I've worked on at least 100 landslides over the last 30+ years. Never saw the need for a pressure meter test of any kind. Explorations, laboratory testing, and analysis vary with each slide, but in general I find the following works best.
Drill several holes in cross sections perpendicular to the slope. Sample using a combination of SPTs and Shelby tubes.
Install inclinometers in a couple of the borings in the mid to lower part of the slope.
Once the depth of slide plane is determined from the inclinometers and the laboratory testing is done, create your stability model in software. I prefer UTEXAS, but other programs can work just fine.
Analyze the slope and modify your strength and water level assumptions until you achieve a FOS of 1.0. You now have a model of the current conditions.
Modify the slope in the model to increase the FOS. Rock buttresses often work well and be relatively inexpensive, but really depends on the situation. I normally shoot for a FOS of 1.25, i.e. a 25% increase in FOS. Sometimes less, sometimes more; depends on the risk tolerance of the client and how well I feel about the slope stability model.
Mike Lambert
