【作者】 高霞；

【导师】 凌贤长；

【作者基本信息】 哈尔滨工业大学 ， 岩土工程， 2013， 博士

【摘要】 震害调查结果表明，地震地基液化大变形引起的桥梁地基和基础的破坏是桥梁震害的主要形式。地震作用下，地基和基础的破坏属于土－桩－结构相互作用范畴，因此开展强震下液化场地土－桥梁桩相互作用研究势在必行。鉴于上述，本论文针对强震下液化场地土－桥梁桩相互作用进行了研究，主要研究工作和取得的成果如下：1、进行了地震作用下液化场地土－桥梁桩相互作用的振动台试验研究。输入地震动为：压缩0.15g El Centro波、0.15g El Centro波和0.50g El Centro波。通过试验研究了频率和振幅对土和桩动力反应的影响。在时域和频域范围内分析了土和桩在地震荷载下的超孔压反应、加速度反应、弯矩反应，揭示了不同频率和振幅下液化场地土和桩的动力反应规律。2、建立了液化场地土－桥梁桩在地震荷载下的三维动力有限元分析模型。该模型考虑了水－土动力耦合作用、土和桩的非线性、土和桩之间的相互作用的影响。从土的动力响应和桩的动力响应两个角度，通过与液化场地土－桥梁桩振动台试验结果的对比分析，证明吻合情况良好。引入均方根误差定量评价所建立模型的可靠性与误差，结果表明该有限元模型具有较好的精度和可靠性。3、基于上述建立的有限元模型，对强震下液化场地土－桥梁桩地震相互作用进行了细致分析。系统研究了液化场地土和桩的动力反应，包括强震下土的超孔压反应、剪应力－剪应变反应、加速度反应、位移反应及桩的加速度位移反应、弯矩曲率剪力反应。明晰了砂土的相对密度、桩径、上部结构配重及振幅对液化场地土－桥梁桩地震相互作用的影响规律。4、在参数分析基础之上，基于液化场地桩的弯曲和屈曲失效理论，判断了不同的砂土相对密度、桩径、上部结构配重、振幅下桩基的失效模式，探讨了强震下液化场地振动台模型中桩的动力失效机理。进一步分析了上覆非液化层对桩基内力和变形的影响，据此给出了液化场地桩基的减震建议。更多还原

【Abstract】 Prvious seismic hazards verified that pile and ground failure are the main forms ofbridge damage caused by soil liquefaction. Earthquake induced liquefaction and lateralspreading is a major cause of failure of civil structures during seismic events. Collapseand severe damages to pile-supported structures and soil strata belong to the category ofsoil-pile-structure interaction. Therefore, it is very necessary to investigate soil-bridgepile interaction under strong earthquake. In view of the above, the main research workand achievements are as follows:1. A series of scaled shaking table model tests were performed to study thebehavior of a single pile in a soil profile comprised of a nonliquefied clay layer over aloose saturated sand layer over a nonliuqefied clay layer. The input earthquake motionsare compressed0.15g El Centro wave,0.15g El Centro wave and0.15g El Centro wave.Detailed instrumentation and data processing procedures enabled fundamentalmeasurements of the soil-pile interaction behavior in the shaking table tests. Themeasurements include the first available time histories of excess pore water pressures,accelerations of the soil and accelerations and dynamic strains of the pile under realisticearthquake shaking motions. Additionally, the bending moment of the pile is obtainedbased on the bending theory of the column. These shake table tests are performed toreveal the soil and pile response in liquefiable ground under different shakingfrequencies and amplitudes.2. A three-dimensional dynamic finite element model was established forstructures supported on pile foundations in a three-layer liquefiable soil. The modelincludes the dynamic couple response of soil and water, the nonlinear responses of soiland pile, and the soil-pile interaction. Results of the shake table testing on a sing pile inliquefiable soil are used to demonstrate the capability of the model for the reliableanalysis of piles under earthquake loading. The root mean square error is introduced toquantatitively evaluate the accuracy of the model. The proposed coupled soil-brige pilemodel was shown to be an effective tool to investigate the interaction response of a pilefoundation in a liquefiable site.3. A verified model was used for a parametric study. The parametric study was carried out by varying the relative density of the liquefying soil layer, the pile diameter,the superstructure mass and the shaking amplitude. The excess pore water pressure andexcess pore water pressure ratio, the stress and strain, the acceleration, the displacementand the bending moment responses, the distribution of sectional forces and thedeformation at different times were investigated. The effects of the soil relative density,the pile diameter, the superstructure mass and the shaking amplitude are clarified on thesoil and pile responses in a three-layer liquefiable site.4. Based on the above parametric studies, the pile failure modes in a liquefible soilwere obtained for different soil densities, pile diameters, superstructure masses, anddifferent amplitudes. Then, the potential failure mechanism for a pile in a three-layerliquefiable site was postulated under strong earthquake based on the pile bendingmechanism. Furthermore, the effects of overlying clayey layer on the pile internal forcesand deformations are evaluated. Finally, Earthquake relief measurements for pile inliquefiable site were subsequently provided.更多还原