| With the rapid development of China’s urbanization and infrastructure construction,the old city transformation and urban expansion were bound to be accelerated.These changes resulted in a more serious use of limited land resources.Therefore,miscellaneous soil-filling area would be inevitably met in construction projects,more excavation supporting would be carried out in miscellaneous soil-filling area.Choosing a suitable supporting scheme had become a key research topic for deep excavation engineering in miscellaneous soil-filling area.The scheme should be safe,reliable,and it had a reasonable cost,a convenient construction,a favorable protection to the environment.This paper was focused on the optimization of supporting scheme for deep excavation engineering in miscellaneous soil-filling area.Meanwhile,Supporting Scheme of 14# High-rise Housing Project for Deep Excavation Engineering in Wangjiafeng Shanty Town in the Dongshan district in Taiyuan City was combined there.Then the improved AHP method was used to choose the optimal supporting scheme among the three designed supporting schemes.After that,Lizheng Software for foundation ditch was used to optimize details for the optimal supporting scheme by the method of orthogonal test.Finally,PLAXIS Finite Element Simulation Software was used to simulate and analyze the detailed optimization scheme.By this software,the safety and feasibility of the the detailed optimization scheme were tested and verified in practical application for deep excavation engineering in miscellaneous soil-filling area.And it can provide some references for selection and optimization for deep excavation engineering in miscellaneous soil-filling area.The main researches of this paper were as follows:(1)In selecting supporting scheme for deep excavation engineering in miscellaneous soil-filling area,based on the analysis and comparison of various factors,combined with the specific engineering project,three kinds of applicable supporting schemes were selected for this deep excavation engineering in miscellaneous soil-filling area: Supporting of the Slope Ratio Method and Composite Soil Nailing Wall,Supporting of Composite Soil Nailing Wall and Vertical Steel Pipe Pile,Supporting of Composite Soil Nailing Pile and Anchor.(2)The concept of optimal transfer matrix was used to improve AHP.By improved AHP,safety,reliability,reasonable cost,convenient construction and environmental protection were selected as goals of the optimization,15 factors were selected as indicators.By improved AHP to compare these there supporting schemes above,Supporting of the Slope Ratio Method and Composite Soil Nailing Wall was selected as the optimal scheme.(3)Details optimization for the supporting scheme.Firstly,the optimized supporting scheme was subjected to construction technology improvement.Secondly,the optimal scheme details were optimized by single factor analysis.After that,the orthogonal experiment was used to conclude factors influencing the overall stability on foundation pit of Supporting of the Slope Ratio Method and Composite Soil Nailing Wall.These factors could be sorted form high to low ranking: horizontal spacing of soil nail> row number anchor cable replacing soil nail>soil nail length>soil nail steel diameter>soil nail hole diameter>incidence angle.(4)Based on the basic principle and application conditions of the finite element numerical simulation software PLAXIS,the deep excavation of the optimized scheme was simulated.The simulation of the whole process was analyzed to get pit wall horizontal displacement and basal heave under different conditions.Through the calculation of PLAXIS,the feasibility and efficiency of the supporting scheme was ensured.The research results of this paper were adopted by the construction company.The engineering practice showed that the scheme was feasible and economical,it was praised by the owner and the construction company.The supporting scheme for deep excavation engineering in miscellaneous soil-filling area provided reference for the implementation of the same type of project. |
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