Search Results (689)

Designers traditionally perform the preliminary sizing of foundations based on engineering judgement, relying on parameters such as superstructure loads and the characteristics of the supporting soil. This process must adhere to strict guidelines for wind turbine foundations to ensure structural stability and compliance with regulatory standards. This study proposes a computational model based on genetic algorithms to optimise the dimensions of wind turbine foundations. The fitness function combines two normalised objectives, namely concrete volume and bending moment, while structural and geotechnical requirements are imposed as constraints. The model was validated using six real-world case studies, achieving consistent reductions in concrete volume compared with the original designs, with an average reduction of 19.5%. Each case was run 10 times to assess the consistency of the solutions obtained. The results demonstrate the effectiveness of the proposed approach in identifying more material-efficient foundation geometries while satisfying the adopted design constraints. It should be emphasised that the reported savings refer specifically to concrete volume reduction and should not be interpreted as total foundation cost savings, since reinforcement design and detailing are outside the scope of the present model. This study is restricted to foundations with circular cross-sections, thereby opening avenues for future research aimed at extending the optimisation framework to alternative geometric configurations and incorporating reinforcement design. Full article

Ground-motion intensity measures (IMs) are key parameters for seismic hazard and risk assessment. However, seismic hazard characterization and code-based design spectra commonly rely on a limited set of parameters, particularly peak ground acceleration (PGA), spectral acceleration, and control periods defining spectral shape. Such representations may not fully capture seismic input relevant to structural response, soil deformation, slope instability, and indirect environmental impacts. This study analyzes 220 horizontal accelerogram components recorded during the Vrancea earthquakes of 4 March 1977, 30 August 1986, 30 May 1990, and 31 May 1990. Twenty-three IMs were computed, covering peak and effective amplitudes, velocity-related measures, cumulative and energy-based indicators, spectral intensities, duration, cyclicity, and impulsivity, together with a set of frequency content-related parameters. Pearson and Spearman correlations were evaluated using both the geometric mean and the maximum of the two horizontal components. Hierarchical clustering, PGA-centered correlation profiles, event-specific comparisons, and spatial representations were used to assess redundancy, complementarity, and relationship stability. Results show that amplitude-, velocity-, and spectrum-related IMs form strongly correlated groups, whereas duration, cyclicity, and impulsivity remain more distinct. Spatial comparisons also show that different IMs may produce different station rankings and regional patterns for the same event. These findings support selecting complementary IM families for more comprehensive, risk-informed structural and geotechnical applications. Full article

Landslides in weathered gypsum deposits present significant geotechnical challenges because progressive weathering, groundwater fluctuations, and residual strength degradation strongly influence slope stability. This study investigates the failure mechanism and remediation of a large translational landslide in weathered gypsum deposits in Çankırı, Türkiye. An integrated engineering geological assessment was conducted using data from 16 boreholes, laboratory tests, and groundwater/inclinometer monitoring records, followed by residual shear strength back-analysis and slope stability evaluation. A three-dimensional geological model was developed, and cross-sections were analyzed using the Morgenstern–Price limit-equilibrium method. Back-analysis identified residual shear strength parameters of c′ = 7.5 kPa and ϕ′ = 10° for the weathered gypsum, while laboratory direct shear tests yielded c′ = 4.0 kPa and ϕ′ = 9.9°. The friction angles obtained from the two approaches are nearly identical, whereas the back-calculated cohesion is slightly higher than the laboratory-derived value. Back-analysis parameters were used to design remediation measures, including slope unloading, rock buttress construction, toe fill improvement, and surface/subsurface drainage. Stability analyses increased the factor of safety to 1.76 under static loading, while pseudo-static analyses satisfied the recommended seismic design criterion (FS ≥ 1.10). Equivalent-linear Newmark analyses predicted a permanent displacement of 15 cm, within acceptable limits. The methodology provides a practical framework for assessing and stabilizing landslides developed in weathered gypsum deposits in seismically active regions. Full article

