Influence of the Ground Displacement and Deformation of Soil around a Tunnel Caused by Shield Backfilled Grouting during Construction

During the shield tunnel construction period, influence of ground displacement and deformation of soil around the tunnel in different grouting pressure must be researched to ensure safety of the tunnel and buildings adjacent to the project. In this paper, some typical sections of the Changsha No. 1 subway is taken as an example. Deformation of soil and displacement of ground are calculated in different geology conditions and grouting pressures. At the same time, the calculation result is contrasted with monitoring data of the real project, and some useful conclusions are drawn that are important to determine the construction parameters reasonably and control the ground displacement effectively. The main conclusions are as follows: (1) while the grouting pressure increases, deformation of surrounding rock and ground displacement decreased obviously, so different grouting pressures should be designed at different parts of the tunnel during excavation period to balance the deformation of the tunnel; (2) displacement curves of the ground perpendicular to the tunnel axis met the character of normal distribution curve, so as grouting pressure increased, values of the ground displacement decreased; (3) the numerical method of the paper was proved to be useful in simulating shield excavation of tunnel, and the Peck method was suitable to forecast ground displacement of tunnel excavation in silty clay layer; and (4) secondary grouting can be used during the construction period to control ground displacement. (C) 2016 American Society of Civil Engineers.