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.

Major earthquakes and rainfall may occur at the same time, necessitating further investigation into the dynamic characteristics and responses of reinforced soil retaining walls subjected to the combined forces of rainfall and seismic activity. Three sets of shaking table tests on model retaining walls were designed, a modular reinforced earth retaining wall was utilized as the subject of this study, and a custom-made device was made to simulate rainfall conditions of varying intensities. These tests monitored the rainwater infiltration pattern, macroscopic phenomena, panel displacement, tension behavior, dynamic characteristics, and acceleration response of the modular reinforced earth retaining wall during vibration under different rainfall intensities. The results indicated the following. (1) Rainwater infiltration can be categorized into three stages: rapid rise, rapid decline, and slow decline to stability. The duration for infiltration to reach stability increases with greater rainfall. (2) An increase in rainfall intensity enhances the seismic stability of the retaining wall panel, as higher rainfall intensity results in reduced sand leakage from the panel, thereby diminishing panel deformation during vibration. (3) Increased rainfall intensity decreases the shear strength of the soil, leading to a greater load on the reinforcement. (4) The natural vibration frequencies of the three groups of retaining walls decreased by 0.21%, 0.54%, and 2.326%, respectively, indicating some internal damage within the retaining walls, although the degree of damage was not severe. Additionally, the peak displacement of the panel increased by 0.91 mm, 0.63 mm, and 0.61 mm, respectively. (5) The amplification effect of rainfall on internal soil acceleration is diminished, with this weakening effect becoming more pronounced as rainfall intensity increases. These research findings can provide a valuable reference for multi-disaster risk assessments of modular reinforced soil retaining walls.

The longitudinal seismic response characteristics of a shallow-buried water-conveyance tunnel under non-uniform longitudinal subsurface geometry and obliquely incident SV-waves was studied using the numerical method, where the effect of the non-uniform longitudinal subsurface geometry due to the existence of a local one-sided rock mountain on the seismic response of the tunnel was focused on. Correspondingly, a large-scale three-dimensional (3D) finite-element model was established, where different incidence angles and incidence directions of the SV-wave were taken into consideration. Also, the non-linearity of soil and rock and the damage plastic of the concrete lining were incorporated. In addition, the wave field of the site and the acceleration response as well as damage of the tunnel were observed. The results revealed the following: (i) a local inclined subsurface geometry may focus an obliquely incident wave due to refraction or total reflection; (ii) a tunnel in a site adjacent to a rock mountain may exhibit a higher acceleration response than a tunnel in a homogeneous plain site; and (iii) damage in the tunnel in the site adjacent to a rock mountain may appear in multiple positions, and the effect of the incidence angle on the mode of compressive deformation and damage of the lining is of significance.