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• <br /> SUBJECT: HDPE Pipe Desi n <br />GOLDER Job Number: 933-2720 Made by BES Date: S/25/94 <br />ASSOCIATES Ref: Checked: Sheet of <br /> Reviewed: <br /> Fib NUnr pig2710.rat <br />CALCULATIONS: (cont.,) <br />Design the pipe for ring deflection <br />Design the pipe rings to withstand the vertical compression of the <br />soil envelope around the pipe. Ensure that the allowable ring <br />deflection of the pipe is greater than the vertical strain of the soil. <br />The modified Iowa Equation will be used: <br />3'o(dy/D) _ (DI * K * P * 100) / ([(2 * E) / (3 * ((SDR -1) ^ 3))] + (0.061 * E")) <br />where: dy =vertical deflection, inches <br />D =pipe diameter, inches <br />DI =Deflection lag factor (use 1.0 for load prism) <br />K =Bedding constant (use 0.1, material enclosing pipe will be gravel) <br />P =Overburden pressure on pipe, psi <br />E =Elastic Modulus of pipe material, psi <br />SDR =Standard dimension ratio <br />E" =Modulus of Soil Reaction <br />E", the modulus of soil reaction (representing soil stiffness) <br />is determined by the method developed by Selig shown in <br />Reference 4. However, E" is not a directly measurable <br />parameter- Therefore, studies have been perfomed to find <br />correlation between Young's Modulus (Es) and <br />constrained modulus (Ms). <br />To determine E", the following relationships were developed: <br />Ms=[ES*(1-VS)]/[(1 +Vs)*(1-2*VS)] <br />where: Vs =Poisson's Ration, use 0.3 <br />Vs = 0.3 <br />E"=K*Ms <br />where: K = .7 to 2.3, use conservative value of ,7 <br />K= 0.7 <br />