This study provides a comprehensive analysis of the undrained failure envelope for spudcan foundations in anisotropic clays using the AUS failure criterion as the soil strength model. The influence of embedment depth (L/D) and anisotropic strength (re) on spudcan behaviour under combined loading conditions is investigated. Failure envelopes are derived through three-dimensional finite element limit analysis (3D FELA) in both (H/ suTCA, M/suTCAD) and (V/Vult, H/suTCA, M/suTCAD) spaces. The study also illustrates spudcan foundation failure mechanisms, providing valuable insights for designing footings in anisotropic clays under combined loads (V, H, M). Additionally, an innovative soft-computing approach is introduced: a machine learning model that integrates categorical boosting (CatBoost) with the flower pollination algorithm (FPA) for optimized predictions of the spudcan failure envelope. The proposed FPA-CatBoost model is validated against numerical FELA results, demonstrating a strong correlation and offering engineers a reliable tool for determining spudcan foundation failure envelopes under varied loading conditions.

This study investigates the shear parameters of sand modified with varying percentages of Portland cement and polyvinyl alcohol (PVA) fibers. Seventy-two static strain-controlled consolidated-drained (CD) triaxial compression tests were conducted on saturated samples. The study evaluated the effects of various factors, including relative density (50% and 80%), cement content (0%, 2%, and 4%), fiber content (0%, 0.5%, and 1%), and confining pressures (50, 100, 300, and 500 kPa), on the peak and residual shear strength parameters of the samples. The findings revealed that increasing the cement content enhances the peak internal friction angle and peak cohesion, while cementation has minimal impact on residual cohesion and residual internal friction angle. Fiber reinforcement improved peak cohesion, peak internal friction angle, residual cohesion, and residual internal friction angle of the sand. The rate of improvement in peak internal friction angle due to fiber addition decreased with higher cement content and dry density, whereas the increase in peak cohesion was more pronounced at higher cement percentages. Furthermore, the influence of cementation on shear strength parameters was more significant in denser samples. These results provide valuable insights for improving the design methodologies of reinforced soil structures such as retaining walls and foundations.

The advantages of constitutive models in energy-conservation frameworks have been widely addressed in the literature. A key component is choosing an appropriate energy potential to derive the hyperelastic constitutive equations. This article investigates the advantages and limitations of different energy potentials found in the literature based on mathematical conditions to guarantee numerical stability, such as the desired order of homogeneity, positive and non-singular stiffness within the application range, and equivalent Poisson's ratio from a constitutive modelling standpoint. Potentials meeting the aforementioned criteria are employed to simulate the response envelopes of Karlsruhe fine sand (KFS). Moreover, the performance of the potentials, in conjunction with plasticity theories, is examined. To achieve this, the hyperelastic constitutive equations have been coupled with the bounding surface plasticity model of Dafalias and Manzari to reproduce the soil response in a hyperelastic-plastic frame. Finally, one of the potentials is modified, whereas recommendations for incorporating other appropriate free energy functions into different soil constitutive models are presented. Furthermore, 100 closed elastic strain cycles have been simulated with the bounding surface plasticity model of Dafalias and Manzari considering the original hypoelastic stiffness and hyperelastic-plastic constitutive equations. Using the hypoelastic framework in the simulation led to stress accumulation after 100 closed elastic strain loops, while a reversible response was predicted using the hyperelastic stiffness tensor.

This paper provides a comprehensive analysis of the undrained failure envelope for embedded foundations in anisotropic clays. Using the AUS failure criterion as the soil strength model, the study examines how the anisotropic strength (re) and embedment depth (D/B) affect the behavior of the footing under combined loading conditions. Failure envelopes are assessed via two-dimensional finite element limit analysis (2D FELA) in both 2D and 3D spaces. This research highlights the failure mechanisms of embedded foundations, offering valuable insights into the engineering design of footings in anisotropic clays subjected to combined loads (V, H, M). Furthermore, this study introduces an advanced soft-computing approach by creating a machine learning model that leverages the adaptive neuro-fuzzy inference system (ANFIS) integrated with the particle swarm optimization (PSO) algorithm to predict the failure envelope of embedded footings, highlighting the novelty and original of this study. The optimised ANFIS model has been validated and demonstrates a strong correlation with the numerical FELA results, offering engineers a valuable tool for determining the failure envelope of embedded foundations in anisotropic clay under different loading scenarios (V, H, M).

