摘要

粒度特征是沉积物的基本特征之一。计算沉积物粒度参数的方法主要有矩法和图解法两种，其中图解法必须通过手工作图求累积曲线，是一项相当繁杂的劳动，不利于计算大量样品。文中提出的方法将图解求沉积物样品的累积曲线百分位数的过程转化为不等区间的一维函数内插值问题，然后利用通用程序MATLAB的函数功能求解百分位数和计算粒度参数。计算结果和验算表明MATLAB计算相当可靠，完全可以代替手工作图。该方法原理简单，使任何懂或不懂编程的沉积分析人员，都能在计算机的帮助下无须作图用图解法计算样品的粒度参数，既能使粒度分析从繁杂的手工劳动中解放出来，又避免了手工操作的不确定性，有很大的应用价值。

The dynamical conditions of transport and deposition of sedimentary materials are usually inferred from their grain size, which is a fundamental property of the materials and may tell us much about the origins and history of the materials. Moment technique and graphical technique are the two principal forms to calculate grain size parameters for sedimentary analysis. Accumulative curves have to be drawn artificially to calculate percentiles in grain size distributions while using the graphic technique. Artificial drawing is a hard work and not of great benefit to calculation of large amount of samples. A mathematical method is suggested in this paper to transform the percentile calculation into an interpolation of a function curve. With this method and a help of MATLAB, a new computer language with strong functional power, the graphic technique can be used to calculate grain size parameters without any kinds of graphic drawing. Comparisons of the results calculated with MATLAB to those by artificial drawing show the high accuracy of the method. With a help of computers this method can save the sedimentary analyzers, who do not know computer program writing, from the hard and complicated artificial works to calculate grain size parameters and is well worth a try.