Download - Keystone

DESIGN MANUAL& KEYWALL OPERATING GUIDEAINFINITE SLOPE SURCHARGE NCMA 2ND EDITION - COULOMB METHODOLOGYThis set of calculations is intended to verify the KeyWall program output of a typical gravity wall designsection. The design follows the procedure outlined in the 1997 NCMA Design Manual for SegmentalRetaining Walls. The pertinent design information is summarized below:1) General Design DataCompac Keystone Units (120 pcf with unit drainage fill and W u = 1.0')Crushed Stone Leveling Pad (φ =40˚ and γ =130pcf)Wall Batter (ι) = 8 degrees (1"-1.25" per 8" unit)Design Height = 3.0' (2.5' exposed + 0 .5' embedment)Backslope, (β) = 1V:4H (14.0 degrees)Length of Backslope = 50' (infinite for design purposes)Surcharge = 0 psf (not applied to infinite slope design)Gravity wall design (FS ot > 1.5)2) Soil Parameters (degrees, psf, pcf)SOIL PARAMETERS φ c γRetained Soil 30 0 120Foundation Soil 30 0 1203) Geometric Parametersφ = 30 degreesδ = 2⁄3 φ = 20 degrees (concrete to soil)α = 98 degrees (90˚ + 8˚)β = 14 degrees (4H:1V slope)4) Coulomb Earth Pressure CalculationEquation (3c)sin² (98 + 30)ka =⎡ sin(30 + 20) sin(30 -14)sin² 98 sin (98 - 20) ⎢1 +⎣ √ sin(98 - 20) sin(98 +14)⎤²⎦ ⎢A.1