Application Of Recoverable Anchor Cable Technology In Large Foundation Pit Supporting

With the rapid development of construction industry and demand of underground space in china, high-rise building foundation pit engineering supporting form gets more and more attention, while the pile anchor supporting structure is one kind of form. But traditional anchor cable is not recycled in the foundation supporting structure, anchor cable is easy to invade nearby underground space and cause environmental pollution to become the follow-up project underground obstacles. In order to solve the problem, prestressed anchor cable with pit supporting form gets fast development.In this paper, on the basis of predecessors’ research and practical engineering, the recycled anchor cable used in Foshan CBD foundation carried out plant material strength experiment, ultimate bearing capacity experiment and tension experiment. Through the monitoring data to explore the destruction of different stages and forms of the anchor cable, bearing formula of anchorage length, formula of ultimate bearing capacity, reason for the loss of prestress and law of anchor cable internal force variation with excavation by software, the article main content is as follows:(1)On the basis of the content, the paper introduces mechanical characteristics and failure forms of the anchor cable under different conditions, summarizes three forms damages of the anchor cable, and it verified by experiment and analysis.(2)The length of anchor cable exist a reasonable value and it is an important indicator of economic benefits and effective stress. It is that the effective length of anchor cable is about 2.4 m through experiment.(3)The types and forms of anchor cable are so abundant, so there is no a unified calculation formula. Base on the practical application of anchor cable, express formula of ultimate bearing capacity.(4)Through the analysis of the observation data of 16 months, it found that the loss value of anchor cable is 12% ~ 25%, and 85% of the value is concentrated in the first two days, although it late days has less change. It summarizes the relationship about stress of anchor cable with excavation of foundation pit. It states the main reason for loss of prestress and measures to reduce the loss.(5)It sorts date about pile lateral deformation, lateral displacement of soil, land subsidence and the change of water level, at the same time analysis the impact of soil and water loss on the monitoring project. Through improvement of construction technology, it will reduce ground settlement.