Clay slopes are particularly sensitive to variations in soil strength, groundwater conditions, and slope geometry, making their rapid and reliable assessment essential for geotechnical design, landslide prevention, and infrastructure risk management. This study develops and evaluates an empirical express method for estimating the stability of clay slopes based on the relationship between soil mechanical parameters, slip surface geometry, and the factor of safety. The proposed approach derives empirical dependencies for the radius of the potential circular slip surface and the coordinates of its centre as functions of slope height, cohesion, internal friction angle, and water-related conditions. The method is supported by long-term field observations and geotechnical investigations of clay slopes, including dry and water-affected scenarios. Two representative stability conditions are considered: dry slopes and slopes influenced by an elevated depression curve. The method was evaluated for 45° clay slopes with heights up to 60 m, using eight representative cases: four dry scenarios and four water-affected scenarios. The calculated factors of safety were compared with GEO5 SLOPE results obtained using Bishop’s simplified method. The comparison showed that most analysed cases presented differences below 5% between the proposed express method and the Bishop-based numerical benchmark, with larger deviations occurring only in selected boundary cases. The results demonstrate that the proposed method can provide a rapid preliminary assessment of clay slope stability, supporting early-stage geotechnical diagnosis, risk screening, and decision-making in regions where clayey formations and slope instability are recurrent. Full article

Clayey sand is a typical transitional coastal alluvial soil controlled by both coarse-grain friction and fine-grain cementation. Current studies focus mostly on remolded samples, lacking systematic understanding of water-induced structural degradation and quantitative physico-mechanical correlations for natural undisturbed clayey sand. In this work, 74 intact undisturbed specimens (0.5–23.0 m depth) were tested via basic physical tests, one-dimensional consolidation and consolidated-undrained triaxial shear tests. Pearson correlation analysis was performed to establish prediction relationships between routine physical indices and mechanical parameters. Results show the soil is classified as SC clayey sand with 39.70% fines and an average natural water content of 23.17%. Natural water content dominates soil engineering performance, presenting strong linear correlations with dry density and void ratio (|r| = 0.90). Higher water content and void ratio increase compressibility and reduce shear strength. The compression coefficient and compression modulus exhibited a consistent nonlinear relationship, reflecting the inherent linkage between these two compression parameters. Burial depth has little influence on soil properties, and plasticity index only serves for soil classification. Mechanistically, increasing moisture may thicken adsorbed water films, weaken interparticle contact and matric suction, and the fine particle-filled skeleton may further enhance the water sensitivity of the soil. The established prediction models support fast evaluation of soil mechanical behaviors, offering theoretical and practical support for geotechnical design of similar coastal clayey sand strata. Full article

Ensuring the stability of coal mine roofs is a critical technical prerequisite for safe underground operations and the structural stability of underground engineering systems in mining areas. However, roof instability is governed by the variability and dependence structure of multiple geotechnical parameters, including elastic modulus, Poisson ratio, cohesion, and internal friction angle. To address the challenges of insufficient modeling accuracy for multivariate joint distributions and the difficulty of tail-risk assessment under small-sample constraints, this study proposes reproducible data generation methods using the D-Vine Copula and Tabular Variational Autoencoder (TVAE) for assessing the reliability risk of coal mine roof structures from multiple sources. Based on 192 sets of measured data, the performance of both methods in simulating the multivariate joint distribution of geotechnical parameters is systematically compared. The results indicate that the key geotechnical parameters of the coal mine roof exhibit pronounced non-normal marginal distributions, nonlinear inter-variable dependence, and sparse data coverage in high-value regions. Both simulation methods are capable of effectively characterizing the asymmetric dependency structures among the parameters. Nevertheless, D-Vine Copula exhibits considerable statistical uncertainty in tail parameter estimation, resulting in substantial extrapolation of simulation samples for elastic modulus and cohesion. In contrast, TVAE provides a more robust statistical basis than the Copula approach for tail risk assessment under extreme parameter combinations. The proposed methodology offers a critical data foundation for stability analysis in complex geological conditions, thereby supporting disaster prevention and providing a reliable engineering basis for the structural design and risk control of underground mining systems. Full article

