The Construction Method of Squeezing Blasting and Road Repairing without Protective Layer on the Full Section of the Bench in the Lower Tunnel

Abstract

The invention relates to the technical field of engineering blasting, in particular to a construction method of full-fracture-surface protective-layer-free extruding blasting, road repair and clear pass keeping of lower-layer steps of a tunnel. The construction method comprises the steps that 1, the tunnel is divided into an upper layer and a lower layer, and excavation is performed by adopting astep method; 2, after the steps of the upper layer are excavated for 60-80 m, the separation distance is kept to perform full-fracture-surface protective-layer-free extruding blasting of the steps ofthe lower layer, and full-fracture-surface one-time blasting formation of the steps of the lower layer is formed by adopting a combined blasting method including main blasting hole differential extruding blasting, exertion of composite reflective energy gathering to foundation surface base boards, protective-layer-free extruding blasting of buffer energy dissipation devices and pre-cracking blasting of two side walls; 3, a slope road is built on a blasting pile produced through extruding blasting, forward route-changing displacement is performed with extruding blasting by keeping the separation distance of 12-24 m. By adopting the method, drilling and blasting operation and slope road pass keeping can be simultaneously performed, parallel construction of steps of the upper layer and the lower layer of a narrow tunnel space is achieved, and the construction progress is greatly promoted.

Description

technical field [0001] The invention relates to the technical field of tunnel construction and blasting construction, in particular to a construction method for extrusion blasting without a protective layer on the full section of the steps in the lower layer of the tunnel and road repair and maintenance. Background technique [0002] For large-section tunnels with narrow tunnel width, none of the existing construction methods can meet the requirements of simultaneous drilling and blasting excavation of the lower steps and simultaneous operation of the two functional areas as the traffic passage of the upper steps, which will affect the tunnel development. Construction progress of excavation. Using the full-section alternate excavation method of positive steps, only one working surface of steps is excavated at a time, so it takes a long construction time period, and the production efficiency is low, which affects the entire production progress. Using the half-width alternate...

AI Technical Summary

Problems solved by technology

Realize the excavation by adopting the positive step method, overcome the adverse effects of blasting excavation on the whole section of the lower step, overcome the influence of single operation construction of only one step on the upper and lower steps, and realize parallel excavation operations by using the upper and lower steps at the same time, Accelerate the construction progress; overcome the difficulty that the lower steps cannot alternately carry out half-width excavation and half-width passage when the tunnel width is narrow, realize the simultaneous construction of the lower steps as traffic roads and blasting excavation, and realize the smooth flow of traffic roads that meet the upper steps It is necessary to realize the blasting and excavation construction of the upper and lower steps at the same time to speed up the construction progress; to overcome the difficulties of low efficiency, high labor intensity and high safety risk of manual wind drilling, and to realize the use of down-the-hole drilling vehicles to drill vertical guns on the lower steps. holes to improve work efficiency, improve labor and safety conditions for workers; realize the differential extrusion blasting of the main blast hole, and make the blasting at the lower steps continue to move forward without cleaning up the blasting slag on the slope road in front of the airport; Rapid excavation blasting without protective layer on the bottom plate of the base surface, and a composite reflection energy-gathering and buffer energy dissipation device is installed at the bottom of the blast hole. It has double energy-gathering effect with reflective energy-gathering jet, which can increase the horizontal fracture line of the rock at the bottom of the blasthole, enhance the ability to break rocks and solve the root residue, and make the foundation surface bottom plate one-time blasting excavation to the design elevation; reflective energy-gathering buffer pad Layer, rigid cushion and buffer energy-dissipating cushion together form a three-layer composite cushion, which has three energy-dissipating buffering effects, can reduce the explosion energy, reduce the damage of the detonation wave to the rock retained on the base plate of the foundation surface, and protect the foundation surface The integrity of the floor rock ensures the quality of the rock at the bottom of the hole; realizes the pre-splitting blasting of the left and right side walls, reduces the damage of the blast shock wave to the retained rock mass, protects the integrity of the rock, and improves the flatness of the rock surface; The entire section of the lower steps is blasted into shape at one time to speed up the construction progress

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