Loess tunnel micro-step construction method

Abstract

The invention discloses a loess tunnel micro-step construction method, and relates to the technical field of tunnel construction. The loess tunnel micro-step construction method comprises the following steps that forepoling of an upper step is carried out; the upper step is excavated for drossing; a middle step is excavated for drossing; the upper and middle steps are sprayed with C25 concrete forthe first time; grille steel frames are erected on the upper and middle steps, and the lower step is excavated at the same time; the upper and middle steps are sprayed with concrete for the second time, and grille steel frames are erected on the lower step; the lower step is sprayed with concrete; excavation supporting of an inverted arch is carried out, and alternating cycle operation of micro-step excavation is maintained in sequence; the excavation supporting of the inverted arch is carried out for secondary lining; a advance long pipe-shed is used as the forepoling of the upper step in the tunnel entrance section; advance short pipe-shed is used as the forepoling for the upper step in the weak surrounding rock section of a hole body; and advanced small pipes are used as forepolings ofthe upper step in the IV class, V class, and VI class surrounding rock sections. According to the loess tunnel micro-step construction method, of the operating space is used fully, the utilization rate of personnel equipment is enhanced, the construction safety is ensured, the working efficiency is improved, and the construction progress is speeded up.

Description

technical field [0001] The invention relates to the technical field of tunnel construction, in particular to a micro-step construction method for a loess tunnel. Background technique [0002] Many collapse accidents have occurred in loess tunnel construction at home and abroad. The main reason is that the surrounding rock cannot be closed in time and the secondary lining is not timely, which leads to the collapse. A patent application for tunnel micro-step excavation construction technology based on the step excavation method (application number 201510623492.4) discloses a tunnel construction method. In this method, the upper step is excavated first, and the upper step is excavated to a height of 4m and a length of 4m. The core soil is not reserved, and the locking foot anchors are drilled obliquely downward at the arch foot. Two locking foot anchors are installed for each arch frame, and two 4-meter-long locking foot anchors are installed at each place to control and mainta...

AI Technical Summary

Problems solved by technology

[0004] The object of the present invention is to provide a kind of loess tunnel micro-step construction method, which can save engineering cost, improve construction efficiency and quality, reduce labor intensity, safe and stable, convenient and quick, to solve the existing loess tunnel construction in the above-mentioned background technology Long construction period, inconvenient construction, high engineering cost, and technical problems that cannot be adjusted flexibly

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