荆门非饱和压实膨胀土的吸力特征及其本构方程

摘要

The suction is closely related to the mechanical characteristics of unsaturated soil,to explore the suction law of unsaturated soil,the total suction and matric suction of Jingmen unsaturated expansive soil are measured under six levels of compactness and thirteen levels of gravitational water content by using the filter paper method.The test cases cover almost the entire range of moisture and dense state of the expansive soil.Test results show that both the moisture and dense state have significant effect on the suction.With one fixed density,the suction of soil can increase greatly with the decreasing degree of saturation.On the other hand,under one fixed degree of saturation,the suction increases with the increasing density.The suction varies within wide range for the samples at the lower degree of density,whereas the suction for the samples at the higher degree of density changes gradually.Based on the test results,the constitutive formula is presented for predicting the suction which is the function of the degree of saturation and the void ratio.The comparison between tested suction and predicted suction indicates that the proposed constitutive formula can describe the suction law of compacted expansive soil in the may range of dense state and water-holding state.%吸力与非饱和土的力学性状密切相关,为探讨非饱和膨胀土吸力变化规律,以滤纸法为研究手段,测定6种不同压实度与13种不同重力含水率组合条件下荆门弱膨胀土的总吸力与基质吸力.试验基本覆盖该膨胀土持水状态与密实状态的可能变动范围.研究表明:土体持水状态与密实状态均对压实膨胀土吸力影响显著.相同密实状态下,吸力随持水程度的增大而降低,且变动幅度较大.相同持水状态下,吸力随密实程度的增大而增大.密实度小的试样吸力变化幅度大,密实度大的试样吸力变化相对平缓.在明确吸力变化规律的基础上,构建吸力-饱和度-孔隙比关系的本构方程,数值再现结果与模型预测结果均表明该方程能够有效描述压实膨胀土在可能密实状态与持水状态范围内的吸力变化规律.