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The uncertainty involved in the interpreted geological model may be categorized as the stratigraphic uncertainty and the properties uncertainty. Note that although the influence of the properties uncertainty on the behavior or performance of the geotechnical system and the geotechnical design has been extensively reported in the literature, the studies that address the stratigraphic uncertainty are limited. This paper presents a study regarding the influence of the stratigraphic uncertainty on the behavior of the geotechnical system and the geotechnical design. In which, the uncertainty in the stratigraphic configuration is characterized using the stochastic Markov random field-based approach with a large number of potential stratigraphic realizations. With these stratigraphic realizations as inputs, the influence of the stratigraphic uncertainty on the behavior of the geotechnical system is evaluated in a probabilistic manner; then, the design of the geotechnical system is formulated as a bi-objective optimization-based problem that considers the design safety and the cost simultaneously. To demonstrate the effectiveness of the proposed probabilistic analysis and design approach, the problem of designing stabilizing piles in a slope consisting of multiple strata is studied. The parametric study is further conducted to analyze how the probabilistic analysis results are influenced by the pile parameters and how the probabilistic design results are influenced by the additional boreholes. • The uncertainty in the stratigraphic configuration is characterized with the stochastic Markov random field-based approach. • The influence of the stratigraphic uncertainty on the behavior of the geotechnical system is studied. • The influence of the pile parameters on the probabilistic analysis results of the reinforced slope is studied. • The superiority of the proposed probabilistic analysis and design over the deterministic approaches is demonstrated with an illustrative application. [ABSTRACT FROM AUTHOR]

The behavior of stabilizing piles with different embedded lengths in bedrock with a hard upper layer and a weak lower layer is examined using physical model tests. Based on the geological model of the landslide with bedrock with a hard upper layer and a weak lower layer, the pile–landslide physical model is developed and includes the data collection system, the pile–landslide model and the loading system. The real-time deformation and moment of the stabilizing pile is obtained in the process of loading at the trailing edge of the landslide for different percentages of hard bedrock. The test results indicate that the percentage of hard bedrock has a strong influence on the deformation and moment of the stabilizing pile embedded in bedrock with a hard upper layer and a weak lower layer. A higher percentage of hard bedrock can result in a greater maximum bending moment of the stabilizing pile and a smaller displacement at the stabilizing pile head, and vice versa. The results also show that 40% of hard bedrock can be considered the critical condition in bedrock with a hard upper layer and a weak lower layer. The percentage of hard bedrock has a limited influence on the deformation of the stabilizing pile when the percentage is greater than 40%. Moreover, four tests with stabilizing piles with different embedded lengths are conducted to investigate the most suitable embedded length in the bedrock with a hard upper layer and a weak lower layer. The results indicate that 28.5 cm is a reasonable embedded length for the stabilizing pile in the two-layered bedrock with a hard rock percentage of 20%. [ABSTRACT FROM AUTHOR]

Due to the inherent spatial variability of the geological bodies, limited boreholes (constrained by budget), and data interpretation errors, the subsurface conditions (in terms of the stratigraphic configuration and associated geo-properties) at a site are hard to ascertain, and considerable stratigraphic and geo-properties uncertainties are induced. The stratigraphic and geo-properties uncertainties could complicate the engineering design. One way to reduce the uncertainties is to adopt an optimal site exploration program under constraints. This paper presents a novel framework for optimizing the site exploration program based on a coupled characterization of the stratigraphic and geo-properties uncertainties. Within the context of the proposed framework, a conditional random field approach, recently advanced by the authors, is employed to characterize the stratigraphic and geo-properties uncertainties simultaneously. Here, the spatial correlation of stratum existence (depicting stratigraphic configuration) and that of geo-properties are estimated with a Bayesian updating scheme. Then, the 'influence zone' at the concerned site, which is often problem-specific, is selected based on a geotechnical performance evaluation. The derived influence zone can be taken as the candidate zone for boreholes. Finally, the optimal locations and depths of boreholes are determined based on the stratigraphic and geo-properties uncertainties characterized within the influence zone. To depict the effectiveness and versatility of the presented framework, two problems (i.e., a shallow foundation problem and a slope stability problem) are analyzed. • A novel framework for optimizing the site exploration program is proposed. • Site characterization and geotechnical performance evaluation are integrated. • Characterizations of stratigraphic and geo-properties uncertainties are coupled. • The spatial correlation structure is estimated with a Bayesian updating scheme. • Geological model characterization is updated in a step-by-step manner. [ABSTRACT FROM AUTHOR]

Site characterization, which aims to characterize the subsurface stratigraphic configuration and the associated geo-properties, has long been a significant challenge in geological and geotechnical practice. Due to the complexity and inherent spatial variability of the geological bodies and the limited availability of borehole data, uncertainty is unavoidable in the characterized subsurface stratigraphic configuration and the associated geo-properties. In previous studies, the stratigraphic uncertainty and the geo-properties uncertainty were characterized separately. This paper proposes a conditional random field approach for a coupled characterization of stratigraphic and geo-properties uncertainties. The spatial correlation of the stratum existence between different subsurface elements and the spatial correlation of geo-properties are characterized by two autocorrelation functions, determined with the maximum likelihood principle. With the knowledge of the spatial correlation of the stratum existence, the stratigraphic configuration can be sampled using a modified random field approach. Then, the spatial correlation of the geo-properties is updated based on the sampled stratigraphic configuration. With the updated spatial correlation of the geo-properties, the spatial distribution of the geo-properties can readily be simulated with the conditional random field theory. The effectiveness of the proposed approach is demonstrated through a case study of probabilistic site characterization of an offshore wind farm site in Taiwan. To extend the applicability of the proposed approach, a probabilistic evaluation of liquefaction potential at this site under a given seismic shaking level is performed. • A probabilistic method for characterizing the geological model is proposed. • Characterizations of stratigraphic and geo-properties uncertainties are coupled. • Stratigraphic configuration is simulated with modified random field approach. • Spatial variability of geo-properties is simulated with conditional random field. • The spatial correlation structure is estimated with maximum likelihood principle. [ABSTRACT FROM AUTHOR]

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. • A probabilistic method for characterizing stratigraphic configuration is proposed. • The spatial correlation of strata is estimated with maximum likelihood principle. • Conditional random field theory and MCMC method are included in this method. • Versatility of this method in modeling 3-D stratigraphic configurations is studied. [ABSTRACT FROM AUTHOR]