特殊应力路径下岸坡饱和土体变形特性模拟

发布时间：2018-01-29 09:43

本文关键词： 循环加卸载应力路径统一硬化模型加卸载准则　出处：《岩土力学》2017年03期 　论文类型：期刊论文

【摘要】：库岸边坡土体受到库水位涨落的周期性影响,其受力过程可描述为在前期固结压力范围内有效应力的多次循环加、卸载过程。通过室内应力路径三轴试验模拟土体孔隙水压力的循环加、卸载,并通过对统一硬化模型的扩展和加、卸载准则的修正,来预测土体的变形发展规律,研究结果表明:循环加、卸载过程中,土体的体积变形呈周期性弹性变化,剪应变呈螺旋上升趋势且增幅随循环次数逐渐减小;卸围压屈服阶段,土体变形呈现体积膨胀的剪胀特征和剪应变增幅加快的脆变趋势,且土体剪切变形在6%左右时即出现实测孔压骤减和峰值强度点;建立压缩曲线系数与加、卸载次数的关系,并修正超固结土的加、卸载准则,扩展后的统一硬化模型能够较好地预测特殊应力路径下岸坡饱和土体的变形特性。
[Abstract]:The soil on the bank of the reservoir is influenced periodically by the fluctuation of the reservoir water level, and the stress process can be described as the cyclic addition of effective stress in the range of pre-consolidation pressure. Unloading process. The cyclic loading and unloading of pore water pressure of soil is simulated by triaxial test of indoor stress path, and the expansion and loading of the unified hardening model and the revision of unloading criterion are carried out. The results show that during cyclic loading and unloading, the volume deformation of the soil changes periodically, and the shear strain increases with the cycle times. At the stage of unloading confining pressure, the deformation of soil presents the tendency of dilatancy of volume expansion and brittleness of the increase of shear strain, and when the shear deformation of soil is about 6%, the measured pore pressure suddenly decreases and the peak strength point appears. The relationship between compression curve coefficient and loading and unloading times is established, and the loading and unloading criteria of overconsolidated soils are revised. The extended unified hardening model can better predict the deformation characteristics of saturated soils on bank slopes under special stress paths.
【作者单位】：三峡地区地质灾害与生态环境湖北省协同创新中心;三峡大学土木与建筑学院;
【基金】：国家自然科学基金(No.51409149)~~
【分类号】：TV223
【正文快照】： 水库建成运行期间,水位周期性涨落,势必造成水库防洪限制水位以下岸坡土体(简称岸坡饱和土体)的孔隙水压力周期性增减变化,由于孔隙水压力是各向同性的增大和减小,故土体的有效竖直方向力和水平方向力将同步变化,即p循环加、卸载而q基本不变(p为有效球应力,q为偏应力,下同)。

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