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采用普通应变控制式直剪仪对非饱和残积砂质黏性土和黏土进行慢剪强度试验,试验结果表明,砂质黏性土的黏聚力和内摩擦角均对含水量变化敏感,黏聚力随含水量的变化呈二次抛物线关系,内摩擦角随含水量增大呈幂函数减小;含水量对黏土强度的影响主要是降低了黏聚力,对内摩擦角影响很小。黏聚力随含水量的增加呈指数减小。针对上述变化规律,分别建立实用的强度经验公式,避免了吸力量测和计算困难。对提出的强度公式进行试验验证,计算预测强度并与实测强度相比较,结果表明不同竖向应力条件下,高竖向应力下强度的预测精度更高。2类残积土的强度公式预测精度均满足工程要求,可为工程实际应用提供参考。
The results of the tests show that the cohesion and internal friction angle of sandy clay are sensitive to the change of water content, Cohesion shows a quadratic parabola relationship with the change of water content. The internal friction angle decreases with the increase of water content. The influence of water content on the strength of clay mainly decreases the cohesion and has little effect on the internal friction angle. Cohesion decreases exponentially with increasing water content. According to the above variation rules, practical empirical formula of strength is established, which avoids the measurement and calculation of suction. The proposed formula of strength is tested and verified, and the predicted strength is calculated and compared with the measured strength. The results show that the prediction accuracy of the strength under high vertical stress is higher under different vertical stress. The prediction accuracy of the strength formula of the two types of residual soil satisfy the engineering requirements, which can provide reference for the practical application of the project.