The presence of underground structures within fault zones has the potential to alter deformation patterns on the ground surface, thereby placing existing structures-typically regarded as safe-at risk. This paper presents findings from four centrifuge model tests and 3D numerical simulations exploring the effects of tunneling in fault zones. This study investigated the values associated with foundation rotation, surface deformations, and the patterns of fault rupture propagation through various soil strata. The results demonstrate that the presence of a tunnel alters the interaction pattern between fault rupture and foundation systems, which can lead to an increase in foundation rotation. Notably, the findings indicate that a precise consideration of superstructure shape can enhance foundation rotation by up to 23%. Furthermore, the presence of a tunnel in the fault zone causes substructures to endure major damage from vertical fault displacements exceeding 0.6 m. In contrast, these substructures experienced similar levels of damage at vertical fault displacements of 1.7 m in the absence of tunnels.

Earthquake-induced fault ruptures present a considerable risk to structures, especially underground systems like pile foundations. Batter pile foundations, among the various foundation types, are commonly employed for their effectiveness in withstanding inclined forces. Therefore, it is crucial to comprehensively understand how batter pile groups respond to fault ruptures under diverse geotechnical conditions to enhance geoengineering practices. In this study, 3D numerical modeling was used to investigate the internal force and damage distribution mechanisms of different batter pile groups subjected to various normal fault ruptures. Additionally, five novel machine learning regression models (i.e. Light Gradient Boosting Machine (LightGBM), CatBoost, Extreme Gradient Boosting (XGBoost), ExtraTrees, and Random Forest (RF)) were developed to learn and predict the impact of four input parameters related to batter piles and normal fault ruptures. A database comprising 375 datasets was extracted from numerical modeling results to build the learning and testing framework. The comprehensive results indicate that LightGBM has the highest potential for estimating the internal force and concrete damage distribution along batter pile foundations due to normal faults. The coefficient of determination (R2) exceeded 0.90 across all models, with reasonable values for mean square error (MSE), root mean square error (RMSE), and mean absolute error (MAE). This study provides an effective method for estimating the response of batter pile foundations to normal fault ruptures. The findings can assist engineers in designing batter pile foundations and evaluating the damage conditions of structures subjected to fault ruptures prior to detailed inspections.

Fault ruptures induced by earthquakes pose a significant threat to constructions, particularly underground structures such as pile foundations. Among various foundation types, batter pile foundations are widely used due to their ability to resist inclined forces. To gain new insights into the response of batter pile groups to fault ruptures caused by earthquakes, this study investigates the deformation and failure mechanisms of batter pile groups due to the propagation of normal and reverse fault ruptures using 3D numerical modeling. An advanced hypoplastic constitutive model for clay, which accounts for small-strain stiffness, and a concrete damage plasticity (CDP) model are employed to simulate the soil and the batter pile foundation, respectively. Results show that following fault propagation, nearly 10% tilting and significant displacement occurred at the pile cap, indicating a total failure of the batter pile foundation. It was also observed that the piles bent towards the slipping direction of the hanging wall. Tensile damage to the pile foundation was notably more severe than compression damage. The most severely damaged regions were not only located at the joints between the piles and the pile caps but were also found along the pile shafts.

This paper presents the findings of field observations conducted in the aftermath of the earthquakes that struck the Pazarcik (Mw7.7) and Elbistan (Mw7.6) in Kahramanmaras province, Turkey on February 6th, 2023. The earthquakes, occurring on the East Anatolian Fault Zone (EAFZ), resulted in more than 50,000 losses of life and damage of more than 1.5 million properties across 11 provinces in Turkey. Field observations presented herein encompass seismological and strong ground motion data, geotechnical observations, as well as damage assessments of underground and above ground structures in various provinces and districts. The types and reasons of the structural damages were discussed. The study also examined the effects of high acceleration values and distribution of strong ground motions on the performance of structures. Soil liquefaction problems were observed in many locations such as Golbasi and Iskenderun. The paper highlights the geology, tectonics, strong motion characteristics, surface deformations, geotechnical and structural aspects, and the evaluation of lifelines in the affected area. Furthermore, the authors provide initial recommendations for improving disaster management, evaluating building stock, prioritizing urban transformation, strengthening infrastructure systems, addressing soil-building interaction issues, ensuring security measures during search and rescue efforts, utilizing satellite imagery effectively, considering seismic effects on water infrastructure, and taking a holistic approach to earthquake effects in industrial facilities.

In earthquake-resistant design, the characteristics of ground motion and soil conditions play a crucial role. Soil liquefaction, a critical issue in earthquake engineering, leads to significant ground deformations, including lateral spreading, settlements, and shear strain accumulation. While extensive research has focused on single-fault rupture, the impact of multiple-fault ruptures on liquefiable soils remains underexplored. This study examines the dynamic behavior of liquefiable soils subjected to single and multiple-fault ruptures through two-dimensional nonlinear fully coupled effective stress analyses within the Open Source Earthquake Engineering System (OpenSees) framework. The seismic response of saturated sandy soils with varying relative densities is simulated by the Pressure Dependent Multi Yield Material 02 (PDMY02) model. Three seismic records (Antakya record from the 2023 Kahramanmara & scedil; earthquake, Sakarya record from the 1999 Kocaeli earthquake, and Izmit aftershock record from the 1999 Kocaeli earthquake) were analyzed to assess settlements, lateral spreading, and excess pore water pressure. The results demonstrate that multiple-fault ruptures induce more complex and severe soil responses than single ruptures. These findings enhance the understanding of soil behavior under seismic loading, emphasizing the necessity of considering multiple-fault ruptures in liquefaction analysis for improved earthquake resilience.

