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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。
Soaking strength and residual strength of lime-soils are often encountered in the continuation of construction projects, reconstruction projects and accident analysis of engineering accidents. Therefore, it is of great value in engineering application to study soils. The author of more than 40 pieces of 2: 8 lime (Lanzhou loess and lime preparation) specimens for static triaxial test to explore the residual strength and the strength of the law changes under water conditions. The test results show that the residual strength of limestone σR and its confining pressure σ3 linear relationship: σR = Aσ3 + B. The law is similar to that of rock because the friction of the rupture surface is similar to that of the rock at the stage of residual strength. The strength of the soil is decreased after the first soaking, but with the increase of the number of soaking The strength has rebounded and finally stabilized at a value not higher than its original strength. In addition, it has also been observed that the dust can not be simply judged as a brittle material whose brittleness is influenced by confining pressure and moisture content The larger the confining pressure is, the less obvious the brittleness is. When the water content decreases to a certain value, the limestone presents brittleness.