3-d Numerical Analysis On Settlement Of Ground Surface Caused By Shallow Metro Tunnel Excavation

A great deal of urban metro engineering will be constructed in order to solve the urban traffic problems. Although shield method is used widely in urban metro tunneling, method of undercutting with shallow overburden is also used frequently due to the situation of our country. Building metro in the city underground, people are more and more concerned about the influence to the surrounding environment. Land subsidence is a main part of the influence to the surrounding environment, so, the research about land subsidence is very important.Aimed at the common factors that influence the land subsidence when designing or tunneling, this paper use geotechnical numerical simulation software FLAC^3D to analyze these factors and proof the results though project example.Through simulating different tunnel thickness-span ratios and high-span ratios, the regularity of land subsidence has been found. The support effect has been evaluated by simulating common support means of undercutting with shallow overburden. The land subsidence caused by precipitation and non- precipitation have been simulated, and both two cases have been compared. At last, the result proofs the reliability of numerical simulation, take the left platform tunnel of XiaoBei station of the fifth line of GuangZhou for example.