Design and construction of a large-diameter wine cave in weak rock

This project involved the design and construction sequencing of a 50-foot high by 75-foot wide wine cave in Napa, California. The cave was constructed as a dome in lahar that consisted of fresh andesite boulders in a matrix of highly weathered rhyolite. Cover over the dome is sloping and relatively shallow, with an average cover of approximately 30 feet. The design included construction sequencing and ground support details using the New Austrian Tunneling Method (NATM), also known as the Sequential Excavation Method (SEM). Final dome. geometry was a multi-radius section, which was designed taking into account both architectural concept drawings and previously excavated tunnel geometry. An 8-foot wide walkway circles the inner edge of the mushroom-shaped dome and is elevated 18-feet above the invert. Ground support for the dome consisted of 16-foot long, 1-inch diameter steel threadbar rock dowels and a shotcrete lining reinforced with welded wire fabric.