【摘要】 黄土是一种特殊的率相关岩土材料,其压缩指标（如弹、塑性压缩系数和前期固结压力等）对加载速率的响应极为敏感.本文以兰州黄土为研究对象,开展了不同干密度和应力加载速率条件下的K₀加载试验.在此基础上基于不同压力条件下应变随时间的时程曲线分析了不同应变速率条件下的应力应变发展规律.结果显示,不同应变速率条件下兰州黄土进入塑性阶段的应力应变曲线为一系列平行线,且这些平行线的位置随着应变速率的增大而升高.对于应变速率相差一个数量级的平行线,其间距为常数.其物理意义为恒定荷载条件下应变与时间对数曲线的斜率.进一步分析表明,使用每级荷载作用下的最终应变得到的应力应变曲线与不同应变速率条件下的曲线大致平行,因而弹、塑性压缩系数以及前期固结压力可以通过最终应力应变曲线获取.其中,弹性压缩系数和前期固结压力与应力加载速率负相关,而塑性压缩系数和恒载应变速率参数受应力加载速率影响较弱.所以,在黄土场地动力学稳定性分析中,应充分考虑应力加载速率的影响,提高稳定性计算的准确性.更多还原

【Abstract】 Loess is a special rate dependent geomaterial,and its compression index（such as elastic,plastic compression coefficient and pre-consolidation pressure）is extremely sensitive to loading rate.In this paper,Lanzhou loess was taken as study object and K₀ compression tests under different dry density and stress loading rates were carried out.Based on the duration curve of strain versus time under different pressure conditions,the law of stressstrain under different strain rates was analyzed.The results show that the stress-strain curves in plastic stage under different strain rates are a series of parallel lines,and the positions of these parallel lines move up with the increase of strain rate.For the parallel lines with strain rate difference of an order of magnitude,the space is constant.Its physical meaning is the slope of the strain versus time logarithmic curve under constant load conditions.Further analysis indicates that the stress-strain curves obtained by the final strain under each load are approximately parallel to the curves at different strain rate conditions,and thus elastic and plastic compressive coefficients and preconsolidation pressure can be obtained by the final stress-strain curve.Among them,the elastic compression coefficient and the pre-consolidation pressure are negatively correlated with the stress loading rate,while the influence of stress loading rate on plastic compression coefficient and the constant load strain rate parameter are not notable.Therefore,in the dynamic stability analysis of loess fields,the effect of stress loading rate should be fully considered to improve the accuracy of stability calculation.更多还原