Process for excavating and constructing micro-steps of tunnels on basis of method for excavating steps

Abstract

The invention provides a process for excavating and constructing micro-steps of tunnels. The process includes steps of excavating upper steps without reserved core soil, obliquely and downwardly drilling foot lock anchor rods at arch feet and hermetically attaching the foot lock anchor rods to base rock by means of grouting or by the aid of anchor agents; controlling and keeping the lengths of the upper steps, simultaneously excavating the upper steps and intermediate steps without reserved core soil and arranging foot lock steel pipes and lock anchor rods for the intermediate steps; circularly carrying out the steps by three times; keeping synchronously excavating the upper steps and the intermediate steps, simultaneously erecting trestles, starting to excavate lower steps and close inverted arches without reserved core soil, and then closing the inverted arches; synchronously advancing excavation of the upper steps, the intermediate steps and the lower steps, and carrying out alternate circular operation for synchronously excavating each upper step, the corresponding left intermediate step and the corresponding right lower step and synchronously excavating the upper step, the corresponding right intermediate step and the corresponding left lower step until the tunnels are completely integrally excavated. The process has the advantage that effects of guaranteeing the tunnel construction safety and increasing the construction speeds can be effectively realized.

Description

technical field [0001] The invention provides a tunnel excavation construction technology based on a step excavation method, and in particular relates to a micro-step excavation construction technology suitable for excavation of Level IV and V weak surrounding rock tunnels. Background technique [0002] In recent years, there have been many collapse accidents in the process of tunnel construction at home and abroad, causing large casualties and property losses. Survey statistics show that the main reason for these accidents is that the length of the tunnel excavation steps is too long, the initial support is not closed in time to form a ring, and the secondary lining is not followed up in time, which leads to the instability of the surrounding rock. [0003] Generally, the three-step seven-step excavation method is adopted in the design of weak surrounding rock tunnels. The distance between the inverted arch and the tunnel face is 35-40m in length. The locking feet of the s...

AI Technical Summary

Problems solved by technology

[0004] The invention provides a tunnel micro-step excavation construction technology based on the step excavation method, which solves the problem that in the prior art, self-advancing anchor rods cannot be constructed in time to lock the steel frame feet, which is not conducive to controlling the deformation in the early stage, and the inverted arch steel frame It cannot form a ring in time, which is not conducive to reducing the deformation rate and has complicated procedures and low construction efficiency. The present invention proposes a new construction technology-the micro-step method, which has achieved better protection of tunnel construction safety and faster construction. The effect of construction speed