To investigate the mechanical properties of coarse-grained soil in high-altitude mountainous areas, experimental research was conducted to explore the shear process, shear modulus, shear dilation, and stress axis rotation of coarse-grained soil under varying conditions. The sensitivity and mechanisms of these factors were also analyzed. The results indicate that increasing water content and fine particle content significantly diminish the strain-hardening characteristic, whereas dry density and normal stress augment this effect. Under shear stress, the samples exhibit pronounced non-uniform shear dilatancy. Elevated water content, fine particle content, and normal stress enhance shear contraction at the rear of the sample while suppressing shear dilation at the front. In contrast, dry density produces the opposite effect. The rotation of the stress axis initially follows a nonlinear growth pattern before transitioning to linear growth. The growth rate and ultimate rotation angle increase monotonically with water content, fine particle content, and normal stress but decrease with increasing dry density. Additionally, the shear modulus decreases exponentially with increasing water content and increases exponentially with dry density, fine particle content, and normal stress. Ultimately, normal stress is identified as the most sensitive factor, followed by dry density and fine particle content, with water content being the least sensitive. These findings can provide geotechnical parameters and a theoretical basis for the scientific prevention of high-altitude geological hazards. These findings can provide indoor mechanical parameters and deformation laws of coarse-grained soils for engineering. Full article

Recycled tire polymeric fiber (RTPF) is a type of nylon fiber recovered from end-of-life tires. Depending on the processing stages, RTPF exists in two forms, fibrils (FS) and fiber bundles (FB). Although fiber reinforcement has been widely investigated for cement-stabilized soils, the fracture behavior and reinforcing mechanisms of RTPF remain insufficiently understood. Three-point bending tests using DIC, CT, and SEM analyses were conducted. The results indicate that RTPF delays crack initiation, increasing both the time interval from initiation to fracture and the ultimate crack width. Flexural strength increases with RTPF content and exhibits a power-law relationship. Both FS and FB significantly improve unstable fracture toughness, increasing it from 0.19 MPa·m^1/2 in the control specimen to 0.37 MPa·m^1/2 and 0.78 MPa·m^1/2, respectively. Fracture energy increases by 49% and 228%, respectively. The peak reinforcing efficiency was achieved at the RTPF content of 0.2–0.4% for FS and 1–2% for FB. The higher distribution coefficients and lower orientation reflect an isotropic fiber distribution, which is beneficial for inhibiting multi-directional crack propagation. A calculation method was developed to estimate fracture toughness from the fiber reinforcing parameter, with the findings showing good agreement with experimental results. These findings demonstrate the feasibility of utilizing RTPF as a sustainable reinforcement material for improving the fracture resistance of cement-stabilized soils in geotechnical engineering applications. Full article

Bauxite residue (red mud) is a highly alkaline byproduct of the alumina refining process generated in large volumes worldwide. Most alumina operations currently rely on long-term storage facilities due to the high costs and technical constraints of residue reuse technologies. Therefore, understanding the mechanical behaviour of bauxite residue is critical to minimising environmental contamination risks, preventing structural failures, and ensuring the long-term stability of storage facilities. However, obtaining reliable geotechnical parameters is challenging due to the residue’s complex composition and chemical characteristics, particularly given the current fragmented state of the literature. This review compiles an extensive database of bauxite residue parameters across alumina operations worldwide, synthesising existing knowledge and research needs. The database encompasses 940 data points extracted from 63 studies across 25 countries. The findings reveal considerable variability in parameter values across countries, potentially exacerbated by inconsistencies in experimental methodologies. Few studies have integrated geochemical conditions, such as pH and salinity, with geomechanical behaviour, thereby limiting understanding of the mechanisms that govern key parameters, including strength and deformability. Enhancing the predictability of bauxite residue behaviour requires the development of standardised experimental protocols that explicitly account for the coupled effects of chemistry and mechanics to support reliable risk assessments of storage facilities. Full article

