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Merno to Russ Means 4 November 14, 2007 <br />Bulkhead Cost :Estimate Pile No. M-2007-0~4 <br />Clearly, with an eight fold decrease in required bulkhead length, low pressure grouting is a necessity for the <br />proposed main bulkhead. <br />Desi for Concrete Shear on Main Bulkhead <br />The length of the bulkhead must be sufficient to keep the shear stress developed i.n the bulkhead concrete <br />below the ACI 318-89 limits. Shear strength of concrete is related to its compressive strength as follows: <br />f'S . 2 f'~ = 2 3000 - 11Opsi (ACI 318-89, Section 11.3.1.1.) <br />where: f'S =concrete shear strength. (psi} <br />f'~ =concrete compressive strength (psi} <br />It can be assumed that the adit wall rock at the bulkhead Location has higher shear strength than the <br />concrete, so concrete shear will control the design. The required bulkhead length for the concrete shear <br />component of design, assuming minimum bulkhead concrete compressive strength is specified at 3000 psi, <br />is calculated as follows: <br />_ pxhx~ _ 64x9x12 =l.Sfeet <br />L - 2xth+p~x f'S 2x9+12}x110 <br />where: L =bulkhead length (feet) <br />p =pressure head {psi) <br />la =decline height (feet) <br />=decline width {feet} <br />f'S =concrete shear strength (psi) <br />Therefore, the; l .G foot minimum. bulkhead length required for pressure gradient s.lightl.y exceeds th.e <br />bulkhead length required for concrete shear, and pressure gradient controls the design. <br />I~esi c~.f:,the,l~an,~ulkl~.ead for C;onstru~tion. ~:as~:_F~vatiatt.~. ~uo~ses <br />The basic cles~an e;l.en~.ents for the proposed train bulkhead are as follows: <br />Note: one foot added to VVhirl~vind M.i.ne workings di.n~ensions to account for r~otch.ing of bulklt.eads <br />bulkhead dimensions are 13' x 10' ~ 1.6' long <br />bulkhead volume is 7.7 cubi.e yards <br />• low pressure grouting is necessary <br />• flexural and temperature shrinkage rebar at both. ends of the bulkhead, both ways <br />+ stainless steel bypass piping is necessary <br />Concrete wi31 use n~aximurn'J4 inch aggregate:, '1'rrpe ~ ce~neatt, 1 o percent fly ash., po~olan, <br />water/com.erit ratio of U.~S by weight, and ~vi.ll_. lie over sanded to erthanc~ pumpability <br />