基于微结构模拟的土体自相关距离分析

土体具有显著的空间变异性，描述土体空间变异性的重要指标是自相关距离。提出基于土体微结构模拟的方法来求解土体的自相关距离。在生成土体的微结构数值模型时，对四参数随机生长法（QSGS法）进行改进，考虑土体的粒径分布信息，使得生成的土体微结构更加合理。改进的四参数随机生长法（MQSGS法）所需的输入参数可以结合土体的扫描电镜试验及粒径分析试验获取。基于生成的土体微结构数值模型，即可计算土体的2点自相关函数，再通过曲线拟合即可求解土体的自相关距离。研究表明：与QSGS法相比，采用MQSGS法生成的土体微结构更加符合自然界的真实土体；基于MQSGS法生成的微结构数值模型计算得到的土体自相关距离略小于QSGS法得出的自相关距离。

Analysis of autocorrelation distance of soil based on microstructure simulation

Soil has significant spatial variability, and an important indicator for describing the spatial variability of soil is the autocorrelation distance. This paper proposes a method based on soil microstructure simulation to calculate the autocorrelation distance of soil. For generating the numerical model of the microstructure of a soil more reasonable, the traditional quartet structure generation set (QSGS) method is modified, by considering the particle size distribution information of the soil. The input parameters required for the modified quartet structure generation set (MQSGS) method can be obtained by combining the scanning electron microscopy test and the particle size analysis test of soils. Based on the generated numerical model of soil microstructure, the 2-point spatial autocorrelation function can be calculated and the autocorrelation distance of soil can be obtained by curve fitting for the 2-point spatial autocorrelation function. The study shows that soil microstructure generated by the MQSGS method is more similar to the real soil structure in nature than that generated by the QSGS method; the autocorrelation distances calculated from the microstructure numerical model generated by the MQSGS method are slightly smaller than those obtained by the QSGS method.