考虑屈服应力的非饱和土土水特征曲线研究

Study of soil water characteristic curve of unsaturated soil with considering the yielding stress

利用非饱和土固结仪进行控制基质吸力条件下,净竖向应力逐渐增大的固结试验,得到不同基质吸力条件下土体的屈服应力;进行净竖向应力为屈服应力时,不同基质吸力条件下的固结试验,通过对试验过程中排出水量的测试,计算出不同基质吸力条件下的稳定含水率,进而得到屈服应力条件下土体的土水特征曲线;利用土体孔隙分布的分形模型对土水特征曲线进行拟合。研究结果表明:屈服应力是影响非饱和土土水特征曲线的重要因素,屈服应力下土水特征曲线明显分为3个区段;同时,屈服应力下土水特征曲线具有良好的分形特性。

The consolidation tests on the condition of controlling matric suction and increasing net vertical stress were carried out by using the unsaturated soil consolidation apparatus and the yielding stress of the studied soil was obtained. Then,the net vertical stress was controlled at the yielding stress,the consolidation tests with different matric suction were carried out. Through the measuring of drainage during the test process,the stable water content under different matric suction could be calculated. Moreover,the soil water characteristic curve under the yielding stress was obtained. Finally,the fractal model of soil pore presure distribution was used for fitting the soil water characteristic curve. The results show that,the yield stress has great influence on the soil water characteristic curve of unsaturated soil. The soil water characteristic curve under the yielding stress can be significantly divided into three sections. At the same time,it has good fractal characteristic.