Abstract: Because the soil permeability coefficient can be changed while the soil is under loading, the change of soil permeability coefficient should be considered in the calculation of the segment load. Based on the experimental results of permeability tests, the simplified relationship between the permeability and the void ratio of soil is obtained. The coupled fluid-solid models for the segment and the soil are developed, including the seepage model and the mechanical model. The soil is divided into elastic zone and plastic zone in the mechanical model. The elastic zone can be farther divided into three zones according to the relationship of void ratio and permeability coefficient. So the effect of the change of soil permeability coefficient on the segment loading can be analyzed. The coupled mechanical and hydraulic calculation method is obtained through the radius of different zones; thus the seepage calculation and the stress calculation can be connected. The analysis results can be applied to design of bearing ability of the segment in shield tunneling.

Key words: load of segment, coupled fluid-solid, permeability coefficient, stress partition