南京地区粉土的不排水三轴压缩试验

通过全自动三轴仪进行了南京地区粉土的三轴不排水的试验,研究了围压和干密度对应力-应变曲线、孔隙水压力曲线和有效主应力比曲线的影响.试验表明:高围压状态下粉土试样呈现出弱应变软化型,而低围压状态下呈现出应变稳定型;低围压下试样在加载初期产生正孔隙水压力,随后产生负孔隙水压力,其后基本保持稳定;干密度越大,主应力差峰值越大,表现出较大的剪胀性,孔隙水压力易出现负孔隙水压力;干密度值较高时,土样处于密实状态,表现出剪胀特性,有效主应力比-应变曲线近于应变软化型;围压较低、干密度较大时,试样易表现出软化特征,试样出现剪切带破坏,强度明显下降.

Undrained triaxial compression test of Nanjing silt

The undrained tests of conventional triaxial compression on Nanjing silt were conducted by the KTG to investigate the effect of confining pressure and dry density on the stress-strain curves,pore water stress-axial strain curves and effective principal stress ratio curves.It was confirmed that silt appears to be weak strain softening under high confining pressure,but exhibits strain stabilization under low confining pressure.In the first loading stage the pore water pressure of the specimen under low confining pressure remains positive,then with the loading incease pore water pressure decreases to negative until that tends to be stabe.The more is principal stress deviator peak,the more possible is to emerge negative pore water pressure and to show more shear dilatation with high dry density.When the dry density is relatively high,this dense specimen shows shear dilatation characteristics,and the effective principal stress ratio tends to be strain softening phenomenon.When the confining pressure is relatively low and dry density is comparatively high,the specimen is apt to show the softening characteristics,and the shear band failure emerges in specimen,the strength drops greatly.