Destructive earthquakes result in significant damage to a wide variety of buildings. The resulting damage data is crucial for evaluating the seismic resilience of buildings in the region and investigating urban resilience. Field damage data from 38 destructive earthquakes in Sichuan Province were collected, classified, and statistically analysed according to the criteria of the latest Chinese seismic intensity scale for evaluating building damage levels. Meanwhile, the construction features and seismic damage characteristics of these buildings were also examined. These results facilitated the development of a damage probability matrix (DPM) for various building typologies, such as raw-soil structures (RSSs), stone-wood structures (SWSs), brick-wood structures (BWSs), masonry structures (MSs), and reinforced concrete frame structures (RCFSs). The damage ratio was employed as the parameter for vulnerability assessment, and a comprehensive analysis was performed on the differences in damage levels among all buildings in various intensity zones and time frames. Furthermore, the DPMs were further refined by simulating additional data from high-intensity zones to more accurately represent the seismic resistance of existing buildings in multiple-intensity zones. Vulnerability prediction models were developed using the biphasic Hill model, which elucidates varying damage trends across different construction typologies. Finally, empirical fragility curves were established based on horizontal peak ground acceleration (PGA) as the damage indicator. This study is based on multiple seismic damage samples from various regions, accounting for the influence of earthquake age. The DPMs, representative of the regional characteristics of Sichuan Province, were developed for different building types. Furthermore, multidimensional vulnerability regression models and empirical fragility curves are established based on these DPMs. These models and curves provide a theoretical foundation for seismic disaster scenario simulations and the seismic capacity analysis of buildings within Sichuan Province.

On February 6, 2023, two major earthquakes with magnitudes Mw = 7.7 and Mw = 7.6 struck southeastern Turkiye, causing catastrophic damage and loss of life across 11 provinces, including Malatya. This study focuses on documenting the geotechnical observations and structural damage in Dogansehir, one of the hardest-hit districts not only in Malatya but in the entire affected region. An overview of the-region's tectonic and geological background is presented, followed by an analysis of ground motion data specific to Malatya. A detailed examination of seismic data from stations near Dogansehir was provided to better understand the seismic demands during the earthquakes. The paper then provides insights into the geotechnical conditions, building characteristics, and a damage ratio map of Dogansehir. The influence of local tectonics and geology on the observed damage is analyzed, alongside an evaluation of the seismic performance of masonry and reinforced concrete structures. Dogansehir, located near the epicenters of the Kahramanmaras earthquakes, suffered major structural damage. This was due to the surface rupture occurring near the settlement areas, the establishment of the district centre on the alluvial soil layer and the deficiencies/errors in the building systems. Building settlements on or near active fault zones, as well as on soft soil, leads to serious consequences and should be avoided or require special precautions.

Triggered by continuous heavy rainfall, a catastrophic large-scale high-locality landslide occurred in Hengshanbei mountain slope of Shangxi Village, Longchuan County, Guangdong Province, China, on June 14, 2022, at 12:10 (UTC + 8). The landslide had an estimated volume of about 1.45 x 105 m3 and resulted in severe damage to the region. To investigate the causative mechanisms of this landslide, a comprehensive study was conducted, involving geological and hydrological surveys of the research area, combined with field investigations, satellite imagery, drone photography, data analysis of rainfall and landslide displacement monitoring, and laboratory experiments. The research focused on analyzing the process of landslide formation and development, trigger factors, destruction characteristics, and instability mechanisms. Additionally, the study employed the Mohr-Coulomb strength theory to explain stress variations during the landslide process. Findings indicated that: (1) the slope soil structure was loose with well-developed pores, mainly composed of kaolinite with strong water absorption properties, causing softening and disintegration of the soil when encountering water, resulting in reduced cohesion and internal friction angle, and overall poor soil properties; (2) continuous heavy rainfall infiltrated the slope through soil pores and eroded channels, increasing pore water pressure and reducing effective stress, subsequently reducing anti-sliding force and increasing sliding force; as well as (3) unfavorable terrain conditions, such as high landslide starting point and high-locality, significant height, and steep slope, lead to landslides running farther and being of larger scale. The study further highlighted that the intrinsic properties of the slope soil were the decisive internal cause of the landslide, while continuous heavy rainfall and adverse terrain were external triggering factors. These findings provide essential insights for understanding and preventing similar landslide disasters.

