Radar Imagery and Bore Hole Data -- A Partnership for Iidentifying a Rock Instability Problem

Abstract

Radar Imagery in conjuction with bore hole data successfully mapped the geometry and extent of a clay seam behind an underground rock wall of questionable stability. This resulted in the modification of the excavation and rock bolting plan in order to increase the stability of the associated rock masses. Uniqueness of the project includes a) the utilization of the excavation and rock bolting geometry to both verify the interpreted clay images and to provide time to depth calibration data and b) the value of deconvolution and the use of color as an aid to data interpretation and presentation.

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.

Meeting Name

4th International Conference on Ground Penetrating Radar (1992: Jun. 8-13, Rovaniemi, Finland)

Department(s)

Geosciences and Geological and Petroleum Engineering

Second Department

Mining Engineering

Comments

Session: Ground Penetrating Radars in general and data processing

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1992 Geological Survey of Finland, All rights reserved.

Publication Date

01 Jun 1992

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