沟槽基坑稳定性和支护结构变形特性研究OA

In the process of urban construction,a large number of trench pits need to be excavated,and the stability of these pits and the deformation of their support structures have become a major focus of research.However,there are currently no design specifications for trench and excavation pit engineering.Taking the excavation of stormwater and sewage pipeline trenches on Zhiyin Side Road in Wuhan as an example,the stability factor of the trench pit was calculated using both the finite element strength reduction method and the traditional limit equilibrium method.The effects of excavation depth,excavation width,insertion ratio,support stiffness,and surface overload on the stability of the trench pit and the deformation of the support structure were explored.The results are as follows:①The traditional limit equilibrium method,which does not consider the trench width,yields a smaller stability factor,leading to a more conservative design of the support structure.②Excavation of the trench pit causes soil heave at the bottom of the pit and surface settlement around the pit.③As the soil strength parameters are reduced,the plastic zone on both sides of the pit wall expands and bypasses the bottom of the support structure,forming interpenetrating sliding surfaces,which leads to failure of the trench pit.④When the width-to-depth ratio(L/H)≤1,the stability factor does not change significantly with increasing depth,but the maximum horizontal displacement of the support structure increases significantly.When the width-to-depth ratio(L/H)>1,the stability factor and displacement tend to stabilize as the width increases.⑤Sensitivity analysis shows that excavation depth and width have the strongest correlation with trench stability and support structure displacement,while the insertion ratio and surface overload have weaker effects.A strong negative correlation exists between trench stability and support displacement.Therefore,compared to the traditional limit equilibrium method,utilizing finite element software for in-depth analysis of trench stability and support structure deformation demonstrates significant advantages.This study confirms that the width and depth of trench pits exert dominant control over trench stability and support structure deformation.The research findings provide technical support for optimizing the design of support structures in trench pits,thereby effectively preventing overdesign of support systems,enhancing the economic efficiency of trench projects,and simultaneously offering reliable scientific basis for related engineering designs.