Seismic stability analysis of expanded MSW landfills using pseudo-static limit equilibrium method

Abstract

Capacity expansion of existing landfills is the most economical alternative to constructing new landfills where cost of land is prohibitive. From the safety point of view, the stability analyses of existing landfills expanded either vertically and/or laterally are required for different stages of construction, operation and during closure of a landfill. In the present study, a pseudo-static limit equilibrium seismic stability analysis was performed for a typical side-hill type municipal solid waste (MSW) landfill expanded using an engineered berm. Seismic stability analyses were performed for the two critical cases, namely when the failure surface passes below the berm (under berm) and when the failure surface passes over the back slope of the berm (over berm). Close-form solutions were developed for the upper bound and lower bound factor of safety and the yield acceleration of such slopes under both failure conditions. From parametric analyses it was observed that as the height of the berm increased, the factor of safety for both the over-berm failure and the under-berm failure conditions also increased. The average factor of safety and yield acceleration coefficient were found and the under-berm failure condition became critical for a back slope steeper than 1.7H : 1V. The average factor of safety decreased as both horizontal and vertical seismic accelerations increased. Comparisons between the present results and those in the literature for the static case showed good agreement and the present results of the pseudo-static seismic case were found to be of particular importance.

Vertical Expansion Stability of an Existing Landfill: A Case Study of a Landfill in Xi’an, China

“…e results showed that landfill expansion is more likely to occur from seismic loads, and the extended landfill was more likely to slide along the interface between the new landfill and the old landfill under seismic loads. Choudhury and Savoikar [11] used a pseudostatic limit equilibrium method to consider the impact of horizontal and vertical seismic acceleration and analyzed the seismic stability of the vertical expansion landfill. e results showed that the average factor of safety decreased as both horizontal and vertical seismic accelerations increased.…”

Seismic stability analyses of reinforced tapered landfill cover systems considering seepage forces

“…The seepage force reduces the effective stress between the soil particles, which consequently results in failure of the landfill cover system. The impacts of the seepage force on the stability of landfill cover systems have been widely investigated through analytical methods for landfill cover systems with uniform profile (Choudhury and Savoikar, 2011; Feng and Gao, 2012; Giroud et al, 1995; Soong and Koerner, 1995; Yamawaki et al, 2017). The obtained results revealed that the seepage force has a significant negative effect on the stability of the landfill cover system.…”

“…There are several methods to assess the performance of the landfill cover systems during an earthquake (Matasovic and Kavazanjian, 2006). The most commonly used seismic analytical method for evaluation the stability of landfill cover systems under seismic loading condition is pseudo static analysis (Kavazanjian, 1998; Choudhury and Savoikar, 2011). In this method, seismic shaking is modeled as a force which acts on the free body diagram in a limit equilibrium analysis in the case of static condition (Nadi et al, 2014).…”

Effect of the amplification factor on seismic stability of expanded municipal solid waste landfills using the pseudo-dynamic method

“…For the expanded landfill with a trapezoidal berm, Qian and Koerner (2009) analyzed the static stability of the landfill based on both over-berm and under-berm failure conditions. Then Choudhury and Savoikar (2011a) investigated the pseudo-static seismic stability of the landfill based on both over-berm and under-berm failure conditions. Although Choudhury and Savoikar (2011a)'s method is based entirely on Qian and Koerner (2009)'s static model of the expanded landfill and their related assumptions, the average safety factor of the two methods is different even when the parameters of the two methods are the same.…”