Exploring the suitability of using Foam concrete as pore pressure dissipation measure for slope Stability: A state of art review

Abstract

Landslides are one of the major factors leading to disruption of transportation and urbanization of north-eastern India (NEI). The primary reasons are continuous precipitation and alarming seismicity at frequent intervals. Among various factors which can trigger landslide, most common is the increase of pore water pressure (PWP). This in turn increases the weight of the backfill and subsequently contribute to the overturning moment. Hence, measures to extract the pore water (PW) from the backfill through provision of drainage path is an efficient and widely followed approach to mitigate landslides. This paper presents a detailed overview on various landslides which have happened in the NEI during rainfalls and earthquake events, confirming these as two main triggering factors. Later, the limitations of various conventional landslide prevention techniques is also discussed. Though RWs are commonly adopted slope stabilization techniques, many case studies exist in where even RWs had failed to stabilize the slopes particularly where the slopes with higher groundwater table were subjected to heavy precipitation. The primary reason of failure was development of excess PWP behind RWs. While weep-holes in the RW play a critical role in dissipating PWP of the backfill, these are clogged resulting in the failure of the RWs. The fact cannot be denied that the effectiveness of the weep-hole depends upon its design, construction as well as its maintenance.Recently few researchers have shown that the Foam concrete (FC), a type of lightweight concrete, act as an excellent draining material to facilitate PW discharge for slope stabilization owing to its high permeability. Further, as the density of air voids in FC is more, rate of clogging is expected to be lesser, thus demanding lesser maintenance when compared to conventional weep-holes. This way, the need of regular maintenance of weep-holes can be minimized by use of FC. It should be highlighted here that though FC has lot of potential to be use in aforementioned application, there is not much of research exist in the literature on use of FC for PWP dissipation application. In this light, the present work also presents an in-depth review on permeation characteristics of FC, enumerating the PWP dissipation mechanism with the help of case studies from the literature.