Leakage of Gas Through Cracked Concrete Walls

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The leakage rate of gas through a crack of the concrete wall can be formulated by the folowing equations.f=W^3・(P^2_-P^2_)/(2・ ・P_0・Q^2・T)f=a^^-(W)・(12・ / )/Q+b(W)f=coefficient of friction Q=leakage rate W=crack width P_1=pressure at inflow side P_2=pressure at outflow side P_0=1.0atm=1.01325X10^5(Pa) =density of gas =viscosity of gas T=wall thicknessa^^-(W) = experimental functions,b(W) = functions of crack widthUnder the following conditions 0.8X10^5(Pa) P_1 1.2X10^5(Pa) 0.8X10^5(Pa) P_2 1.2X10^5(Pa) P_1-P_2 0.2X10^5(Pa) Re=2・ ・Q/ 10^2,the leakege rate can be estimated by the next equation. Q=a^^-(W)・P_1-P_2)/( ・T) a^^-(W)=experimental function, function of crack widthIn case that the crack width changes slowly along the surface of the wall and does not change across the wall section, the leakage rate can be calculated by simple integration.