桩柱结构在地震作用下非线性响应研究

发布时间：2018-04-29 23:12

本文选题：非线性响应 + 桩-土耦合　；参考：《岩土力学》2016年05期

【摘要】：基于试验基础上建立的经典弹塑性模型——剑桥模型能够准确描述正常固结土的应力-应变关系。当土体的应力历史上经历过卸载或受到循环交变荷载作用即进入超固结状态,它作为土的应力历史的反映,相比正常固结土受力特性有着显著的差异。为研究超固结因素对土体加载特性的影响,在引入能考虑超固结状态影响的下负荷面剑桥模型后,通过三轴压缩和剪切试验对处于超固结状态下土体的受力特性进行了对比分析,并对循环剪切加载下的应力-应变关系以及超固结比的演化规律进行了研究。结果表明,下负荷面剑桥模型能准确反映超固结因素对土体力学特性的影响,相比原状土有着更高的屈服强度。而通过数值模拟自由场地基在地震作用下的动力响应可以看出,超固结因素对地基的动力响应起到了不可忽略的影响,尤其在强震下更需要考虑其影响。在自由场地基地震动力响应基础上,通过对桩柱结构桩-土耦合系统在地震作用下非线性动力响应的模拟对土体非线性以及超固结因素的影响进行了对比研究,研究表明:土体的非线性因素能显著降低结构振动响应中的高频成分,由于土体在交变加载下很快进入超固结状态,相对于剑桥模型,下负荷面剑桥模型在考虑超固结因素后土体的承载性能显著提高,尤其在强震作用下超固结因素带来的影响更加明显,因此,建议对桩基结构物地震响应研究考虑超固结因素影响,以提高桩基结构物地震响应模拟的精确度和可靠性。
[Abstract]:The classical elastoplastic model-Cambridge model based on test can accurately describe the stress-strain relationship of normal consolidated soil. As a reflection of the stress history of soil, the stress history of soil has been overconsolidated when it has been unloaded or subjected to cyclic alternating load, which is different from that of normal consolidated soil. In order to study the influence of overconsolidation factors on the loading characteristics of soil, the lower load surface Cambridge model, which can consider the influence of overconsolidated state, is introduced. By means of triaxial compression and shear tests, the stress characteristics of soil under overconsolidation are compared and analyzed, and the stress-strain relationship and the evolution law of overconsolidation ratio under cyclic shear loading are studied. The results show that the lower load surface Cambridge model can accurately reflect the influence of overconsolidation factors on the mechanical properties of soil, and has higher yield strength than undisturbed soil. Through the numerical simulation of the dynamic response of the free site foundation under seismic action, it can be seen that the overconsolidation factor has played an important role in the dynamic response of the foundation, especially in the strong earthquake. On the basis of the vibration response of the free site base, the effects of nonlinear dynamic response of pile-column structure pile-soil coupling system under earthquake on soil nonlinearity and over-consolidation factors are compared and studied. The results show that the nonlinear factors of soil can significantly reduce the high frequency components in the vibration response of the structure. Because the soil is rapidly overconsolidated under the alternating loading, compared with the Cambridge model, the nonlinear factor of the soil can significantly reduce the high frequency components in the vibration response of the structure. The load-bearing performance of soil is improved significantly by considering the overconsolidation factor, especially under strong earthquake, so the influence of overconsolidation factor is more obvious. In order to improve the accuracy and reliability of seismic response simulation of pile foundation structure, it is suggested that the influence of overconsolidation factors should be taken into account in the study of seismic response of pile foundation structure.
【作者单位】：大连理工大学港口海岸与近海工程国家重点实验室;南京水利科学研究院;
【基金】：国家创新研究群体科学基金(No.51221961) 国家高技术研究发展计划(863计划)(No.2007AA11Z130)~~
【分类号】：TU435

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