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为了探讨降雨和蒸发所引起的渗流对非饱和土土压力的影响,本文将基质吸力与渗流的关系式引入到基于统一强度理论的非饱和土抗剪强度公式中,得到了降雨和蒸发条件下考虑中主应力影响的非饱和土抗剪强度公式;结合土体的极限平衡理论,推导出了受降雨和蒸发影响的主动土压力、被动土压力、静止土压力系数公式;最后通过数值算例进行了分析。结果表明:在降雨和蒸发条件下,非饱和土主动土压力最小值为-145kPa,被动土压力最小值为139kPa;而常规方法计算的主动土压力最小值为-13.85kPa,被动土压力最小值为41.57kPa;在降雨和蒸发条件下,非饱和土主动土压力小于饱和土主动土压力,而被动土压力则相反;在非饱和土中,降雨和蒸发所引起的渗流使得静止土压力系数随着与地下水位距离的增加而减小,在地表附近将会达到-1;而在饱和土中,本算例中各计算点的静止土压力系数总是常数(K0=0.5)。
In order to investigate the influence of seepage on rainfall and evaporation, the paper introduced the relationship between the matrix suction and seepage into the unsaturated soil shear strength formula based on the unified strength theory. Under rainfall and evaporation conditions Taking into account the principal stress of unsaturated soil shear strength formula; combined with the limit equilibrium theory of soil, derived by the rainfall and evaporation of active earth pressure, passive earth pressure, static earth pressure coefficient formula; finally numerical examples Analyzed. The results show that under the condition of rainfall and evaporation, the minimum value of active earth pressure of unsaturated soil is -145 kPa and the minimum value of passive earth pressure is 139 kPa; while the minimum of active earth pressure calculated by conventional method is -13.85 kPa and the minimum of passive earth pressure Is 41.57 kPa. Under rainfall and evaporation conditions, the active earth pressure of unsaturated soil is less than that of saturated soil, while the passive earth pressure is opposite. In unsaturated soil, the seepage pressure caused by rainfall and evaporation makes the static earth pressure coefficient Decreases with the increase of the distance to the groundwater table and will reach -1 in the vicinity of the surface. In saturated soil, the static earth pressure coefficient of each calculation point in this study is always constant (K0 = 0.5).