Long-short pile composite foundation top-down construction method

Abstract

The invention discloses a long-short pile composite foundation top-down construction method, comprising: a) carrying out construction for a short pile according to the design requirement; b) casting foundation bottom plate and obligating a long-pile hole site during construction; c) constructing an upper structure; d) constructing a long pile; and e) closing a long-pile hole. In the invention, the short pile and soil form composite foundation to be loaded firstly, thereby improving the stress level of the short pile and the soil in early stage of loading and increasing the load sharing ratio of the short pile and the soil; afterwards, the long pile participates in the load, which is favorable for the short pile, soil and long pile to work together; besides, the vertical pressure of soil between piles is increased so that the lateral additional stress in the foundation is enhanced correspondingly, the frictional resistance around piles of the long pile and the short pile is improved, edge load effect is generated at the end of long pile, and the load ability of the long pile is enhanced; the design should consider the foundation bearing ability and settlement situation under two different foundation states which is similar to check calculation of composite beam during structural engineering; the long pile in the topdown construction is a soil extruding pile generally, and informatization feedback should be strengthened and parameters such as speed of pile construction should be strictly controlled, thereby preventing the quality of the short pile body from being affected. The invention is beneficial to improving the coaction level of piles in the long-short pile composite foundation, improves the safety and reliability of the composite foundation and shortens the construction period.

Description

technical field [0001] The invention relates to a long-short pile composite foundation reverse construction method, which is suitable for the field of civil engineering foundations. Background technique [0002] The long-short pile composite foundation is a new type of composite foundation. Its principle is to bear the load of the superstructure through the joint action of long piles, short piles and soil. Usually, the long piles have higher stiffness and the short piles have lower stiffness. Pile and short pile are generally constructed at the same time. Therefore, under load, long piles are prone to stress concentration due to their high stiffness, while short piles and soil are difficult to play a role due to their low stiffness. In the prior art, measures such as cushion layers are generally used to improve the stress exertion of short piles and soil, but the joint effect of short piles and soil is not good when the elastic moduli of long piles, short piles, and soil ar...

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Problems solved by technology

[0003] The technical problem to be solved by the present invention is to provide a long-short pile composite foundation reverse method construction method, which can avoid short piles and soil stress from lag

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