液化场地桩基加速度反应试验与数值模拟

为研究液化场地桥梁桩基加速度反应特性,采用自编的土-结地震相互作用有限元分析程序,输入三种试验记录工况,进行可液化场地桥梁桩基地震反应振动台试验与数值模拟.结果表明:三种地震输入下,自下而上沿桩-柱墩长度方向,加速度峰值放大系数变化基本一致且均出现在10～20s时段内,加速度时程曲线的形状也极其相似;压缩0.15g El Centro波输入下加速度反应在砂土层与黏土层过渡带有增大趋势、在地表则有一定程度减小,且压缩0.15g El Centro波较0.15g El Centro波输入下均偏小,0.15g El Cen-tro波输入下自下而上桩的加速度时程幅值和峰值放大系数的试验值、计算值均一直有较大幅度增大;0.5g El Centro波输入下,加速度时程幅值的计算值和试验值在桩折断位置之下一直增大、至砂土层与黏土层过渡带则大大减小,加速度峰值放大系数的试验值和计算值在砂土层与黏土层过渡带突变增大、而在地表则明显减小,且较0.15g El Centro波输入下桩的峰值放大系数要偏小.

Numerical simulation and shaking table test for acceleration response of piles in liquefiable ground

The acceleration response of bridge piles in liquefiable ground was investigated using the self-compiled numerical program. Numerical simulation and shaking table tests for acceleration response of piles in liquefiable ground were performed under three earthquake events. Results show that the amplification coefficients of peak acceleration resemble with each other along the depth with the same rules for acceleration histories time under three earthquake events, and the peak acceleration coefficient occurs after 10-20 s of input motion; the acceleration response tends to be intense near the interface between sand and clay and be weak near the ground surface under scaled 0.15g El Centro earthquake; the experimental and numerical acceleration responses under scaled 0.15g El Centro earthquake are weaker than those under 0.15g El Centro earthquake; in experimental and numerical results, both of the peak acceleration amplitude and the amplification coefficient increase largely from bottom to top under 0.15g El Centro earthquake; the experimental and numerical acceleration amplitudes always increase below the pile break location and decrease notably near the interface under 0.5g El Centro earthquake. Meanwhile, the peak acceleration amplification coefficient suddenly changes near the interface and decreases notably near the surface under 0.5g El Centro earthquake, which is less than that under 0.15g El Centro earthquake.