Supporting structure of extra-large cross-section loess tunnel and construction method thereof

Abstract

The invention relates to a supporting structure of an extra-large cross-section loess tunnel and a construction method thereof. Larger deformation and even collapse accidents occur in the construction process of the loess tunnel easily. At present, aiming at the large cross-section loess tunnels, the construction of the large cross-section loess tunnel with the excavating area of 140 m<2> is realized by a reserved core soil short step method successfully; the construction of a new loess tunnel with the burial depth of 25 m and the excavating area of 120 m<2> under-passing the existing railway is realized by a CRD method; and the difficulty and the risk of the construction increase gradually along with further increment of the excavated cross-section of the loess tunnel. The supporting structure comprises an initial support, an archwall secondary lining and an inverted arch, wherein a small conduit leading support is arranged along the contour line of the tunnel arch part; and a waterproof layer is arranged between the initial support and the archwall secondary lining. The supporting structure and the construction method thereof have the advantages of effective guarantee of construction safety of the extra-large cross-section loess tunnel, simple construction process, large excavating space, convenient operation for a large-size machine and fast tunnel construction progress.

Description

technical field [0001] The invention relates to tunnels, in particular to a support structure and a construction method for an extra-large section loess tunnel. Background technique [0002] During the construction of loess tunnels, large deformations and even landslide accidents are prone to occur. At present, for large-section loess tunnels, the method of reserving short steps of core soil has been successfully applied to solve the excavation area of ​​140m2. 2 The construction of large-section loess tunnels, and the use of CRD method to solve the problem of buried depth of 25m and excavation area of ​​120m 2 Construction of a new loess tunnel under an existing railway. With the further enlargement of loess tunnel excavation section, its construction difficulty and risk also gradually increase. Although the side wall pilot tunnel method can effectively control settlement, there are many construction steps, narrow construction space, slow construction progress, and high p...

AI Technical Summary

Problems solved by technology

Although the side wall pilot tunnel method can effectively control settlement, there are many construction steps, narrow construction space, slow construction progress, and high project cost. Especially for the construction of long-distance and super-large-section loess tunnels, it is necessary to achieve safe and rapid , economical construction, must adopt appropriate support structure measures and reasonable excavation methods

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