Carbonation technology using MgO and CO2 has been considered a rapid, effective, and environmentally friendly method for improving weak soils, mainly applied in shallow foundation treatments. This study introduced a novel MgO-carbonated composite pile (MCP) technique developed by injecting CO2 through a gas-permeable pipe pile into a MgO-mixing column for carbonation and solidification and its applications in weak subgrade treatments. Several field tests were carried out to study the characteristics of MCP as well as the performance of the MCP-reinforced foundations, including carbonation reaction temperature monitoring, pore-water pressure monitoring, standard penetration tests (SPTs), unconfined compressive strength (UCS) tests, static load tests, and subgrade deformation monitoring. Results showed vigorous and uniform carbonation within the MgO-mixing column, confirming the feasibility of constructing large-diameter MgO-mixing columns. The distribution, evolution, and affected zone of excess pore-water pressure induced by MCP installation were determined. The MCP exhibited good pile quality, with average SPT blow count and UCS value of 39 and 1021 kPa, respectively. MCP's bearing capacity was superior to prestressed high-strength concrete pipe piles, with ultimate vertical and lateral bearing capacities of 1920 and 119 kN, respectively. The MCP-reinforced foundation exhibited a small settlement of 54.5 mm under embankment loads. Life cycle assessment indicated significant carbon reduction benefits for MCP, with 44.7% lower carbon emissions compared to traditional composite piles.

Many large-scale landslides have occurred along the active Pingding-Huama fault in Zhouqu segment, Gansu, China. To better understand the failure mechanisms of these landslides, we use the Yahuokou landslide as a detailed case study. Field investigation was conducted to retrace the kinematics of the landslide and corresponding timeline of triggering mechanics. Dynamic triaxial tests were conducted to quantify the effect of rainfall and rockfall load on the physical and mechanical character of the landslide materials with in -situ stress level. Numerical simulation was used to evaluate the landslide stability under rainfall and rockfall load. The results show that a smaller initial rockfall of the limestone blocks along the upper headscarp of the landslide triggered a series of larger failure events that propagated through the greater landslide complex. We proposed that continuous rainfall and this rockfall load increased the pore water pressure and significantly reduced the shear strength parameters of the sliding materials. In addition, the rockfall load destroyed the structure of the shallow soil with buried depth <5 m, increasing the pore volume and water absorption capacity, which may cause the water content of the soil to exceed its liquid limit, and finally promoted plastic flow. Stability calculation further showed that rainfall alone was not sufficient to induce the landslide failure, but rather the coupled action of rainfall and rockfall load was needed. The conclusions drawn from this study outline complex failure mechanics of the Yahuokou landslide and may be helpful in understanding the fault -zone landslides widely distributed along the Pingding-Huama fault.

It is essential to investigate soil hydro-thermal behavior to reduce the potential damage to geotechnical constructions caused by varying climatic conditions. In this work, an in-situ monitoring station was built on a clay slope with high groundwater table, situated in Yixing, China. Ten SMT-100 sensors were instrumented on the site to record the evolutions of soil temperature and volumetric water content at various depths. Meteorological information, including relative humidity, air temperature, rainfall, wind speed and solar radiation, and slope runoff was collected. A numerical investigation was also conducted to analyze the variations of soil hydrothermal response to the recorded climatic conditions by combing coupled hydro-thermal model and soilatmosphere interaction model. The profiles of soil temperature and volumetric water content suggest that the diurnal changes are limited to depths <40 cm, and the seasonal changes are usually approaching a location deeper than 120 cm. Soil heterogeneity can affect its hydro-thermal response, e.g., higher volumetric water content was observed at the points with lower dry density, which is mainly related to soil water retention capacity. However, appropriate theoretical models to consider soil heterogeneity in the description of soil hydrothermal properties need to be further investigated.

Subarctic wetlands that exist as bogs, fens, swamps, marshes and shallow water, comprise 3% of the Canadian landscape. They have been recognized as important ecotones between the arctic tundra and boreal forest. Recently, there has been growing research interest in the hydrological characteristics of arctic and subarctic wetland systems in the need for more efficiently conserving wetlands and assessing climate change related impacts. This research targets the Deer River watershed near Churchill, Manitoba, which represents a typical subarctic wetland system in the Hudson Bay Lowlands. An extensive field investigation was first conducted during the summer from 2006 to 2008 to facilitate in-depth understanding of the wetland hydrology. The results provided evidence to indicate a strong relationship between air temperature and evapotranspiration. Permafrost table, soil moisture and streamflow were monitored and analyzed to advance the acknowledgement of the climatic, geographical and hydrological characteristics of subarctic wetlands. To quantify the water cycle and further validate the findings from field investigation, a Canadian distributed hydrological model, WATFLOOD, was employed to simulate the hydrologic processes in the targeted watershed. The results demonstrated that snowmelt in the spring season (April-June) was the major source of water supplement of subarctic wetlands. Most light and moderate rainfall events in summer (July-September) generated relatively small amounts of runoff which can be related to canopy interception, depression storage, porous soil layers, impermeable permafrost and intensive evapotranspiration. A lag of 2-8 days between the peaks of rainfall and stream runoff was observed in both summer and fall. This study is expected to benefit wetland conservation and the assessment of climate change related impacts in the Canadian northern regions.