Study On The Stability Of Abandoned Underground Civil Air Defense Projects

With the development of national and economy improvement of people’s living standard. The pace of city construction also become more and more quickly, in addition, the city and its surrounding land is increasingly tense. The land utilization rate is more and more high, housing construction and transformation of the city on the underground building is often seen. There are many shelters and underground caverns in China’s urban and rural. With the development and the transformation of the old city construction, their impacts on urban and rural construction are more and more obvious. They cause more and more engineering accidents and geological disasters. They can always be found difficultly and there is almost no visual information. Once collapsed, they may cause serious consequences. Therefore, people should strengthen the investigation of underground civil air defense projects and analyze the stability of surrounding rock so that reasonable and reliable measures can be taken. It has great practical significance to people’s life and property safety and urban construction planning.Based on the exploration project of subsidence disaster in Shunyi District Long wan town in Beijing, this paper analyze the collapse characteristics and distribution characteristics with the related geological exploration data and means of geophysical engineering methods. Besides, this paper analyze the stability of caverns in numerical simulation. The main results are as follows:(1) According to the local geological exploration data and collapse disaster situation of the abandoned caverns. The distribution of caverns is mixed and disorderly. The internal influence factors of the stability of underground tunnels include soil physical and mechanical properties and the shape of the caverns. The external influence factors include rain, earthquake, human engineering activities and so on.(2) This papers choose the typical crisscross caverns to build a model. Surrounding stress, displacements and surface subsidence characteristics of the caverns model are studied by numerical simulation in natural conditions and rainstorm condition.(3) This paper apply the seismic load on cavern model and choose the key positions of three typical sections to study the characteristics of the duration of stress and displacement surrounding the caverns. At the same time, the peaks of the ground settlement are compared in the seismic conditions.(4) Based on the numerical results of cavern stability in conditions of the nature rainfall and earthquake, this paper draws several conclusions.