Study On Pit Support Technology Of Ultra-Deep Foundation In Sandy Soil

With the development of the city,people have paid more and more attention to the utilization of underground space. The pit becomes deeper and deeper,and there has been an ultra-deep foundation which has a depth of tens of meters. These ultra-deep foundations are always located in the heart of the city and usually have complex surroundings which require better protection. More and more attentions from engineering field and academia have been paid to the ultra-deep foundations.To ultra-deep foundation in sandy soil, it usually happens that the confined water break through the overlaying soil which leads to overall lifting, pwelling sand,water butsting or upwelling soil and so on. Dealing with the confined water with measures of decompression or precipitation causes uneven settlements of the surrounding ground which do manage to surrounding buildings and other public facilities. Whether it is considered from the aspect of the excavation safe or from the viewpoint of the impact on the surroundings, the control of confined water is a very important aspect for studying the ultra-deep foundation in sandy soil.In this paper,based on the foundation pit engineering at the QianJiangShiJiCheng H-07-1,a series of research work was conducted. The details are as follows:1.The type of the retaining structures commonly for the foundation pits were summarized. Besides that, the methods of structures calculation and foundation pits stability analysis were also reviewed.2. Research on control of undergroungd water and confined water of ultra-deep foundation in sandy soil were done and environmental effects caused by lowering the level of confined water were also studied.3.The retaining structures for H-07-1land block were designed.Through the design process,some practical experience has been obtained for designing the ultra-deep and foundation pits in sandy soil,which maybe useful for similar engineerings.