基于土体渗透系数变化的管片荷载流-固耦合解析

土体在承载过程中渗透系数会发生变化，因此，在渗流作用下计算管片荷载需考虑土体渗透系数的变化。首先，根据土体渗透系数试验结果，给出了简化的分段孔隙比-渗透系数关系曲线。然后，建立了管片和土体的流-固耦合分析模型，包括渗流模型和力学模型；力学模型中土体分为弹性区和塑性区，其中弹性区根据孔隙比-渗透系数关系曲线进一步分区，从而考虑土体渗透系数变化的影响。最后，通过各分区半径取值将渗流和力学计算之间建立起联系，得到流-固耦合计算方法。计算结果为管片承载设计提供了参考。

Coupled fluid-solid analysis of bearing characteristic of segment based on change of soil permeability coefficient

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.