CAJ | 학술논문

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。
만곡하류적빈하초전대억제하안붕탑화유지하만완연구유중요작용。2011—2014년，재황하원구란목착곡적만곡하단대하안식피근계、붕탑괴궤하척촌、근토복합체물리화역학특성등개전야외조사，병통과원위랍발시험측정하안붕탑면식피근계항랍강도，진이분석초전형만곡하도적붕안궤제。초전형만곡하류적빈하식피근계망락구유교강전요화고결토체작용，하안근계적역학특성시억제요안붕안적관건인자。근안수류도쇄작용집중우근계작용범위이하적사란석층，당사란석층피도쇄지상부현공，재자중작용하체도림계상황，하안연종심방향출현관천성렬봉，최후붕탑괴과탑첩주하안。붕괴적파배형식이현비식장랍파배위주。붕탑괴적식피근계장도여붕탑괴후도정명현대수함수관계，기체적야수근계장도증대이증가。분석초전형만곡하류적신붕안모식，건립료근안근토복합체붕안적림계력구평형방정，병간화득도붕탑괴적림계관도표체식。붕탑괴체적림계관도시붕탑괴근계장도화근계산생적항랍강도증량적함수，림계관도적계산치여실측치교위부합。
Riparian meadow plays a key role on controlling bank failure and maintaining channel meander?ing 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 sur?face was measured by in situ pull-out test in order to study bank failure mechanism. Root system of ripari?an 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 fail?ure 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 vol?ume of slump block increases with root length increasing. By the new bank failure pattern of meadow mean?dering river, a critical equilibrium equation of moment of force was derived to describe the cantilever ten?sile 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 predict?ed value of critical width is in good agreement with the measured value.