The K & uuml;& ccedil;& uuml;k & ccedil;ekmece-Avc & imath;lar corridor of the D100 highway constitutes a critical component of Istanbul's transportation infrastructure. Given its strategic importance, ensuring its operational continuity following the anticipated major Istanbul earthquake is imperative. The aim of this study was to investigate the liquefaction-induced geotechnical risks threatening the K & uuml;& ccedil;& uuml;k & ccedil;ekmece-Avc & imath;lar segment of the D100 highway. Initially, the study area's liquefaction susceptibility was assessed through Liquefaction Potential Index mapping. Subsequently, post-liquefaction ground displacements were quantified using semi-empirical methodologies and advanced numerical analyses focused on representative critical sections. Numerical simulations incorporated various constitutive models for liquefiable soils, enabling a comparative assessment against semi-empirical estimations. The results revealed that semi-empirical approaches systematically overestimated the lateral displacements relative to numerical predictions. Moreover, the analyses highlighted the sensitivity of model outcomes to the selection of constitutive parameters, underscoring the necessity for careful calibration in modeling liquefiable layers. Despite considering the most conservative displacement values from numerical analyses, findings indicated that the D100 highway is likely to experience substantial damage, potentially leading to extended service disruptions following the projected seismic event.

On May 1, 2024, a small embankment collapse occurred in the early hours of the morning on the Meida Highway in Meizhou City, Guangdong Province, resulting in 48 fatalities. The small-scale collapse caused massive casualties and garnered widespread attention. In detail, there is a significant lack of precipitation at the time of the 51 Meida collapse disaster, lagging 10 h behind the peak precipitation. The collapse occurs on a mountainous slope, with a hollow catchment area located above the embankment. Multiple potential streams converge in the area, contributing to the water flow towards the slope. Within the western zone of the Lianhua Mountain fault, the collapse area is crossed by fault lines at approximately 800 m on the upper side and 650 m on the lower side. Bedrock fractures formed by faults act as water conduits. The combination of catchment topography and potential faults enriches the water around the embankment slope, contributing to its instability. The disaster site is situated within granite formations. The refilling soil, composed of weathered granite, exhibits poor hydro-mechanical properties, making the slope particularly susceptible to failure due to the effects of multi-source water infiltration. A key insight from this research is that potentially unstable embankment slopes should be identified by considering the interaction between multi-source water and soil/rock. Greater emphasis should be placed on factors such as fault development and hollow topography above the slope, which influence the effects of multi-source water. These factors should be quantified in future studies to improve the assessment of unstable highway slopes in mountainous regions. The findings and strategies outlined in this study can serve as a valuable reference for assessing both embankment and natural slopes in mountainous areas.

This research proposes an artificial intelligence (AI)-powered digital twin framework for highway slope stability risk monitoring and prediction. For highway slope stability, a digital twin replicates the geological and structural conditions of highway slopes while continuously integrating real-time monitoring data to refine and enhance slope modeling. The framework employs instance segmentation and a random forest model to identify embankments and slopes with high landslide susceptibility scores. Additionally, artificial neural network (ANN) models are trained on historical drilling data to predict 3D subsurface soil type point clouds and groundwater depth maps. The USCS soil classification-based machine learning model achieved an accuracy score of 0.8, calculated by dividing the number of correct soil class predictions by the total number of predictions. The groundwater depth regression model achieved an RMSE of 2.32. These predicted values are integrated as input parameters for seepage and slope stability analyses, ultimately calculating the factor of safety (FoS) under predicted rainfall infiltration scenarios. The proposed methodology automates the identification of embankments and slopes using sub-meter resolution Light Detection and Ranging (LiDAR)-derived digital elevation models (DEMs) and generates critical soil properties and pore water pressure data for slope stability analysis. This enables the provision of early warnings for potential slope failures, facilitating timely interventions and risk mitigation.

Soil with high liquid limit is often encountered in southern China, which is unsuitable for direct use as embankment fill. Current soil reinforcement methods entail high carbon emissions, necessitating mitigation for a low-carbon future. In this study, a reconstituted soil is reconstituted to simulate the soil with high liquid limit from the site of the reconstruction and expansion project for the Zhangshu-Ji'an Highway in Jiangxi, China. This reconstituted soil was reinforced using steel slag, varying in grain sizes and employing two mixing methods. The mechanical characteristics of the pure and reinforced soil were examined by a series of monotonic and cyclic triaxial tests. The results indicate that decreasing the grain size of steel slag increases the monotonic shear strength and leads to a decrease in the permanent strain under cyclic loading, regardless of the mixing methods. The reduction in grain size of steel slag increases the total frictional surface area, thereby enhancing soil strength and resistance to deformation. Compared to the samples by uniform mixing with the steel slag, the samples by layered mixing results in a greater shear strength and a more significant permanent strain, because the concentrated steel slag grains and reconstituted soil particles produce greater friction and more significant compressibility, respectively. Overall, smaller grains of the steel slag by uniform mixing are more effective for reinforcing weak soil with high liquid limit, as it provides a higher monotonic strength and a lower permanent deformation, and reduces rapid energy dissipation under cyclic loading, compared to layered mixing.

