强震区桩?土?断层耦合作用下桩基动力响应

为研究桩-土-断层耦合作用下桩基动力响应特性，利用振动台试验选取0.35g地震动峰值加速度时4种类型地震波，研究断层上下盘桩基加速度响应、桩顶相对位移、弯矩及桩基损伤情况。试验表明：断层上盘桩基各项参数明显大于断层下盘，呈现出上盘效应；桩顶峰值加速度大于桩底峰值加速度，上部土层对输入地震波具有滤波作用；桩顶加速度响应相较于桩底具有滞后性；桩顶峰值加速度与桩顶加速度放大系数α在输入El-Centro波时最大；上、下盘α 差值在输入Kobe波时最大；弯矩和桩顶相对位移峰值在输入Kobe波时最大；弯矩在土层分界面处较大，输入不同地震波时弯矩峰值均未超过桩身抗弯能力；提出了强震区近断层桩基可根据验算内容选取合理地震波进行验算的抗震设计建议。

Dynamic response of pile foundation under pile-soil-fault coupling effect in meizoseismal area

In order to study the dynamic response characteristics of pile foundation under the pile-soil-fault coupling effect, four different types of seismic waves with the peak acceleration of 0.35g are selected for shaking table test. The acceleration response, relative displacement of pile top, bending moment of pile body and damage of pile foundation under different types of seismic waves are studied. The test results show that the parameters of the pile on hanging wall are obviously larger than those on the footwall of the fault, showing the hanging wall effect. The peak acceleration of pile top is greater than that of pile bottom, and the upper soil layer has filtering effect on the input seismic wave. The acceleration response of pile top has hysteresis compared with that of pile bottom. The acceleration at the top of the pile and the amplification coefficient α of the peak acceleration are the largest for the El-Centro wave. The α difference between the hanging wall and footwall is the largest for the Kobe wave. The peak values of relative displacement of pile top and bending moment of pile foundation are the largest for the Kobe wave. The bending moment of pile body is larger at the soil interface. When different types of seismic wave are applied, the peak value of bending moment of pile body does not exceed the bending capacity of pile body. It is suggested that the pile foundation of bridge near fault in strong earthquake area can be checked according to different seismic waveforms.