川藏公路培龙沟路段堆积物的分形特征及其地质意义

川藏公路培龙沟路段有多种不同类型的堆积物。本文应用分形理论,探讨了培龙沟路段泥石流堆积物、冰碛堆积物、冲洪积堆积物以及坡积或者残坡积物的分形特征。通过粒度分析法计算出不同类型堆积物的粒度分维,得到泥石流堆积物分维最大,冰碛堆积物分维较大,坡积或者残坡积堆积物较小,冲积物或者洪积物分维最小的规律。最后系统论述了堆积物粒度分维的地质意义,认为堆积物粒度分维是对堆积物物质组成的复杂性和自组织性、堆积物形成过程和形成时间以及泥石流、冰川、河流和洪水等搬运能力和运动过程的反映和度量。该研究为野外不同类型堆积物的区分、成因、形成过程等研究提供了一种新的方法,具有一定参考价值。

FRACTAL FEATURE AND GEOLOGICAL SIGNIFICANCE OF ACCUMU LATIONS AT PEILONG SECTION ALONG SICHUAN-TIBET HIGHWAY

In this paper,the authors explored the fractal features of debris flow accumulations,moraine accumulations,alluvial accumulations and residual accumulations at Peilong section along Sichuan-Tibet Highway.According to the fragmentation model and grain size analysis,grain-size fractal dimension were calculated for different types of accumulations.The results showed that fractal dimensions vary for accumulation: the debris flow accumulation with the greatest fractal dimension,the moraine accumulation with the second,residual accumulation with the third,and the alluvial accumulation with the smallest.At the end of the paper,geological significance of grain-size fractal dimension of accumulations was discussed in detail.The grain-size fractal dimension of accumulations reflects the complexity and self-organization property of accumulation,forming process,history of accumulation,and the carrying capacity of the dynamic process,such as debris flow,glacier,river,flood,and so on.Therefore,it can be used as an indictor for classification of accumulations and identification of their origins.This new method is anticipated to provide a better insight into origins of accumulations,which in turn could help gain a better understanding of engineering geological behaviors.