Search Results (560)

Sustainable building construction encounters challenges stemming from escalating expenses and time delays associated with geotechnical assessments. Developing and optimizing geotechnical soil maps (SMs) using existing data across heterogeneous geotechnical formations offer strategic and dynamic solutions. This strategic approach facilitates economical and prompt site evaluations, and offers preliminary ground models, enhancing efficient and sustainable building foundation design. In this framework, this paper aimed to develop SMs for the first time in the rapidly growing district of Gujrat using the optimal interpolation technique (OIT). The subsurface conditions were evaluated using the standard penetration test (SPT) N-values and soil classification including seismic wave velocity to account for seismic effects. Among the different geostatistical and geospatial models, the inverse distance weighting (IDW) model based on an optimized spatial analyst approach yielded the minimum error and a higher association with the field data for the understudy region. Overall, the optimized IDW technique yielded root mean square error (RMSE), mean absolute error (MAE), and correlation coefficient (CC) ranges between 0.57 and 0.98. Furthermore, analytical depth-dependent models were developed using SPT-N values to assess the bearing capacity, demonstrating the association of R² > 0.95. Moreover, the study area was divided into three geotechnical zones based on the average SPT-N values. Comprehensive validation of different strata evaluation based on the optimal IDW for the SPT-N and soil type-based SMs revealed that the RMSE and MAE ranged between 0.36–1.65 and 0.30–0.59, while the CC ranged between 0.93 and 0.98 at multiple depths. The allowable bearing capacity (ABC) for spread footings was determined by evaluating the shear, settlement, and seismic factors. The study offers insights into regional variations in geotechnical formations along with shallow foundation design guidelines for practitioners and researchers working with similar soil conditions. Full article

In soft soil foundations, the utilization of box-type retaining walls as a support method represents a novel approach. This study focuses on investigating the key factors influencing lateral wall deflection and ground settlement behind the wall in deep excavation projects supported by box-type retaining walls. Based on a practical engineering case in Shanghai, the large deformation Lagrangian numerical simulation software FLAC-3D is employed to simulate the displacement of box-type retaining walls as well as the surface settlement surrounding the excavation pit during the excavation process of deep-foundation pits. This research encompasses aspects such as the box size, the filling material within the box, and the constituent materials of the retaining wall. Ultimately, it is concluded that variations in the size of the box-retaining wall have a significant impact on wall deflection and surrounding ground settlement, while the filling material and constituent materials have relatively minor effects. This study provides a theoretical basis and scientific reference for the design and construction of box-type retaining walls in deep-foundation pit engineering. Full article

Ground settlement is a crucial indicator for assessing the safety of shield tunneling and its impact on the surrounding environment. However, most existing settlement prediction methods are based on historical data, which can only be applied with effective monitoring conditions. To overcome this limitation, this paper proposes the mechanism-driven intelligent settlement prediction method (MISPM), which considers the mechanisms of settlement and attitude movements during construction to design new features that can indirectly reflect settlement. Simulation experiments were used to compare the impact of different candidate features and algorithms on prediction performance, verifying the validity and accuracy of the model. The efficacy of MISPM in predicting settlement changes in advance was substantiated by practical engineering applications. Results showed that MISPM could accurately predict settlement changes even without ground monitoring, thereby corroborating its reliability and applicability in supporting safe tunneling in complex geological environments. In the construction of urban infrastructure, this method has the potential to enhance the efficiency of tunnel construction and ensure environmental safety, which is of great significance for the development of smart cities. Full article

Taking the foundation pit of the Suzhou Chunshenhu Road Expressway Reconstruction Project as an example, the excavation process of the foundation pit was numerically simulated using a three-dimensional finite element method. The measured data and simulated data of the lateral deformation of the enclosure structure, surface settlement deformation of the ground outside the pit, and settlement deformation of the building were compared to analyze the impact of foundation pit construction on adjacent buildings. The influence of foundation pit floor and diaphragm wall thickness on wall displacement, building settlement, and foundation pit uplift was also discussed. The results showed the following: (1) Adding a foundation pit floor has a significant effect on reducing the lateral displacement of the diaphragm wall, settlement of the building, and uplift of the foundation pit. Increasing the thickness of the foundation pit floor has a limited effect on reducing the displacement, while increasing the thickness of the diaphragm wall has a small effect. (2) The displacement curve of the underground diaphragm wall increases with depth. It reaches a maximum at the excavation surface and then decreases gradually. (3) The surface settlement increases first and then decreases with distance from the foundation pit, showing a concave shape. As the depth of excavation increases, the settlement value increases. (4) Through analysis of the monitoring data of vertical displacement of buildings, it can be seen that during foundation pit excavation, buildings undergo five stages: initial slow descent, steep descent, mid-term slow descent, late steep descent, and stable deformation. The buildings are dominated by settlement deformation. Full article

