Search Results (139)

Fluidized solidified soil piles combine slurry-like constructability with post-hardening strength development and provide a potential approach for soft ground improvement. This study investigated the vertical bearing behavior and load-transfer mechanism of fluidized solidified soil piles in layered soft ground through field single-pile vertical static load tests, core drilling, and three-dimensional numerical simulation. The field tests and core drilling provided experimental evidence for evaluating load–settlement behavior, pile integrity, and material strength, while the internal load-transfer mechanism and geometric parameters were mainly interpreted using the numerical model. The field results showed that the Q-s curves exhibited staged deformation characteristics, with relatively stable settlement development during the main loading stage and more pronounced nonlinearity under high load levels. The ultimate vertical bearing capacities of the 10 m and 20 m test piles were 1050 kN and 950 kN, respectively. Core drilling indicated that the two pile groups had similar material strength, suggesting that the bearing capacity difference was mainly associated with the pile toe bearing stratum rather than pile material strength. After comparison with the measured Q-s curves, the numerical analysis showed that the 20 m pile mobilized a longer shaft resistance range and a higher shaft resistance contribution, but its pile toe extended into the lower mucky soil layer, resulting in reduced pile toe resistance. Parametric analysis indicated that increasing pile length does not necessarily improve bearing performance when the pile toe bearing stratum is unfavorable, whereas increasing pile diameter more directly reduces pile head settlement under the same pile toe bearing condition. These findings highlight the need to consider both shaft resistance mobilization and pile toe bearing stratum in the design of fluidized solidified soil piles in layered soft ground. Full article

Land-use change from natural vegetation to agricultural systems significantly affects watershed hydrology and water quality. This study assesses the long-term effects of historical land-use change on hydrologic processes and nitrogen transport in the Straight River watershed, Minnesota, USA, using the Soil and Water Assessment Tool Plus (SWAT+) model. Three land-use scenarios were created to assess changes in water balance and nitrate levels. These scenarios represent the reconstructed pre-settlement conditions from 1855, established agricultural development from 2006, and current conditions from 2022. Results show a significant increase in water percolation and groundwater recharge. Percolation more than doubled, increasing from about 118 mm under reconstructed pre-colonial conditions to over 256 mm in 2022. Streamflow increased to 2.1 m³s⁻¹ in 2022, indicating improved hydrologic connectivity and groundwater contributions. Nitrate leaching increased from about 1.14 kg N ha⁻¹ to more than 32 kg N ha⁻¹ (1850s–2022), and nitrate export increased by >2000%, indicating strong nitrate loading. The significant increase in nitrate compared to water fluxes points to agriculture as the primary source of groundwater pollution and downstream nutrient loading. These findings highlight the importance of land-use change in affecting water balance and nutrient behavior. They also point out the need to include a historical baseline in watershed assessments. The results show the importance of better land and nutrient management strategies to reduce nitrate losses and protect water resources in intensively managed agricultural areas. Full article

Ground improvement for foundations supported on soft soils is traditionally problematic because of low bearing capacity and a large magnitude of settlement. One sustainable method for mitigating these problems is the use of stone columns (SCs), particularly geosynthetic-encased stone columns (GESCs), to improve load transfer, confinement, and consolidation. This review critically synthesizes recent advances in the analysis and design of SC systems using experimental investigations, numerical simulations, and machine learning (ML)-based methodologies. The article indicates that GESCs, when integrated with modern data-driven techniques, especially hybrid metaheuristic ML models, represent a reliable and sustainable solution for soft soil stabilization. Traditional analytical and empirical methods remain useful; however, they are often inadequate for very soft soils (Undrained shear strength (c_u) < 15 kPa), where excessive bulging and large deformations dominate system behavior. Consequently, intelligent hybrid modeling approaches are emerging as the next generation of optimized, data-driven design tools in geotechnical engineering. Different failure mechanisms of SCs, including bulging, punching shear, and general shear failure, are critically discussed along with the governing design parameters. Previous studies consistently indicate that spacing ratios within the range of s/D = 2–3 can improve the bearing capacity ratio (BCR) by approximately 50–100%. Numerical and experimental studies further demonstrate that SC systems can transfer nearly 60–80% of the applied load through stress concentration and soil arching mechanisms. Furthermore, the application of geosynthetic encasement enhances the performance of SCs in very soft soils by increasing confinement, reducing lateral deformation, and enhancing bearing capacity by nearly 3–6 times compared with ordinary SCs. The review also evaluates the growing role of artificial intelligence techniques in forecasting settlement and bearing capacity behavior. ML techniques such as artificial neural networks (ANN), support vector regression (SVR), random forest (RF), XGBoost, and hybrid metaheuristic–ML models have shown high predictive capability, often achieving prediction errors below 5%. Despite these advancements, many existing ML studies still suffer from limited datasets, a lack of generalization, and insufficient incorporation of physical mechanisms. Full article

