2008-04-21_REVISION - M1977300 (2)

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Project, Steve Adit Tunnel Bulkhead, As-Built By MEL/JFA Date 10/29/08 Sta.2+65 Sheet 2 of 8 10' Thick, 7'-7" Wide, 8'-2" 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) °ovb =overburden rock stress per ft depth (ft) wfs =factored static fluid bulkhead load (psf) ~fse =factored static fluid bulkhead earthquake load (psf) ~fle =factored line-of--sight fluid earthquake bulkhead load (psf) cage =factored concrete bulkhead earthquake load (psf) Bulkhead length for allowable hydraulic pressure gradient: Maximum (design) hydraulic pressure, p := H 44w psi p = 52 psi Bw'~w Minimum contact grout pressure, Qmingp ~= 144 psi 6mingp - 49.8 psi 2•Bw'^rr Maximum contact grout pressure, 6maxgp ~= 144 psi 6maxgp - 260 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 := 4 ft Lhp = 1.27 ft Load increase design factors Fluid static load, ifs := 1.40 Earthquake acceleration of static fluid ~fe := 1.05 load, Earthquake acceleration of line-of--sight lea := 1.40 impounded fluid and bulkhead loads, vi1 =nominal limiting shear stress, wb/Lt<2 (psi) vi2 =nominal limiting shear stress, wb/Lt = 2-5 (psi) aS =flexural stress (psi) 6n,;ngp =minimum contact grout pressure (psi) 6m~gp =maximum contact grout pressure (psi) Depth below surface to prevent hydrofrac of rock around tunnel: Available formation breakdown pressure, Overburden pressure, per ft of depth, Height of rock to prevent hydrofrac, Bp := p 1'r Dovb ~= 144 Z := Bp 2' Dovb Bp = 52 psi Dovb = 1.132 psi/ft Z = 23 ft