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通过试验确定了非饱和黏土层的土-水特征曲线和强度参数,通过理论分析建立了非饱和堤岸渗流-应力耦合模型。在此基础上,利用耦合计算程序分析了非饱和土堤岸在河水位变动时的非稳定渗流场特征,结合强度折减有限元法分析了河水位反复升降后非饱和堤岸稳定性的变化。结果表明:水位快速上升时,堤脚渗透流速下降后又逐步上升并趋向稳定,河水位快速上升使堤岸边坡的稳定性降低,随着渗流场中孔隙水压力的调整,堤岸边坡的安全系数又有所回升;河水位骤降时,黏性土层饱和度变化相对滞后,水位骤降加大了堤岸的渗透流速,边坡的稳定性迅速降低,水位下降约120 h后堤岸边坡进入较危险时段;非饱和土的基质吸力提高了堤岸边坡整体稳定性,河水位反复升降降低了堤岸边坡整体稳定性,且河水位越低,水位反复升降对堤岸稳定性产生的影响越大。
The soil-water characteristic curve and strength parameters of unsaturated clay layer were determined through experiments. The seepage-stress coupling model of unsaturated bank was established by theoretical analysis. Based on this, the unsteady seepage field characteristics of unsaturated embankment in fluctuating river water level are analyzed by using coupled calculation program. The stability of unsaturated embankment after repeated rise and fall of river level is analyzed with the strength reduction finite element method. The results show that when the water level rises rapidly, the infiltration velocity decreases and then gradually increases and tends to be stable. The rapid rise of water level reduces the stability of bank slope. With the adjustment of pore water pressure in the seepage field, the embankment slope The safety factor of the slope increased again. When the water level plunged, the saturation of the cohesive soil layer lagged behind. The water level plummeted and increased the infiltration velocity of the embankment, and the stability of the slope decreased rapidly. After the water level dropped about 120 h, The shore slope enters a more dangerous period; the matrix suction of unsaturated soil improves the overall stability of the bank slope; the repeated rise and fall of the river level reduces the overall stability of the bank slope; and the lower the river level, the steady rise and fall of the water level affects the bank stability The greater the impact of sexuality.