摘要:
液化场地下高层建筑桩基抗震性能一直是防灾减灾工程中的热点问题，故本文通过开展液化场地-桩筏基础-高层建筑结构体系动力响应大型离心机振动台试验，并基于STKO软件构建立三维数值模型，通过对比土体超孔压比、土体加速度、上部建筑结构加速度和桩基弯矩等，验证数值模型的正确性和有效性，基于已验证的数值模型，输入不同峰值加速度的El-Centro地震波，探究不同地震动强度对上部建筑结构及桩基动力响应的影响规律。结果表明：地基液化是由浅至深发展的，埋深越浅处液化程度越高，加速度衰减幅度越大；土层液化对上部建筑起到了一定的减震作用；上部建筑加速度在小震作用下放大效应明显，随着地震波峰值的增加，建筑顶部加速度峰值逐渐增加，在中震和大震情况下由于土体液化的影响，峰值加速度放大倍数明显减小，但仍然大于1；在小震作用下，桩身顶部会出现弯矩较大值，随着地震波峰值的增加，桩身弯矩峰值点位置下移，大震作用下，桩身中部位置由于接近反弯点出现弯矩缩减，角桩、边桩及中桩的桩弯矩峰值均出现在液化层与非液化层交界处附近。
Abstract:
The seismic performance of pile foundations for high-rise buildings on liquefiable ground has always been a hot topic in disaster prevention and mitigation engineering. Therefore, this paper conducts a large-scale centrifuge shaking table test on the dynamic response of the liquefiable ground-pile raft foundation-high-rise building structure system, and establishes a three-dimensional numerical model based on the STKO software. By comparing the soil excess pore water pressure ratio, soil acceleration, upper building structure acceleration and pile foundation bending moment, etc., the correctness and effectiveness of the numerical model are verified. Based on the verified numerical model, El-Centro seismic waves with different peak accelerations are input to explore the influence law of different seismic intensities on the dynamic response of the upper building structure and pile foundation. The results show that the ground liquefaction develops from shallow to deep, the shallower the burial depth, the higher the liquefaction degree, and the greater the acceleration attenuation amplitude; soil liquefaction plays a certain damping role for the upper building; the acceleration amplification effect of the upper building is obvious under small earthquakes, and the peak acceleration at the top of the building gradually increases with the increase of the peak value of the seismic wave. Under medium and strong earthquakes, due to the influence of soil liquefaction, the amplification factor of the peak acceleration is significantly reduced, but still greater than 1; under small earthquakes, a large bending moment value will appear at the top of the pile, and with the increase of the peak value of the seismic wave, the peak bending moment point of the pile body moves downward. Under strong earthquakes, the bending moment at the middle position of the pile body is reduced due to the proximity to the inflection point. The peak bending moments of corner piles, edge piles and middle piles all occur near the interface between the liquefiable layer and the non-liquefiable layer.
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