苏中腹地湖相沉积土层相关距离的统计分析

摘要

Correlation distance is a very important parameter for random field theory in modelling soil profiles,and also a key point for the application of random field theory to reliability analysis in geotechnical engineering.Based on the collections of tip resistance indexes from field Cone Penetration Tests(CPT)of a project located in the centre of Jiangsu province,correlation distances of silty clays are statistically calculated by adopting different sample intervals.The influence of sample intervals on the results is also analysed.Hence,a procedure for selecting sample interval is recommended based on scale-matching principle in actual practice.In addition,many in-situ CPT data are obtained from the geotechnical investigation of an expressway in the centre of Jiangsu province.The vertical and horizontal correlation distances of lacustrine sedimentary soils are statistically analyzed by means of mean-crossings, moving average and correlation function.The conclusions of this paper provide not only a new prescription for determining sample interval in statistically estimating correlation distance,but also the characteristic values of correlation distances of regional soils in central Jiangsu.What is more,it can be very helpful to lay a solid foundation for establishing the random field model of regional soil properties and provide essential reference for reliability and statistics in geotechnical engineering in the central region of Jiangsu province.%相关距离是用随机场理论建模土层剖面的一个非常重要的参数，也是利用随机场理论进行岩土工程可靠性分析的关键所在。基于苏中地区某建筑工程原位静力触探测试数据中的锥尖阻力指标，针对粉质黏土层，利用不同取样间距对相关距离进行了统计计算，分析了取样间距对相关距离计算结果的影响及原因，提出了实际应用中基于尺度匹配原则的取样间距确定方法；随后，基于江苏中部某高速公路工程地质勘察所提供的大量原位静力触探测试数据，结合相关距离计算的平均零跨距法、递推空间法和相关函数法，对该区湖相沉积土层土性参数的竖直向和水平向相关距离进行了系统地统计分析。研究成果不仅提供了土性参数相关距离计算过程中取样间距的确定原则，而且获得了相关距离的区域性代表值，为区域性土性参数随机场模型的建立打下坚实的基础，能对苏中地区岩土工程可靠性分析提供参考。