平衡饱和度差异性产生机理及其对非饱和土力学特性的影响

通过双孔隙结构分析结果确定在同一基质吸力下的试样将因孔隙分布的随机性而表现出不同的平衡饱和度, 进一步通过理想非饱和土的水气分布确定饱和度差异将影响非饱和土的力学性质研究. 采用压力板仪与直剪仪的简化组合试验对上述理论分析结果进行验证, 研究结果表明：平衡饱和度差异存在并随着基质吸力的增大而逐渐减小；在同一基质吸力下试样的抗剪强度随平衡饱和度的增加而降低；进一步的拟合结果显示平衡饱和度对与基质吸力相关的内摩擦角影响显著；通过对试验数据及其平均值的研究建议在最小与最大基质吸力下进行多次平行试验, 可以在不显著增加试验时间的同时减小平衡饱和度差异的影响.

A MECHANISM FOR CALCULATING THE DIFFERENCE IN EQUILIBRIUM SATURATIONS AND THEIR IMPACT ON THE MECHANICAL BEHAVIORS OF UNSATURATED SOILS

A biporous system was analyzed, and the results show that specimens under the same matric suction have different equilibrium saturations because of the random distribution of their pore structures. The water-air distribution of an ideal unsaturated soil was analyzed, and the results show that the mechanical behaviour of unsaturated soil is affected by the difference in equilibrium saturations. The above results were further confirmed by pressure plate test and direct shear test. Results show that there are differences in equilibrium saturation, and that these differences decrease with increasing matric suction. Specimen shear strength decreases with increasing equilibrium saturation for the same matric suction. Further fitting results show that the internal friction angle related to matric suction is significantly affected by the equilibrium saturation: the maximum difference is about 45.18% of average value. Based on the test results and mean value, the following test structure is proposed: multiple parallel tests should be done under both the minimum and maximum matric suctions, and then the mean value obtained. This format can help to improve test results and save time.