Early earthquakes often trigger landfill slope failures and damage to cover and liner systems, resulting in gas leakage, environmental contamination, and significant risks to landfill safety. Accurately assessing the static and dynamic characteristics of mechanically biologically treated (MBT) waste is crucial. Centrifuge shaking table tests offer a robust method to address the limitations of conventional shaking table tests by effectively simulating the static and dynamic stress-strain fields of prototype soils, fulfilling the requirements for comprehensive static and dynamic analysis. Accordingly, this study conducted experimental research on MBT waste using a centrifuge shaking table. Key findings are as follows: (1) The Poisson's ratio of MBT waste is 0.483, and its small-strain shear modulus increases with depth, with a derived equation representing the relationship between small- strain shear modulus and depth. (2) MBT waste demonstrated a significant dynamic amplification effect, with an amplification factor ranging from 1.122 to 1.332. (3) The equivalent shear modulus of MBT waste decreases with increasing strain but increases with depth, with a surface equation established between the equivalent shear modulus, strain, and depth. (4) The equivalent damping ratio of MBT waste varies with strain and depth, and a surface equation was established to capture this relationship. (5) A comparison of the normalized equivalent shear modulus and equivalent damping ratio between MBT waste and municipal solid waste (MSW) shows that both parameters are higher in MBT waste than in MSW. These findings provide valuable insights for seismic stability analysis of MBT landfills.

Expansive soil is known for its ability to undergo significant volume changes in response to changes in moisture levels. Several investigations have been conducted to explore the stabilisation of expansive soils, encompassing a variety of reinforcement techniques and stabilisation approaches. Analysing dynamic properties such as shear modulus and damping ratio in expansive soil is imperative as they provide vital insights into the soil's response to dynamic loads. The use of lime and fibre treatment for stabilising expansive soil offers a comprehensive solution that addresses both chemical and physical stabilisation. This approach enhances soil properties and reduces the risk of damage to structures. To understand the complex behaviour of soil systems under varying conditions, cyclic triaxial tests on expansive soil were conducted using fibre-lime treatment. The variations in dynamic shear modulus and damping ratio with respect to shear strain amplitude, as well as the dynamic shear stress-strain curves, were studied across various confining pressures. The paper also presents the small strain shear modulus and modulus reduction curves. Besides, for a comprehensive understanding of the microstructural reactions of the fibre-lime-treated soil, specimens subjected to cyclic loading were examined using SEM analysis. A comparative analysis, examining the dynamic properties of soil under varying lime percentages, with and without 0.5% polypropylene (PP) fibre, as well as comparing scenarios with different lime contents between 0 and 0.5% PP fibre conditions has been presented. The experimental findings suggests that the fibre-lime treatment led to an enhancement in the dynamic shear modulus and damping ratio, with the increase of confining pressure. From the SEM analysis of the fibre-lime-treated soil, the microstructure displays a fabric-like pattern with cementitious gel connecting soil particle clusters. The images also show clay particles bonding together, forming a compact structure.

The increasing use of finite element analysis in modern infrastructure design emphasizes the importance of determining soil stiffness at small strains. This is usually represented by the normalized shear modulus degradation curve, which is crucial for accurate design. In the absence of specific measurements on the local soil, engineers often rely on empirical correlations and assume comparable behavior of soils with similar intrinsic properties. However, the application of this approach leads to uncertainties, especially for unique geological formations such as the soft cohesive soils of the Ljubljana Marsh. The main objective of this study was to determine the small strain shear modulus of Ljubljana Marsh soil with a plasticity index between 11 and 35%. Isotropic and anisotropic stress conditions were investigated as part of an extensive laboratory test program that included 45 bender element and 89 resonant column tests on 20 soil samples. By emphasizing the importance of measuring soil stiffness at small strains, this study not only provides reliable data for the development of the built environment in the Ljubljana Marsh and similar areas, but also underlines its necessity.