强震作用下嵌岩群桩时程响应振动台试验
Shaking Table Test on Time-History Response of Rock-Socketed Pile Group Under Strong Earthquake
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摘要: 地震动荷载作用下,由于"群桩效应",群桩基础表现出不同于单桩的动力时程响应规律.通过大型振动台模型试验,选取强度均为0.35g人工合成的5002波、5010波,以及典型的Kobe波、El-Centro波,探明嵌岩群桩基础的动力时程响应规律及基频损伤情况.振动台试验结果表明,地震波频谱特性对嵌岩群桩基础的各动力响应参数具有显著影响;El-Centro地震波作用时嵌岩群桩加速度峰值较大,桩顶峰值出现时刻较为滞后;Kobe波作用下,桩顶水平相对位移、弯矩峰值较大,但在El-Centro波时均出现最早;弯矩峰值均没有超出其抗弯极限承载力,且基频未发生明显变化,说明强震作用下群桩基础未发生损伤破坏;因此,可通过不同频谱特性的地震波对嵌岩群桩的抗震性能进行优化设计,并提出相应工程建议.Abstract: Due to the 'pile groups effect',pile groups show dynamic time-history response law different from the single pile under seismic dynamic load.Through large-scale shaking table model test,5002wave,5010wave,El-Centro wave,and Kobe wave with the intensity of 0.35g are selected to study the time-history response law and fundamental frequency damage of rock-socketed pile groups.The shaking table test results show that the seismic wave spectral characteristics have a significant influence on the dynamic response parameters of rock-socketed pile groups.The pile groups’ peak acceleration under the El-Centro wave is large,and the peak value of the pile top is lagging behind.Under the action of Kobe wave,the horizontal relative displacement of pile top and the peak value of bending moment are large,but they all appear the earliest in El-Centro wave.The bending moment peak values do not exceed its ultimate bending capacity.The fundamental frequency of pile groups does not change obviously,indicating that there is no damage to pile groups under the strong earthquake.Therefore,the seismic performance of rock-socketed group piles can be optimized through seismic waves with different spectral characteristics,and corresponding engineering suggestions can be put forward.