Large-strain analysis for cylindrical cavity contraction in strain-softening geomaterials

This study presents a large-strain analysis for cylindrical cavity unloading-contraction problem in strain-softening geomaterials. Based on the unified strength theory (UST) and non-associated flow rule, the process of cavity contraction in cohesive-frictional geomaterials is regarded as a large-strain problem by introducing the UST parameters and the volumetric force of seepage into the conventional cylindrical cavity contraction analysis, the effects of strain-softening characteristic, intermediate principal stress, large-strain, and seepage are considered. Finally, according to the comparison of the results of the radius ratio with those in the published literature, the correctness and reliability of the theoretical method are proved. The results show that it is necessary to consider the effect of volume force of seepage in the stability of excavation problem in geomaterial, the larger the volume force of seepage, the smaller the plastic radius. The traditional two-dimensional cavity contraction solution overestimates the plastic radius. The results provide a theoretical basis for the elasto-plastic analysis of excavation in rich water geomaterial and have a certain reference value for engineering design.