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

The shape of the transverse settlement trough can be described by a GaussianProbability distribution curve as shown Figure 3. The settlements are approximatedby a Gaussian probability distribution curve in the direction perpendicular to thetunnel axis. It can be seen that the trough has its maximum slope at the point ofinflection, which is located at the distance i from the tunnel centerline. This pointseparates the sagging zone from the hogging zone.The shape of the Gaussian Probability distribution curve is a function of the distancefrom tunnel centerline to the inflection point. As the distance to the point ofinflection increases, the curve is generally wider and flatter and as the distancedecreases, the curve is generally narrower and taller. Case history data presented inMair and Taylor (1997) indicates the distance to the point of inflection (i) can berelated to tunnel depth (Z o ), where:iK = (Eq. 1)ZShannon & Wilson indicate that the K values utilized vary along the length of thetunnel alignment. The following values were utilized are as follows:K = 0.35 between Stations 200+00 to 217+00K = 0.50 between Stations 217+00 to 281+00K = 0.35 between Stations 281+00 to EndThe settlement, S z , at a point of interest is a function of the horizontal distance fromthe tunnel centerline, x; and the vertical distance above the tunnel springline, z. Forsurface settlements, the vertical distance z is equal to the depth to the tunnelspringline, Z.The Alaskan Way Viaduct & Seawall Replacement Program March 2010Proposed SR 99 Bored Tunnel - Assessment of Settlement Impacts to Buildings 16Public Disclosure Request 11-0123 for Elizabeth Campbell - 2nd installment