摘要

粒度特征是沉積物的基本特征之一。計算沉積物粒度參數的方法主要有矩法和圖解法兩種，其中圖解法必須通過手工作圖求累積曲線，是一項相當繁雜的勞動，不利于計算大量樣品。文中提出的方法將圖解求沉積物樣品的累積曲線百分位數的過程轉化為不等區間的一維函數內插值問題，然后利用通用程序MATLAB的函數功能求解百分位數和計算粒度參數。計算結果和驗算表明MATLAB計算相當可靠，完全可以代替手工作圖。該方法原理簡單，使任何懂或不懂編程的沉積分析人員，都能在計算機的幫助下無須作圖用圖解法計算樣品的粒度參數，既能使粒度分析從繁雜的手工勞動中解放出來，又避免了手工操作的不確定性，有很大的應用價值。

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.