Hydrologic-land surface models (H-LSMs) offer a physically-based framework for representing and predicting the present and future states of the extensive high-latitude permafrost areas worldwide. Their primary challenge, however, is that soil temperature data are severely limited, and traditional model validation, based only on streamflow, can show the right fit to these data for the wrong reasons. Here, we address this challenge by (1) collecting existing data in various forms including in-situ borehole data and different large-scale permafrost maps in addition to streamflow data, (2) comprehensively evaluating the performance of an H-LSM with a wide range of possible process parametrizations and initializations, and (3) assessing possible trade-offs in model performance in concurrently representing hydrologic and permafrost dynamics, thereby pointing to the possible model deficiencies that require improvement. As a case study, we focus on the sub-arctic Liard River Basin in Canada, which typifies vast northern sporadic and discontinuous permafrost regions. Our findings reveal that different process parameterizations tend to align with different data sources or variables, which largely exhibit inconsistencies among themselves. We further observe that a model may fail to represent permafrost occurrence yet seemingly fit streamflows adequately. Nonetheless, we demonstrate that accurately representing essential permafrost dynamics, including the active soil layer and insulation effects from snow cover and soil organic matter, is crucial for developing high-fidelity models in these regions. Given the complexity of processes and the incompatibility among different data sources/variables, we conclude that employing an ensemble of carefully designed model parameterizations is essential to provide a reliable picture of the current conditions and future spatio-temporal co-evolution of hydrology and permafrost.

The synergetic effects of alkaline red mud (RM) and sulfate-based phosphogypsum (PG) on the undrained triaxial behavior of cement-admixed clay were explored in this study. A series of isotropically consolidated undrained triaxial tests were performed on stabilized clay with respect to different admixed RM/PG proportions. The triaxial behavior of stabilized clay is presented in terms of a stress-pore pressure-strain relationship, failure mode, undrained deformation modulus, stress path, and failure envelope. Scanning electron microscopy (SEM) tests were conducted to survey microscopic evolution. The results showed that the brittleness of the specimen intensified with a high RM content, which was manifested by a predominant postpeak strength reduction. As the PG content increased, the strain-softening behavior weakened and gradually evolved into strain-hardening. The failure mode changed from local shear failure to the single cone failure and bulging failure correspondingly. The RM played a role in increasing soil cohesion, whereas PG contributed to a larger frictional angle at the postyield stage. Microscopic observations indicated that the alkali source from RM significantly promoted pozzolanic reactions and strengthened cementation bonds, which increased the peak strength, deformation modulus, and cohesion. In addition, the sulfate in PG contributed to ettringite generation among clay particles and clusters, resulting in a more ductile behavior and a larger frictional angle due to large clusters formed.

This paper proposes a new method for computing the undrained lateral capacity of Reinforced Concrete (RC) piles in cohesive soils, overcoming inherent conservativeness of classical Broms' theory. The proposed method relies on a new theoretical distribution for the limiting soil resistance, simple enough to derive closed-form solutions of the undrained lateral capacity, for different restraints at the pile head and for all possible failure mechanisms. After validation against numerical results and experimental data, the model is used to compute the failure envelope of RC piles under generalised loading. 3D FE analyses are used as benchmark to identify the main factors governing the ultimate response of RC piles. To this purpose, the Concrete Damaged Plasticity model is adopted to reproduce nonlinear concrete behaviour, which is an essential ingredient when modelling pile behaviour under horizontal loading. FE analyses show that, contrary to what observed for rigid and elastic piles, the ultimate response of RC piles relies on the soil strength mobilised at shallow depths, where the normalised lateral soil resistance basically depends on the sole adhesion factor. The proposed solutions are readily applicable to the design of single piles, as well as to the computation of three-dimensional interaction domains of pile groups.

