Landslide Remediation Using Unconventional Methods

Abstract

Landslides are very common within the residual soils and sedimentary rock of Southern Indiana. A substantial amount of the Indiana State budget is spent on road repair and maintenance from damage caused by landslide. The landslide remedial technique frequently applied by the Indiana Department of Transportation (INDOT) is the excavation and backfill method, which in most instances is successful. However, in many cases more liberal landslide treatments may be applied that would arrest movement, provide a sufficient safety factor, and at a lower cost. The objective of this study is to propose economically feasible landslide remedial methods that may be used as an alternative to the excavation and backfill method. “Unconventional” landslide remedial methods describe stabilization methods that are not commonly practiced in Indiana, and for which design criteria are not available. Unconventional stabilization methods will likely have the greatest benefit applied to relatively small landslides requiring constant maintenance because these landslides are in a delicate equilibrium. Relatively modest improvements in stability may be sufficient to stop persistent movements. Proposed landslide remedial methods are conventional horizontal drains, driven horizontal wick drains, driven recycled plastic pins, railroad rail piles, lime piles, biotechnical remediation, and gravity mass retaining systems. A landslide inventory containing various attribute information of geologic environment and landslide geometry was compiled. The inventory includes 284 landslides with attribute information of each individual landslide. Landslide locations were entered into a geographic information system (GIS) database along with geographic and geologic information. The constructed GIS database allowed easy correlation of landslide occurrence with geologic features. It is concluded that landslide occurrence is a function of topography and bedrock geology. Suitability of landslide stabilization methods depends upon the characteristics of the sliding mass, which include the geologic environment and geometry of the landslide. A landslide classification scheme was developed which recommends suitable remedial solutions based upon the landslide classification. Eleven landslide types are recognized by the classification scheme, which is based upon four landslide attributes.