排水刚性桩群桩抗液化性能的振动台试验研究

排水刚性桩是一种将竖向排水体与刚性桩相结合的新型抗液化处理措施。为研究排水刚性桩群桩的抗液化作用效果，开展了桩顶竖向荷载作用下排水刚性桩处理可液化地基的振动台试验研究，分析了地基土体的超孔压响应、加速度响应及桩顶结构的水平位移响应，并与未设置排水体的普通桩群桩工况进行对比。结果表明：加载开始后，排水桩桩身排水通道有大量超孔隙水排出，普通桩桩身没有排水现象。采用排水桩时超孔压比峰值比普通桩中减小12%，孔压消散稳定后超孔压比减小13%左右，排水桩桩身的排水通道对超孔压的消散作用集中在振动作用的前期。排水桩桩顶的侧向永久位移较普通桩桩顶侧向永久位移减小约27%。试样土体液化前，剪应力-应变滞回圈包络面积较大，土体呈现一定的剪胀特性。液化后，排水桩的剪应力-应变滞回圈的割线模量更大。上述试验结果均表明了排水刚性桩在抗液化方面的有效作用。

Investigation on liquefaction resistance performance of rigid-drainage pile groups by shaking table

The application of rigid-drainage pile, combining vertical drainage and rigid pile, is a new technology for mitigation of liquefaction. Shaking table tests were carried out to investigate the performance of the rigid-drainage pile against liquefaction. The response of excess pore water pressure, acceleration and lateral displacement of pile top were monitored and analyzed. The results indicated that the use of rigid-drainage pile was an effective method to mitigation of liquefaction. There was much water drainage from the drainage pile when the shaking motion was applied, yet no water drainage for the ordinary pile. The mean value of peaks of excess pore water pressure decreased 12% for the rigid-drainage pile comparing to the ordinary pile. The value of excess pore water pressure approximately decreased 13% when the excess pore water pressure became stability. The effect of drainage was mainly in the previous period of shaking. The lateral permanent displacement on pile top decreased 27% for rigid-drainage pile compared with ordinary pile. The liquefaction, shear-strain hysteresis loops at previous stage were more pronounced than that of post liquefaction stage. the secant modulus of rigid-drainage pile is larger than the ordinary pile. The results of the tests illustrated the effectiveness of rigid-drainage pile in mitigation of liquefaction.