中文摘要：

相关距离是随机场理论应用于实际工程可靠度分析的一个重要参数。根据随机场理论，对土性参数相关距离的计算方法进行了研究和改进，提出求解相关距离的波动函数法和加权拟合相关函数法，使相关距离的计算更加简便易行，且精度有所提高。结合大量工程地质勘察资料，对天津港地区典型土层的垂直向相关距离及水平向相关距离进行了计算和统计，获得相关距离的地区性代表值，可作为此地区实际工程的参考。同时，对取样间距及土性指标对相关距离的影响进行了分析，提出了当取样间距变化时相关距离的确定原则，并指出相关距离是反映土的空间固有变异性的基本属性，由不同土性指标求得的相关距离值基本相同。

英文摘要：

The correlation distance is one of the important parameters for the application of random field theory to reliability analyses. The traditional methods for estimating the correlation distance are studied and improved based on the random field theory. The fluctuation function method and weighted curve fitting method are presented which can make the calculation of correlation distance easier and get a more precise result. The vertical and horizontal correlation distances of typical stratum in Tianjin Port are analyzed in statistics based on a large amount of investigation data and the representative values of correlation distance of local area are obtained. Finally, the influence of sample spacing and soil index on the correlation distances is analyzed. The principle for determining the correlation distance with the varied sample spacings is presented. In addition, it is proved that the correlation distances estimated by different soil indices are similar because the correlation distance is the basic characteristic which is used to describe the variance of soil properties.