Construction Method of Arch Cover and Excavation of River Crossing Tunnel

Abstract

The invention discloses a cover digging construction method of an arch cover of a river crossing tunnel. The cover digging construction method of the arch cover of the river crossing tunnel comprisesthe steps that first, the ground surface is measured and lofting, and arch roof and arch foot positions are measured according to terrain; trees and weeds in a ground surface range of the river crossing channel are removed, and arch grooves are excavated and applied as cut drainage ditches; longitudinal bracket beam trenches are excavated and tied with steel bars, and the outer contour elevation 1m upward lined according to the design is repaired to an arch shape and applied as cement mortar plaster; arch steel frames are installed, arch steel frame arch feet extend into longitudinal bracketbeams and bind to the longitudinal bracket beam steel bars to form the whole, pipe sheds are arranged longitudinally along the arch steel frames, and the steel bars are bound to the arch steel framesand concrete is cast; when the arch cover reaches the design strength, geomembrane and waterproof boards are paved on the arch cover; C group packing layering filling is adopted, layering compaction is achieved, the backfill area surface uses the steel bar concrete to be paved; and the river crossing tunnel dark excavation construction is carried out. The cover digging construction method of the arch cover of the river crossing tunnel solves the technical problems of easy seepage, easy water inrush, large disturbance and easy collapse in the construction process of the rock layer river crossing tunnel.

Description

technical field [0001] The invention relates to tunnel construction, in particular to a construction method for arch cover and excavation of a river crossing tunnel. Background technique [0002] River-crossing tunnels usually refer to tunnels crossing rivers. At present, river-crossing tunnels are mainly constructed by wall top excavation method. However, there are many disadvantages in adopting the open-cut method of construction: during the open-cut process, it is necessary to protect the temporary side slope of the open-cut section, and the temporary side slope for grading, and the inside and outside of the excavation contour of the vertical excavation surface shall be protected by spray anchor nets , when the height of the highest side slope exceeds 10m, and there is an obvious boundary between soil and rock, the risk of landslide is relatively high. If the lag of construction of open hole structure and backfilling (at least 4 months lag) is considered, the slope needs ...

AI Technical Summary

Problems solved by technology

However, there are many disadvantages in adopting the open-cut method of construction: during the open-cut process, it is necessary to protect the temporary side slope of the open-cut section, and the temporary side slope for grading, and the inside and outside of the excavation contour of the vertical excavation surface shall be protected by spray anchor nets , when the height of the highest side slope exceeds 10m, and there is an obvious boundary between soil and rock, the risk of landslide is relatively high. If the lag of construction of open hole structure and backfilling (at least 4 months lag) is considered, the slope needs to be slowed down , the corresponding excavation and backfilling works will increase exponentially; the waterproof layer needs to be laid outside the open tunnel lining, because the temporary side slope at the side wall is vertical, the construction of the waterproof layer is difficult, and the waterproof layer at the junction of horizontal and vertical light and dark It is not easy to connect, and the waterproof layer and the lining of the open hole cannot be closely adhered in the strict sense, leaving a safety hazard for operation safety; the open-cut construction is not conducive to environmental protection, and the surface vegetation within the drainage ditch will be destroyed in a large area, and open-cut earth and rocks will be destroyed. Temporary land acquisition and spoil sites are required, and waterproof and drainage systems and protections must be implemented for the borrow and spoil sites; cofferdams need to be built for the section of the river-crossing tunnel to intercept and divert the flow, with a large amount of work and open-cut construction It is greatly affected by the climate. If construction in rainy season or heavy rain occurs during construction in dry season, the probability of temporary slope instability will increase. At the same time, it will also cause a large amount of water in the foundation pit, which will seriously affect the safety of tunnel construction and operators.

Although the cover-excavation construction method as mentioned above is suitable for the construction of subway tunnels crossing rivers in soft soil layers, it still cannot solve the problems existing in the construction of tunnels crossing rivers in rock layers, and is not suitable for the construction of tunnels crossing rivers in rock layers

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