MATLAB CFTool在图解沉积物粒度参数计算中的应用

Application of MATLAB CFTool in the Graphical Calculation of Grain Size Parameters

沉积物粒度参数是用来表征粒度分布特征的数值,包括平均粒径、分选系数、偏态和峰态等。计算沉积物粒度参数的方法主要有矩算法和图解法2种,其中图解法必须通过手工作图求累积曲线,对批量样品粒度参数计算是一项相当繁琐的工作。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对概率累计曲线的模拟和插值问题,为了保证数据的单调性和形状,利用MATLAB CFTool中Shape-preserving插值方法快速准确求解批量样品概率累计曲线上第5、16、25、50、75、84、95百分数所对应的值粒径,进而由Folk-Ward图解法公式求得粒度参数,并与传统手工作图方法计算的粒度参数进行比较。结果表明,该方法拟合效果理想,计算结果可靠,明显提高图解粒度参数计算效率。

Sediment grain size parameters are used for numerical characterization of particle size distribution,including average grain size,sorting coefficient,skewness and kurtosis among others.Moment and graphical techniques are the two principal forms to calculate grain size parameters for sedimentary analysis.The graphic method must calculate the cumulative curve by hand working diagram,which is hard and less benefit the calculation of large amount of samples.The method proposed in this study is to convert the process of the cumulative curves of sediment samples into the simulation and interpolation problems of probability cumulative curve,in order to guarantee the data's monotone and shape. CFTool shape-preserving interpolation method in MATLAB was used to quickly and accurately solve the particle diameter of 5,16,25,50,75,84 and 95 of the probability cumulative curves of the samples,then the grain size parameters were obtained with the Folk-Ward graphic method and compared with the traditional manual plotting method to calculate the grain size parameters.The results showed that the method is effective,and the results are reliable,and the calculation efficiency is improved obviously.