The accurate and rapid estimation of water content in granular materials is important for geotechnical engineering, construction-material evaluation, agricultural monitoring, and non-destructive material assessment. This study presents a controlled laboratory feasibility framework for estimating water content in sand–water mixtures using microwave S-parameter measurements and physically interpretable features. Sixty measurements were acquired from six nominal mixture levels containing 0%, 5%, 10%, 15%, 20%, and 25% water by mass using a WR-229 waveguide-based fixture over 3.30–4.90 GHz. Descriptors were extracted from the raw and empty-reference-normalized S₁₁ and S₂₁ responses, including extrema, slopes, area-based indicators, band-averaged values, selected-frequency responses, and phase statistics. Ridge regression, partial least squares regression, support vector regression, Gaussian process regression, random forest, and gradient boosting regression were evaluated. The selected PLS model achieved RMSE = 3.56%, MAE = 2.92%, and R² = 0.826 under leave-one-mixture-level-out group-wise cross-validation, which was used as the primary indicator of generalization to an unseen mixture level. The substantially lower error obtained under repeated-measurement leave-one-out cross-validation primarily reflects within-level repeatability under controlled conditions and should not be interpreted as evidence of universal calibration performance. The results demonstrate that magnitude- and phase-derived microwave descriptors, particularly transmission-based features, provide an interpretable and repeatable framework for water-content estimation under the specific sand type, sample geometry, water source, and laboratory conditions investigated. Further validation using independent preparation batches, different granular materials, measured water conductivity, temperature variation, and field-like conditions is required before practical deployment. Full article

The coefficient of earth pressure at rest, K₀, is central to defining initial stress states in soils, yet its estimation remains uncertain because formulations differ in calibration basis, governing variables, and physical meaning. This review examines and compares more than 40 analytical, empirical, experimental, and constitutive-model-based approaches for estimating K₀. The formulations are classified by soil type, stress history, determination method, and limitations, covering friction-angle- and OCR-based correlations, laboratory testing, in situ inference, and field-oriented developments. The comparison shows that values reported under the common notation K₀ are not necessarily equivalent, because they may represent different loading paths, material states, or interpretations of zero lateral strain. For the selected friction-angle-based formulations, extreme predictions define a relatively broad envelope, whereas most expressions cluster within a narrower band. However, this variability does not translate uniformly into engineering response. Its significance depends on soil type, stress history, and whether the initial stress state persists or is modified by construction-induced deformation and stress redistribution. The unresolved issue is therefore not the absence of estimation methods but their limited transferability across geotechnical contexts. K₀ should consequently be selected as a modelling parameter with explicit consideration of its physical basis, applicability, and expected influence on the problem under analysis. Full article

Earthquake-induced soil liquefaction represents a severe geohazard causing catastrophic infrastructure failure in prone coastal zones, requiring an advanced environmental spatial assessment for their sustainable land-use planning. This study utilizes advanced computational intelligence models to predict earthquake-induced soil liquefaction in Boumerdès, Algeria, an area heavily affected by the 2003 (M_w 6.8) earthquake. Utilizing a comprehensive subsurface database of 1984 geotechnical records encompassing lithology, hydrogeological configurations, and seismic parameters, advanced deep learning frameworks are developed and optimized via automated Neural Architecture Search (NAS). The continuous Factor of Safety (F_s) is calculated to distinguish stable profiles from vulnerable strata, benchmarking conventional ANN and DNN models against NAS-optimized variants (NAS-ANN and NAS-DNN) using a stratified 5-fold cross-validation scheme. The optimized hybrid NAS-DNN framework effectively captured non-linear soil responses, achieving a training correlation coefficient ($R_{train}$) of 0.9518, a validation coefficient ($R_{validation}$) of 0.8843, and a cross-validated mean $R$ of approximately 0.82, demonstrating improved predictive reliability compared to traditional models. Ultimately, this optimal network is embedded into the ‘GeoLiquefy-AI (v1.0)’ interface. To ensure reliability for safety-critical applications, we integrated a SHAP explainable AI framework, validating the model’s geomechanical logic by mapping physical soil-liquefaction dependencies. This deployment-ready tool enables rapid, transparent hazard calculations, providing a scalable platform for seismic microzonation and proactive urban risk mitigation. Full article

