In performance-based design, it is crucial to understand deformation characteristics of geocell layers in soil under footing loads. To explore this, a series of laboratory loading tests were carried out to investigate the influence of varying parameters on the strain levels within the geocell layer in a sandy soil under axial strip footing loading. The results were analyzed in terms of maximum strain levels, strain variation along the geocell layer and the correlation between horizontal and vertical strains. In this study, the maximum observed strain levels for geocellreinforced strip footing systems reached 2.3 % for horizontal (tensile) strain and 1.4 % for vertical (compressive) strain. Furthermore, most strain levels were concentrated within a distance of 1.5 times the footing width from the axis of strip footing. In geocell-reinforced footing systems, the interaction between horizontal and vertical strains becomes a key factor, with the ratio of horizontal to vertical cell wall strains ranging approximately from 1 to 2.5. The outcomes of this study are expected to contribute to the practical applications of geocell-reinforced footing systems.

Recent studies have highlighted the potential benefits of allowing inelastic foundation response during strong seismic shaking. This approach, known as rocking isolation, reduces the moment at the base of the column by transferring the plastic joint beneath the foundation and into the soil bed. This mechanism acts as a fuse, preventing damage to the superstructure. However, structures with a low static safety factor against vertical loads (FSv) may experience unacceptable settlements during earthquakes. To address this, shallow soil improvement is proposed to ensure sufficient safety and mitigate risks. In this study, a small-scale physical model of a foundation and structure (SDOF model, n = 40) was placed on dense sandy soil, and seismic loading was simulated using lateral displacement applied by an actuator. A group of short-yielding piles with varying bearing capacities (QU/NU = 0.1-0.8) was installed beneath the rocking foundation. The results of the small-scale tests demonstrate that the use of short-yielding piles during seismic loading reduces the settlement of the shallow foundation by up to 50% and increases rotational damping by 59%. This is achieved through the frictional yielding of the pile wall and the yielding of the pile tip, which dissipate energy and enhance the overall seismic performance of the foundation. The findings suggest that incorporating yielding pile groups in the design of rocking foundations can significantly improve their seismic performance by reducing settlement and increasing energy dissipation, making it a viable strategy for enhancing the resilience of structures in earthquake-prone areas. The optimal bearing capacity ratio (QU/NU = 0.25-0.5) provides a straightforward guideline for designing cost-effective seismic retrofits.

Seismic actions are usually considered for their inertial effects on the built environment. However, additional effects may be caused by the volumetric-distortional coupling of soil behaviour: the fast cyclic shaking on saturated soils caused by earthquakes generates temporary undrained or quasi-undrained conditions and subsequent pore pressure variations that, if positive, reduce the effective stresses, eventually leading loose granular soils to liquefaction. Whatever the amount of seismically induced pore pressure build up, buildings on shallow foundations suffer settlements and tilts that may be extremely large when soils approach liquefaction, as demonstrated by several recent case histories. The paper proposes an equivalent elastic approach in effective stresses to predict the co-seismic (undrained) component of the seismically induced settlement of shallow foundations, which usually is the most relevant one, by considering the decrease of soil stiffness during the seismic event. The total settlement can be then estimated by adding the post-seismic (drained) component, also evaluated in this paper via a quite simple approach. Even though the equivalent elastic model is stretched into a highly non-linear soil behaviour range, especially when the soil is approaching liquefaction, the model considers the relevant capacity and demand factors and proved effective in simulating some centrifuge tests published in the literature. In the paper, the simplifying assumptions of the approach are clearly indicated, and their relevance discussed. It is argued that notwithstanding some limitations the model is physically based and therefore it allows for understanding and checking the relative relevance of all the parameters related to soil, foundation, and seismic action. Thus, it is a tool of possible interest in the design of shallow foundations in liquefaction-prone seismic areas.

