学术论文

      冻土覆盖下液化场地桩基地震响应的振动台试验研究

      Shaking table test study on seismic responses of pile foundations embedded in liquefiable ground with the frozen crust

      摘要:
      利用振动台进行了在地震激励下冻土、可液化砂土与钢管桩之间的相互作用模拟试验研究。试验设计柔性模型箱装填土体以模拟边界影响,通过配比试验制备混凝土砂浆模拟上覆冻土层,采用饱和砂土作为液化土,利用顶部附加集中质量的方法模拟钢管桩的惯性荷载。试验过程中选取调幅地震波模拟地震激励,通过实时测量桩的应变、桩/冻土位移和砂土内的孔隙水压力等方面的数据,分析冻土层覆盖下砂土的液化情况和与之对应的桩基动力反应情况。试验结果显示:在地基液化发生前,冻土层可以给桩基提供一定的侧向约束,有利于提高其承载力并抑制其侧向变形;然而一旦出现液化,冻土层则可能增强地基液化的趋势,导致桩基承载性能下降。
      Abstract:
      The seismic responses of a single steel-pipe pile built in the frozen crust and the liquefiable sand soil were studied by shaking table tests. A flexible soil container was designed and used to construct the soil profile in order to minimize the boundary effect. The frozen crust was simulated through the mortar which was made of cement, sand and water by the mixture ratio. Liquefaction can occur in the saturated sand soil beneath the frozen crust. A lumped mass was exerted at the top of the pile to satisfy the inertia con-ditions. During the tests, several amplitude-scaled ground motions were chosen as input seismic waves. The liquefying levels of the sat-urated sand soil and the dynamic responses of the pile can be analyzed via the measured real-time data including strains of the pile, dis-placements between the pile and the frozen crust and pore water pressures in the sand. Experimental results show that before liquefac-tion occurs, the frozen crust can provide a lateral constraint, and thus improve the load bearing capacity of the pile and suppress its lat-eral deformation. It is also found that once liquefaction occurs, the frozen crust may further strengthen this tendency and deteriorate the performance of the pile.
      作者: 杨润林 [1] 乔春明 [1] ZHANG Xiao-yu [2] YANG Zhao-hui [2]
      Author: YANG Run-lin [1] QIAO Chun-ming [1] ZHANG Xiao-yu [2] YANG Zhao-hui [2]
      作者单位: 北京科技大学土木与环境工程学院,北京,100083 阿拉斯加安克雷奇大学工学院,安克雷奇99508,美国
      刊 名: 北京科技大学学报 ISTICEIPKU
      年,卷(期): 2014, (1)
      分类号: TU475
      机标分类号: TU7 TU4
      在线出版日期: 2014年2月16日
      基金项目: 中美合作研究项目