A Construction Method for Vibration Absorption of Tunnel Exit with Very Small Clear Distance

Abstract

The invention discloses an out-of-pit tunneling damping construction method for a minimal clear-distance tunnel. The out-of-pit tunneling damping construction method comprises the following steps thatan advanced tunnel is excavated firstly, the advanced tunnel is subjected to out-of-pit tunneling, a middle rock pillar of the advanced tunnel is subjected to grouting reinforcement, and a secondarylining of a tunnel entrance section of the advanced tunnel is constructed through a spaced driving method; a subsequent driving tunnel is excavated, a pilot heading is excavated at the subsequent driving tunnel firstly, a pilot heading primary support is constructed, a double-row cut seam pipe presplit blasting method is matched with a mechanical cold excavation method to conduct expanded excavation on the side, close to the middle rock pillar, of an upper step of the subsequent driving tunnel, an upper step primary support is constructed, the pilot heading primary support is dismantled, a lower step section of the subsequent driving tunnel is excavated, a lower section primary support, an inverted arch and a filling layer are constructed, and then a second lining of the subsequent drivingtunnel is overall built through formworks; and the second step is repeated till out-of-pit tunneling construction of the subsequent driving tunnel is completed. According to the out-of-pit tunnelingdamping construction method, the damage of blasting vibration to the middle rock pillar and the concrete linings is lowered, and the problem that during blasting construction through an existing construction method, the middle rock pillar and a tunnel lining are prone to being damaged is solved.

Description

technical field [0001] The invention relates to the technical field of tunnel construction, in particular to a construction method suitable for shock absorption of a tunnel exit with a small clear distance or a very small clear distance. Background technique [0002] In the prior art, due to considerations of route planning requirements and terrain constraints, it is sometimes unavoidable to adopt tunnels with a small clear distance for traffic routes. Especially where bridges and tunnels are connected, most of them are bifurcated tunnels, that is, they gradually transition from separate, small clear distance, and extremely small clear distance tunnels. In the tunnel entrance section with a very small clear distance, the current tunnel blasting construction method has the following disadvantages: (1) the blasting of the rear tunnel will cause damage to the lining and middle rock wall of the tunnel ahead; (2) the excavation footage is too small or During mechanical excavatio...

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Problems solved by technology

[0005] The main purpose of the present invention is to provide a construction method for shock-absorbing tunnel exit with a very small clear distance, so as to at least solve the technical problem that the existing construction method is easy to cause damage to the middle rock pillar and the tunnel lining when constructing a very small clear distance tunnel

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