Life Member 2006
Georg Kjerbol worked with HNTB in Seattle.
Among other publications, he co-authored "Unearthing Mt. Baker Tunnel," which appeared in Civil Engineering December 1985 and won ASCE's John O. Bickel Award in 1987.
From the abstract: "A new tunnel under Mt. Baker in Seattle is part of major improvements to I-90 between Bellevue and Seattle's business district. Feasibility studies began in 1963, but it was not until 1977 that the concept of a single bored tunnel was accepted by WSDOT. Conventional full face tunneling was not suitable for the site, which had silty clays beneath a residential area. Instead, the stacked drift liner system was used, with 24 bores driven in a circular pattern and filled with concrete before excavation began on the 63 ft diameter tunnel. The liner was designed as a semi-flexible support system capable of adjusting to non-uniform external loading by deforming until equilibrium is reached. Structurally, it acts as a ring in compression. Because they are only 9 ft in diameter, the drifts were excavated with conventional equipment. Access pits 90 ft in diameter and 90 ft deep were converted to vertical retaining walls for the cut-and-cover end portions of the 1,500 ft tunnel."
Posted June 2012