基于"动力组分"思想的沉积物粒径趋势模型
A grain size trend modal based on the concept of "dynamic populations"
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摘要: "粒径趋势分析"的基本思想是利用沉积物粒度参数的空间变化(粒径趋势)来反推沉积物输运路径。依据"动力组分"思想,通过建立一个一维的悬浮沉积物输运模型来正演沉积物输运方向上的表层沉积物粒度分布和粒径趋势,探讨水动力能量沿程衰减和沿程增强两种不同情形下的粒径趋势特征。研究表明:粒径趋势形成的直接原因是沉积物中不同"动力组分"的混合比在净输运方向上的一定距离内单调变化。在沉积物净输运方向上,当水动力能量沿程衰减时可以先后出现两种粒径趋势类型,水动力能量沿程增强时最多可先后出现三种粒径趋势类型。水动力能量的沿程变化速度对于粒径趋势的转换有重要影响,变化速度越快,则粒径趋势类型完成转换时的距离越短。和分选系数相比,峰度值有着相同的变化趋势且对混合比的变化更为敏感。Abstract: As a method of inferring net sediment transport pathway from spatial distribution of grain size parameters, the grain size trends analysis (GSTA) has been employed widely in cases of marine geology studies. In this paper, based on the concept of "dynamic populations", a one dimension suspended sediment transport modal has been established to deduce the formation of grain size trend in the net sediment transport direction. The result show that:if the hydrodynamic energy level decreasing along sediment transporting direction, two kinds of grain size trend can form successively in the transporting direction; whereas, if the hydrodynamic energy increasing along sediment transport direction, three kinds of grain size trend can form successively at most. The speed of hydraulic dynamic energy enhancing/attenuation can obviously change the GST distribution along transporting path, Higher speed can enable the GST transform complete in shorter distance. The value of kurtosis has the same variation trend as Std and can be more sensitive to mixing ratio changing, therefore, better result can be gained if we replace the Std with kurtosis in GSTA.
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Key words:
- grain size trend /
- dynamic population /
- sediment transporting modal
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