Effect of 3D water table profile of horizontal drains on slope stability and idealization of 3D-FEM flow modeling to 2D-FEM flow modeling

Horizontal drains (HDs) are commonly used in the groundwater regime management of landslides. The groundwater table (GWT) profile of slopes with HDs have a complicated formation in three-dimensional (3D) space, requiring 3D analyses to obtain accurate results. However, owing to the complexity of 3D simulations, idealized two-dimensional (2D) cross sections are widely used in numerical simulations of such slopes. Unfortunately, stabilities are overestimated by 2D simulations because the 3D variation of the GWT is neglected. Finite element analysis is performed in this study to evaluate the effect of 3D variation of the GWT on the stability of slopes with HDs and to evaluate the effectiveness of 2D idealizations. The results demonstrate that idealized 2D analyses neglect the high pore water pressures between HDs, thereby overestimating the slope stability, especially with high rainfall intensities and large drain spacings. Alternatively, accurate results can be obtained in 2D analyses by manually estimating an average GWT profile using the Crenshaw and Santi method for steady-state conditions. Each method has its own limitations and, therefore, the selection of an appropriate method should be made based on the specific conditions and requirements of the problem

Case study on viability of using head-separated micropiles as foundation system for check dams

Check dams constructed in steep mountainous areas require the rationalization of the dam body and foundation system. In general, soil cement replacement or caissons are often adopted for foundations. In such cases, reducing the construction effort is a critical issue. To address this, the authors studied the viability of a new type of check dam foundation consisting of a group of micropiles whose heads are structurally disconnected from the dam body. The system, coined a head-separated micropile group (HMG) foundation, enables the saving of labor and a reduction in the cross-sectional forces applied to the micropiles. Firstly, a full-scale loading test of the HMG was conducted. Then, a finite element model was formulated and its parameters fitted to make it suitable for reproducing the experimental results. Finally, using the FE model, the performance of a typical rigidly connected micropile foundation and that of the HMG system were compared in terms of the bearing capacity and displacement of the check dam body. The results confirmed that, although its displacement was 1.25 times larger than that of the rigidly connected foundation, the HMG system led to a factor of safety of 3.5 against micropile buckling

Exploring the possibility of assessing the damage degree of liquefaction based only on seismic records by artificial neural networks

This study presents a new approach to determine the damage degree of liquefaction caused by a large earthquake. We propose an artificial neural network (ANN) model based only on the seismic records of ground and define the degree of liquefaction “DDL” as a damage index. This ANN model predicts the degree of excess pore water pressure increase as the correct output label based on the seismic records obtained from the three-dimensional shaking table test. The proposed model achieved high accuracy, and the outcomes from training data indicated that the ANN model is suitable to function as a liquefaction assessment system. Further, to evaluate the applicability of the proposed ANN model in the real world, the datasets of waves from three actual seismic records were input to the ANN as validation data. The DDL judgment obtained was a good fit with the real phenomena observed

Abstracts of The Second Eurasian RISK-2020 Conference and Symposium

This abstract book contains abstracts of the various research ideas presented at The Second Eurasian RISK-2020 Conference and Symposium.The RISK-2020 Conference and Symposium served as a perfect venue for practitioners, engineers, researchers, scientists, managers and decision-makers from all over the world to exchange ideas and technology about the latest innovation developments dealing with risk minimization