The study presents a comprehensive study on the assessment of the bearing capacity of closely spaced strip footings on c-& oslash; soil, considering spatial variability in soil properties. A linear elastic model is employed for footings and elastic-perfect plastic soil behaviour via the Mohr-Coulomb yield criterion. Soil properties obtained from extensive field investigations of Taranto Blue Clay (TBC) in Italy are modelled as stationary random fields (RFs) generated using the Fourier series method. The cohesion and friction angle RFs are integrated with the Z-soil FE code. The final results are obtained according to the random finite element method (RFEM). The study investigates the influence of spacing distances between footings and spatial correlation lengths of soil parameters on the bearing capacity. Results show how spacing distance affects bearing capacity. Moreover, it indicates that neighbouring footing bearing capacity is strongly correlated with investigated parameters. In the case of small spatial correlation lengths, the patterns were obtained as non-symmetrical, transitioning to more symmetrical patterns at larger lengths. The manuscript concludes by presenting reliability-based design considerations for the ultimate bearing capacity, considering the horizontal spatial scale of fluctuation (SOF). The findings emphasize the importance of evaluating allowable design bearing capacity for proximity structures using RFEM and provide valuable insights into the interplay between spacing distances and spatial variability in soil properties. To this end, the study underscores the critical interplay between spacing distance, spatial correlation lengths, and random soil properties in assessing neighbouring footing-bearing capacities.

This study explores the transverse response of bridge piers in riverbeds under a multi-hazard scenario, involving seismic actions and scoured foundations. The combined impact of scour on foundations' stability and on the dynamic stiffness of soil-foundation systems makes bridges more susceptible to earthquake damage. While previous research has extensively investigated this issue for bridges founded on piles, this work addresses the less explored but critical scenario of bridges on shallow foundations, typical of existing bridges. A comprehensive soil-foundation structure model is developed to be representative of the transverse response of multi-span and continuous girder bridges, and the effects of different scour scenarios and foundation embedment on the dynamic stiffness of the soil-foundation sub-systems are investigated through refined finite element models. Then, a parametric investigation is conducted to assess the effects of scour on the dynamic properties of the systems and, for some representative bridge prototypes, the seismic response at scoured and non-scoured conditions are compared considering real earthquakes. The research results demonstrate the significance of scour effects on the dynamic properties of the soil-foundation structure system and on the displacement demand of the bridge decks.

Shallow foundations are commonly used to support various equipment in industrial projects. If the subsoil is too weak to withstand the equipment loads, the settlement or tilting of the foundations takes place. To avoid further distress to such foundations, weak soil beneath the damaged foundation is required to be strengthened. This paper presents a similar case study wherein the strengthening of subsoil was performed beneath the shallow foundations which experienced settlement and tilting beyond the permissible limits due to the presence of weak subsoil. The stabilisation of soil was performed using injection grouting with colloidal silica-based chemical grout to prevent further settlement and tilting of foundations. The particulars of the chemical stabilisation program, injection methodology, chemical consumption, field trials, and laboratory test results are explicated in this paper with the details of post rectification performance of the test foundation. The properly executed injection grouting using chemical components was observed to be an effective measure to stabilise the subsoil by enhancing its engineering properties to a certain extent. The key factors that can affect the performance of colloidal silica-based chemical and precautions to be considered during soil stabilisation are also discussed in this paper.

