Laserfiche WebLink
Page Two <br />8 November 2016 <br />M16043GE <br />Factors that have an adverse influence on slope stability can <br />generally be classified as those that increase the stress <br />(driving force) on the system or decrease the strength (resisting <br />forces) of the soil. <br />Our stability analyses of the site slope soil material was <br />based on the Bishops Method of Slices. This method is based on <br />the assumption that the slope soil mass will fail in a rotation <br />mode on a circular arc plane. In this method of analysis the <br />mass of soil is divided into vertical slices. The forces acting <br />on each slice are evaluated from the equilibrium of the slices; <br />that is, the forces that tend to drive the slice downhill and the <br />forces that tend to resist the movement of the slice. The <br />equilibrium of the entire mass is determined by summing the <br />driving and summing the resisting forces acting on all slices and <br />comparing these forces. <br />Our slope stability analysis was performed using "XSTABL" by <br />Interactive Software Designs, Inc. Our slope stability analysis <br />considered Cross Section A -A' with a total of about 100 separate <br />possible failure surface iterations per condition to help <br />identify the potential theoretical slope stability. Our discus- <br />sions and data presentation is based only on the calculated <br />critical circle which presented the lowest factor of safety <br />against failure. Our presentation does not include the results <br />of all of the iterations which resulted in a theoretical factor <br />of safety greater than the lowest factor of safety and therefore <br />were not critical. <br />The soil strength values used in our analysis included: <br />internal angle of friction of thirteen (13) degrees, <br />cohesion of one hundred twenty one (121) pounds per square <br />foot and, <br />moist unit weights of one hundred twenty five (125) pounds <br />per cubic foot, <br />Using the above noted soil strength parameters, the theoretical <br />calculated factor of safety ranges from 1.405 to 2.030. <br />Attachment 2.05.3(3)-35 <br />Consulting Geotechnical Engineers <br />And Material Testing <br />Page 3 October 2016 (TR -76) <br />