Study On Deep Excavation Of Tai An New City In Yun Nan Province

Deep excavation is a high comprehensive and systematic project that many factors influence each other, it plays an important role in urban high buildings. Deep excavation accidents not only cause an increasing cost in the project, but also make project schedule delay and serious casualties. The reasons of many engineering accidents are due to the selection and design of support measure. Therefore, the preferred selection and design of deep excavation support measure is essential to construction.In this paper, I use Yunnan Dali Tai’an New City deep excavation project as practical engineering background to study on how to select the appropriate support measure and optimize the design to meet the deep excavation stability and economic requirements. To achieve the goal I summarize the calculation and design of the relevant specification and paper. I summarize advantages and disadvantages of a variety of common deep excavation support measures and their suitable site conditions. In the end, I use comprehensive analysis of fuzzy optimization theory and analytic hierarchy process to compare different deep excavation support measures. I use Lizheng Deep Excavation software to make detail design and stability computations and three-dimensional finite element software MIDAS-GTS to optimize the design.In the process of support measures selection, each support measure vary in the mechanical characteristics and site engineering geological conditions. By analyzing the various excavation accident cause and the relevant literature, I summarized the corresponding site engineering geological conditions and grade deformation requirements of normal support measures. Construction safety, construction convenience, cost and environmental impact, duration of the work are five main evaluation index to select a deep excavation support measure. Use comprehensive analysis of fuzzy optimization theory and analytic hierarchy process to compare different deep excavation support measures. After analyzing the site condition of Yunnan Dali Tai’an New City deep excavation project, I select piles+anchor wire support measure by comparing retaining walls, piles+inner rows and piles+anchor wire three support measures.For the selected programs, I use Lizheng Deep Excavation software to make detail design and stability computations. To ensure the safety of support measure, I use three-dimensional finite element software MIDAS-GTS to make 3D simulation. Finally, use the finite element software MIDAS-GTS to optimize design parameters. In the process of optimization, using pile displacement and internal forces as optimizing indexes, I optimize pile spacing, embedded depth, pile diameter three design parameters. By changing the embedded depth, pile spacing, pile diameter three variables, I get the optimal design parameters through comparing bending moment and displacement.Through comparing the support measure getting from fuzzy optimization theory and analytic hierarchy process with the original design, I demonstrate the effectiveness of this method. Using three-dimensional finite element software MIDAS-GTS to simulate excavation, I optimize the design parameters of the support measure. Through my work, I decrease the cost of the support measure successfully.