Laserfiche WebLink
The overall results of the analyses may be described as <br />follows. The residual strength conditions in the colluvium <br />1 modeled the worst possible stability condition and the worst <br />possible shear strength performance in the colluvium. The peak <br />strength conditions model the most optimistic stability condition <br />and most optimistic shear strength performance in the colluvium. <br />This condition would model the performance of an area which has <br />J remained unsubjected to instability to date or the anticipated <br />J performance of the colluvial materials after experiencing <br />"healing" between long periods of inactivity. If analyzed under <br />residual strength conditions, virtually all slopes containing any <br />significant thickness of colluvial soil (landslide debris) were <br />found to be unstable with theoretical factors of safety less than <br />unity. Under peak strength conditions for the colluvial soil, <br />virtually all those slopes which were before unstable were found <br />1 to have a condition of marginal stability with factors of safety <br />slightly above unity. One exception to this is Section A where, <br />despite the most optimistic assumptions with regard to shear <br />strength, indicated factors of safety remain below unity. We <br />would anticipate that, with respect to the true stability <br />condition present on site at this time, factors of safety lie <br />somewhere between 1.0 and those factors of safety indicated for <br />] the peak strength condition. The marginal level of stability <br />indicated by the analysis correlates well with qualitative <br />observations on stability conditions made by Rocky Mountain <br />J Geotechnical and others (in particular, Walter R. Junge of the <br />Colorado Geological Survey). <br />10 <br />