Study On Fuzzy Optimization Method And Application Of Support Scheme For A Deep Foundation Pit In Beijing

With the rapid economic development and the improvement of people's quality of life,construction,infrastructure and other projects continue to increase,a large number of land developments,more and more deep foundation pit projects,larger and larger scales,deeper and deeper excavations,and The engineering geological environment and surrounding environment of the foundation pit are more complicated than before,and the construction difficulty is more difficult.It is very important to optimize the foundation pit support plan.Therefore,it is one of the key control items in the current foundation pit engineering to optimize the plan from the aspects of technical feasibility,environmental impact,safety and reliability,construction maneuverability,reasonable economic cost,and cost reduction and efficiency increase.This paper mainly takes a deep foundation pit project in Beijing as a research project example.Considering the engineering geological conditions,the excavation depth,the scale of the foundation pit,the safety level,the buried pipelines,and the surrounding environment of the foundation pit,three alternatives suitable for this project were initially selected,namely soil-nailed wall support.Support,double-row pile support and pile anchor support.Based on the principles of safety and feasibility,environmental protection,construction controllability,and economic rationality,4 first-level evaluation index factors(technical feasibility of the scheme,environmental impact,construction maneuverability,and economic rationality)and 12 second-level evaluations are selected Index factors(support reliability,support stability,scientific plan,traffic influence,building settlement,underground pipelines,construction noise,site requirements,construction period,construction difficulty,construction machinery,total cost),utilization level The analysis method constructs a judgment matrix,weights the first-level evaluation index and the second-level evaluation index,and checks the consistency of the judgment matrix.Then,based on the fuzzy theory,the expert scoring method is used to calculate the membership degree of the first-level index and the second-level index,and the fuzzy comprehensive evaluation based on the first-level index and the fuzzy comprehensive evaluation based on the second-level index are constructed respectively.The results show that the pile-anchor support is the best Optimal plan,so the pile-anchor support form is selected to design the foundation pit.Using Lizheng deep foundation pit support design and calculation software to simulate the support plan,the obtained reinforcement design,overall stability check,embedded depth check,and pull-out bearing capacity check,etc.,all meet the requirements of the specification and are supporting The protection plan preferably provides a strong basis.At the same time,collecting on-site foundation pit monitoring data,and verifying the safety,reliability and rationality of the support scheme of this project through the curve diagram of the most affected monitoring point,providing reference and reference for other similar foundation pit projects in the future significance.