中文摘要：

根据变形等效原则介绍确定折减吸力的具体方法，采用折减吸力代替真实吸力进行非饱和土土压力系数和膨胀量的计算，计算不同水位条件下非饱和土的静止土压力、主动土压力、被动土压力以及不同水位条件下非饱和土的膨胀量和降雨条件下非饱和土的膨胀量。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。将计算结果与离心模型试验和模型槽试验结果进行对比，两者具有很好的一致性。

英文摘要：

A method of determination of reduced suction based on the principle of equivalence of deformation is introduced; and the reduced suction is used as an essential variable in the earth pressure calculation of unsaturated soils on retaining wall and swell increment. The rest soil pressure, active soil pressure, passive soil pressure of unsaturated soil under different water table conditions, and swell increment of unsaturated soil under different water level conditions and swell increment that are caused by rainfall have been considered. The calculation results have rationally reflected the distribution trend of unsaturated soil pressure and swell increment. Comparing the calculation results with the results of centrifugal model test and the model trough test, it is found that they have very good consistency. Calculation results also verify the proposed formulation.