Abstract: Based on a series of field monitoring data of earth pressures acting on the shield tunneling segments, the earth pressures for both long-term and construction period are analyzed respectively. The results show that the depth of the ground water level plays an important role on the distribution of earth pressures in the circumferential direction. The earth pressure upon shield tunnel lining will be influenced by the stiffness ratio of ground to lining; the reasonable value of stiffness ratio is 1.5 since the soil reaction acting on segments will be relative smaller. The loads during construction can not be ignored in various strata, the segments are considered to receive larger loads if the backfill grouting pressure or the grouting ratio are larger than design. The earth pressure distribution can be divided into four stages. i.e. segments assemble stage, the backfill grouting stage, grout solidification stage and the stabilization stage. The distribution of earth pressure in the circumferential direction is uneven during construction, the earth pressure in the backfill grouting stage is 2-3 times as much as in the stabilization stage. The insights obtained from this study can contribute to an improvement of load considerations in shield lining design.

Key words: shield tunneling, earth pressure, stiffness ratio of ground to segment lining, construction load