Clay deposits typically exhibit significant degrees of heterogeneity and anisotropy in their strength and stiffness properties. Such non-monotonic responses can significantly impact the stability analysis and design of overlying shallow foundations. In this study, the undrained bearing capacity of shallow foundations resting on inhomogeneous and anisotropic clay layers subjected to oblique-eccentric combined loading is investigated through a comprehensive series of finite element limit analysis (FELA) based on the well-established lower-bound theorem and second-order cone programming (SOCP). The heterogeneity of normally consolidated (NC) clays is simulated by adopting a well-known general model of undrained shear strength increasing linearly with depth. In contrast, for overconsolidated (OC) clays, the variation of undrained shear strength with depth is considered to follow a bilinear trend. Furthermore, the inherent anisotropy is accounted for by adopting different values of undrained shear strength along different directions within the soil medium, employing an iterative-based algorithm. The results of numerical simulations are utilized to investigate the influences of natural soil heterogeneity and inherent anisotropy on the ultimate bearing capacity, failure envelope, and failure mechanism of shallow foundations subjected to the various combinations of vertical-horizontal (V-H) and vertical-moment (V-M) loads. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Foundation designs typically rely on traditional soil mechanics principles, which assume the soil is either completely saturated or entirely dry. However, the impact of soil suction associated with the alternate wetting and drying conditions in the unsaturated zone (i.e. soil suction) is generally overlooked in traditional design approaches. This may lead to ground heave or differential settlement contributing to extreme distress to various infrastructures built in unsaturated expansive soils. Shallow foundations are usually built above the groundwater table, leaving much of the soil beneath them unsaturated. As a result, soil suction greatly affects the bearing capacity and settlement behaviour. Further, deep foundations extend through the active layer of unsaturated expansive soil until reaching the bedrock or rest on a high-quality soil-bearing stratum. The volume-changing behaviour of the unsaturated expansive soil typically moves upward along the pile, creating additional positive friction that can potentially uplift lightly loaded structures. This paper presents a review of foundation behaviour in unsaturated expansive soils. Particularly, this review focuses on the influence of matric suction on soil-volume expansion which contributes to the ground heave, soil-structure interface shear strength properties, bearing capacity, and load-settlement behaviour of foundations.

Rocking shallow foundations interrupt the seismic transmission path from the base of the structure and possess advantages, such as effective seismic isolation, self-resetting capabilities post-earthquake, and low costs. A numerical model of the rocking shallow foundation was developed in OpenSees (version: Opensees 3.5.0) based on field test data using numerical simulation. The effect of different parameters (column height, foundation sizes, top mass, and soil softness and stiffness) on the seismic response characteristics of rocking shallow foundations is investigated, and the seismic response characteristics of rocking shallow foundations are analyzed under the action of sinusoidal waves of different frequencies and various seismic wave types. The results of the study show that, as the height of the column increases, the bending moment decreases and settlement decreases; as the size of the foundation increases, the bending moment increases and settlement increases; as the mass of the top increases, the bending moment increases and settlement increases; and as the soil becomes softer, the bending moment decreases, and settlement increases. Inputting a sine wave that matches the structure's natural oscillation frequency may induce resonance. This phenomenon can significantly amplify the structure's vibrations; thus, it is essential to avoid external excitation frequencies that coincide with the foundation's natural oscillation frequency. Under seismic loading, the rocking shallow foundation can mitigate the bending moment in the superstructure. When the displacement ratio remains within -0.5 to 0.5 percent, the foundation settlement is minimal. However, when the absolute displacement ratio exceeds 0.5 percent, the soil exhibits plastic deformation characteristics, resulting in increased foundation settlement. This study is an important contribution to the improvement of seismic performance of buildings and an important reference for improving seismic design standards and practices for buildings in earthquake-prone areas. In the future, the seismic response characteristics of rocking shallow foundations under bidirectional seismic action will be investigated.

The cyclic loading of foundation structures in sand leads to an accumulation of plastic deformations in the structures. For shallow foundations of high and slender structures such as wind energy converters (WECs), an accumulation of the plastic rotations is expected under cyclic eccentric loading that is imposed by wind loads, which could be crucial for the proof of serviceability. A practical approach to predict the behavior of shallow foundations under high-cycle eccentric loading is under research. In this paper, a numerical approach, the cyclic strain accumulation method (CSAM), which has been validated for cyclically loaded monopiles, is adopted for shallow foundations under eccentric cyclic loading. Modifications to the CSAM are described, which are necessary to apply it to shallow foundations. The results that are gained with the modified method are compared with a medium-scale model test, in which the deformations of a footing with a diameter of 2.0 m under eccentric one-way cyclic loading were investigated. It can be concluded that the CSAM can make realistic predictions and shows satisfying agreement with the measured cyclic behavior. Although more experiments are needed to finally validate the method, the CSAM could be a promising numerical approach to account for the cyclic behavior of shallow foundations under eccentric cyclic loading in sand.