Self-drilling hollow bar micropiles (HBMPs), which integrate drilling, grouting, and reinforcement into a single process, have broad application prospects in mountainous transmission lines and offshore wind power projects. However, existing research has focused mainly on friction piles in soil layers, and there is a lack of systematic understanding of the load-transfer mechanism and bearing capacity calculation method for rock-socketed HBMPs. Based on field static load tests of rock-socketed HBMPs, this study systematically investigates the vertical bearing behavior and capacity calculation method of single rock-socketed HBMPs through a combination of test data analysis, finite element numerical simulation, and theoretical analysis. The field test results show that the load-settlement curves of rock-socketed HBMPs are of a slowly varying type, exhibiting mixed friction-end-bearing characteristics. After data screening, the average Q-s curve of Pile No. 1 and Pile No. 5 was taken as the benchmark, and the representative ultimate bearing capacity of a single pile determined by the 40 mm settlement criterion is 5860 kN. The test data of Pile No. 3 and Pile No. 4 were retained as independent validation data. A three-dimensional finite element model considering the cohesive contact behavior at the pile–rock/soil interface was established using ABAQUS. After calibration with the test results, the error between the simulated and measured bearing capacity is −3.4%, demonstrating good model reliability. Parametric analysis indicates that the bearing capacity increases linearly with the grouting volume increase rate $V_{\mathrm{inc}}$, with the expansion effect being the main enhancement mechanism; the improvement amplitude under hard rock conditions is significantly smaller than that in cohesive soils. The effect of uniaxial compressive strength $q_u$ of hard rock on bearing capacity is negligible because the capacity is controlled by the pile–rock interface shear strength. The bearing capacity increases approximately linearly with the rock-socketed depth $L_r$, and a minimum rock-socketed depth of 1.0 m is recommended. Analysis of the load-transfer mechanism shows that rock-socketed HBMPs rely mainly on shaft resistance (accounting for 90.6%), and the axial force decays significantly along the pile length. Elastic compression of the pile accounts for 78% of the pile head settlement, and the limited displacement at the pile tip leads to insufficient mobilization of end bearing. A modified bearing capacity formula considering the grouting expansion effect is established with shaft resistance as the core. A hierarchical validation strategy is adopted to test its predictive ability: for the finite element cases not participating in parameter calibration, the prediction error is within ±2%; for the field test piles, the prediction error is +7.9%; and for Pile No. 3 and Pile No. 4, the errors are +1.7% and −2.1%, respectively. These values are significantly better than those of existing methods (errors ranging from −72.1% to +54.5%). The research results can provide a theoretical basis for the design of single HBMP bearing capacity under rock-socketed conditions. Full article

Understanding the movement behavior of upper blocks along rock joints or weak planes is crucial for the geological hazard forecast and prediction. This paper presents experimental and numerical investigations of a saw-tooth joint under shear and normal load conditions. Multi-stage direct shear tests under different normal load conditions were conducted using a direct shear box apparatus. The reverse dilation behavior of the upper specimen was observed by measuring the normal displacement at the four corners of the upper block. Laboratory test results show that, under lower normal loads, the normal displacement of the upper specimen on the applied shear force side initially decreases (settlement), while the settlement reverses to heave (dilation) when the shear displacement reaches a certain value. However, the settlement reverse behavior does not occur under large normal loads. Corresponding numerical simulation confirms that this settlement reversal is controlled by the specimen fracturing. The saw-tooth asperities are sheared off under a large normal load, while the upper specimen climbs along the slope of the bottom specimen under lower normal loads. Consequently, the changes in contact area, interface normal stress, interface shear stress, and normal displacement of the joint differ significantly between large and low normal load conditions. This research deepens our understanding of the shear-induced dilation and fracture behavior of saw-tooth joints, and the results can provide guidelines for evaluating the stability of geological rock mass. Full article

