Study on Strength Characteristics and Damage Constitutive Model of Cemented Soil

In order to investigate the influence of confining pressure on strength characteristics of cemented soil and establish a damage constitutive model under different confining pressures, triaxial shear tests under different confining pressures at room temperature and freezing state were carried out. The influence of confining pressure on mechanical parameters of cement soil was investigated. A modified Hoek-Brown strength criterion which can reflect the strengthening effect of low confining pressure and the weakening effect of high confining pressure on the strength of frozen cement soil was established. It is assumed that the distribution law of cement soil micro-element strength obeys the two-parameter Weibull function. Based on the Hoek-Brown strength criterion and its modified form, the micro-element strength of cement soil at room temperature and frozen state is determined, respectively, and the statistical damage constitutive model considering the influence of confining pressure is established. The results show that the damage constitutive model based on Hoek-Brown strength criterion and its modified form can describe the stress-strain curves of cement soil at room temperature and freezing state, and can reflect the strain softening phenomenon under low confining pressure and strain hardening phenomenon under high confining pressure. Under different confining pressures at room temperature, the damage variables change with the axial strain in a similar shape, showing a monotonic S pattern as the axial strain increases. Low confining pressure inhibits the damage and deterioration of cement soil under freezing condition. High confining pressure increases the degree of damage deterioration, and the damage variable reaches a larger value when the axial strain is very small. Keywords :   cement soil,  strength,  stress-strain relationship,  Hoek-Brown strength criterion,  damage constitutive model