The partial replacement of cement with waste-derived materials is a promising strategy for reducing cement consumption in soil–cement technologies and developing more sustainable construction materials. This study investigates fluidized bed bottom ash (BA), an industrial combustion by-product, as a partial Portland cement substitute in geotechnical cement–soil composites. Cement was replaced with BA at 5%, 10%, and 15% by mass, and specimens were tested after 3, 7, 14, and 28 days of curing. The research program combined SEM-EDS characterization, high-resolution X-ray computed tomography, uniaxial compression tests, in situ CT observations during loading, and FLAC3D mesoscale numerical modelling calibrated against experimental stress–strain curves and observed crack propagation. The results showed a non-monotonic effect of BA addition. Up to 10% BA, the median pore size remained relatively stable, whereas 15% BA increased porosity and enlarged the upper tail of the pore-size distribution. The calibrated model reproduced the global mechanical response with acceptable accuracy and captured main features of damage localization. The analyses are accompanied by a life cycle assessment (LCA). The study demonstrates that waste-modified cement–soil composites intended for sustainable soil stabilization should be evaluated not only by strength parameters, but also by internal structure, defect distribution, and environmental impact. Full article

Compression index (Cc) and recompression index (Cur) are essential parameters in one-dimensional consolidation and settlement analysis, yet their direct determination from oedometer testing is time-consuming, costly, and often limited by sparse recompression data. This study develops an interpretable and physically constrained machine-learning framework for the joint prediction of Cc and Cur from four routinely measured index properties: liquid limit (LL), plasticity index (PI), initial void ratio (e), and natural water content (w). A curated subset of 459 natural clay records from the global CLAY/Cc/6/6203 database was used to benchmark single-output and multi-output Random Forest, gradient-boosted tree, and deep neural network models. In addition to conventional random train–test and cross-validation protocols, a leave-one-location-out validation was introduced to evaluate transferability across 81 Country–Location groups. Under the random-split setting, Cc was predicted with moderate-to-good accuracy, with baseline models achieving test R² values of approximately 0.61–0.70 and a geotechnically enriched Random Forest model increasing the test R² to 0.777. Cur was more difficult to predict. Although feature enrichment improved its test R² to 0.507, location-aware validation reduced Cur performance substantially, confirming its stronger dependence on site-specific stress history, fabric, and geological structure. SHAP interpretation identified e and w as the dominant controls on Cc, while Cur exhibited weaker and more diffuse dependence on the available index properties. A physically constrained target transformation based on the bounded ratio of Cur/Cc guaranteed mechanically admissible predictions with Cur < Cc, but did not fully recover the missing information needed for accurate Cur estimation. The proposed constraint is not a governing-equation-based physics-informed model. Rather, it is a mechanically constrained target transformation that preserves the admissible relationship Cur < Cc. The results show that routine index properties can support the useful preliminary prediction of Cc, whereas Cur should be treated as a screening-level estimate unless explicit stress history descriptors are available. Full article

To clarify the bearing characteristics and load transfer mechanisms of long large-diameter pile foundations in dense silty fine sand strata within the middle and lower reaches of the Yellow River, a graded tension–compression anchor reaction loading test method was devised and implemented using a field-configured apparatus. This approach enables graded static load testing on large-tonnage long bored cast-in-place piles. Then, the relative displacement and settlement between pile and soil under vertical cyclic loading were analyzed. Finally, numerical simulations were adopted to study the settlement behavior of pile tops and ends under cyclic loads representative of beam yard operational conditions (20 cycles). Results indicate that, under vertical loading, the shaft friction resistance and tip resistance of large-diameter long bored cast-in-place piles are not mobilized simultaneously, but sequentially. The degree of shaft friction is related to the magnitude of pile top loading, soil properties, burial depth, and construction methods. The soil between piles generates vertical resistance to horizontal force-transfer rods, becoming part of the pile foundation’s bearing capacity and sharing the load. Moreover, in dense silty fine sand strata, long large-diameter pile foundations exhibit pure friction pile behavior. When calculating the bearing capacity of such piles, parameters from geotechnical reports based on code-specified values should be multiplied with corresponding correction coefficients. In addition, the shaft friction resistance in dense silty fine sand layers remains under-mobilized. Limited loading–unloading cycles in permanent–temporary integrated beam yard operations do not induce significant deformation in pile foundations, indicating minimal impact on their bearing performance. Full article