Soft soils are characterized by low bearing capacity, high compressibility, and susceptibility to excessive settlement. Granular columns are commonly used to improve such soils; however, conventional column materials such as sand, gravel, and crushed stone are increasingly depleted. As a sustainable alternative, crushed waste glass (CWG) has been identified as a potential granular column material due to its physical and chemical properties being comparable to those of natural aggregates. Despite this potential, limited studies have investigated how key design parameters, such as penetration ratio (PR) and CWG gradation, affect the consolidation behavior and undrained shear strength of reinforced soft soils. This study evaluates the performance of CWG granular columns installed in soft soil represented by kaolin clay. The floating and end-bearing CWG columns with varying gradations were investigated under undrained and consolidation loading conditions. Consolidation and shear strength responses were assessed to quantify the effect of the PR and CWG gradation on soil performance. The results indicate that the CWG column significantly reduces settlement and soil compressibility while improving drainage characteristics. Among the tested configurations, the end-bearing well-graded CWG column provided the greatest improvement, demonstrating a high reduction in total settlement and fast consolidation due to enhanced vertical drainage. These findings highlight the potential of crushed waste glass as an alternative recycled material for granular column reinforcement in soft soil improvement. Full article

Ottoman mosques represent a unique synthesis of architectural elegance and structural ingenuity, where massive masonry domes are balanced on slender supports through carefully engineered load transfer systems. These monumental buildings, constructed centuries ago without modern analytical tools, continue to challenge contemporary engineers seeking to understand their behavior under seismic loading. This study presents an integrated evaluation of the structural and geotechnical performance of the 16th-century Sultan Selim Mosque in Konya, Türkiye, one of the most prominent examples of Classical Ottoman architecture. The research combines ambient vibration testing (AVT), geotechnical investigations, and finite element modeling (FEM) to assess the existing structural condition and soil–structure interaction (SSI) effects. Dynamic identification through AVT provided the modal characteristics of the mosque, which were used to calibrate a detailed three-dimensional FEM developed in ANSYS Workbench using a macro-modeling approach. The numerical analyses showed that observed deformation patterns and stress concentrations are consistent with field damage observations, indicating that differential settlements and heterogeneous subsoil stiffness are the primary factors influencing the structural response. The findings enhance understanding of the seismic behavior of monumental masonry domed structures and offer a solid basis for the evaluation and conservation of Ottoman-era architectural heritage. Full article

This study investigates the thermo-mechanical response of geocell-reinforced concrete pavements through scaled model tests and three-dimensional finite element analyses. Static, thermal, traffic, and coupled temperature–loading tests were conducted to clarify the deformation evolution, strain distribution, and damage-related response of the reinforced structure. The results show that, under static loading, pavement settlement evolves through three stages, namely initial compaction, plastic development, and stable strengthening, indicating progressive mobilization of geocell confinement. Under thermal loading, slab strain exhibits pronounced spatial and temporal non-uniformity, and the slab center is identified as the thermally sensitive zone. Under coupled temperature–loading conditions, both strain and settlement show a non-monotonic response near 1.1–1.3 kN, suggesting a potential damage-initiation range. Post-test crack observations further provide direct qualitative evidence that local cracking damage occurred in the slab under representative loading conditions. Under traffic loading, permanent deformation accumulates with load repetitions and is highly sensitive to load amplitude, indicating a load-sensitive transition in cumulative deformation behavior rather than a definitive fatigue threshold. Numerical results further show that geocell reinforcement reduces central settlement by 17.4% relative to plain concrete pavement and by 7.6% relative to doweled pavement, while producing a smoother deflection basin and a more uniform stress distribution. Parametric analyses indicate that the optimum geocell height is approximately one-third of the slab thickness; beyond this range, the marginal reinforcement benefit decreases. Overall, the results demonstrate that geocell reinforcement can effectively improve load transfer, deformation compatibility, and thermo-mechanical stability of concrete pavements under the investigated conditions. Full article

