Stability augmentation and solidification method for large-section water-rich saturation fine-silt railway tunnel

Abstract

A stability augmentation and solidification method for a large-section water-rich saturation fine-silt railway tunnel comprises the following steps that (1) advance dewatering is conducted by means of a double-side-wall advance pilot tunnel on the lower portion of the tunnel, and dewatering and solidification are conducted on a construction sand layer of the tunnel; (2) partial excavation is conducted, vertical steel frames are erected, the lower pilot tunnel is excavated in an upper and lower step core soil reserve method, the vertical steel frames are erected longitudinally, the whole ring of the primarily-erected steel frame of a main tunnel is divided into a plurality of units, and steel boards are utilized as flanges among the units and are connected through high-strength bolts; (3), fore shaft anchor pipes are fixedly connected to the steel frame connection boards, the anchor pipes are welded to the steel frames, the anchor pipes are filled with mortar, the steel frame connection boards are fixedly connected with longitudinal connection U-steel, and longitudinal connection reinforcing steel bars among the steel frames are distributed in a Z shape; (4) cement single fluid is poured to the back of the primarily-erected steel frame timely in a pressing mode after excavation is completed, and grouting and solidifying are conducted on the disturbed sand layer. According to the stability augmentation and solidification method, self-bearing ability of surrounding rock can be enhanced, and therefore construction safety is guaranteed.

Description

Technical field: [0001] The invention belongs to a tunnel engineering construction method, in particular to a method for increasing stability and consolidation of a large-section water-rich saturated silty 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. [0003] The conventional method for constructing tunnels in water-rich and saturated silt fine sand strata is to excavate in sections to strengthen the rigidity of the initial support steel frame. Excavation. However, since the original sand layer is dense without excavation and disturbance, the grout diffusion range is very limited, and the grouting consolidation effect is poor, and sand gushes and slides still occur during ex...

AI Technical Summary

Problems solved by technology

During the construction of the test section, it was found that due to the uneven convergence and deformation of the steel frame settlement, the welding between the steel frame and the longitudinal connecting bars occurred many times, resulting in cracking of the sprayed concrete along the circumferential direction

Without optimization and improvement, construction safety cannot be guaranteed

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