| With the rapid development of China’s economic construction and urban construction,the high-rise buildings are cascaded,and the construction of foundation pit projects will increase,and the underground environment of foundation pit construction will become more and more complicated,and the degree of construction difficulties will increase.The optimization of the support structure of the pit engineering raises higher requirements.Therefore,choosing a foundation pit support scheme that is safe and reliable,simple in construction,economically reasonable,and other aspects can achieve the maximum benefits,is the most important part of all the work of the foundation pit project.In this paper,based on the construction of a pipeline foundation pit in baoding city as an engineering example,the geological structure characteristics of the foundation pit,the relevant information of soil layer and the type and depth of groundwater are learned from the geological survey report,and three suitable alternatives are selected on this basis.Then,the software of Lizheng deep foundation pit is used to design and verify the three alternative schemes,and the results show that the overall stability check,the anti-pulling capacity check and the anti-overturning stability check of the three support schemes all meet the standard requirements,which provides a basis for the optimization of the later foundation pit schemes.According to the safety factor in the design result,it is divided into 4 primary evaluation index factors and 13 secondary evaluation index factors,which constitute the evaluation index system of foundation pit support scheme.In this thesis,fuzzy mathematics theory is used to construct an evaluation model of foundation pit support scheme based on comprehensive weights.Then construct a judgment matrix between the target layer and the criterion layer,and determine the weight set between them.Finally,construct a judgment matrix between the target layer and the indicator layer,and find the total weight vector.;Then,by constructing a membership matrix,according to the fuzzy optimization model,find the membership values of the three schemes,;Finally,the maximum value is selected according to the principle of maximum membership asu2（28）.0927,That is,the best support scheme is the composite soil nail wall support scheme.Then the finite element software is used to carry out numerical simulation analysis on the foundation pit,and it is concluded that the settlement generated during the excavation of the foundation pit is small and will not affect the surrounding buildings. |
