Geotechnical Asset Management Inspection for Mechanically Stabilized Earth Walls

Transportation geotechnical assets generally include walls, slopes, embankments, and subgrades within the right of way. This paper describes how we developed an inspection sheet for mechanically stabilized earth (MSE) walls and the condition of the assets, to be incorporated in a geotechnical asset management (GAM) plan. The inspection sheet was based on existing GAM programs and optimized to meet the Kansas Department of Transportation (KDOT) monitoring goals. This included 14 inspectable items, including a measurement of the backfill using electrical resistivity. Laboratory electrical resistivity measurements were obtained in previous research and an in situ electrical resistivity measurement was developed for inspection purposes, which is described herein. KDOT selected 18 walls that were surveyed using the new inspection sheet and in situ electrical resistivity method. The inspection tool used an overall rating on a four to one scale, where four was “good” and one was “severe,” based on a weighted average of the 14 item ratings. The weighting system was developed from the opinions of 30 experts from various industries related to MSE walls across North America. The final rating also accounted for safety/mobility risks. Using the final risk-adjusted score, four walls were considered very good, eight were good, three were satisfactory, and three were fair. When fully developed, access to data about MSE conditions via this rating system and photographs will be easily retrievable through a common, computer-based system. The life cycle of an asset or assets can be tracked individually or as a part of a class that could be based on asset type, construction method, contractor, material supplier, or any other criteria. This information can be used to evaluate the relative benefits of a wide range of engineering options. Furthermore, by implementing this system now, KDOT can begin to track how emphasizing the inspectable elements with the weighting system relates to the long-term behavior of an MSE wall. It will be valuable to reevaluate the weighting system in 10−15 years to note which elements were actually indicative of an issue with the wall. Such data are not currently available.