charge coil and the small spacing, the blasting energy density is high. When encountering weak and jointed rocks, it usually causes Over-excavation and under-excavation phenomena; in recent years, market standard specifications have been used: PVC pipes, ABS pipes, PPR thermoplastic pipes, etc. The hole forms a two-way energy-concentrating tube at an angle of 180° on both sides of the tube, which can make the explosive energy produce a strong directional cutting effect along the cutting holes on both sides of the tube wall, weaken the blasting effect in other directions of the blast hole, and have a high success rate of light blasting, but due to the device Adopt the centralized charging method of installing 1-2 volumes of 500mm energy-concentrating tubes at the bottom of the hole with large-diameter powder rolls of 32mm-35mm (the length of the explosive is 300-600mm). Cutting effect occurs, the actual effective smooth surface depth only accounts for 1 / 3 of the hole length, the smooth surface forming effect is poor, and due to the concentrated large-diameter and high-density charge at the bottom of the hole will cause a lot of over-undercutting

The use of small-diameter D-shaped tubes with an inner diameter of 27mm and an outer diameter of 32mm reduces the energy density of the surrounding explosives, increases the distance between the surrounding holes to 600-800mm, reduces the number of drilling holes in the surrounding holes, and saves drilling time to a certain extent. , but for rock drilling rigs, the actual time saving is very limited (it only takes 2 minutes for a rock drilling rig to drill a 3m deep hole, and the drilling efficiency is very high, which basically solves the problem of drilling speed and reduces the number of surrounding drilling holes 10 pieces, only save 20 minutes, time saving is limited); at the same time, because the energy is all concentrated on the directional cutting on both sides, there is no cutting effect along the radial direction of the roadway, resulting in more large pieces of gangue produced by peripheral eye blasting. unfavorable

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