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Probabilistic characterization of subsurface stratigraphic configuration with modified random field approach
Engineering Geology ( IF 6.9 ) Pub Date : 2021-04-09 , DOI: 10.1016/j.enggeo.2021.106138
Chao Zhao , Wenping Gong , Tianzheng Li , C. Hsein Juang , Huiming Tang , Hui Wang

Accurate and precise characterization of the subsurface stratigraphic configuration (geological model) at a given site is crucial to geotechnical engineering work. The uncertainty in the derived stratigraphic configuration can be significant, due to the strata's complexity and inherent spatial variability coupled with the limited availability of borehole data. The characterization and reduction of this uncertainty should be part of any site characterization project. This paper presents a method for characterization of the subsurface stratigraphic configuration with limited borehole data. Within the framework of the proposed method, the spatial correlation between the existence of a stratum in one subsurface zone and that in the other subsurface zone (or the spatial correlation of the existence of the stratum) is captured by an autocorrelation function determined with the maximum likelihood principle. The initial stratigraphic configurations are first sampled with the conditional random field theory. Next, the maximum-a-posteriori (MAP) estimates of the initial stratigraphic configurations are derived using Markov Chain Monte Carlo (MCMC) and taken as the final stratigraphic realizations. The effectiveness of the proposed method and its advantages over the existing stratigraphic characterization methods are demonstrated through a series of comparative analyses. The versatility of the new approach in modeling the 3-D stratigraphic configuration is further revealed through a case study of a site in Western Australia. This paper adds to the literature on stratigraphic uncertainty characterization and provides a basis for a risk-based geotechnical assessment that considers geological and geotechnical uncertainties.



中文翻译:

改进的随机场方法对地下地层构造的概率表征

给定地点的地下地层构造(地质模型)的准确和精确表征对于岩土工程工作至关重要。由于地层的复杂性和固有的空间变异性以及有限的井眼数据可用性,因此得出的地层构造的不确定性可能很大。表征和减少这种不确定性应成为任何现场表征项目的一部分。本文提出了一种利用有限的井眼数据表征地下地层构造的方法。在建议的方法框架内,通过使用最大似然原理确定的自相关函数,可以捕获一个地下区域中某个层的存在与另一地下区域中某个层的存在之间的空间相关性(或该层存在的空间相关性)。首先使用条件随机场理论对初始地层构造进行采样。接下来,使用马尔可夫链蒙特卡洛(MCMC)得出初始地层构造的最大后验(MAP)估计,并将其作为最终地层实现。通过一系列对比分析,证明了该方法的有效性及其相对于现有地层表征方法的优势。通过对西澳大利亚某地点的案例研究,进一步揭示了该新方法在3D地层构造建模中的多功能性。本文增加了关于地层不确定性表征的文献,并为基于风险的岩土评估提供了基础,该评估考虑了地质和岩土的不确定性。

更新日期:2021-04-13
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