A triaxial cell was developed to investigate the shear strength of unsaturated silt under elevated temperatures and high suction magnitudes. The results from a series of drained triaxial compression tests on compacted silt specimens are presented in this paper. After anisotropic compression, some specimens were heated before suction was applied, while others were heated after the application of suction. The shear stress–strain curves of the soils under high suction magnitudes showed a brittle failure mechanism, with a clear increase in peak shear strength with net confining stress. Heating after suction application led to a greater peak shear strength than reference tests at ambient temperature, whereas heating before suction application led to a lower peak shear strength. Despite the observed path effects, a single peak failure envelope was defined when evaluating the data in terms of effective stress. The suction stress concept was used to define the effective stress, and the values of suction stress were found to be linked with a non-isothermal definition of the soil-water retention curve.

In recent years, there has been a focus on improving geotechnical systems by implementing and constructing new deep foundation such as helical and expanded piles. This study examined the effects of parameters such as embedment depth, pile geometry, and axial loading direction on the load-displacement behaviour of these piles. To conduct the research, a database was compiled consisting of 80 axial loading test records for different piles. The embedment depth of the piles ranged from 2.4 to 36.8 m, and the diameter of helices or expanded parts ranged from 254 to 1500 mm. The ultimate load of the piles was determined using the 2.5% and 5% displacement ratio criteria and the Brinch-Hansen 80% method. Additionally, hyperbolic functions were fitted to the load-displacement curves, allowing for consistent estimation of the limit load and the initial tangent modulus. Analysis of the results from the database revealed that the dominant factors influencing the ultimate load, limit load, maximum measured load, initial stiffness, and load-displacement behaviour were the ratio of helices or expanded part diameter to shaft diameter, shaft and toe surface area, and load direction. Correlations derived from the database were validated using measurements from eight full-scale helical and expanded piles.

Although tire-derived aggregate (TDA) has been used as an alternative backfill in geotechnical engineering applications, the interaction between TDA having large particle sizes (e.g. TDA with a maximum particle dimension of 300 mm) and reinforcing geosynthetics has not been studied. This paper presents results from pullout tests on uniaxial and biaxial geogrids embedded in Type B TDA using a new large-scale pullout device having internal areal dimensions that can accommodate TDA layers with a height up to 1470 mm. Normal stresses ranging from 10 to 60 kPa were applied to TDA layers using dead weights atop a rigid plate and the pullout force was applied via hydraulic actuators operated in displacement control to a bolted-epoxy sandwich-type grip mounted on slide bearings that permit pullout displacements of up to 810 mm. The maximum pullout force increased with normal stress, with a displacement at maximum pullout force ranging from 100 to 350 mm. Internal displacements measured using tell-tales indicate gradual mobilization with pullout force, and the TDA layers all contracted during geogrid pullout. Uniaxial and biaxial geogrids with square-shaped apertures showed higher pullout capacity than uniaxial geogrids with rectangular-shaped apertures, but they experienced combined tensile-pullout failure at higher normal stresses.