红砂岩粗粒土剪胀效应大型三轴试验研究

 采用大型三轴试验仪，进行不同应力状态下的红砂岩粗粒土三轴试验，研究粗粒土在不同应力状态下的剪胀性和剪胀趋势影响因素。试验研究表明围压对粗粒土的剪胀性具有明显影响，在不同围压状态下，红砂岩粗粒土整体表现为高压剪缩低压剪胀，并且低围压下表现出先剪胀后剪缩趋势。当围压＜200 kPa时，体积增量比dev/de1为负值，土样表现为剪胀趋势；当围压＞400 kPa时，体积增量比dev/de1在整个剪切过程中为正值，土样表现为剪缩趋势。粗粒土剪胀趋势还随着轴向总应变发展而改变，开始时剪胀明显，随着轴向应变增加剪胀趋势缓减。粗粒土Rowe模型剪胀参数K值离散性较大，充分反映粗粒土剪切过程中粗、细颗粒间变形不协调性，并且随着总应变值e1的增加，K值离散性减小。本试验结果认为红砂岩粗粒土的Rowe剪胀模型参数K = 20～25。

STUDY OF DILATANCY EFFECT OF REDSTONE COARSE GRAINED SOIL BY LARGE SACLE TRIAXIAL TESTS

In order to study the dilatancy effect of granular soil and effects on the dilatancy tendency under different confining pressure conditions，a series of red stone granular soils tests are executed by the large scale triaxial shearing apparatus. The test results show that the confining pressure has obvious effects on the dilatancy effect of granular soil，and the different dilatancy effects are observed from the different confining pressure tests. When the confining pressure is less than 200 kPa，the ratio of volume increment to axial strain(dev/de1) is negative，which shows dilatancy tendency. When the confining pressure exceed 400 kPa，the ratio of volume increment to axial strain(dev/de1) is positive，and the red stone granular soil samples shows shearing shrinkage tendency in the tests. The red stone granular soil dilatancy tendency is also changed by the axial strain increment，with firstly quick dilatancy tendency and then slow dilatancy tendency. The coefficient K of Rowe shearing dilatancy model is obviously discrete during the shearing procedure，which reflects the deformation incompatibility between the coarse grains and fine grains in red stone granular soil. The discrete degree is minishing with the total axial strain increment. The shearing dilatancy coefficient K of Rowe is identified as 20–25 for the red stone granular soil in these test data.