Hydro-Mechanical Transition and Collapse Behaviour of a Natural Lateritic Soil Under Wetting and ShearFalcão, Patricia Rodrigues; dos Santos, Jose Leonardo; Gomes, Luigi Tavares; Prior, Angelo Dotto Ragagnim; Baroni, Magnos
doi: 10.1007/s40098-026-01564-9pmid: N/A
This study investigates the wetting-induced collapse behaviour of a natural lateritic soil from southern Brazil, emphasizing the coupled hydraulic and mechanical effects that govern its instability. A comprehensive experimental program was conducted, combining one-dimensional consolidation, direct shear, and direct simple shear tests on undisturbed specimens, complemented by soil-water retention and microstructural analyses. The soil exhibits a pronounced dual-porosity structure that controls both suction retention and mechanical response. Upon wetting, an abrupt loss of strength and stiffness occurs due to the breakdown of interparticle bonding and suction, followed by structural reorganization and partial recovery of strength. Collapse deformation measured during shearing closely matches that obtained from conventional consolidation tests, confirming that collapse evolves concurrently with shear strain. Microscopic observations revealed structure breakdown and the formation of a denser and more aligned fabric after flooding under shear. The integrated approach adopted in this research enables a direct evaluation of hydro-mechanical transitions from suction-controlled to friction-dominated behaviour under realistic stress paths. The findings highlight the need to incorporate shear-path effects into the experimental assessment and design of foundations and earth structures on collapsible lateritic soils, contributing to a better understanding of wetting-induced instability in tropical environments.
Engineering Geological Baseline Condition Assessment of Sobe–Owan Bridge Substructure Using Integrated Non-destructive Geophysical Techniques and In-Situ Penetration TestingFalowo, Olumuyiwa Olusola; Oluwasegunfunmi, Victor; Ajiboye, Oluwatobi Babatunde; Otuaga, Moses Philip
doi: 10.1007/s40098-026-01562-xpmid: N/A
In Nigeria, bridge maintenance and monitoring programmes rarely include post construction subsurface geological material assessment. The geological material evaluation of the bridge site, even after construction, would assist in the identification of concrete spalling, lithologies delineation, developed fractures, groundwater level variation, scouring activities, and soil settlement. On this basis, the Sobe–Owan bridge site was investigated based on elevated vibration intensity recorded in previous studies. The study utilized integrated geophysical methods, stream water physical parameter measurement, and cone penetration testing. The result of the geological succession revealed alluvium sand and red sand (topsoil), clay alluvium sand mixture (i.e., subsoil, with an angle of friction of 40.86° and cohesion of 384.8 kPa), shale, and sandstone (basal rock). The depths to the basal rock vary from 20.7 to 38.4 m of irregular topography. Degree of scouring activity is at near surface (less than 5 m), with the occurrence of cross-cutting linear structures signified degree of sedimentation, water saturation, and scouring. The scouring action occurs notably within the vicinity of the foundation piers. The stream water’s high velocity during flow and physical quality showed that the water is capable of causing damage/spalling to the concrete due to favourable values of some parameters during the seasons. The minimum depth to pier/pile cap was found to be between 3.30 and 6.25, which implies there could be more stages of pier/pile cap within the subsurface system, since the minimum depth to basal sandstone is 20.7 m. This study concludes that no serious geological hazard has been identified, except near-surface scouring zones, which are normal for bridges over stream channels, although weakened/distressed rebar within the correct and or concrete might not be underrated.
Seismic Influence on the Behavior of Cantilever Sheet Pile Walls Under Strip-Type LoadingSingh, Akshay Pratap; Chatterjee, Kaustav; Bharti, Govind Kumar
doi: 10.1007/s40098-026-01545-ypmid: N/A
The dynamic response of cantilever sheet pile walls under strip surcharge loading and seismic activity is critical in earthquake-prone regions, emphasising the effects of distance, width of the surcharge, and seismic motions. The numerical analysis is being carried out in FLAC2D using a finite difference formulation to simulate a cantilever sheet pile wall installed in a liquefiable sand layer described by the UBCSAND model, resting on an underlying non-liquefiable layer characterized by the Mohr–Coulomb constitutive relationship. The backfill model included a strip load with variable width (0–4 m) and variable spacing (0–4 m) from the top of the wall, with a uniform surcharge of 20 kPa. Three significant seismic motions were analyzed: the 1994 Northridge, 1989 Loma Gilroy, and 2001 Bhuj earthquakes. Model performance was evaluated by comparing results with experimental results, demonstrating consistent trends in lateral displacement, bending moment distribution, and excess pore pressure development. It was observed that the maximum top displacement of the wall reduced from 1800 to 1660 mm with increased distance from the wall, while the maximum bending moment along the wall varied, reaching 211 kNm/m at a distance of 0 m for the Northridge motion. The study highlights the significant impact of strip surcharge loading on earth pressure distribution and liquefaction effects, providing valuable insights for designing and analyzing sheet pile walls in areas prone to seismic activity.