Along the southern North Sea coast from the Netherlands to Denmark, human cultivation efforts have created a unique cultural landscape. Since the Middle Ages, these interactions between humans and natural forces have induced major coastal changes. In North Frisia (Germany), storm floods in 1362 AD and 1634 AD turned wide areas of embanked cultural land into tidal flats. Systematic geoarchaeological investigations between Nordstrand and Hallig Südfall comprise coring, trenching, sedimentary, geochemical and microfaunal palaeoenvironmental parameter analyses and radiocarbon dating. Together with geophysical prospection results and archaeological surveys, they give insights into the landscape’s development and causes for land losses. Results reveal that fens and bogs dominated from c. 800 BC to 1000 AD but are mostly missing in the stratigraphy. Instead, we found 12th to 14th cent. AD settlement remains directly on top of a pre-800 BC fossil marsh. This hiatus of c. 2000 years combined with local ‘Hufen’ settlements implies an extensive removal of peat during cultivation eventually resulting in the use of underlying marshland for agricultural purposes. Fifteenth cent. AD tidal flat deposits on top of the cultivated marsh prove that human impact lowered the ground surface below the mean high water of that time, clearly increasing the coastal vulnerability. We consider these intensive human–environment interactions as a decisive trigger for the massive loss of land and establishment of the tidal flats in North Frisia that are currently part of the UNESCO World Heritage “Wadden Sea”. Full article

In a complex urban environment, the impact of building demolitions by blasting on the structural integrity of nearby metro tunnels is critical. This study systematically analyzed the blasting and demolition process of a building adjacent to a metro tunnel using various monitoring methods, including blasting vibration, dynamic strain, deformation and settlement, pore water pressure, and displacement. The results indicate that the metro tunnel’s vibration response can be divided into four stages: notch blasting, notch closure, overall collapse impact, and auxiliary notch blasting. The most significant impact on the tunnel segments occurred during the building’s ground impact phase, with a peak particle velocity of 0.57 cm/s. The maximum tensile and compressive stresses induced in the tunnel segments did not exceed 0.4 MPa, well within the safety limits. Displacement and settlement changes in the tunnel structure were less than 1 mm, far below the warning threshold. Additionally, blasting vibrations significantly affected the pore water pressure in the surrounding soil. However, fluctuations caused by ground impact vibrations were minimal, and the pore water pressure quickly returned to its initial level after the blasting concluded. Throughout the process, no adverse effects on the metro tunnel structure were observed. Full article

Ground collapse is one of the common geological hazards in modern cities. With the development of urbanization, the risk of ground collapse increases, which has a great impact on urban public safety. Ground collapse accidents typically occur due to the presence of unstable cavities under the surface, or the generation and expansion of cavities induced by triggering factors. Investigating the stability of cavities in the strata is significant for identifying subsidence risks and mitigating the consequences of subsidence. This study proposed a method for predicting ground subsidence settlement based on the ARMA model. Firstly, CFD-DEM coupled simulation is employed to simulate the mechanism of cavity changes in the soil layers under the influence of triggering factors and to calculate the safety coefficient for ground subsidence stability. Subsequently, the safety coefficient data at different time points are fitted to predict the subsequent stability of the subsidence. We selected a subway permeable collapse accident in Foshan City, Guangdong Province for experimental verification, and compared the predicted results with the actual situation. The result shows that this method can effectively predict the changes in ground collapse safety factor and the collapse time point. With 40% of the data, high accuracy prediction can be achieved, improving the efficiency of collapse evolution prediction and providing strong support for ground collapse risk prevention and control. Full article

Tunnel boring machines (TBMs) are essential for excavating metro tunnels, reducing disruptions to surrounding rock, and ensuring efficient progress. This study examines how machine learning (ML) models can predict key tunneling outcomes, focusing on making these predictions clearer. Specifically, the models aim to predict surface settlements (ground sinking) and the TBM’s penetration rate (PR) during the Athens Metro Line 2 extension to Hellinikon. For surface settlements, four artificial neural networks (ANNs) were developed, achieving an accuracy of over 79%, on average. For the TBM’s PR, both an XGBoost Regressor (XGBR) and ANNs performed consistently well, offering reliable predictions. This study emphasizes model transparency mostly. Using the SHapley Additive exPlanations (SHAP) library, it is possible to explain how models make decisions, highlighting key factors like geological conditions and TBM operating data. With SHAP’s Tree Explainer and Deep Explainer techniques, the study reveals which parameters matter most, making ML models less of a “black box” and more practical for real-world metro tunnel projects. By showing how decisions are made, these tools give decision-makers confidence to rely on ML in complex tunneling operations. Full article

