附加衰减模式及其对场地地震响应影响

收集了各类土体受大振幅振动影响的Gmax试验数据,分析得到强结构性和弱结构性土的不同Gmax附加衰减模式.通过编制可以考虑Gmax附加衰减影响的一维场地地震响应有效应力分析程序,对典型场地地震响应进行分析对比,发现Gmax附加衰减对场地加速度和切应力响应均有较大的影响,且加速场地液化、扩大场地最终液化范围.考察了场地条件和输入波卓越周期的影响,发现Gmax附加衰减对场地地震响应的影响程度随地下水位的下降而增强,随场地土层厚度的增加无明显变化；强结构性土场地受到的影响比弱结构性土场地更大；不同卓越周期输入下均表现出由于Gmax附加衰减加快场地液化的现象.

Modes of additional attenuation of Gmax andits influence on seismic site response

Two additional attenuation modes of Gmax were proposed based on the collected test data, corresponding to strong and weak structural soils under large amplitude cyclic loading. A refined program of one-dimensional equivalent linearization method was composed based on effective stress principle in order to analyze the influence of additional attenuation of Gmax. Results show that the additional attenuation of Gmax influences the responses of both accelerations and shear stresses. The additional attenuation of Gmax can speed up the liquefaction of site and expand the final liquefied range. The influences of different site conditions and different input waves on seismic site response were investigated. Results indicate that the influence of the additional attenuation of Gmax on site increases as the underground water level declines, but hasnt apparent change as the thickness of site increases. The influence of the additional attenuation of Gmax on strong structural soil site is greater than that on weak structural soil site. The phenomenon of speeding up the liquefaction of site can be found under different predominant period waves input situations．