This study underscores the critical need to integrate changing climatic conditions into corrosion models for civil engineering infrastructures, particularly highway bridges, given the potential reduction in structural performance post-seismic events. The paper introduces a novel framework for assessing the seismic resilience of deteriorated highway bridges in the context of changing climatic conditions. The framework is demonstrated on a non-seismically designed simply supported highway bridge situated near the sea in a seismically active region of Gujarat, India. An improved corrosion deterioration model is used that considers the impact of climate change and non-uniform pitting corrosion for evaluating the deterioration of RC bridge components. A detailed threedimensional finite-element model of the case-study bridge is developed that can accurately simulate various failure modes of corroding bridge piers. Time-varying seismic fragility curves are developed using damage limit states and probabilistic seismic demand models while considering the influence of climate change. Bridge seismic resilience is estimated by aggregating the seismic vulnerability, losses, and recovery functions. Results show that incorporation of changing climatic factors will considerably reduce the seismic resilience of the 75-year corroded bridge up to 56 %. Finally, a comparison of seismic fragility and resilience is carried out using the proposed and conventional corrosion deterioration model to evaluate the significance of considering the effects of climate change in the seismic resilience assessment framework.

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%.

Soil erosion on highway side-slope has been recognized as a cause of environmental damage and a potential threat to road embankments in the high-altitude permafrost regions. To assess the risk to roads and to protect them effectively, it is crucial to clarify the mechanisms governing roadside erosion. However, the cold climate and extremely vulnerable environment under permafrost conditions may result in a unique process of roadside erosion, which differs from the results of current studies conducted at lower altitudes. In this study, a field survey was conducted to investigate side-slope rill erosion along the permafrost of a highway on the Qinghai-Tibet Plateau of China. Variations in erosion rates have been revealed, and intense erosion risks (with an average erosion rate of 13.05 kg/m2/a) have been identified on the northern side of the Tanggula Mountains. In the case of individual rills, the detailed rill morphology data indicate that the rill heads are generally close to the slope top and that erosion predominantly occurs in the upper parts of highway slopes, as they are affected by road surface runoff. In the road segment scale, the Pearson correlation and principal component analysis results revealed that the protective effect of vegetation, which was influenced by precipitation, was greater than the erosive effect of precipitation on roadside erosion. A random forest model was then adopted to quantify the importance of influencing factors, and the slope gradient was identified as the most significant factor, with a value of 0.474. Accordingly, the integrated slope and slope length index (L0.5S2) proved to be a reliable predictor, and a comprehensive model was built for highway side-slope rill erosion prediction (model efficiency = 0.802). These results could be helpful for highway side-slope conservation and ecological risk prediction in alpine permafrost areas.

The warming trend presents a significant threat to the underlying permafrost. Talik formation is widely recognized as a significant mechanism of permafrost degradation. Our research indicates that the term talik has undergone a long period of development and gradually formed, referring to unfrozen layers in permafrost. The talik has already resulted in extensive damage to the infrastructure built in permafrost areas. Here, we provide a brief overview of the current research status of talik. Accurately identifying talik presents a significant challenge. However, by integrating multiple identification tools with technology, the precision of talik detection can be enhanced, resulting in more accurate results. This paper discusses the strengths and weaknesses of each approach. While numerical simulations can enhance our understanding of the development mechanism and evolution process of taliks, most simulations focus on the evolution of taliks beneath lakes. These simulations emphasize the impact of subpermafrost groundwater flow on the development of lake taliks and the surrounding permafrost thickness. Today, there is a scarcity of relevant studies about taliks in cold zone engineering. The presence of talik exacerbates the occurrence of permafrost-related subgrade diseases, which are chronic and irreversible. Additionally, it poses a threat to the stability of the subgrades and worsens settlement issues. Therefore, we have analyzed the causes and distribution characteristics of talik beneath the subgrade and proposed a novel measure for preventing and controlling it. This measure aims to enhance the long-term service performance of subgrade in permafrost regions. The modified polyurethane material is injected into the talik through grouting technology as a replacement. This material has low thermal conductivity, strong water resistance, and certain strength. It effectively improves the hydrothermal environment conditions necessary for talik formation, preventing the formation of new taliks or impeding their development. As a result, the subgrade performance is enhanced.

Road infrastructure construction in developing countries such as Vietnam requires an enormous amount of natural sand. The scarcity of river sand is becoming increasingly severe, with predictions indicating a sustained drop in its supply. Hence, it is essential for the construction industry to implement a sustainable strategy by combining waste materials with abundant resources in order to effectively address this challenging situation. The objective of this study is to investigate the mechanical properties and evaluate the potential application of mixtures comprising rock quarry dust and sea sand for the roadbed layers of expressways. The researchers conducted a series of experiments, including the moisture content, specific gravity, angle of repose of material, and triaxial tests to study the composition and mechanical behaviors of mixtures at different ratios. Extensive parametric investigations in conjunction with the calibration in Plaxis' soil-test module obtain the Young's modulus E50 and confining pressure curves. Based on the assessment of materials utilized in roadbed layer of highway, as determined by the California bearing ratio (CBR) coefficient, it demonstrates that combining sea sand and quarry dust can generate the mixtures possessing appropriate properties for application in the construction of the roadbed of highway.

Irregular plan geometries and soil-abutment-structure interaction, as well as the torsional components of ground motions (TGMs) are significant contributing factors that result in excessive torsional demand during seismic events that may lead to premature and asymmetric failure of shear keys. Therefore, a design method that ensures the effectiveness of shear keys in mitigating the seismic response of highway bridges is proposed. The proposed method follows the conventional approach to capacity-protect the substructure components, however, formalizes a practical procedure to specify desired deformation limits associated with i) gap size between the superstructure and shear keys, and ii) ultimate deformation capacity of shear keys. The efficacy of the method is demonstrated through nonlinear response history analyses of a series of example bridges. It is demonstrated that excessive inplane deck rotations and the extent of damage can be limited when the effectiveness of shear keys is maintained throughout the duration of seismic excitation. Furthermore, probable deck unseating may be prevented when the deck displacements are restrained due to shear keys that are designed to remain intact.