Experimental study on liquefaction characteristics of saturated Yellow River silt under cycles loading

Abstract

The Yellow River silt can be effectively used as highway subgrade filler, which cannot only relieve the flood control pressure in the lower reaches of the Yellow River, but also meet the economic development needs of the areas along the Yellow River, with significant economic and social benefits. It cannot be ignored that the highway subgrade may be produced liquefaction under the action of earthquake and traffic loads. The problem of the dynamic characteristics of the Yellow River silt is a fundamental scientific problem that needs to be solved urgently. In this paper, a series of undrained tests were carried out on saturated Yellow River silt. Effects of relative density Dr, effective confining pressure σ3c, loading frequency f and cycles stress ratio CSR on pore pressure, axial strain development characteristics and dynamic strength characteristics of saturated Yellow River silt were studied. The test results show that: The number of cycles vibration required for liquefaction failure of the Yellow River silt was affected by relative density, loading frequency, effective confining pressure and cycles stress ratio. There are significant differences in the stress-strain development patterns of the Yellow River silt under different frequencies. Under the action of low frequency load, the Yellow River silt presents “hardening” liquefaction characteristics. Under the action of high frequency load, the Yellow River silt presents the characteristics of “softening” liquefaction. The Yellow River silt doesn't liquefy under the effect of weak earthquakes, while it is highly susceptible to liquefaction under the effect of strong earthquakes. Compared with the high-frequency load, when the low-frequency load is applied, more energy is required for the Yellow River silt to reach the initial liquefaction state. The cycles stress ratio CSR and the relative density Dr have significant effects on the pore pressure development of the Yellow River silt. Finally, a modified Seed model was proposed to characterize the pore pressure development of the Yellow River silt.