Abstract: Taking the sediment of Yongding River as an example, the authors discussed the changes of relationship between sedimentary facies and engineering geological features of recently deposited soil vertically and horizontally. It showed that the qualities of recently deposited soil is getting worse as the sediment transforming from riverbed facies to flooded facies vertically, and as for an identical sedimentary facies, the qualities of physical properties seemed to be worse from the upper reaches to the lower reaches of the Yongding River.

Key words: The recently deposited soil, sedimentary facies, engineering geological characteristics

摘要： 冲积平原上河流冲积物所具有的沉积层向上逐渐变细的正韵律特点会引起新近沉积土的工程地质特性随沉积层变化而变化。同时，河流出山以后，河谷展宽，水力梯度减小，使得冲积平原上的河流冲积物从上游至下游具有逐渐变细的趋势，各不同沉积相土层的工程地质性质也随之发生相应的变化。以永定河的河流冲积物为例分别从垂向上和水平方向上来讨论新近沉积土的工程地质特性与沉积相变化之间的关系，并对新近沉积土的工程地质特性进行了评价。

关键词: 新近沉积土, 沉积相, 工程地质特征