Design method of subway foundation pit end-suspended pile enclosing structure in rock stratum with soft upper portion and hard lower portion

Abstract

The invention provides a design method of a subway foundation pit end-suspended pile enclosing structure in rock stratum with a soft upper portion and a hard lower portion, and relates to the technical field of underground building engineering construction, in particular to a method for designing a foundation enclosing structure when an underground subway station is excavated and built in the decayed rock stratum with the soft upper portion and the hard lower portion. Large-rigidity and large-diameter cast-in-situ bored piles are adopted in the soft upper portion of the rock stratum for enclosing, as the weakly-decayed flow liner rock stratum which is hard and large in strength on the lower portion is small in deformation and large-diameter drill holes are difficult to construct, small-diameter steel pipe piles easy to construct are adopted, and the two kinds of piles are effectively connected. The problem that enclosing piles in the decayed rock stratum with the soft upper portion andthe hard lower portion are difficult to construct is solved; the problem about effective connection of the two kinds of up-and-down discontinuous piles of a foundation pit is solved; and the purposesthat the upper cast-in-situ bored piles and the lower steel pipe piles are connected, spuds are locked by anchor cables, and the upper cast-in-situ bored piles are prevented from toppling and stability lose are achieved.

Description

technical field [0001] The invention relates to the technical field of underground construction engineering; in particular, it relates to a method for designing an enclosure structure of a foundation pit in excavating and constructing an underground subway station in a weathered rock stratum that is soft at the top and hard at the bottom. Background technique [0002] With the development of cities and the construction of rail transit, more and more cities are building subways. For cities with well-developed underground rock formations, such as Qingdao, Shenzhen, Xiamen, Chongqing and other cities, due to the influence of weathering on the upper part of the underground rock formations, the strength of the rock formations is low, and the slightly weathered rocks in the lower part are less affected by weathering and have high strength, forming strata that are soft at the top and hard at the bottom. When excavating subway foundation pits in the weathered rock strata that are so...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a design method for the surrounding structure of the suspension piles of the subway foundation pit in the upper soft and lower hard rock formations, which solves the technical problems existing in the prior art

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