Ground surface deformation caused by synchronous grouting of shield tunnels

The back-filled grouting is a key step in shield tunnel construction, which has a significant influence on controlling the ground surface deformation. For the purpose of establishing a calculation theory of the ground surface deformation caused by synchronous grouting, the pressure effect of synchronous grouting on the surrounding soils is simplified as an expansion problem of cylindrical cavity in semi-infinite elastic solid. Based on the mechanism analysis of synchronous grouting acting on the surrounding soils, a formula for calculating the ground surface deformation resulting from synchronous grouting is deduced by using the image method. Through a specific example, the influencing factors of the ground surface deformation caused by synchronous grouting are analyzed as well. The results show that the ground surface deformation caused by synchronous grouting is affected by many factors such as grouting pressure, tunnel depth, excavation radius, initial soil and water pressure, elastic modulus and Poisson's ratio of soils.