Prediction On Ground Settlements Due To Metro Tunnels Construction

The ground settlement due to metro construction is one of the most important safety factors. Excessive excavation may make the metro collapsed. It is very important to reduce the influences of construction on surrounding environment,including buildings and pipelines. Metro excavation can cause both horizontal and vertical ground deformation. Therefore, empirical method is used in this thesis to predict the influences of construction on the ground settlement herein.Detailed analysis for urban parallel two-lane tunnel constructed by shallow mining method is given in this thesis. Brief introduction about shallow mining method, the mechanism of ground deformation due to shallow mining method, rules of metro excavation both horizontally and vertically are made in this thesis and it also figures out the influence quantity of various factors which affect the ground settlement. In reality, ground deformation depends on a number of factors, including hydro-geological and geotechnical conditions, tunnel geometry and depth, excavation methods and the quality of workmanship and management. Both peck formula method and the migration parametric method are used in this thesis. The fitting results of ground settlement resulted from the ground deformation of tunneling are presented and the migration parametric method which has higher fitting accuracy is used to reveal the rules of horizontal ground deformation. It combines the actual situation of the project and the subway construction standards. Statistical analysis about the ground settlement is given by the parameters, such as trough width parameter, experience factor, ground loss, the maximum surface settlement etc. The range and rules of these parameters can help to guide the future construction.