# Dynamic Stability Finite Difference Time Domain Analysis of Landfill Based on Hypergravity Test
## 1 Introduction  
Landfills globally serve as an important method for disposing of municipal solid waste (MSW), typically characterized by leachate within them. Due to the significant proportion of food waste in MSW, landfills in China generally have higher leachate levels compared to those in other countries or regions [1; 2; 3; 4; 5]. A study has pointed out that the failure of a landfill correlates with the increase in leachate levels [6]. Furthermore, research has shown that earthquakes can trigger landslide disasters, and landfills as artificial slopes can also be affected by earthquakes [7]. The stability of landfills in China has been threatened by earthquake activities. A failure in the slope of a landfill could be geotechnically and environmentally disastrous. For instance, landslides at the Leuwigajah dumpsite and the Payatas landfill resulted in the destruction of numerous residential houses, claimed the lives of hundreds of people, and caused severe pollution to the local environment [8; 9]. Therefore, the seismic stability of landfills with high water levels has become a major concern in China. Laboratory tests and field measurements are essential for comprehending the dynamic properties of MSW. Several studies have revealed the strain-hardening behavior of MSW [10; 11], which complicates the determination of strength parameters. Furthermore,this behavior often makes it challenging to observe an obvious failure in MSW. Studies have also uncovered a reduction in dynamic shear modulus with the development of strain in MSW [11; 12; 13; 14]. The property is crucial when analyzing a landfill's seismic stability. Nevertheless, these tests are not enough to investigate the seismic stability of a landfill. Currently, the centrifuge test has become a popular approach for studying the seismic stability of landfills. Using centrifuge tests, many scholars have conducted research on the dynamic response or stability of MSW landfills, owing to the fact that the prototype stress field of a landfill can be restored in centrifuge tests. [PERSON] [15] studied the displacement and acceleration response of landfills under unidirectional and bidirectional seismic waves through shaking table tests under hypergravity conditions, revealing that the water level within a landfill greatly impacted its stability. [PERSON] and [PERSON] [16] studied the response of landfills with different slopes under different sizes of seismic actions and obtained the relative displacement time history between the bottom of the landfill and the bedrock. [PERSON] [11] studied the influence of a slope gradient, leachate water level, and seismic intensity on the stability of landfills using double-sided slope models. His work yielded insights into pore pressure response, settlement at the top of the landfill slope, deformation patterns and modes of potential instability failure of the slope under earthquakes, and suggested that instability of landfills occurred when the water level is high and the earthquake is strong. The research conducted by [PERSON] et al. [17] overlooked the influence of leachate; thus, no significant instability or failure phenomenon in the landfill was observed during their experimental process. [PERSON] et al. [18] studied the failure behavior of a landfill slope with and without fibers using a centrifuge shaking table and found that fibers mainly provide slope stability. Overall, few experimental studies have investigated the impact of dynamic pore pressure response within a landfill on its stability during seismic activities. And centrifuge model tests considering the influence of water level and seismic intensity have not been validated yet. Although centrifuge tests can be applied to investigate the seismic stability of a landfill, factors such as the high cost of centrifuge tests and the limited availability of experimental equipment make it inconvenient for scholars or engineers to conduct a large number of model tests. Additional studies concerning the seismic analysis of landfills often relied on numerical analysis.