灰土的浸水强度及残余强度的试验研究

Study of immersion strength and residual strength of lime-loess

灰土的浸水强度和残余强度在续建工程、改建工程及工程事故分析中经常遇到,故对其进行研究有着重要的工程应用价值。笔者对40余件2:8灰土(兰州黄土与石灰配制)试样进行静三轴试验,探讨其残余强度和浸水条件下强度的变化规律。试验结果发现,灰土的残余强度σR与其围压σ3呈线性关系:σR=Aσ3+B。其规律类似于岩石,原因是由于残余强度阶段灰土碎裂成块,破裂面上的摩擦作用类似于岩石碎裂时的作用;灰土首次浸水后强度有所下降,但随着浸水次数的增加其强度有所回升,最后稳定于一个不高于其原始强度的值;另外还观察到,灰土不可简单地判断为一种脆断性的材料,其脆断性受围压和含水率等因素的制约,围压越大,脆性越不明显,当含水率降低到某一值时灰土表现为脆断性。

The immersion strength and residual strength of lime-loess is an operation frequently encountered in subsequent projects,reconstruction projects and analyzing the engineering accident.So there will be an important engineering significance if we work for it.The conventional triaxial test was conducted with forty samples of loess-lime of Lanzhou in China,the immersion strength and residual strength of lime-loess were discussed specially.From these tests results it was found that the residual strengthσ Rwith the confining pressureσ 3appears a linear relationship.This law is similar to rock,because the lime-loess was broken into masses in the period of the residual strength,and the friction effect on the crack face was so similar to the rock.;the strength will decrease after the lime-loess was immersed;but the strength will appear up after a few times immersion;and the strength will remain on a constant volume which is not more than its original strength.In addition,we can＇t define it brittle materials simply.It is found that the lime＇-loess fragility is depended on confining pressure and water content;the loess-lime＇fragility will be more evident when the confining pressure become more high.It will be fragility when the water content decrease to a certain value.