非自由液化场地地基动力性能大型振动台模型试验研究  

Study of large-scale shaking table proportional model test of the dynamic property of foundation in unfreedom ground of liquefaction

作　　者：凌贤长[1] 王丽霞[1] 王东升[2] 王志强[3] 王臣[1] 

机构地区：[1]哈尔滨工业大学土木工程学院,黑龙江哈尔滨150090 [2]大连理工大学土木水利学院,辽宁大连116023 [3]同济大学桥梁工程系,上海200092

出　　处：《中国公路学报》2005年第2期34-39,共6页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(50178027);国家自然科学基金项目(50378031)

摘　　要：基于1∶10模型大型振动台试验,研究非自由液化场地的地基动力性能。液化场地条件下,与自由场地基相比,非自由场地地基的自振频率明显加大、动力耗能作用提高较小。土层液化前且在小震输入下,地基动力变形的线性特征较突出,主要表现为对地震波的动力放大作用,加速度反应自下而上逐渐增大;土层完全液化后,地基加速度反应自下而上也逐渐增大,这是由于液化地基的层间剪切运动加快且加快的速率自下而上逐渐增大所致。地基孔压变化主要受两方面因素影响:一是随埋深减小,孔压减小,但孔压比增大;二是离桩距离越近,孔压和孔压比越大。土层液化前,输入波主要峰值过后,自下而上孔压消散逐渐减慢。较大震输入下,自下而上孔压有减小的趋势,但最大孔压比均很快达到液化孔压比;输入波主要峰值过后,孔压消散很缓慢,尤其是孔压消散随埋深减小越来越慢。试验中还出现瞬时负孔压的有趣现象,这也许是由于可液化土层发生瞬时膨胀作用所致。On the basis of the large-scale shaking table 1:10 scale model test, the dynamic property of foundation in unfreedom ground of liquefaction is studied. In ground of liquefaction, compared to freedom foundation, the self-vibration frequency of unfreedom foundation obviously increases, yet its property of dynamic energy dissipation improves a little. Before liquefaction of soil and in input of a small shake, the dynamic deformation of foundation mainly appears linear characteristics, which primarily exhibits in the amplification effect to earthquake waves, the response of acceleration gradually strengthens from bottom to top. After soil liquefied entirely, the response of foundation acceleration also gradually strengthens from bottom to top, which is that the shear movement between layers of liquefied foundation is accelerated and the increased speed of the shear movement is gradually accelerated from bottom to top. The variation of pore pressure in foundation is primarily affected by following two factors: the first is that with depth decreasing, the pore pressure will decrease while the pore pressure ratio will increase; the second is that the smaller the distance to a pile, the bigger the pore pressure and pore pressure ratio. Before soil liquefied, and when the primary peak of inputted waves has gone, the dissipation of pore pressure becomes gradually slower from bottom to top. While inputting a bigger shake, the pore pressure is in the tendency of lowing from bottom to top, but the peak pore pressure ratio all arrives at the liquefaction pore pressure ratio, and when the primary peak of inputted waves has gone, the pore pressure dissipates very slowly, particularly the dissipation of pore pressure becomes slower and slower with the decrease of depth. In this test, it is occurred that an interesting phenomena of transient minus pore pressure is perhaps attributed to the transient shear swell effect of liquefaction soil.

关 键 词：桥梁工程 非自由液化场地 大型振动台模型试验 地基动力性能 加速度反应 孔隙水压力 

分 类 号：U442.55[建筑科学—桥梁与隧道工程]