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Transit Mix <br /> 12/30/16 <br /> Page 3 <br /> Slope Stability Steady State Wash Fines <br /> Name:Embankment <br /> Model:Mohr-Coulomb Name:Coarse Alluvium <br /> Unit Weight:130 pcf Model:Mohr-Coulomb <br /> Cohesion':100 psf Unit Weight:135 pcf <br /> Phi':35° Cohesion':0 psf <br /> Phi':35° <br /> Name:Wash Fines <br /> Model:Mohr-Coulomb Name:Pierre Shale <br /> Unit Weight:90 pcf Model:Mohr-Coulomb <br /> Cohesion':0 psf Unit Weight:135 pcf <br /> Phi': 10° Cohesion':500 psf <br /> Phi':30° <br /> Name:Foundation-Eolian <br /> Model:Mohr-Coulomb <br /> Unit Weight:125 pcf <br /> S az° tssz <br /> Cohesion': 100 psf <br /> 5810 Phi':32° <br /> 5,800 <br /> 5790 <br /> 5.7 <br /> C 57 <br /> F <br /> 5,760 <br /> W 5.750 <br /> 5M <br /> 5 730 <br /> 5 720 <br /> 5710 : <br /> 5.700 '* <br /> 3 100 CO 300 <br /> Distance <br /> Figure 1. Slope Stability Analysis for Long Term Steady-State <br /> The Daniels Sand wash fines embankment was analyzed for seismic stability assuming that it is <br /> classified as a significant hazard dam per the State of Colorado Rules and Regulations for Dam <br /> Safety and Dam Construction (2007). Although the SEO considers the embankment to be non- <br /> jurisdiction, we conservatively assumed the significant hazard case. Per the State's guidelines, <br /> a pseudo-static analysis is acceptable. Pseudo-static loading approximates a typical earthquake <br /> load by applying a user defined horizontal load to the model, approximating the equivalent <br /> ground acceleration from the design earthquake. Selection of the pseudo-static coefficient was <br /> in accordance with the Hynes-Griffin and Franklin work concluding that earth dams with pseudo- <br /> static factors of safety greater than 1.0 using kh=0.5ama,,/g would not develop dangerously large <br /> deformations. <br /> Per the State guidelines, for a significant hazard dam, the dam shall be designed for a 2% <br /> chance of exceedance in 50 years (approximately 2500-year return frequency). For a pseudo- <br /> static analysis, the pseudo-static coefficient selected for analysis must be at least 50% of the <br /> design peak bedrock acceleration, but not less than 0.05g. <br /> The PGA(peak ground acceleration)was calculated using the USGS 2008 Interactive <br /> Deaggregation website. The PGA is 0.088g for the 2% in 50 year return earthquake. In <br /> accordance with the State's requirements, a horizontal pseudo-static coefficient of 0.05g was <br /> BRIERLEY <br /> ASSOCIATES <br /> Creating Space Underground <br />