Mechanical behavior of fissured loess under true triaxial conditions

Fissured loess is an important geological factor contributing to geohazards in the Loess Plateau region. Understanding the evolution of its mechanical behavior and deformation under true triaxial conditions is therefore essential for geohazard mitigation and engineering safety in the Loess Plateau region. In his study, true triaxial tests on fissured loess with different fissure angles were conducted to investigate the variation of mechanical behavior of fissured loess under different confining pressures and different b values. The results show that the peak axial stress of loess specimens with different fissure angles presents three different development patterns: gradually increasing, first decreasing and then increasing, and gradually decreasing. Under confining pressures of 100 kPa with b=0.5, 0.75 and 1.0, and 200 kPa with b=0 and 0.25, the axial stress-strain curves of 90° fissured specimens show inflection points. The principal strains of loess specimens with different fissure angles can be divided into three development stages: shear contraction development, stable development, and shear expansion development with the development of the major principal strain. The shear expansion stage becomes shorter with the increase of confining pressure. At the same crack inclination angle and relatively low b values, with the increase of generalized shear stress, the intermediate principal strain shows a shear expansion, and the larger the fissure angle, the more obvious the shear expansion. This study can provide a support for the prevention and control of engineering disasters and stability evaluation of fissured loess.