Crack propagation analysis of angled surface-crack clay under compressive loading

Abstract

This study develops a dual-criterion framework integrating maximum circumferential stress (MCS) and maximum shear stress (MSS) theories to characterize fracture initiation in angled surface-crack clay under axial compression, systematically incorporating the complete T-stress tensor components ($T_x,T_y$ and $T_{\mathrm{xy}}$) to establish predictive models for critical fracture process zone (FPZ) sizes and crack initiation angles. Comparative analysis reveals that the MCS criterion incorporating $T_x$ and $T_y$ provides optimal predictive capability for the initiation of new fractures in clay specimens containing mid-upper surface cracks, while the T-stress-excluded MCS criterion yields better agreement for right-upper and top-right cracks, with MSS-based predictions consistently showing significant deviations regardless of crack locations. The results demonstrate that the T-stress exerts a relatively limited influence on crack initiation angles in clay specimens containing angled surface cracks under axial compression. Concurrently, the critical FPZ size of 1.28 mm for mid-upper surface cracks is revealed. These findings provide a significant theoretical basis for fracture mechanics analysis of geomaterials and predictive modeling in geotechnical engineering applications.