LIDAR AND SPLIT-FX AS TOOLS TO ENHANCE KINEMATIC STABILITY AND ROCKFALL HAZARD EVALUATIONS

Kinematic stability analyses have historically been conducted using rock mass discontinuity data collected using a Brunton Compass in the field on exposed rock faces. Development of laser scanning survey (LiDAR) equipment and computer software developed to process the massive amount of data collected by LiDAR have resulted in improved efficiency, effectiveness and/or safety of bedrock mapping programs. The SplitFX application has been used by GZA in the last five years in conjunction with terrestrial LiDAR survey for evaluation of rock cuts in Massachusetts, Connecticut and Vermont. Rock characterization using SplitFX to reduce LiDAR point clouds, in conjunction with limited hand mapping, has been shown to result in more robust data sets relative to kinematic stability and rockfall hazard evaluations. Validation of SplitFX-generated discontinuity orientations has been conducted using hand measurements and has indicated that the variability between the data sources is insignificant relative to variability of joint orientations for the sites analyzed. The presentation will focus on specific data collection and evaluation challenges that have been addressed using LiDAR and SplitFX for rock slope projects undertaken by GZA. Technical challenges that will be addressed include: rapidly collecting data along the upper portion of tall cuts, reducing the extent of ropes access work and reducing mapping time; eliminating hand mapping below extremely unstable areas; assessing local variations in the bedrock structure that are difficult to assess visually or by hand due to access; and developing accurate cross sections and rockfall source geometries/volumes that cannot be readily defined by hand or conventional survey. A discussion of validation of SplitFX discontinuity measurements will be presented for the projects where LiDAR has been utilized. Limitations of the use of LiDAR and SplitFX will also be addressed.