太湖疏浚前后波浪扰动下的底泥再悬浮特征

Sediment resuspension characteristics under wave distributing of dredging in Taihu Lake

  • 摘要: 在室内波浪水槽中,研究不同底泥容重、不同波浪动力条件下底泥的再悬浮特征.结果表明:静止状态下,水体垂向悬浮物浓度差别不大,小波作用时底泥未普遍起动,各层悬浮物浓度增加不明显.随着大波浪的作用,底部切应力远大于底泥起动临界切应力,水体悬浮物浓度急剧增加,10 min内悬浮物浓度增加10~15倍,60 min内再悬浮量占总悬浮量的80%左右,悬浮物浓度垂向分层明显.试验底泥湿容重包括1.34 g/cm3、1.47 g/cm3、1.55g/cm3、1.59 g/cm3,比较了3种切应力下,底泥再悬浮量随容重的变化关系,结果均显示水体内总再悬浮量与底泥容重呈高度负线形相关.

     

    Abstract: Sediment resuspension characteristics are studied using the laboratory wave flume with different sediment bulk densities(1.34g/cm3,1.47 g/cm3,1.55g/cm3 and 1.59g/cm3)and wave hydrodynamics.Results show that the vertical concentration of suspended sediments is almost uniform without the influence of wave action.Only local sediment resuspension can be observed for small wave amplitudes.The vertical variation in suspended sediment concentrations is insignificant.When the wave height reaches 9cm,the bottom shear stress will be much greater than the critical shear stress.Thus,there will be a sudden increase in suspended sediment concentrations.The concentration will be 10 to 15 times higher than that for small wave amplitudes after 10 minutes.The resuspension quantity can account for about 80% of the gross resuspension within 60 minutes.Large variations are observed in the vertical profile of gross resuspension.The bulb density is highly correlated to the gross resuspension.The larger the bulb density is,the smaller the gross resuspension will be.

     

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