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黄河下游游荡段是下游河床冲淤变化的主要河段,滩岸侵蚀是该河段清水冲刷期河床演变的一个重要特点,其过程与滩岸土体组成及力学特性密切相关.本文首先分析了花园口至高村游荡段近期的滩岸侵蚀情况,然后对这一河段的10个典型滩岸进行了现场查勘与室内土工试验,最后根据试验结果,较为全面地揭示了游荡段滩岸土体组成,而且深入分析了滩岸土体的力学特性,定量地解释了游荡段滩岸侵蚀严重的两个原因.结果表明,游荡段大部分滩岸土体属于黏性土,且具有较为明显的垂向分层结构;滩岸土体因黏粒含量少、抗冲强度弱,其起动切应力(0.1~0.3Pa)比近岸平均水流切应力(2~3Pa)小一个数量级,故容易冲刷;滩岸土体的抗剪强度随土体含水率增加而降低,其凝聚力可由34kPa急剧降低到4kPa,故滩岸土体容易在汛期发生崩塌.
The wandering section of the lower reaches of the Yellow River is the main section of the riverbed erosion and sedimentation in the lower reaches of the lower reaches of the Yellow River. Beach erosion is an important feature of the riverbed evolution during the flushing period. The process is closely related to the composition and mechanical properties of beach banks. Huayuankou to Huachuang wandering section of the recent bankside erosion, and then the 10 typical beaches in this section of the site survey and indoor soil test, and finally based on the test results, a more comprehensive disclosure of wandering beach bank soil , And further analyzes the mechanical characteristics of the beach bank so as to quantitatively explain the two reasons for the serious beach erosion in the wandering section.The results show that most of the beach bank soil in the wandering section belongs to the cohesive soil and has more obvious Vertical stratification structure. The beach bank soil is easy to scour due to less clay content and weak impact strength. The initial shear stress (0.1-0.3 Pa) is one order of magnitude smaller than the average coastal flow shear stress (2-3 Pa) The shear strength of the beach bank soil decreases with the increase of the soil moisture content, and the cohesion force of the beach bank can be drastically reduced from 34 kPa to 4 kPa. Therefore, the beach bank soil tends to collapse in the flood season.