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桩柱结构在地震作用下非线性响应研究

ISSN号：1000-7598
期刊名称：岩土力学
时间：0
页码：-
分类：TU473[建筑科学—结构工程;建筑科学—土工工程]
作者机构：[1]大连理工大学港口海岸与近海工程国家重点实验室,辽宁大连116024, [2]南京水利科学研究院,江苏南京210029
相关基金：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）
相关项目：海洋环境灾害作用与结构安全防护

关键词：非线性响应, 桩-土耦合, 下负荷面剑桥模型, 超固结, nonlinear response, pile-soil coupling, subloading surface Cam-clay model, overconsolidation

中文摘要：

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。

英文摘要：

As a classic elastoplastic constitutive model, the Cam Clay model can precisely describe the stress-strain relationship of remolded and normally consolidated clay. While soil stress experiences unloading or cyclic loading, the soil may become overconsolidated. An overconsolidated soil shows different mechanical behavior compared to its normally consolidated counterpart. To investigate the mechanical properties of overconsolidated soil, a subloading-surface Cam Clay model, which takes overconsolidation factor into account, is introduced. Then a comparative analysis is carried out for the triaxial compression tests and shear tests of overconsolidated soil, and the stress-strain relationship and OCR variation of the soil under cyclic loading are also studied in detail. The results show that overconsolidation factor can significantly influence the mechanical properties of soil, and the soil has higher yield strength than its normally consolidated counterpart. In addition, the dynamic response of free field under earthquake incidence is analyzed, showing that the influence of overconsolidation factor plays a very important role in the seismic response of soil ground, especially under high-magnitude earthquake incidence. Based on the results of the free-field analysis, the nonlinear dynamic response of a typical pile-soil coupled system under earthquake incidence is analyzed. The results show that the high-frequency component of structure is significantly suppressed by the influence of soil nonlinearity. Because the soil quickly turns into overconsolidated state under cyclic loading, its strength increases significantly, if the subloading-surface Cam Clay model is adopted, when the overconsolidation factor is taken into account, especially under the incidence of high-magnitude earthquake. Therefore, to guarantee the accuracy and reliability of the simulation for pile supported structure under earthquake incidence, it is necessary to account for the overconsolidation effect.

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