Large-section water-rich saturated fine sand railway tunnel excavation method

Abstract

The invention relates to a large-section water-rich saturated fine sand railway tunnel excavation method. The method includes the following steps that firstly, pilot tunnels of double side walls are constructed in the lower half section of a positive hole of a tunnel in advance and are excavated with sub-steps, temporary inverted arches are arranged on the pilot tunnels respectively, rings are formed in a sealed and segmented mode, and sub-steps are used for carrying out look-ahead dewatering and drainage on the pilot tunnels; secondly, a method that an arc pilot channel is used for reserving core earth is used for excavating the upper section of the positive hole of the tunnel, the core earth is used for stabilizing a tunnel face, arc excavation is performed in place at a time, the positive hole primary supporting steel frame is spliced in place at a time, the temporary inverted arches and a middle partition wall which are next to the tunnel face are constructed to make an upper portion supporting structure form a ring in a sealed mode, the sub-steps are manually cut to excavate the core earth, an overall positive hole primary supporting lagging jack structure is rapidly established, the inverted arches are cast and concrete filling can be carried out in time; thirdly, a result is analyzed according to monitoring measurement data, the inner side wall in the hole, the temporary inverted arches and the middle partition wall are detached in a segmented mode and a composite lining is constructed in time. By means of the method, the construction problem that the self stability of the fine sand is poor and the fine sand rapidly deteriorates when encountering water and surges outwards like quicksand is solved.

Description

Technical field: [0001] The invention belongs to the technical field of tunnel engineering construction, and in particular relates to an excavation method for a large-section water-rich saturated silty-fine sand railway tunnel. Background technique: [0002] The geological conditions of water-rich and saturated silt-fine sand strata determine the particularity of tunnel construction. At present, it is rare to build tunnels in water-rich and saturated silt-fine sand stratum in China, and there is no corresponding construction experience for reference. Tunnel construction in weak surrounding rock strata generally adopts the middle partition method (CD method), the cross middle partition method (CRD method) and the double-side wall pilot pit method. Based on the construction principles of strict grouting, early closure, frequent measurement, and lining follow-up", drawing on the traditional forming method and organizing relevant experts to discuss and study, it was first decide...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art, and provide a method for excavating a large-section water-rich and saturated silt-fine sand

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