2008-04-21_REVISION - M1977300 (2)

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Project, Pierce Adit Bulkhead, As-Built By MEL/JFA Date 3/28/08 Sta.2+84 Sheet 2 of 8 12' Thick, 11'-7" Wide, 11'-8" High, #6 Rebar Notation continued: Inputs continued: • • V„ =nominal concrete shear strength (lb/ft) V„ =factored concrete shear strength (lb/ft) vs = rebar shear stress (psi) W =total bulkhead load (lb) Z =height of rock to prevent hydrofrac (ft) Dove =overburden rock stress per ft depth (ft) c,~s =factored static fluid bulkhead load (psf) c,~Se =factored static fluid bulkhead earthquake load (psfj ale =factored line-of--sight fluid earthquake bulkhead load (psf) ~e =factored concrete bulkhead earthquake load (psf) Load increase design factors Fluid static load, ~ps := 1.40 Earthquake acceleration of static fluid ~ge := 1.05 load, Earthquake acceleration of line-of-sight lea := 1.40 impounded fluid and bulkhead loads, vil =nominal limiting shear stress, wb/LC<2 (psi) vie =nominal limiting shear stress, wb/L~ = 2-5 (psi) as =flexural stress (psi) 6iriigp =minimum contact grout pressure (psi) 6maXgp =maximum contact grout pressure (psi) Bulkhead length for allowable hydraulic pressure gradient: Maximum (design) hydraulic pressure, p := H 44w psi p = 52 psi B w''Y w Minimum contact grout pressure, Qmingp ~= 144 psi Qmingp = 54.2 psi 2• Bw''Yr Maximum contact grout pressure, Qmaxgp ~= 144 psi ~maxgp - 283 psi Allowable 41 psi/ft pressure gradient for low-pressure grouting of upper part of concrete/rock contact: Required bulkhead thickness for low-pressure contact grouting, Lhp := P ft Lhp = 1.27 ft 41 Depth below surface to prevent hydrofrac of rock around tunnel: Available formation breakdown pressure, Bp := p 'y r Overburden pressure, per ft of depth, Dovb ~= 144 Bp Height of rock to prevent hydrofrac, Z :_ 2' Dovb Bp = 52 psi Dovb = 1.132 psi/ft Z = 23 ft