Enhancing Cyclic Liquefaction Resistance Through Targeted Calcite Precipitation: The Critical Role of Early-Stage Dilative Behavior and Relative AngularitySimatupang, Minson; Edwin, Romy Suryaningrat; Putra, Heriansyah; Mangidi, Uniadi; Sulha, ; Adityawan, Muh. Handy Dwi
doi: 10.1007/s40098-026-01555-wpmid: N/A
Calcite precipitation is a promising bio-mediated technique for liquefaction mitigation. Its influence on early-cycle dilative behaviour, particularly between 0.2 and 0.5% double-amplitude (DA) axial strain, remains poorly quantified. This study investigates the undrained cyclic response of Toyoura sands and Keisha No. 4 treated with 0.4 or 0.8% calcite (by dry weight), cured at 30% or 97% saturation (Sr), and tested at confining pressures (CP) of 50, 100, and 200 kPa (relative density DR = 50%). The number of cycles (N) to three strain thresholds: \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\text{N}}_{3}$$\end{document}, \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\text{N}}_{2}$$\end{document}, and \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\text{N}}_{1}$$\end{document} have been tracked. Results show that low Sr = 30% and fine grain size (\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\text{D}}_{50}$$\end{document}= 0.17 mm) synergistically enhance cyclic resistance: for Toyoura sand at \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\upsigma}_{\text{c}}^{^{\prime}}$$\end{document} = 100 kPa and 0.8% calcite, \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\text{N}}_{3}$$\end{document} increased from 9 (untreated) to 52 cycles (+ 478%), whereas Keisha No. 4 (\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\text{D}}_{50}$$\end{document}= 0.825 mm) showed only a + 222% increase under identical conditions. Critically, calcite bonding delays the phase transformation only up to ~ 0.5% DA; beyond this, relative angularity, defined as the ratio of calcite crystal size to grain size, governs post-bonding dilation and dominates \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\text{N}}_{1}$$\end{document}–\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\text{N}}_{2}$$\end{document} gains. At \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\upsigma}_{\text{c}}^{^{\prime}}$$\end{document} = 200 kPa and 0.8% calcite, lowering Sr from 97 to 30% increased \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\text{N}}_{1}$$\end{document} by sixfold (from 10 to 61 cycles) in Keisha No. 4, directly linked to more contact-localized calcite deposition (SEM-verified). These findings demonstrate that optimizing microstructural efficiency, not just calcite content, is key to extending cyclic life in the critical pre-liquefaction window.
A Elastoplastic Constitutive Model for Cemented Sand and Gravel (CSG) Incorporating the Effects of Bonding and FillingMa, Jingen; Ren, Honglei; Li, Hongxuan
doi: 10.1007/s40098-026-01546-xpmid: N/A
Cemented sand and gravel (CSG) exhibits enhanced stiffness, strength, and dilatancy compared with conventional granular materials. However, the current understanding of its mechanical behavior remains limited, and most existing constitutive models are largely adapted from frameworks developed for granular materials such as rockfill. In this study, a series of mechanical tests on CSG are first conducted, and available experimental data are synthesized to provide a comprehensive characterization of its compressive and shear behavior. Subsequently, within the framework of the Unified Hardening (UH) model, an elastoplastic constitutive model incorporating both filling and bonding effects is developed. Pressure-dependent hardening parameters related to gel content are introduced to describe compressive behavior, while a bonding factor and a filling factor are defined to capture cohesive strength and dilatancy, respectively. In addition, state parameters are incorporated to characterize the evolving shear state, and a non-associated flow rule is adopted. The proposed model is validated against a series of triaxial shear and consolidation tests, including both the present experimental results and data from the literature. The results demonstrate that the model can effectively reproduce the compressive and shear behavior of CSG, accurately capture strain hardening and softening as well as volumetric contraction and dilatancy, and provide reliable predictions of the effects of gel content and effective confining pressure.