非饱和重塑膨胀土各向等压加载试验研究

为分析裂隙和胀缩对非饱和膨胀土屈服和水量变化特性的影响,首先对重塑膨胀土试样进行常温条件的干湿循环,使其形成不同程度的裂隙和孔洞;其次以多功能土工三轴仪为研究工具,对已产生结构损伤的重塑土试样进行控制吸力为常数、净平均应力增大的各向等压加载试验。试验结果表明:随着干湿循环次数的增加,膨胀土试样裂隙和孔洞发育愈加明显,排水能力相应提高;同一吸力条件下,屈服应力随着干湿循环次数的增大而减小;同一干湿循环次数条件下,试样所受吸力越大,屈服应力则相应增大;干湿循环次数增多时,膨胀土的压缩指数在发生屈服前后呈现不同规律,前者一直增大,而后者可看作一常数。

Experimental Research on Isotropic Pressure Loading Test of Unsaturated Remolded Expansive Soils

In order to analyze the impact of fissure and swell-shrink on the characteristics of yield stress and water changes of unsaturated remolded ex- pansive soil, firstly, a test sample ofremolded expansive soil is drying-wetting cycled under normal temperature condition to cause fissures and holes of different sizes; then, a loading test is done to the test sample of damaged structure with normal suction control and increasing net mean stress. The re- sults show that fissures and holes of the expansive soil sample grow and drainage ability enhances obviously with the Increment of drying-wetting cy- cles; yield stress weakens with the increment of drying-wetting cycle under the same suction condition; yield stress grows with the growing of suction under the same times of drying.wetting cycle; the comprehension index of expansive soil before and after yielding presents different patterns with the in- erament of drying-wetting cycle, the former constantly increases while the latter is in normal condition.