Permanent deformation and uplift caused by fault rupture is one of the most significant hazards posed by earthquakes on the built environment. In this paper, we use smoothed particle hydrodynamics (SPH) to explore the effects of soil layering or stratification on the trajectories and deformation patterns caused by rupturing reverse faults in bedrock, as well as in the foundations of engineered earth structures. SPH is a continuum meshfree numerical method highly adept at modeling large deformation problems in geotechnics. Through the use of constitutive models involving softening behavior as well as critical state type models, we isolate the effects of rigid body rotation from critical state behavior of soil in helping explain the frequently observed rotation of shear bands emanating from the bedrock fault. This analysis is facilitated by the fact that the SPH method allows us to track the propagation of shear bands over substantial amounts of vertical uplift (more than 50% of the total height of the soil deposit), far beyond many previous computational studies employing the finite element method (FEM). We observe and characterize various emergent features including fault bifurcations, stunted faults, and tension cracking, while providing insights into practical guidelines regarding the potential surface distortion width, and the critical amount of fault displacement required for surface rupture depending on the multilayered constitution of the soil deposit. Finally, we predict the expected amount of surface distortion and internal damage to earthen embankments depending on varying fault location and soil makeup.

The 2022 Paktika earthquake (moment magnitude: 6.2) occurred on June 22, 2022, near the border between the Khost and Paktika Provinces of Afghanistan, causing heavy damage and casualties in Paktika Province. This study evaluated the crustal deformation and associated strong motions induced by the Paktika earthquake. Crustal deformations were determined using the Differential Interferometric Synthetic Aperture Radar (DInSAR) technique and three-dimensional finite element method (3DFEM) and the results were compared. The permanent ground displacements obtained from the DInSAR and 3D-FEM analyses were similar in terms of amplitude and areal distribution. Strong motions were estimated using the 3D-FEM with and without considering regional topography. The estimations of maximum ground acceleration, velocity, and permanent ground deformations were compared among each other as well as with those inferred from failures of some simple structures in the Spera and Gayan districts. The inferred maximum ground acceleration and velocity from the failed adobe structures were more than 300 Gal and 50 cm/s, respectively, nearly consistent with the estimates obtained using empirical methods. The empirical method yielded a maximum ground acceleration of 347 Gal, whereas the maximum ground velocity was approximately 50 cm/s. In light of these findings, some surface expressions of crustal deformations and strong ground motions, such as failures of soil and rock slopes and rockfalls, have been presented. The rock slope failures in the epicentral area were consistent with those observed during various earthquakes in Afghanistan and worldwide.

Seismic risk expresses the expected degree of damage and loss following a catastrophic event. An efficient tool for assessing the seismic risk of embankments is fragility curves. This research investigates the influence of embankment's geometry, the depth of rupture occurrence, and the underlying sandy soil's conditions on the embankment's fragility. To achieve this, the response of three highway embankments resting on sandy soil was examined through quasi-static parametric numerical analyses. For the establishment of fragility curves, a cumulative lognormal probability distribution function was used. The maximum vertical displacement of the embankments' external surface and the fault displacement were considered as the damage indicator and the intensity measure, respectively. Damage levels were categorized into three qualitative thresholds: minor, moderate, and extensive. All fragility curves were generated for normal and reverse faults, as well as the combination of those fault types (dip-slip fault). Finally, the proposed curves were verified via their comparison with those provided by HAZUS. It was concluded that embankment geometry and depth of fault rupture appearance do not significantly affect fragility, as exceedance probabilities show minimal differences (<4%). However, an embankment founded on dense sandy soil reveals slightly higher fragility compared to the one founded on loose sand. Differences regarding the probability of exceedance of a certain damage level are restricted by a maximum of 7%.

We propose a new approach for performing drained and undrained loading of elastoplastic geomaterials over large deformations using smoothed particle hydrodynamics (SPH), a meshfree continuum particle method, combined with the modified Cam Clay (MCC) model of critical state soil mechanics. The numerical approach draws upon a novel one-particle two-phase penalty-method based formulation for handling undrained loading in saturated soils, which allows tracking of the buildup of pore-water pressures under combined shearing and compression. Large-scale parallelized simulations are employed to accommodate a significant number of degrees of freedom in a three-dimensional setting. After verification and benchmark testing, the SPH based formulation is used to analyze the propagation of reverse faults through fluid-saturated clay deposits and the rupture of strike-slip faults across earthen embankments. The computational methodology tests the robustness of the meshfree approach in situations where the soil tends to dilate on the 'dry' side of the critical state line and to compact on the 'wet' side, but cannot, because of the incompressibility constraint imposed by undrained loading. Our results extend the current understanding of fault rupture modeling and further demonstrate the potential of our framework together with the SPH method for large deformation analyses of complex problems in geotechnics.

Fault rupture propagation through near-surface soil deposits and the anticipated damage on adjacent structures have been thoroughly investigated focusing on single fault rupture. Nevertheless, large secondary faults have also been observed in field investigations. For this reason, the development of contemporaneous fault ruptures -and the resulting soil displacements-caused by complex combinations of oblique-slip main and non-parallel secondary faults is investigated herein. Moreover, the response of buried steel pipelines crossing such geohazardous areas is also examined aiming to assess pipeline vulnerability due to the presence of secondary faults. The investigation is conducted utilizing a decoupled numerical methodology, in which soil displacements are calculated utilizing a 3D numerical model, and subsequently, they are applied to a separate numerical model for the assessment of pipeline distress. Useful conclusions are drawn regarding the developed fault rupture patterns and the sequent pipeline distress under such detrimental conditions that may occur in seismotectonic regions.