Replacing soil with waste materials offers significant opportunities for advancing geoenvironmental practices in the construction of large-scale geostructures. The present study investigates the viability of utilizing sugarcane bagasse, a massively produced agricultural waste material, as a partial replacement for soil and its potential to control soil liquefaction. Utilization of bagasse in large geostructures not only aids in the management of a significant volume of bagasse but also facilitates the conservation of natural soil resources. Experimental investigations were conducted through a series of isotropically consolidated, stress-controlled, undrained cyclic triaxial tests. Various volumetric proportions of bagasse to sand, extending up to 50:50 (bagasse: sand), were examined to evaluate the performance of the mix under different cyclic loading conditions. The study evaluates the cyclic strength, stiffness degradation, cycle retaining index, etc., for different bagasse sand mixes across the expected cyclic stresses corresponding to Indian seismic zones 3, 4, and 5. Variation of these properties with relative density has also been studied. Results indicate that the bagasse can effectively be utilized as a geomaterial to partially replace the soil in large proportions ranging from 19 % to 41 % without compromising the initial cyclic strength of the natural soil. Notably, at an optimal content of 30 %, the bagasse sand mix exhibits higher resistance to the accumulation of excess pore water pressure, maximizing its liquefaction resistance. Furthermore, the utilization of bagasse as a partial replacement for soil increased the cyclic degradation index within the suggested range of bagasse content.

The Makran Subduction Zone (MSZ) represents a convergent plate boundary where the Arabian Plate is subducting beneath the Eurasian Plate. This study assessed liquefaction susceptibility and ground response in Gwadar region, located on the eastern side of MSZ. A comprehensive dataset of seismic records, compatible with Pakistan design code BCP: 2021 rock spectrum, was used as input motions at bedrock. A series of one-dimensional (ID) non-linear effective stress analyses (NL-ESA) was conducted using DEEPSOIL v7 numerical tool. The findings revealed that pore water pressure ratio (r(u)) exceeded the threshold value for liquefaction onset (r(u) > 0.8) at various depths within the site profiles. A significant de-amplification of peak ground acceleration values was observed at liquefiable depths in soft soils. The liquefied stratum exhibited a non-linear response, with high shear strain values manifesting plastic deformations. A comparison of computed design spectra with code spectra revealed significant discrepancies. It is demonstrated that BCP: 2021 underestimated site amplification for site class D profiles in the 0.1 to 0.8 s period range, while overestimating it for site class E profiles across the entire period range up to 1.6 s. The findings will benefit infrastructure development in the region, particularly within the China-Pakistan Economic Corridor.

Coral sandy soils widely exist in coral island reefs and seashores in tropical and subtropical regions. Due to the unique marine depositional environment of coral sandy soils, the engineering characteristics and responses of these soils subjected to monotonic and cyclic loadings have been a subject of intense interest among the geotechnical and earthquake engineering communities. This paper critically reviews the progress of experimental investigations on the undrained behavior of coral sandy soils under monotonic and cyclic loadings over the last three decades. The focus of coverage includes the contractive-dilative behavior, the pattern of excess pore-water pressure (EPWP) generation and the liquefaction mechanism and liquefaction resistance, the small-strain shear modulus and strain-dependent shear modulus and damping, the cyclic softening feature, and the anisotropic characteristics of undrained responses of saturated coral sandy soils. In particular, the advances made in the past decades are reviewed from the following aspects: (1) the characterization of factors that impact the mechanism and patterns of EPWP build-up; (2) the identification of liquefaction triggering in terms of the apparent viscosity and the average flow coefficient; (3) the establishment of the invariable form of strain-based, stress-based, or energy-based EPWP ratio formulas and the unique relationship between the new proxy of liquefaction resistance and the number of cycles required to reach liquefaction; (4) the establishment of the invariable form of the predictive formulas of small strain modulus and strain-dependent shear modulus; and (5) the investigation on the effects of stress-induced anisotropy on liquefaction susceptibility and dynamic deformation characteristics. Insights gained through the critical review of these advances in the past decades offer a perspective for future research to further resolve the fundamental issues concerning the liquefaction mechanism and responses of coral sandy sites subjected to cyclic loadings associated with seismic events in marine environments.