Damping blasting method for steep dip small crossing angle layered surrounding rock small-distance tunnel excavation

Abstract

The invention provides a damping blasting method for steep dip small crossing angle layered surrounding rock small-distance tunnel excavation to solve the technical problem. The method comprises the following steps: dividing two small-distance parallel tunnels into a beforehand cavity and an afterwards cavity, wherein the beforehand cavity and the afterwards cavity are constructed in a staggered mode, dividing an excavated section of the tunnel into an upper bench excavating area, an upper bench excavating boundary, a lower bench excavating area and a lower bench excavating boundary; processing the upper bench excavating area by hole millisecond blasting excavating and processing the upper bench boundary by smooth blasting. After the upper bench excavating area is processed by excavating, the lower bench excavating area is processed by horizontal shallow hole blasting and the lower bench boundary is processed by smooth blasting. The damping blasting method for the steep dip small crossing angle layered surrounding rock small-distance tunnel excavation has the advantages that surrounding rock of the layered surrounding rock small-distance tunnel is prevented from losing balance during the blasting process or fissure of a blasting layer is prevented from being too deep to influence the stability of the tunnel, operating efficiency is improved and reinforce and maintain cost is reduced.

Description

technical field [0001] The invention relates to a blasting construction method in tunnel excavation engineering, in particular to a shock-absorbing blasting method used for excavation construction of a steep-inclined, small-intersection layered surrounding rock with a small clear distance. Background technique [0002] Steep-inclined small-angle layered surrounding rock tunnel with small clear distance refers to tunnels with small clear distance in parallel arrangement formed by excavating in natural layered rock mass (when the surrounding rock grade is IV~V, the clear distance is less than 2~3 times the excavation width of the tunnel), at this time the tunnel axis is consistent with the strike of the rock strata or intersects at a small angle (the angle of intersection is less than 15°-20°), but the dip angle of the rock strata is relatively large (generally the dip angle is greater than 45°-60°). When excavating tunnels in layered rock masses with medium and steep dips, bl...

AI Technical Summary

Problems solved by technology

Due to the effect of blasting and earthquakes in these methods, the layered surrounding rock of the tunnel may be cracked, destroying the integrity of the original rock, reducing the self-stability of the rock mass, and may even lead to the collapse of the formed tunnel.

This not only affects the smooth progress of the construction, but also increases the difficulty of lining construction and increases the project cost.

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