Several methods have been used over time to improve the mechanical properties of fine-grained soils. One of the recently introduced materials for soil stabilization is incinerated sewage sludge ash (ISSA). This material is a by-product of the wastewater treatment process that is usually disposed of during the treatment cycle. This paper investigated the effects of adding the optimum amount of ISSA and a mixture of ISSA with hydrated lime (IL) on the mechanical properties of dispersive fine-grained soil. The effects of curing time on the UCS was also evaluated. The Mohr-Coulomb failure envelope parameters of the mixtures were subsequently estimated based on the performed test results using the Consoli et al (J Mater Civ Eng 27(5):04014174, 2015) method which eliminates the need to perform triaxial tests. The results indicated that ISSA and IL can improve the mechanical characteristics of the dispersive soil effectively and that curing time was substantial for better performance of the treated soil. Finally, the application of the Consoli and others method to predict the failure envelope parameters of the treated soil was evaluated using triaxial tests. The comparison of the results proved the suitability of the proposed method to estimate the failure envelope parameters of the ISSA and IL-treated dispersive soil.

The contribution presents the results of field research aimed at assessing the effects of the Phlaegrean Bradyseism phenomena on a building system located in the historic centre of Pozzuoli (Italy). The study falls within the scope of building fa & ccedil;ade vulnerability analyses conducted by the authors to support the Public Administration in managing bradyseismic emergencies. Considering that the seismic-deformation phenomena connected to Bradyseism affect the performance and integrity of fa & ccedil;ade components, the research focused on studying its impact on the technical elements within the Technological Unit Classes of Load-bearing Structure, Enclosure, and External Partition, which directly project onto the external environment and collectively constitute the Building Envelope. The methodology for impact assessment was developed by correlating data acquired from a monitoring system installed on the fa & ccedil;ade of a surveyed building with characteristic parameters related to seismic events and soil deformations in a specific reference period. The analyses conducted excluded any significant impact of these seismic-deformation forcings on the building's Load-bearing Structure, both in terms of displacements and damage. On the other hand, significant impacts were found on the technical elements of the building envelope, which, due to their lower resistance and ductility, represent a constant hazard for the exposed urban system's safety, configuring a Building Risk scenario.

Given the critical role of true triaxial strength assessment in underground rock and soil engineering design and construction, this study explores sandstone true triaxial strength using data-driven machine learning approaches. Fourteen distinct sandstone true triaxial test datasets were collected from the existing literature and randomly divided into training (70%) and testing (30%) sets. A Multilayer Perceptron (MLP) model was developed with uniaxial compressive strength (UCS, sigma c), intermediate principal stress (sigma 2), and minimum principal stress (sigma 3) as inputs and maximum principal stress (sigma 1) at failure as the output. The model was optimized using the Harris hawks optimization (HHO) algorithm to fine-tune hyperparameters. By adjusting the model structure and activation function characteristics, the final model was made continuously differentiable, enhancing its potential for numerical analysis applications. Four HHO-MLP models with different activation functions were trained and validated on the training set. Based on the comparison of prediction accuracy and meridian plane analysis, an HHO-MLP model with high predictive accuracy and meridional behavior consistent with theoretical trends was selected. Compared to five traditional strength criteria (Drucker-Prager, Hoek-Brown, Mogi-Coulomb, modified Lade, and modified Weibols-Cook), the optimized HHO-MLP model demonstrated superior predictive performance on both training and testing datasets. It successfully captured the complete strength variation in principal stress space, showing smooth and continuous failure envelopes on the meridian and deviatoric planes. These results underscore the model's ability to generalize across different stress conditions, highlighting its potential as a powerful tool for predicting the true triaxial strength of sandstone in geotechnical engineering applications.