Effect of Confining Pressure on Strength Behaviour of Frozen Soil

Triaxial compressive tests were conducted on frozen Lanzhou sand under condition of high confining pres-sure.The. test results showed. the plasticity of frozen soil is increased obviously with increasing confining pressure.Meanwhile. with increasing confining pressure.the strength of frozen soil also increases,until it reaches a maximum value. Then with further increase of confining pressure, it decreases gradually. Namely, the increase of confining pressure can suppress as well as induce the effect of dilatancy softening of dilatancy softening of frozen soil. The variation of strength with increasing confining pressure can be divided into three regions:the increase region of strength; the slow decrease re-gion of strength and sudden drop region of strength. Based on the variation of strength, the melting pressure offrozen Lanzhou sand is given accordingly.