The Design Of Foundation Pit Support In The Expansion Of The Land Area And The Measurement Of Construction

In the recent years, the national construction has been developing very fast, urban population is now larger and larger, and so the city circle is constantly expanding. Given the problem of larger urban population and limited land, high-rise buildings have become the main means of using the urban space fully and effectively, and metro has become a major tool to solve urban traffic congestion. And the construction of almost all high-rise buildings and subway projects isn’t inseparable from the design and construction of deep foundation pit. Relative to the upper part of the main structure of the project, the support of deep foundation pit is more complex. Selecting of support pattern about the deep foundation pit was not only to take into account local hydrogeological conditions, but also taking into account the circumstances about surrounding buildings and infrastructure. Deep excavation project is a temporary project, but it is directly related to whether the follow-up project can be proceed smoothly or not, and it is more related to the life and property, its importance can not be ignored. Deep excavation in many cases is conducted in the center of the city, where surrounding buildings tend to be more intensive, and many will have urban pipeline, and the construction site is very narrow. So design and construction of the excavation have brought much more difficulty, and it will have a great impact on the security during the construction and on the protection of the surroundings, especially poor soil engineering area will bring great security risk.Hefei is located between Jianghuai, it is a typical area where much more expansive soil covers. Expansive Soil is a kind of special clay which will swell when it is with water, dehydration and will contract when it is without water. When conducting excavation in expansive soil, improper disposal project would cause great harm. The paper is based on the deep excavation of two basement of a building in Hefei, analyzing the hydrogeological conditions and the surrounding environment of the project, to find out the cause of safety hazard risks in expansive soil, and thus preliminarily to design the support pattern of deep foundation pit, according to Lizheng Deep Foundation software and ANSYS finite element analysis software to validate the preliminary design and to model the excavation, comparing the data from excavation simulated with the data from measuring, indicating the feasibility of ANSYS insimulation of excavation, and demonstrating the availability of supporting pattern in expansive soil, then coming up with the concrete measures of deep excavation to ensure the safety.Through this paper, to expansive soil, I have a deeper understanding of this particular rock, and grasp the calculation methods and the principles of deep excavation, and I am familiar with the use of software. It fully exercised my ability of solving practical problems. It will be of great help in my future work and study, this thesis is also having some use of reference on the similar projects in the future.