Study On Excavation Stability Of Deep Rocky Foundation Pit With Cavity

With the increasing level of urbanization in China,urban land is becoming more and more tense.Exploitation and utilization of underground space is an effective way to reduce ground occupancy and improve urban ecology.In Chongqing,the ground high-rise buildings,underground subway tunnels criss-cross,and because of its special historical and geographical reasons,there are a large number of known and unknown air defense chamber,so in the pit excavation project often encountered underground Caverns.In the future urban construction,there will be more and more deep foundation pit project,will face the situation will be more complex.Therefore,it is necessary to carry out in-depth study on excavation stability of deep excavation with borehole rock.This project relies on the excavation project of Chongqing deep foundation pit in Yuzhong District of Chongqing Municipality.As the first high-rise building in the southwest area of China’s future construction,the surrounding environment of the project is complicated,the environmental protection is high and adjacent to the underground tunnel.Dug in the process encountered a waste hole.In this paper,based on a large number of on-site monitoring data,combined with numerical simulation,the excavation stability of deep excavation with caverns is studied,and the following results are obtained:(1)According to the geological conditions of mountainous area in Chongqing,the deep foundation pit of rock caverns is classified.Based on the relevant data,the failure modes of deep foundation pit in cave chamber are classified,and the mechanical mechanism of each failure mode is summarized;(2)The three-dimensional finite element model of excavation of deep excavation with cave chamber is established by using international joint finite element software ABAQUS,The displacement and stress distribution of support structure and soil are studied.(3)Using the method of numerical simulation,the paper analyzes the relationship between the depth of the hole,the distance between the hole of the hole and the edge of the foundation pit,the angle between the axis of the cavern and the foundation pit.The excavation of the deep foundation pit and the stress of the foundation rock Distribution of the impact,and summed up the impact of the law.(4)This paper summarizes the influence of the depth of the cavity,the distance between the hole of the hole and the edge of the foundation pit,the angle of the hole between the cavity and the foundation of the foundation,and the stability coefficient and stability coefficient of the deep foundation pit in the limit state.The Main Points of Supporting Design under Operating Conditions.In this study,the numerical simulation results and field monitoring results confirm each other,and the numerical model can simulate the engineering conditions well.It shows that the research results of this paper have some significance to the design of foundation pit support and the safety monitoring of foundation pit and information construction in practical engineering.