Radar imagery and bore hol data - a partnership for identifying a rock instabilty problem

As part of the expansion program of the Jefferson National Memorial Expansion Memorial in St. Louis, Missouri, the National Park Service contracted an expansion to the associated museum. This required the floor of an existing room of dimensions 18 m by 25 m be lowered an average of 3 m. In order to maximize seating in the theater, it was also necessary to cut the walls of the excavation as close to flush under the existing footings as could be achieved. The memorial and associated museum are located in the downtown portion of St. Louis and are toured by some two million visitors each year. Consequently, the excavation of the proposed facility was to accomplished without the use of conventional blasting techniques. Figures 1 and 2 illustrate the original ground contour and the required final geometry, respectively. It was estimated that approximately 1200 cubic meters of material needed to be removed. The High Pressure Waterjet Laboratory of the University of Missouri-Rolla proposed to accomplish the work by means of innovative techniques, specifically the use of high pressure water jets and rock splitters designed by the Center. The proposal was accepted, a contract signed and work begun.