Design and Construction Observations of the Neutrino Detection Chamber at Fermi National Accelerator Laboratory

摘要

The design approach used to build the new Near Detector Hall (NDH) at Fermilab withoutrnjeopardizing the integrity of the existing MINOS Hall and MINOS Access Tunnel is discussed. The NDH isrnseparated from the existing access tunnel by a relatively thin pillar that is 9.5 ft wide at its thinnest section.rnThe relatively weak Scales Formation and the thin pillar necessitated some changes by the contractor’srndesigner to the original design proposed by the owner’s engineer. The alternative design implemented shorterrnexcavation drifts and use of pre-tensioned rock bolts in the pillar and at selected locations in the existing accessrntunnel to minimize movements. The competent rock in the floor beneath the pillar played an important role inrnminimizing the deformation during construction. A comparison between predicted and observed responses forrnthe underground openings is also presented.