Prediction of longitudinal ground deformation due to tunnel construction with shield in soft soil

Assuming soil was undrained,the computing formulas of longitudinal ground deformation induced both by bulkhead additive thrust and force of friction between shield and soil were derived from the Mindlin solution in elastic mechanics.Combining the formula of ground deformation induced by ground loss,the formula of total longitudinal ground deformation induced by shield was obtained.This method was applied to the construction phase.Compared with two engineering cases,the calculated results could be fitted with the measured field data.As shown in analytical calculation,bulkhead additive thrust would make the frontal soil of excavation face hunching up and the surrounding soil subsiding.Surface deformation induced by bulkhead additive thrust was small during normal construction,and the curves were antisymmetric about axes of excavation face.The surface deformation induced by friction force was great.Its distribution curve was similar to bulkhead additive thrust with the axes at the middle of shield.The parameters of soil exerted great influence on surface deformation.