A Pre-splitting Blasting Method for Stress Relief in Deep Tunnels

Abstract

The invention discloses a deep-buried tunnel stress relieving pre-splitting blasting method. According to the method, perimeter holes or cushion holes parallel to an excavation progress direction in a conventional drilling and blasting excavation scheme are used as stress relieving holes, so that workload is reduced, construction progress is quickened, and the damaging range to surrounding rock is reduced; stress relieving hole blasting parameters are optimized according to surrounding rock main stress level and direction; when blasting is performed, the stress relieving holes are blasted firstly, so that rock masses, close to a certain range of the external side, of an excavation tunnel face are broken in advance so as to release energy, in such a way, when a tunnel main body is excavated, the aims of expanding a stress concentration area to deep surrounding rock and reducing the surrounding rock energy releasing rate are achieved, and the stress relieving effect is fully ensured; meanwhile, the damage to retained surrounding rock masses, caused when cutting holes and breaking holes are blasted also can be reduced, and finally, rockburst occurrence rate is greatly reduced. The deep-buried tunnel stress relieving pre-splitting blasting method disclosed by the invention can be widely applied to drilling and blasting excavation of deep buried tunnels in fields of mining, water conservancy and hydropower, transportation and the like under high geological stress conditions.

Description

technical field [0001] The invention belongs to the technical field of geotechnical engineering, and in particular relates to a stress-relief pre-splitting blasting method for a deeply buried tunnel. Background technique [0002] Rockburst is a severe dynamic damage phenomenon that occurs in the surrounding rock during the excavation of deep underground caverns or deep mining in the fields of water conservancy and hydropower engineering, transportation, mining, etc. It is the sudden damage of the surrounding rock mass caused by excavation. Accompanied by the sudden release of the strain energy of the compressed rock, it is often a dynamic phenomenon in the form of rock chip ejection, a large number of rock collapses or mine shocks, which can cause serious damage to the excavation face, equipment damage and casualties. [0003] Due to the great harm caused by strong rockbursts, methods such as bolting, shotcrete, steel mesh plus shotcrete, and water injection softening are of...

AI Technical Summary

Problems solved by technology

However, the current stress relief technology needs to re-drill the stress relief holes on the outer ring of the face on the basis of the conventional drilling and blasting scheme design, which increases the workload. The line is inclined at a certain angle, which makes the drilling difficult to operate and the damage to the surrounding rock is large.

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