Predicting the settlement behavior of jet-grout column groups in reclaimed coastal areas remains a significant geotechnical challenge, as conventional models do not capture the complex interaction between isolated stiff columns and the compliance of the composite system under wide-area loading. This study presents a field-calibrated analytical approach that reconciles single-column mechanics with full-scale group performance at a port terminal founded on highly compressible, liquefaction-prone marine backfill improved by 800 mm jet-grout columns. An extensive field-testing program—including cone penetration tests (CPTs), single-column load tests (SCLTs), and surface loading tests (SLTs)—was conducted. SCLT results revealed an elastic modulus exceeding 10 GPa, and CPT data confirmed up to a 250% increase in inter-column soil tip resistance. However, SLTs under an 85 kPa operational load yielded a back-calculated system stiffness of approximately 105 MPa, which is drastically lower than the theoretical unit cell prediction of 933 MPa. This empirical relation demonstrates that unit cell models fundamentally overestimate jet-grout group stiffness. Rather than proposing a site-specific static mobilization factor (β ≈ 0.11), this study introduces a novel, adaptive methodology. By systematically integrating single-column rigidity, group interaction, and stress transfer mechanics into untreated soil, this framework establishes a robust paradigm for accurately predicting composite stiffness and settlements across diverse geotechnical conditions. Full article

This study investigates the seismic response of reinforced soil retaining walls through reduced-scale 1 g shaking table experiments, with particular emphasis on deformation behavior and pore water pressure generation in saturated sandy soils. Physical models were constructed using Firuzkuh silty sand and extensible fabric reinforcement, considering two soil conditions: an undisturbed loose state and a compacted state with a relative density of 35%. Horizontal dynamic loading with peak acceleration ranging from 1 g to 3 g was applied, while acceleration, displacement, and pore water pressure responses were continuously monitored. The results demonstrate a pronounced depth-dependent pore water pressure response, with deeper soil layers exhibiting higher magnitudes and longer persistence of excess pore pressures. In the undisturbed loose sand, the excess pore water pressure ratio approached unity at depth, indicating near-liquefaction conditions. In contrast, moderate densification significantly reduced pore pressure buildup and promoted partial dissipation during shaking. Reinforcement and compaction were found to effectively limit lateral displacement and settlement, leading to improved seismic performance. The findings highlight the critical roles of soil fabric, density, and reinforcement in controlling deformation and liquefaction susceptibility of reinforced soil retaining walls under seismic loading. Full article

This paper presents the design and analysis of solar systems for agricultural applications and the sustainable energy supply of villages, based on a case study of a rural settlement comprising 30 households. The village energy demand is quantified through a detailed assessment of hourly load profiles for daytime and nighttime operation, identifying peak loads and total daily energy consumption. Energy usage patterns are established for residential buildings, agricultural water pumping, public lighting, healthcare facilities, and commercial services. To meet these energy requirements sustainably, a 60 kW photovoltaic (PV) system is proposed in combination with a solar thermal water heating system designed to supply domestic and agricultural hot water. This study details the design methodology and simulation of the solar thermal system, including heat transfer modeling and system dimensioning. MATLAB (V.22b) simulations are conducted to evaluate system performance, covering PV energy generation, battery charge–discharge cycles, and thermal behavior over a 24 h period. Comparative analyses of standalone PV, hybrid PV/T, and combined PV and solar thermal configurations demonstrate that separate PV and thermal systems provide superior cost-effectiveness, operational reliability, and reduced maintenance requirements. The results confirm the technical feasibility, economic viability, and environmental benefits of solar-based solutions for rural electrification and agricultural applications. The results indicate that the analyzed rural settlement has an estimated daily electricity demand of approximately 590 kWh. Based on this demand, a 60 kW photovoltaic system was selected to ensure sufficient daytime electricity production while also allowing battery charging for nighttime consumption. In addition, the solar thermal system can increase the water temperature from approximately 10 °C to 55–80 °C, depending on solar irradiance conditions. The combined PV and solar thermal configuration demonstrates the potential to provide a reliable and sustainable energy solution for rural off-grid communities. Full article

