中文摘要：

非饱和土力学的研究水平目前还未进入实用阶段，主要原因在于吸力量测的困难。折减吸力的提出避免了吸力量测的困难。根据变形等效原则介绍了确定折减吸力的具体方法，为了避免吸力量测的困难，采用折减吸力代替真实吸力提出了一个计算膨胀土静止土压力的方法。进行不同水位和降雨入渗情况下的膨胀土静止土压力系数的计算，计算结果合理地反映了非饱和土土压力和膨胀量的分布趋势，计算结果验证了方法的合理性。

英文摘要：

Until now the research activities in the field of unsaturated soils have been still in the academic stage. The key point of troubles is the measurement of suction. To avoid the difficulty in the determination of soil suction, the so-called reduced suction had been proposed recently. A method to determine of reduced suction based on the principle of equivalence of deformation was introduced, and the reduced suction was used as an essential variable in the calculation of earth pressure of expansive soils at rest on retaining wall. The results of calculation have rationally reflected the distribution trend of unsaturated soil pressure at rest. The proposed formulation was verified by the calculated results.