Theoretical prediction of ground movements induced by tunnelling in multi-layered soils

The theoretical predictions of ground movements induced by tunnelling are usually based on the assumptions that the ground is homogeneous. Actually, layered formations with different soil properties are usually encountered in situ and effects of soil stratification should be taken into account. This paper presents the displacement controlled boundary integral method aimed specially at investigating the effect of soil stratification on the tunnelling-induced ground movements. The modified elastic layered half-space model is combined with the method to consider the soil non-homogeneous characters, whereas the Kelvin and Mindlin solution based on homogeneous materials are employed previously. The applicability of the proposed method is verified with other available published results as well as the displacement controlled finite element analysis. Surface settlements and lateral displacements induced by tunnelling on the layered soil condition are compared with those based on the homogeneous soil. The results discussed in this paper show that the soil stratification, neglected in previous solutions, have a significant influence on the tunnelling-induced ground movements in multi-layered soils.

Research highlights
► Displacement controlled model is applied to simplify the tunnelling process.
► Layered half-space model is applied to consider soil non-homogeneous character.
► Layered half-space model is combined with the traditional boundary element method.
► The traditional boundary element method is developed.
► Soil stratification has a significant influence on the ground movements due to tunnelling.