To address the potential threat of surface subsidence caused by coal mining to the safe operation of buried gas pipelines in goaf collapse areas, this study investigates the geological conditions of the Mugu Coal Mine in Shanxi Province, China, and a gas pipeline passing through its surface mining area. Using a combination of numerical simulations and physical analog modeling, the mechanical response and deformation characteristics of the pipeline under mining-induced influences were systematically analyzed from three perspectives: the failure mechanisms of surface soil, the pipe–soil interaction behavior, and the damage evolution of the pipeline within the goaf. The research reveals a separation-induced failure pattern of the gas pipeline in mining-affected areas, referring to the mechanism in which differential settlement causes pipe–soil detachment, leading to unsupported bending deformation and stress concentration. Results show that the subsidence basin expands rapidly when the working face advances between 150 m and 210 m. Before this stage, the pipeline and surface soil deform synergistically with a symmetric subsidence curve centered on the goaf and uniformly distributed loads, showing no significant damage. During this stage, non-synergistic deformation occurs, leading to separation between the pipeline and soil. The maximum subsidence point shifts away from the center, destroying symmetry and causing stress concentration at the mining boundary, the advancing working face, and the goaf center, resulting in severe bending and rapid failure. After this stage, the pipe–soil interaction restabilizes with reduced separation height and extent, though pipeline deformation and damage continue to increase gradually. These findings provide a theoretical basis for engineering design optimization, targeted reinforcement measures, and monitoring strategies for gas pipelines in similar goaf collapse areas. Full article

This study investigates the mechanical behavior of jointed rock mass tunnels through numerical simulations using UDEC software. Focusing on the time-dependent variation in joint shear stiffness, a theoretical model is proposed to characterize the evolution of shear stiffness over time. Based on this model, numerical simulations are conducted to analyze tunnel stability and associated deformation patterns. A variable shear stiffness model is first established in UDEC, which effectively captures the evolution of shear creep displacement along rock joints. Incorporating this model, an adaptive support scheme involving locally extended rock bolts is introduced to improve long-term tunnel stability. The proposed approach is further validated through a comparative analysis with field monitoring data obtained from a tunnel in Yunnan Province. The results indicate that creep effects significantly influence tunnel behavior, leading to rapid increases in crown settlement and expansion of the surrounding rock disturbance zone during the early stages following excavation. Optimizing the bolt layout is shown to effectively reduce the extent of the disturbed zone and enhance the tunnel’s load-bearing capacity. Finally, a novel reinforcement optimization method for jointed rock mass tunnels is proposed, along with a key threshold value for assessing tunnel stability, thereby providing theoretical support for practical engineering applications. Full article

Earthfill dams located in seismic regions are highly vulnerable to earthquake-induced deformations, particularly when founded on soft alluvial soils. This study presents a comparative numerical investigation of earthfill dams with asphalt and clay cores subjected to seismic loading. A 20 m-high zoned embankment dam founded on soft alluvial deposits was modeled in PLAXIS2D and subjected to four earthquake records. The dynamic responses at the crest and downstream slope were evaluated in terms of acceleration, settlement, and lateral displacement. The results indicate that while lateral displacements are nearly identical for both core types, dams with clay cores experience significantly higher seismic settlements, reaching up to 35% more than those with asphalt cores under strong earthquake loading. Overall, the asphalt core demonstrated enhanced resilience, exhibiting reduced settlement due to its higher stiffness, viscoelastic behavior, and inherent capacity for self-healing following seismic loading. Full article

This paper presents a comprehensive methodology for developing a numerical model of a masonry wall using the Non-Smooth Contact Dynamics (NSCD) method implemented in the open-source software LMGC90 version 2025. The modeling procedure relies on Python scripting and includes defining material properties, importing geometry from CAD tools, configuring the model, and specifying contact interactions between discrete elements. Each brick is modeled as an individual rigid element, allowing realistic simulation of frictional and cohesive behavior at joints. It outlines key theoretical aspects of the NSCD framework, including the formulation of global and local variables, interaction laws, and numerical integration. Numerical examples demonstrate the discrete element approach’s ability to capture complex in-plane and out-of-plane structural phenomena induced by seismic loading and differential foundation settlement. The results highlight the advantages of discrete modeling in representing discontinuities and failure processes that are difficult to simulate with a conventional continuum-based approach. Full article