Classification Support Applied Research Deep Foundation In Soft Soil Area

With the development of urban construction in soft soil area, the situation of the urban land shortage is getting severe. How to improve the utilization ratio of land becomes the theme of urban construction nowadays. Although the overground space is developed for use and the storey height rises gradually, the storey height is limited which requires us to endeavor to make full use of the underground space. Therefore, the soil body supporting issue is generated when it comes to developing the underground space. How to choose the reasonable and safe supporting structure used for developing the underground space needs the powerful support of science and technology. Especially, the improper selection of supporting structure for the foundation pit in the deep silt seam is easy to cause the excessive displacement and collapse of foundation pit, the damage of the surrounding pipelines and roads which will have a great impact on the environment. Thus, it is necessary to deeply study all the characteristics of soft soil and their impact on the supporting structure under different excavation condition. And then the optimal supporting manner can be proposed for excavating the deep and huge pit in the area with deep soft soil.From a large number of practices regarding the supporting project for the deep foundation pit in the area with deep soft soil, it is found the difference value between the actual earth pressure and the theoretical earth pressure in the supporting project of the deep foundation pit is relatively large and the earth pressure at different depths takes on nonlinear variation. How to reduce the drastic variation of active earth pressure caused by excavating the foundation pit to the fullest extent is the critical issue in the process of foundation pit supporting. However, the hierarchical supporting is the effective method of dispersing earth pressure and improving the rigidity utilization of supporting structure.Hence, it is adequately considered to employ the hierarchical and comprehensive supporting, reduce the maximum supporting height of the single supporting structure, give full play to the advantages of various supporting structures in the process of deep foundation pit supporting in the soft soil area. However, how to scientifically and reasonably combine various supporting structures for use under different stratum conditions constitutes an important task badly in need of being solved at present.Combined with the actual project cases, this thesis analyzes and studies systematically the intercoordination of earth pressure and supporting structure in the hierarchical combination supporting of the deep foundation pit in the deep soft soil. The specific research achievements mainly include:1. The application condition of the hierarchical combination supporting structure system under the different stratum conditions;2. The calculation of earth pressure and its actual distribution of the hierarchical combination supporting for the deep foundation pit in the soft soil area;3. The special application of small-size cylinder supporting structure in the hierarchical supporting structure.