| 朱海丽,李志威,胡夏嵩,李国荣,宋路,付江涛.黄河源草甸型弯曲河流的悬臂式崩岸机制[J].水利学报,2015,46(7):836-843 |
| 黄河源草甸型弯曲河流的悬臂式崩岸机制 |
| Cantilever bank failure mechanism of meadow meandering river in the Yellow River source region |
| 投稿时间：2015-02-08 |
| DOI：10.13243/j.cnki.slxb.20150187 |
| 中文关键词: 弯曲河流 滨河草甸 崩岸 崩塌块 抗拉破坏 |
| 英文关键词: meandering river riparian meadow bank failure slump block tensile failure |
| 基金项目:国家自然科学基金资助项目(41302258);青海大学中青年科研基金资助项目(2012-QGY-5);青海大学“123 高层次人才培养工程”资助项目;青海大学“地质资源与地质工程创新团队”(4056051201);中国博士后科学基金资助项目(2014M550740) |
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| 中文摘要: |
| 弯曲河流的滨河草甸对抑制河岸崩塌和维持河湾蜿蜒具有重要作用。2011-2014年,在黄河源区兰木错曲的弯曲河段对河岸植被根系、崩塌块几何尺寸、根土复合体物理和力学特性等开展野外调查,并通过原位拉拔试验测定河岸崩塌面植被根系抗拉强度,进而分析草甸型弯曲河道的崩岸机制。草甸型弯曲河流的滨河植被根系网络具有较强缠绕和固结土体作用,河岸根系的力学特性是抑制凹岸崩岸的关键因子。近岸水流淘刷作用集中于根系作用范围以下的砂卵石层,当砂卵石层被淘刷至上部悬空,在自重作用下达到临界状况,河岸沿纵深方向出现贯穿性裂缝,最后崩塌块垮塌贴住河岸。崩块的破坏形式以悬臂式张拉破坏为主。崩塌块的植被根系长度与崩塌块厚度呈明显对数函数关系,其体积也随根系长度增大而增加。分析草甸型弯曲河流的新崩岸模式,建立了近岸根土复合体崩岸的临界力矩平衡方程,并简化得到崩塌块的临界宽度表达式。崩塌块体的临界宽度是崩塌块根系长度和根系产生的抗拉强度增量的函数,临界宽度的计算值与实测值较为符合。 |
| 英文摘要: |
| Riparian meadow plays a key role on controlling bank failure and maintaining channel meandering of meadow meandering rivers in source region of the Yellow River. Field investigation in 2011-2014 was conducted on root system of riparian vegetation, geometric dimension of slump blocks, and physical characteristics of root-soil composite in the Lanmucuoqu River. Root tensile strength across collapsing surface was measured by in situ pull-out test in order to study bank failure mechanism. Root system of riparian meadow has a great contribution to reinforce soil mass that is an inherent factor to restrict near-bank erosion and bank failure. Near-bank flow laterally erodes sand and gravel bed beneath the root system until the upper root-soil composite is hanging to reach a critical condition under self-weight action. If exceeding the critical condition, a long crack penetrating the root-soil composite along river bank induces bank failure with a slump block toppling bank slope. Meadow bank failure is dominated by cantilever tensile failure pattern. Results indicate that slump block thickness has a logarithmic function with root length,and the volume of slump block increases with root length increasing. By the new bank failure pattern of meadow meandering river, a critical equilibrium equation of moment of force was derived to describe the cantilever tensile failure of root-soil composite, and further to obtain a critical width expression of slump blocks. The critical width is the function of root length and tensile strength increment by root reinforcement. The predicted value of critical width is in good agreement with the measured value. |
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