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将非饱和土基质吸力对土体强度的贡献等效为小主应力增量,通过分析土体极限应力莫尔圆的几何图形,求得小主应力增量,并认为土体在破坏时处于极限状态,提出了粘聚力和内摩擦角同时变化时的土体强度计算方法,得到了强度参数随含水量变化的函数关系式,研究了非饱和黄土破坏时大主应力随含水量变化的关系曲线。分析结果表明:计算曲线与试验曲线的变化规律相同,随着含水量的增大,大主应力计算值和实测值的差异越来越小,其相对误差最大值为11.63%,最小值为1.59%,说明该计算方法是可靠的;随着含水量的增大,当粘聚力和内摩擦角同时变化时,大主应力计算值较小,当仅有内摩擦角变化时,大主应力计算值较大,两者相差1.26～2.17倍,说明含水量的变化对非饱和黄土的强度有显著影响。
The contribution of the unsaturated soil matrix suction to the soil strength is equivalent to the small principal stress increment. The small principal stress increment is obtained through the analysis of the geometrical figure of the Mohr circle of the soil ultimate stress. The calculation method of soil strength with cohesion and internal friction angle changes is proposed. The function of strength parameter with water content is obtained, and the relationship between the principal stress and the water content of unsaturated loess is studied Relationship lines. The results show that the variation of the calculated curve and the experimental curve are the same. With the increase of water content, the difference between the principal stress and the measured value becomes smaller and smaller, the maximum relative error is 11.63% and the minimum is 1.59 %, Indicating that the calculation method is reliable. With the increase of water content, when the cohesion and internal friction angle change at the same time, the calculated value of the principal stress is small. When only the internal friction angle changes, the principal stress The calculated value is larger, the difference between them is 1.26 ~ 2.17 times, indicating that the change of water content has a significant influence on the strength of unsaturated loess.