Prediction of Strength of Expansive Soils in the Low Suction Range

在低吸力范围内，针对膨胀土开展三轴压缩实验。实验所用试样借助轴平移技术实现吸力平衡。试验结果表明试样处于低吸力时应力应变曲线为硬化型曲线，当试样处于相同围压下时，试样基质吸力越大抗剪强度越大，当试样处于相同的基质吸力时围压越大，抗剪强度越大；在基于Bishop公式对非饱和膨胀土强度进行预测时将预测公式中的有效应力系数替换为有效饱和度可以使预测结果更为准确。Triaxial compression experiments were carried out on expansive soils in the low suction range. The specimens used in the experiments were balanced in suction with the help of axial translation technique. The results show that the stress-strain curve is hardened when the specimen is in the low suction range; when the specimen is in the same suction range, the greater the matrix suction the greater the shear strength; when the specimen is in the same suction range, the greater the perimeter pressure, the greater the shear strength; when the strength of unsaturated expansive soils is predicted based on the Bishop’s formula, the effective stress coefficient in the prediction formula is replaced by the effective degree of saturation, which can make the prediction results more accurate. The effective stress factor in the prediction formula can be replaced by the effective saturation degree to make the prediction more accurate.