Inclinometer Data Analysis for Remediated Landslides

Landslides are frequently remediated by constructing engineered fills, improving drainage, or other more specialized construction methods. Monitoring instruments, such as surface monuments and inclinometers, are sometimes installed to evaluate the performance of the remedial measures. Where remediation involves engineered fills, the engineer should recognize that compacted fills undergo an equilibration process that can take years. This process can involve heave caused by expansive soil and consolidation due to the weight of the fill and imposed structural loads. Additionally, fills placed upon hillsides can be subjected to differential settlement consistent with fill thickness and development changes, surface creep, and lateral extension. Monitoring data can indicate various subsurface movements which are a product of settlement of the fill mass and lateral extension, and not related to movement of the remediated landslide. Some of these conditions were encountered at a site in Northern California. Misinterpretation of the gathered data could easily have occurred, possibly initiating unwarranted remedial measures or preventing development. However, the use of certain analytical and data presentation methods clearly showed that the remediated landslide was performing as designed.