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粗粒土卸载-再加载力学特性试验研究

ISSN号：1000-7598
期刊名称：岩土力学
时间：0
页码：1914-1919
分类：TU411.5[建筑科学—岩土工程;建筑科学—土工工程]
作者机构：[1]河海大学岩土力学与堤坝工程教育部重点实验室,南京210098, [2]河海大学岩土工程研究所,南京210098, [3]南通中房建筑设计研究院有限公司,江苏南通226000, [4]山东农业大学水利土木工程学院,山东泰安271018
相关基金：水利部公益性行业科研专项“高心墙堆石坝安全性评价技术研究”（No.200801133）;国家自然科学基金（No.50809023）;国家杰出青年科学基金（No.50825901）.
相关项目：高土石坝静、动力学特性与应力变形分析

关键词：粗粒土, 三轴试验, 卸载体缩, 回弹模量, coarsegrained soil, triaxial tests, volumecontraction in unloading, rebound modulus

中文摘要：

进行了3种不同粗粒土的常规三轴加载一卸载一再加载的剪切试验，对粗粒土的卸载一再加载的力学特性进行了分析。结果表明：粗粒土存在卸载体缩现象，且随着应力水平的增加，卸载体缩量增加；随着围压的增加，卸载体缩量减小。根据试验数据总结了卸载体缩量与应力水平、围压之间关系式。回弹模量随应力水平的增加呈驼峰型曲线，即应力水平在0．7左右时最大，小于或大于0．7时的弹性模量均较小。平均回弹模量与单调加载时的初始弹性模量的比值随围压呈幂函数降低，母岩硬度大的土料，该比值较大，相反，母岩较软的土料，该比值较小。由单调加载得出的邓肯模型参数k、n和卸载回弹确定的K_ur、n_ur的大致关系为K_ur（2．64-4．60）K_ur=（0．540-0．885）n。

英文摘要：

The test results of three different coarsegrained soils are obtained with conventional triaxial cyclic loading test. Based on these results, some useful conclusions are drawn from the discussion and analysis of the phenomenon of volumecontraction in unloading of coarsegrained soils： The phenomenon of the volumecontraction in unloading of coarsegrained soil is more obvious with the increasing of stress level and with the decreasing of confining pressure. According to the test data, a relationship formula among volume contraction in unloading and stress level and confining pressure is obtained. Rebound modulus presents the curve of hump shape with the increasing of stress level and the maximum is obtained when stress level is 0.7. The ratio of average rebound modulus and initial elastic modulus with monotonic loading present decrease of a power function, this ratio of soil material whose mother rock is high hardness is larger and the ratio of soil material whose mother rock is soft is smaller. The general relationship between kur and n_ur which is obtained from rebound in unloading and k and n which is obtained from monotonic loading is that K_uriS approximately from 2.46 times to 4.60 times ofk and nur is approximately from 0.540 times to 0.885 times ofn respectively.

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