工程地质学报2011，Vol.19Issue(4)：467-471,5.
马兰黄土动强度及其微结构变化实验
DYNAMIC STRENGTH AND MICROSTRUCTURE CHANGE OF MALAN LOESS UNDER TRIAXAL CYCLIC LOADING
摘要
Abstract
Failures of Loess slopes have been a bottleneck of rural urbanization and ground transportation construction in loess area. They and their hazards have been a current research focus of in engineering geology. One of the bases to reveal loess slope failure mechanism is to examine loess stress and microstructure changed due to effects of shock (vibration) or dynamic loading. This paper is based on the CDS Lab System, uses the equivalent sine wave loading gradually under strain controlling. Dynamic triaxial tests on loess samples are carried out. It further uses the scanning electron microscope to observe the differences of microstructures before and after the test. It analyzes the reasons of decreasing in dynamic strength. The results show the following findings. There is an obvious phenomenon of stress relaxation during the cyclic loading test on Malan loess. The degree of stress relaxation decreases with the increasing of confining pressure and strain. The dynamic failure stress increases linearly with the increasing of confining pressure. The Mole-Coulomb failure criterion is used to get the dynamic strength. Comparing the static strength and the dynamic strength,the dynamic internal friction angle decreases significantly,while the dynamic cohesion decreases slightly. The internal reason of decreasing on strength is as follows. By the role of cycling dynamic loading, the macro-cementation structure damages. On the other hand,the relationship between particles contact way changes from the point to point contact to the surface to surface contact. Thereby, the strength of the Malan loess is reduced. The micro-structure type is also changed into a mosaic micropore macro-cementation structure.关键词
马兰黄土/GDS试验系统/应力松弛/微结构Key words
Malan loess/ Slope failure/Geohazards/Stress relaxation/ Micro-structure/Cylic loading分类
天文与地球科学引用本文复制引用
王念秦,罗东海,姚勇,陈效星,杨建国..马兰黄土动强度及其微结构变化实验[J].工程地质学报,2011,19(4):467-471,5.基金项目
国家自然科学基金(40972174)铁三院地路处科研项目(科研06-2). （40972174）
