Abstract: Grouting lifting technique is considered as an effective method to dispose uneven settlement of shield tunnel; but the overlying earth pressure on the shield tunnel during lifting is complex and has not been investigated deeply, which makes it hard to estimate the stress and deformation condition of the shield tunnel lining. A small scale model test system is firstly developed to simulate shield tunnel lifting in the laboratory，in which the transparent soil and PIV technology are applied. The limit overlying earth pressure as well as velocity field of the overlying soil layer are obtained through the tests. Then the shear-slipping features are studied, which indicate that the overlying soil layer could be divided into four different motion regions. A calculation model of limit overlying earth pressure is established based on the associated flow rules together with velocity field of overlying soil layer; then the calculation formulas are derived on the basis of virtual work equation. It turns out that the calculated limit overlying earth pressures are 4%-15% higher than the results obtained from model tests.

Key words: shield tunnel, lifting, transparent soil, model test, limit overlying earth pressure