SR99 Bored Tunnel-Assessment of Settlement Impacts ... - SCATnow

machine excavated face (X T ) was then varied in increments from a starting position2Kz before the building station to an ending position 2Kz after the building station.At each step a Boscardin and Cording damage calculation was performed andrecorded from which a comparison could then be made to the full predictedsettlement Boscardin and Cording damage estimate.The settlement equations for the transient analysis augment the equations providedby the Geotechnical Engineer and are based upon Attewell, et al [1982].Settlement:δ =δ final⎛ X − X⋅G⎜⎝ iT⎟ ⎠⎞(Eq. D1-2)Horizontal strain normal to tunnel alignment:εhy2δ ⎛ y⎟ ⎞= ⎜ −12z ⎝ i ⎠(Eq. D1-3)Horizontal strain parallel to tunnel alignment:εhx( X − X )δ ⎪⎧final ⎛ X − X ⎛T ⎞ −⎨1− ⎜ ⎟exp⎜z 2π⎪⎩ ⎝ i ⎠ ⎝ 2i=2T2⎞⎪⎫⎟⎬⎠⎪⎭(Eq. D1-4)Where,δ final = Full predicted ground settlement in accordance with Section 4.1.G((X-X T )/Kz) = a function “G” returning the numerical integration of thestandard probability curve at the point ((X-X T )/Kz as is illustrated inFigure D-5.i is as defined in Section 4.1.K is as defined in Section 4.1.Note that due to the three dimensional settlement profile, horizontal ground strainsexist both normal to and parallel to the tunnel alignment axis. To account for thetunnel parallel strain (ε hx ) upon the Boscardin and Cording damage estimate theprojection of ε hx into the plane of each building wall was found and added to theBoscardin and Cording wall strain ε h described in step 8 previously.The Alaskan Way Viaduct & Seawall Replacement Program March 2010Proposed SR 99 Bored Tunnel - Assessment of Settlement Impacts to Buildings D-4Public Disclosure Request 11-0123 for Elizabeth Campbell - 2nd installment