Expansive soils exist in many countries worldwide, and their characteristics make them exceedingly difficult to engineer. Due to its significant swelling and shrinkage characteristics, expansive soil defies many of the stabilization solutions available to engineers. Differential heave or settlement occurs when expansive soil swells or shrinks, causing severe damage to foundations, buildings, roadways, and retaining structures. In such soils, it is necessary to construct a foundation that avoids the adverse effects of settlement. As a result, building the structure’s foundations on expansive soil necessitates special consideration. Helical piles provide resistance to uplift in light structures. However, they may not fully stabilize foundations in expansive soils. A granular anchor pile is another anchor technique that may provide the necessary resistance to uplift in expansive soils using simpler methods. This review and numerical study investigate the fundamental foundation treatments for expansive soils and the behavior of granular anchors and helical piles. Results indicate that granular anchor piles performed better than helical piles for uplift and settlement performance. For heave performance, the granular anchor and helical piles perform nearly identically. Both achieve heave reductions greater than 90% when L/H > 1.5 and D = 0.6 m.

The construction of tunnels in densely populated urban areas poses a significant challenge in terms of anticipating the settlement that may result from tunnel excavation. This paper presents a new and more realistic modeling method for tunnel excavation using a Tunnel Boring Machine (TBM). This method is compared with other reference modeling methods using a validated model of a subsurface tunnel excavated by a TBM with a slurry shield. A parametric study is conducted to investigate the impact of key parameters, including structure width, foundation depth, eccentricity, load on the structure, overburden depth, and tunnel diameter, on tunnel–soil–structure interaction and the resulting structure settlements. The results reveal that the tunnel diameter, eccentricity, and overburden depth have a significant impact on structure settlements, with values of 22.5%, 17%, and 7.1%, respectively. Finally, the paper proposes an equation for predicting the maximum settlement of a structure, considering the critical parameters. The validity of the equation is evaluated by comparing its results with the outputs from various case studies, including a newly validated model, two real-life case studies, and centrifuge tests. The results indicate a high level of consistency between the calculated and measured settlements.

Soft soils with unfavorable properties can be improved using various ground-improvement methods. Among these methods, geosynthetic-reinforced pile-supported (GRPS) embankments are considered a reliable option for challenging ground conditions and time-bound projects. Nevertheless, the intricate load transfer mechanism of the GRPS embankment presents challenges due to the multiple interactions among its components. To overcome the limitations of current design methods that do not fully account for all interactions, a simplified design method has been developed for GRPS embankments. This method uses numerical analysis to predict pile load efficiency and geosynthetic tension. In this study, a validated model of the GRPS embankment, which incorporates certain simplifications for design purposes, was adopted. Based on this simplified model, a database of load efficiency and geosynthetic tension was collected to derive the design equations. The design method employed six parameters, namely, pile cap width, pile spacing, embankment height, oedometric modulus of the subsoil, geosynthetic stiffness, and embankment fill unit weight. The design process utilized Plaxis 3D and Curve Expert software. The results showed reasonable agreement between the findings of the proposed design method and the field measurements of eight case studies.

This study investigates the performance of granular anchor piles and helical piles in expansive soils. Expansive soils pose challenges for engineering due to their significant swelling and shrinkage characteristics. Special considerations are required for constructing foundations on expansive soil to mitigate volumetric changes. While helical piles provide uplift resistance in light structures, they may not fully stabilize foundations in expansive soils. In contrast, granular anchor piles offer a simpler alternative for resisting uplift forces. A numerical study was conducted to analyze the pullout loads, compressive loads, and heave behavior of these anchor techniques. The results demonstrate that granular anchor piles outperform helical piles in terms of pullout and compressive performance, with improvements ranging from 17% to 22.5% in pullout capacity and 0.5% to 19% in compressive capacity, depending on specific pile lengths and diameters examined. However, both techniques show similar effectiveness in reducing heave, achieving reductions of over 90% when specific conditions are met. Additionally, the use of high-rise cap piles contributes to significant heave reduction, effectively minimizing heave to nearly negligible levels compared to low-rise cap piles. It is found that the relative density of the granular material has a more pronounced effect on the pullout load compared to the compressive load, and its impact varies depending on the length of the pile. Therefore, it is recommended to avoid high relative density when the pile is entirely within the expansive soil while utilizing higher relative density is beneficial when the pile penetrates and settles in the stable zone.

This research focuses on advancing the geosynthetic-reinforced pile-supported embankment technology over loose sandy soil. A small-scale laboratory model supported by floating piles and a geotextile layer was constructed, and a numerical model was validated against laboratory measurements. This study aims to achieve a more uniform distribution of the load over all piles of the system via a parametric study that analyzes the influence of embankment fill material, horizontal reinforcement scenarios, pile cap shape, and pile type. The results demonstrate that using embankment fill with high cohesion and internal friction properties leads to a significant reduction of 46% and 37% in maximum settlements, respectively, and similarly, results in a noteworthy reduction of 48% and 50% in differential settlements. The incorporation of two geotextile layers contributes to a reduction of up to 30% in maximum settlement. The utilization of plus-shaped caps in small areas, with an area equal to three times the cross-sectional area of the pile, has been substantiated as the preeminent approach for the reduction of settlements. Piles with caps also present better behavior regarding differential settlements compared to longer piles and piles with bigger diameters under the same volume condition.

This work aims to highlight gravity segmental retaining walls with their varied advantages. The paper investigates the dynamic behavior analysis of segmental retaining walls. The stability analysis is conducted on the basis of a pseudo-static Mononobe-Okabe theory that provides safety factors against sliding and overturning failure. The results demonstrate that the crucial safety factor of internal stability is the safety factor against overturning. Moreover, the positive wall inclination angle contributes to an improvement in the stability of the segmental retaining walls and the effect of the vertical seismic coefficient on the stability can be disregarding. Finally, a new equation is proposed for the elementary design of the segmental retaining walls. This work aims to highlight gravity segmental retaining walls with their varied advantages. The paper investigates the dynamic behavior analysis of segmental retaining walls. The stability analysis is conducted on the basis of a pseudo-static Mononobe-Okabe theory that provides safety factors against sliding and overturning failure. The results demonstrate that the crucial safety factor of internal stability is the safety factor against overturning. Moreover, the positive wall inclination angle contributes to an improvement in the stability of the segmental retaining walls and the effect of the vertical seismic coefficient on the stability can be disregarding. Finally, a new equation is proposed for the elementary design of the segmental retaining walls.