三峡水库蓄水初期近坝区淤积形态成因初步分析

Preliminary analysis on the causes of reservoir sedimentation pattern in the vicinity of Three Gorges Project during its early filling

  • 摘要: 三峡水库蓄水运用后,库区泥沙淤积将显著增加.基于三维水沙数值模型及实测资料分析,对水库蓄水初期近坝区泥沙淤积形态的成因进行了初步探讨.研究结果表明坝前淤积形态的成因既与坝前水流流态的三维特性有关,又与水库蓄水初期坝前淤积物颗粒特性有关.水库蓄水初期沉积在近坝区的泥沙颗粒较细,初始干容重较低,使得淤积物表现出一定的浮泥特性.坝前淤积总量较大主要是宽谷河段水流特性造成的;而基底深槽处淤积物厚度较大、淤积面呈水平状的主要原因则是浮泥状淤积物在重力作用下向河底运动、并沿深泓线在基底深槽中汇集.

     

    Abstract: Sediment deposition in Three Gorges Reservoir(TCR)is likely to increase significantly after the filling of TCR.The causes of reservoir sedimentation pattern in the vicinity of Three Gorges Project(TCP)during the early filling of TCR are examined using the observed data and a 3D mathematical model for flow and sediment transport.Results show that the sedimentation characteristics in the vicinity of TCP are not only related to the 3D properties in flow patterns,but also related to the characters of deposited sediment particles during the early filling of TCR.The formation of fluid mud is the result of deposited fine sediment particles in the vicinity of TCP during early filling.The particle is in a fine form and the initial dry unit weight of deposited sediment is also small,which exhibit a typical feature of fluid mud.The sedimentation volume value nearby TCP is tremendous due to the lower flow velocity.The deposited sediment particles in the form of fluid mud slide move downward to the lowest position of cross-sections under the influence of gravity,and then accumulate there in a horizontal form following the thalweg line.

     

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