空间随机场模型的建立与桩基竖向承载力的可靠度分析

为了研究桩基础的可靠度设计方法，搜集和整理了大量的海洋土钻孔资料，开发了用于地基可靠度分析的数据库系统。利用数据库强大的数理统计功能建立起土性剖面的空间随机场模型，进而将随机场理论与可靠度理论相结合，对渤海海域中海工结构物桩基础的稳定性进行了可靠度分析，详细阐述了各个设计指标的变化对分项系数及可靠度指标的影响规律，并对各指标的灵敏度进行比较分析。结果表明，在各个设计参数中厚土层的强度指标以及设计荷载是2个重要的参数，在渤海海域中应用API标准 (美国桩基规范) 中规定的荷载抗力系数进行设计是安全可靠的。

Random field modeling and reliability analysis of vertical bearing capacity of pile foundation of ocean structures

Pile foundation is widely used in platform foundation. The reliability design method has been adopted worldwide. When it was introduced into China, it is pointed out that designers could refer to the standard (Recommended practice for planning, designing and constructing fixed offshore platforms-load and resistance factor desing ) when the environment conditions and the design method were coincided with those in China. Otherwise, difference criterion and data should be taken according to the specified environment conditions in China. As a result, more attentions should be paid on studying the foundation design method of offshore structures. In this paper, a database management system has been established, in order to manage and analyze the data of the geotechnical properties of foundation soils. This database includes almost all the borehole logs and properties of the soils of SZ36-1 Oil Field. Based on the database, the stationarity and ergodicity of a soil profile in SZ36-1 Oil Field have been examined and a random field modeling has been established. The correlation function, correlation distance and variation reduction function of SZ36-1 Oil Field have been simulated. A calculating model for pile foundations has been established, on the basis of the established database and design experiences. As an example, reliability analysis for a pile foundation has been performed. The influence of variations of soil properties and loads on the reliability index has been analyzed, and the calculated partial factors compared with those recommended by the API (American petroleum instituted) Criterion.