论文部分内容阅读
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。
Based on the test, the classic elastic-plastic model-Cambridge model can accurately describe the stress-strain relationship of normal consolidated soil. When the stress of the soil has experienced unloading or cyclic cyclic loading, it enters the overconsolidated state. It is a reflection of the stress history of the soil, which is significantly different from the stress characteristics of the normal consolidation soil. In order to study the influence of overconsolidation on the loading characteristics of soil mass, after introducing the under-load surface Cambridge model that can consider the effect of overconsolidation state, the soil under over-consolidation condition Force characteristics were compared and analyzed, and the stress-strain relationship under cyclic shear loading and the evolution of overconsolidation ratio were studied. The results show that the Cambridge model under load surface can accurately reflect the effect of overconsolidation on the mechanical properties of soil, which has a higher yield strength than undisturbed soil. By numerical simulation of free-field foundation dynamic response under earthquake, it can be seen that the overconsolidation factors have a negligible effect on the dynamic response of the foundation, especially under strong earthquakes need to consider its impact. Based on the seismic response of the free-field foundation, a comparative study on the nonlinear and overconsolidated factors of soil-pile coupling between the pile-soil coupling system and the nonlinear dynamic response of the pile-soil coupling system under seismic load is carried out. The results show that: The soil nonlinear factors can significantly reduce the high frequency components of the structure vibration response. Because the soil quickly enters the overconsolidated state under the alternating loading, compared with the Cambridge model, the under load surface Cambridge model, considering the factors of overconsolidation The bearing capacity of soils significantly increases, especially under over-consolidation caused by strong earthquakes. Therefore, it is suggested that the study of seismic response of pile-structure should consider the influence of overconsolidation to improve the structure of pile foundation Seismic response simulation accuracy and reliability.