2007-11-16_REVISION - M1977300 - Laserfiche WebLink

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11/13/2007 13:56 FAX Z003/018 Project, Pierce Adit Tunnel Bulkhead Stn. 3+04 By M.EL/JFA Date 10/30/07 _12' Thick, 12' Wide, 12' Hiah, #6 Rebar Sheet 2 of 8 Notation continued: Nuts continued: V„ = nominal concrete shear strength (lb/ft) Load increase design factors V, = factored concrete shear strength (lb/ft) Fluid static load, '- 1.40 V, = rebar shear stress (psi) Earthquake acceleration of static fluid fife := 1.05 W = total bulkhead load (lb) load, Z = height of rock to prevent hydrofrac (ft) Earthquake acceleration. of line-of-sight 0 := 1.40 A,,,b = overburden rock stress per ft depth (ft) ,a impounded fluid and bulkhead loads, cots = factored static fluid bulkhead load (pst) v„] = nominal limiting sl-iear stress, wi,/Lt<2 (psi) a)l;c =factored static fluid bullchead vn2 = noiiiinal limiting shear stress, cob/Lt= 2-5 (psi) earthquake load (psf) QS = flexural stress (psi) con,, =factored line-of-sight fluid earthquake bulkhead load (psf) 6,,,;ngp = minimum contact t grout pressure (psi) a,,,,,csI) = maximum contact grout pressure (psi) o)fbe = factored concrete bulkhead earthquake load (psf) Bulkhead IenQth for allowable hydraulic pressure grat,dient: Maximum desi n h draulic ressure II yW ( g) Y P P '- 144 psi p = 52 psi Bw'"1'w Minimum contact grout pressure, Qn,ingp P' si 144 viningp = 54.2 psi 2.$w.?(r Maximum contact grout pressure, 01inaxgp :- 144 psi Qmaxgp = 283 P5i 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, LI,p := A ft LI,p = 1.27 ft 41 Death below surface to prevent hydrofrac of rock around tunnel: Available formation breakdown pressure, Bn p B13 = 52 psi Overburden pressure, per ft of depth, ?ovb Ir4 povI, = 1.132 psi/fr 14 13p Height of rock to prevent hydrofrac Z Z = 23 ft 2'Aovb