干密度对非饱和黄土基质吸力的影响  

Influences of Dry Density and Stress on Suction State Characteristics of Undisturbed Unsaturated Loess

作　　者：褚峰[1] 邵生俊[1] 陈存礼[1] 

机构地区：[1]西安理工大学岩土工程研究所,西安710048

出　　处：《地下空间与工程学报》2015年第6期1431-1436,共6页Chinese Journal of Underground Space and Engineering

基　　金：国家自然科学基金(41272320);陕西省黄土力学与工程重点实验室科研计划项目(2010JS084)

摘　　要：为了研究起始湿度、天然密度以及竖向荷载对吸力特性的影响,对西安原状黄土进行不同起始湿度、密度条件下的常含水量压缩试验,提出无应力作用下同时反映初始含水率和天然干密度的基质吸力表达式。研究结果表明:天然干密度、初始含水率、应力相关的干密度对基质吸力的影响程度都与试样的起始湿度有关,起始湿度小于试样塑限含水量时,影响都比较大,起始湿度大于试样塑限含水量时影响都很小。净竖向荷载对吸力特性的影响与起始湿度、天然密度有关,净竖向荷载小于等于400 k Pa时,对吸力的变化影响很小,可不考虑净竖向荷载影响,可用未受荷载作用时的SWCC曲线来描述原状试样的吸力特征;净竖向荷载大于400 k Pa时,对吸力的变化影响较为显著。视起始湿度和天然密度的不同,净竖向应力相关的干密度增大引起基质吸力非单调增减或单调下降,天然干密度的增大引起基质吸力单调上升。Using consolidation apparatus for unsaturated soils,the confined compression tests at constant water content are conducted on unsaturated undisturbed loess of natural dry density in Xi ’an under different water contents. Effects of initial water content and stress state as well as natural dry density on the matrix suction characteristics are determined and illustrated. A formula is obtained to determine the matrix suction under zero-applied stress,which take initial water content and natural dry density into account. Experimental results show that degree of influence of initial water content and natural dry density as well as dry density related to stress on the suction state is dependent on size of water content. When the water content is smaller than plastic limit,the influences are large. When that is larger than plastic limit,the influences are little. The regularity of the suction affected by applied stress greatly depended on initial water content and natural dry density,and the degree of that greatly depended on the magnitude of applied stress. When the net applied stress is small（ 〈 400 k Pa）,the impact is little under different water content,and the soil-water characteristics is illustrated by the relation between suction and water content under zero-applied stress for the sake of convenient use in engineering. When the net applied stress is large（ 〉 400 k Pa）,the impact is larger. The relationship between matric suction and dry density related to stress during constant water content is different from natural dry density. The suction increases and then decreases or decreases monotonously with the increase of dry density related to applied stress under different initial water content and natural dry density. It increases with the increase of natural dry density.

关 键 词：原状非饱和黄土 基质吸力 干密度 竖向应力 含水率 

分 类 号：TU411[建筑科学—岩土工程]