Abstract:Conversion methods from seismic loads to uniform-amplitude loads are basic research topics in geotechnical earthquake engineering.Through a series of dynamic triaxial tests,the feature of soil deformation under irregular seismic wave loading and the relationships of soil deformation under irregular seismic wave loading and fixed-number wave loading are analyzed.The ratio of residual strain under a constant-amplitude sinusoid wave with 20 cycles and an amplitude of 0.65 times the seismic wave peak value to residual strain under seismic loading is defined as the strain ratio C,and the relationship between the strain ratio C and sand density is investigated.The results show that soil deformation development under irregular seismic loading obviously differs from that under sinusoidal loading,and the strain time history is mainly controlled by the performance of ground motion,rather than seismic loading amplitude and soil type.Under impact loading,the peak value (instead of other pulses) plays a significant role in control.Under a vibrating wave,besides the peak value,some other pulses with similar amplitudes and peak values have influences on the soil deformation.The strain ratio C will decrease with the increase of the relative density of the sand.When uniform sinusoidal loading,with 20 cycles and an amplitude of 0.65 times the seismic wave peak value,is employed instead of irregular seismic loading to modify residual deformation of soils under real seismic loading,the strain ratio C will decrease with the increase in the relative density of the sand.Meanwhile,the strain ratio C of impact-type loads is much larger than that of vibrating loads.