The land section of the Huangdao end of the Jiaozhou Bay Second Submarine Tunnel is extensively underlain by the Quaternary Loose Accumulation Layer. The tunnel passes through a weathered granite fracture zone with well-developed rock joints beneath the buildings. The tunnel excavation process significantly disturbs the buildings above, making them prone to settlement, cracking, and tilting. This research conducts numerical simulations of three tunnel excavation methods, and based on the results, compares the deformation behaviors of the ground surface and buildings under various conditions. The findings show that the double side-wall guide pit method has better adaptability in controlling surface settlement and building deformation than the vertical or curved CD method. Moreover, the removal of temporary supports significantly affects building settlement and tilt; this risk can be effectively reduced by controlling the stress relief ratio during the removal phase of the temporary supports in the tunnel. The significance of the study lies in the fact that by choosing an appropriate tunnel excavation support scheme, the disturbance impact on the overlying buildings can be minimized, and the construction safety and stability of the surrounding buildings can be guaranteed. The results of this study can provide initial guidance for constructing shallow-buried tunnels beneath existing buildings. Full article

This study assesses subsidence-induced risk to urban infrastructure in three major Italian cities—Rome, Bologna, and Florence—by integrating satellite-based persistent scatterer interferometric synthetic aperture radar (PSInSAR) ground displacement data with urban vulnerability metrics into a novel risk assessment workflow, incorporating land use and population data from the Copernicus Land Monitoring Service (CLMS)—Urban Atlas. This analysis exploits ERS-1/2, ENVISAT, and COSMO-SkyMed PSInSAR datasets from the Italian Extraordinary Plan of Environmental Remote Sensing, plus Sentinel-1 datasets from CLMS—European Ground Motion Service (EGMS), and spans a 30-year period, thus capturing both historical and recent subsidence trends. Angular distortion is introduced as a critical parameter for assessing potential structural damage due to differential settlement, which helps to quantify subsidence-induced hazards more precisely. The results reveal variable subsidence hazard patterns across the three cities, with specific areas exhibiting significant differential ground deformation that poses risks to key infrastructure. A total of 36.15, 11.44, and 0.43 km² of land at high to very high risk are identified in Rome, Bologna, and Florence, respectively. By integrating geospatial and vulnerability data at the building-block level, this study offers a more comprehensive understanding of subsidence-induced risk, potentially contributing to improved management and mitigation strategies in urban areas. This study contributes to the limited literature on embedding PSInSAR data into urban risk assessment workflows and provides a replicable framework for future applications in other urban areas. Full article

The increasingly frequent pluvial flood of West African urban settlements indicates the need to investigate the drivers of local rainfall changes. However, meteorological stations are few, unevenly distributed, and work irregularly. Daily satellite rainfall datasets can be used. Nevertheless, these products often need to be more accurate due to sensor errors and limitations in retrieval algorithms. The problem is, therefore, how to characterize rainfall where there is a need for ground-based rainfall records or incomplete series. This study aims to characterize urban rainfall using two satellite datasets. The analysis was carried out in the Sirba river catchment, Burkina Faso, using the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) and the Tropical Applications of Meteorology using SATellite and ground-based data (TAMSAT) datasets. Ten indices from the Expert Team on Climate Change Detection and Indices (ETCCDI) of precipitation were calculated, and their statistical trends were evaluated from 1983 to 2023. The study introduces two key innovations: a comparative analysis of precipitation trends using two satellite datasets and applying this analysis to towns within a previously understudied 39,138 km² catchment area that is frequently flooded. Both datasets agree on the increase of (i) annual cumulative rainfall over all towns, (ii) five-day maximum rainfall over the town of Manni, (iii) rainfall due to very wet days in Gayéri, (iv) days of heavy rainfall in Bogandé, Manni and Yalgho, and (v) days of very heavy rainfall in Yalgho. These findings suggest the need for targeted pluvial flood prevention measures in towns with increasing trends in heavy rainfall. Full article

