Abstract:

During shield construction in deep soft soil, different ground loss rates bring various displacement and stress change, and cause impacts on soil arching effect. By adjusting the radius of the excavation area in calculation model, seven kinds of ground loss rate are set, which can establish the corresponding relationship between ground loss and soil arching effect. Through analysis, the results show that: (1) When the shield excavation is carried out in depth with 4 times the diameter, the active areas of arching effect are formed in the range of 1-2 times the diameter above tunnel; (2) With the ground loss rate increasing, the earth pressure load at crown reduced greatly, and the soil arching effect is more obvious. When the ground loss rate reaches a certain value, the soil arching effect of shield tunneling is close to the critical value.

Key words: shield excavation, deep strata in soft soil, ground loss rate, soil arching effect