Construction method of portal section, passing through loose media, of tunnel

Abstract

The invention discloses a construction method of a portal section, passing through loose media, of a tunnel. The method comprises the steps of 1, reinforcing the surface of a portal section; 2, protecting the side slope at the portal, excavating the slope surface by adoption of an excavator, manually repairing the slope surface, carrying out a concrete injection operation by adoption of a concreteinjector, placing an anchor drilling machine for hole drilling after the injected concrete achieves the designed strength, manually mounting an anchor after the hole is formed, and carrying out anchor grouting adoption of a backward grouting method; 3, constructing a slide-resistant pile and a crown beam at the portal; 4, constructing a protection arch and a pipe shed at the portal; 5, reinforcing the foundation at the portal; and 6, constructing a tunnel underground excavation section. According to the method, a holing supporting form which adopts a pile and arch structure in combination with the pipe shed is put forward; and the cantilever structure stress state of pipe shed holing is converted into a favorable stress structure of two fixed ends, so that the core problems that the supporting structure below the loose media at the portal is easy to slide and the settlement deformation is large are solved, and the aim of safe, feasible and reliable holing is achieved.

Description

technical field [0001] The invention relates to the technical field of a construction method for an entrance section of a tunnel engineering, in particular to a construction method for an entrance section of a tunnel passing through a loose body. Background technique [0002] China has a vast territory and complex terrain and geological conditions. During the construction of tunnels, there are also unfavorable geological conditions such as tunnel openings located in broken zones, loose bodies, weak strata, water gushing, and sand gushing layers. For tunnel entry in such geological sections, long pipe sheds are often used as the main measure in China at present; Excavation disturbances, cracking and slippage may still occur after the side elevation of the tunnel entrance section is unstable, resulting in the risk of excessive settlement in the tunnel and intrusion into the tunnel clearance; subsequent treatment and rectification will be required, such as changing the arch or ...

AI Technical Summary

Problems solved by technology

Before the tunnel is excavated into the hole, after the vertical slope of the hole is excavated in place, the guide wall of the pipe shed is constructed, the guide pipe is pre-buried, and the drill pipe is processed at the same time, and a high-power air compressor is equipped. The locator is positioned, and the deviation is corrected in time according to the drilling deviation of the rod body during the drilling process. At the same time, the power is adjusted according to the drilling length and the address of the soil layer to ensure the depth and position of the drilling rig. After the drilling is completed, separate the drilling rig with the drill pipe and grouting; start the construction of the next pipe shed to form a stable arch ring outside the excavation. The technical solution is accurate in the drilling process and high in hole forming efficiency. deficient in shifting

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