To investigate the dynamic mechanical response and damage evolution behavior of ice-rich frozen clay, split Hopkinson pressure bar (SHPB) tests were performed on frozen clay specimens with initial moisture contents of 20%-1,000% under different temperatures, strain rates, and stress states. The stress-strain curves, dynamic strength, peak strain, absorbed energy density, failure mode, and failure progress were studied. The experimental results revealed the following: (1) in the radial-free state, the stress-strain curve of frozen clay with initial moisture contents ranging from 20% to 85% and 1,000% could be divided into three stages: elasticity, plasticity, and failure. In addition, a double peak phenomenon occurs in the stress-strain curves within the initial moisture content range of 120%-480%. (2) In the radial-free state, as the initial moisture content increased, the dynamic strength first increased to a maximum value, then decreased to a minimum value less than the dynamic strength of ice, and eventually increased marginally to the dynamic strength of ice. However, the variation in dynamic peak strain with initial moisture content followed a decrease-increase-decrease three-stage pattern. (3) In the passive confining pressure state, the initial moisture content of frozen soil determined its sensitivity to the confining pressure. (4) The high-speed camera test results indicated that the failure of the ice-rich frozen clay was mainly caused by tensile cracks. The degree of failure of the frozen clay specimens became more evident as the moisture content and strain rate increased. In the passive confining pressure state, the ice-rich frozen clay specimens remained intact except for a small amount of edge peeling.

To investigate the effect of oyster shell powder (OSP) on the static and dynamic properties of expansive soil, the mechanical properties of modified soil were obtained. Taking Ningming expansive soil as the research object, triaxial shear test, dynamic triaxial test and scanning electron microscope test were carried out on plain soil and 9 % expansive soil modified by oyster shell powder (ESMO). The results show that compared with plain soil, the effective cohesion of modified expansive soil with d(osp) < 1 mm (ESMO (d(osp) < 1 mm)) and d(osp) < 0.075 mm (ESMO (d(osp) < 0.075 mm)) is increased by 15.4 % and 32.8 %, respectively. Under cyclic loading, compared with plain soil, the plastic strain stability value of ESMO (d(osp)<0.075 mm) is reduced by 40.2 %, the pore water pressure stability value is reduced, and the stiffness is increased. The dynamic mechanical properties of ESMO (d(osp)<1 mm) showed the opposite trend. Through microscopic experimental analysis, the main reasons for this phenomenon are the particle size distribution, bonding form, and cementation of the two. The results can provide a theoretical basis for the practical application of ESMO and the establishment of constitutive model.