洪水期岸滩崩塌有关问题的研究

结合洪水期堤岸渗透与崩塌的特点,以岸滩稳定分析为基础,本文重点研究了崩滩与渗透险情的关系、洪水浸泡河岸及水位升降等对崩岸的影响。研究结果表明,岸滩崩塌对河岸堤基的渗透和渗透破坏(管涌、流土)有重要的促进作用,作者推导了堤后(或堤脚)发生流土破坏的临界内滩宽度公式;洪水长期浸泡后,河岸土壤的内摩擦角和内聚力有较大幅度的减小,河岸稳定系数减小;对于黏土岸滩,洪水迅速上涨期间,水压力对河岸的稳定是有利的,而洪水骤降时,河岸崩塌的几率增大;对于非黏土岸滩,洪水缓慢上涨期间,河岸稳定性变化不大,而洪水缓慢下降后,岸滩稳定系数减小。

Study on bank collapse during flooding periods

The authors studied the relationship between bank collapse and seepage failure of embankment foundation and the impact of flood soaking and water level variation on bank stability during flooding periods. Some results were obtained. Bank collapse had an important impact on seepage failure ( such as piping and soil flow) of the embankment foundation. A formula was derived to calculate the critical width of the beach area when soil flows occurred behind the embankment or at the embankment toe. The internal friction angle and the cohesion of the bank soil would greatly decrease after a long period of soaking, this would result in a decrease of the stability coefficient . For cohesive banks, water pressure was favorable for the bank stability in a water level rising process, but the possibility of bank collapse would increase in a water level falling process. For non-cohesive soil, the bank stability would not change very much when the water level rises slowly, but the bank stability coeff icient would reduce when the water level slowly falls.