ARCHIVED REPORTS_1989 - Laserfiche WebLink

Home Browse Search

AM. 5.1.2 Seismic Analysis The Newmark Method of analysis (1965) was used to evaluate the stability of slopes under seismic loading conditions. This method evaluates the slope stabil- ity in terms of the permanent slope displacements that result from the seismic loading. The procedure is based on the assumption that a slope will move and permanently displace during the period of acceleration when the yield accelera- tion is exceeded. The Newmark Method uses the ratio between the yield acceleration and the average peak horizontal ground acceleration (Ky/Kp) to determine the expected amount of permanent displacement. The Newmark graph shown on Figure 5 was used for the seismic stability evalua- tion. This graph was developed by Dr. Robert Pyke, Consulting Engineer, Berke- ley, California, based on previous work by Franklin and Chang (1977) and Mak- disi and Seed (1977). The chart shows the relationships between the accelera- tion ratio and estimated displacements for Richter magnitude earthquakes (M) of 6.5 to 7.7 and 8 or greater. 0 5.2 CROSS SECTION GEOMETRY E The locations of the cross sections analyzed are shown on Figures 1 and 2 as - Cross Sections Al -Al, A2 -A2, and A3 -A3. Cross Section Al -Al, as shown on Figure 6, represents final grading of the landfill with maximum slopes of 12 percent. Cross Section A2 -A2, as shown on Figure 7, represents the maxi- mum height of excavation of the proposed landfill. The maximum height of exca- vation is 50 feet, and the average height is 30 feet at a 3:1 (horizontal to vertical) slope. Cross Section A3 -A3, as shown on Figure 8, represents a typical refuse moving face at a 3:1 (H:V) slope. The height of the refuse moving face was var- ied during the analysis to determine the maximum height of the refuse moving face. The engineering properties of the slope and foundation materials were dis- cussed in Section 3.0. The ground -water surface was assumed to be at eleva- tion -25 feet MSL, about 125 feet below the ground surface. PJ9 9390217.00W 11 Rev. 0 May 23,1989