岩土工程可靠度分析中方差折减函数确定的一般规律

将可靠度理论应用于岩土工程稳定性分析过程中，即使是已证明安全的工程所得到的边坡或地基的失效概率通常较大，导致这一现象的原因是估算的方差偏大。计算土性指标的试验数据仅表征了该试验点的特征，而不是空间平均特征。在随机场理论应用于岩土工程可靠度分析的过程中，方差折减函数是将点特性过渡为空间平均特性的必要参数。首次对闫澍旺等提出的完全不相关距离理论中完全不相关距离的确定方法进行改进，不但理论上有所突破，而且计算方法更为简洁。对折减函数值的确定过程进行了分析，得到了用完全不相关距离方法确定折减函数的一般规律。

Regularity of determination of reduction function of variance in reliability analysis of geotechnical engineering

The calculated failure probability for foundation and slope is usually very large, even though the project is proved to be safe in reality. This phenomenon is resulted mainly from the method to estimate variance in practical project. Data of soil index is just property of a certain point rather than the space average characteristic of soil profile. In the process of reliability analysis of geotechnical engineering, the reduction function of variance is the key parameter to transit the point property into spatial average property. It’s the first time that improvement on the method to calculate the no correlation distance put forward by YAN Shu-wang et al. is made, which not only makes the calculation more convenient, but also is a breakthrough of theory. The procedure of calculation of reduction function by the improved method is analyzed, and general regularity of determining reduction function through calculation of no correlation distance is obtained.