Analyzing the mechanisms of soil instability in tunnels due to sudden water ingress is essential for construction safety. This kind of problem belongs to the category of seepage deformation, mostly due to the near tunnel range of water pipeline blowing cracks and heavy rainfall flooding rainwater into the tunnel. Distinguished from general infiltration behavior, the relevant problems have the characteristics of rapid occurrence and short action time. This study develops a 3D fluid–solid coupling model for soil deformation in tunnels with water ingress, grounded in Biot’s theory and Darcy’s law while considering water level variations within the tunnel. The governing equations are discretized in space and time, and the model’s accuracy is validated through comparison with actual measurements from a Zhengzhou subway project. The study analyzes pore pressure, stress-deformation responses, and surface settlement patterns in surrounding soil and rock mass under soil–water coupling. The findings show that (1) the tunnel cavern, as a seepage source, has minimal impact on the lateral settlement trough width, while seepage mainly affects the vertical deformation of surrounding rock; (2) pressure dissipation exhibits hysteresis in clay strata; (3) water ingress increases soil saturation and decreases effective stress, resulting in persistent surface settlement until drainage. There is a minimal discrepancy between model-calculated and measured settlements. Full article

Landscape-oriented approaches in archaeology have moved beyond site-based research to interpret how people have engaged with, modified, and constructed the environment and how the legacies of these activities continue to influence land use. In the Maya Lowlands, landscape archaeology is related to the analysis of settlement patterns, households, agricultural intensification, and water management. The increasing availability of LiDAR data has revolutionized the mapping of archaeological landscapes under vegetation, especially in tropical environments like the Maya Lowlands, but researchers still emphasize site-oriented settlement densities and infrastructure. Furthermore, the accessibility of drone-based LiDAR platforms has the potential to collect data across several seasons or years to facilitate change detection. In this paper, we compare three LiDAR datasets collected from 2018 to 2023, using both occupied and unoccupied airborne systems. The landscape surrounding the archaeological site of El Infiernito, Chiapas, Mexico near the Classic period (AD 250–800) dynastic capital of Piedras Negras, Guatemala was selected to compare these LiDAR datasets in the context of prior, extensive ground-based fieldwork. These data were used to interpret the built environment, land use, hydrology, landscapes of movement, and other infrastructure constructed and modified by several communities beginning in the Late Preclassic period (400 BC–AD 250) to the present. When used alongside systematic survey and ground verification, the combination of several LiDAR platforms to collect data across different seasons at El Infiernito enhanced the understanding of the spatial distribution of archaeological sites and features across the karst landscape. Full article

To mitigate the impact of foundation pit construction on adjacent existing structures, grouting reinforcement techniques are often employed to enhance the deformation strength of the soil. This study focuses on the expansion project of the Dayun Comprehensive Hub in Shenzhen, conducting full-scale numerical simulations of the excavation of deep foundation pits adjacent to existing elevated railways and examining the effects of different grouting reinforcement schemes. The results indicate that the single-row and double-row grouting schemes increased the bearing capacity of the foundation piles by 23.7% and 31.9%, respectively, significantly enhancing the structural bearing performance. After reinforcement, the maximum deformation position of the elevated bridge foundation piles shifted upward, and the settlement distribution of the cap beam became more concentrated, indicating that grouting reinforcement effectively controlled the ground settlement and the deformation of the foundation piles. Furthermore, compared to controlling the deformation of the retaining structures, grouting reinforcement was more effective in controlling ground settlement and pile deformation, highlighting its advantages in complex environments. Although the double-row grouting scheme demonstrated superior technical performance, the single-row scheme remains the preferred option considering reinforcement efficiency and economic factors. Full article

In low-temperature stable permafrost regions, both active and passive cooling measures are commonly employed to ensure the long-term stability of highway structures. However, despite adopting these measures, various types of structural issues caused by permafrost degradation remain prevalent in high-grade highways. This indicates that in addition to preventing permafrost melting, structural reinforcement of the foundation is still necessary. Based on the analysis of the long-term foundation temperature field and settlement using the finite element method, which was validated through an indoor top-down freeze–thaw cycle test, this paper explores, for the first time, the feasibility of applying geosynthetic-encased gravel pile composite highway foundations—previously commonly used for permafrost destruction—in low-temperature stable permafrost areas where permafrost protection is the primary principle. By analyzing the long-term temperature field, settlement behavior, and pile–soil stress ratios of permafrost foundations influenced by both the highway structure and composite foundation, it was found that when the pile diameter is 0.5 m, pile spacing is 2 m, and pile length is 11 m, the mean monthly ground temperature of the permafrost foundation will not be significantly affected. Therefore, the properly designed geosynthetic-encased gravel pile composite highway foundation can be adopted in low-temperature stable permafrost regions where permafrost protection, rather than destruction, is required. Full article