Effect of the Elastic Properties of Rocks on Civil Engineering Design
Published:January 01, 1959
In recent years the engineering geologist has entered a picture formerly occupied primarily by mining engineers concerned with the nature of rock bursts in mine tunnels. Now, the civil engineer can achieve better and more economical designs by utilizing the engineering geologist to weave together the tectonic history of a site with the test results and the future effect of forces to be imposed by the man-made structure. Knowledge of the uncon-fined compressive strength of rock no longer is considered adequate. Reliable data on the modulus of elasticity and Poisson’s ratio of the rocks that will underlie the structure permit the civil engineer to take advantage of the inherent elastic properties of the rocks. Reductions can be achieved in the amount of steel in tunnel linings, concrete in arch dams, support in underground chambers, and yardage to be excavated in conjunction with these structures. For example, tests prior to the final design of the Cubatafo Underground Powerplant (Brazil) tunnels resulted in the elimination of almost 80 per cent of the lining steel; it was found that a considerable part of the internal hydrostatic pressure could be transmitted to the rock surrounding the lining.
Despite the wealth of available data on rock properties, much is conflicting, uninterpreted, or inapplicable to civil-engineering problems. A major research problem is how to correlate field tests in situ with laboratory tests on rock specimens. A corollary is: “Which test method most nearly provides the actual in situ properties of a rock foundation?”
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Engineering Geology Case Histories Number 3: Symposium on Rock Mechanics
Prepared by the Case Histories Committee for the Engineering Geology Division of the Geological Society of America, these histories are intended as reference material for the practicing geologist and for the college student. The Symposium on Rock Mechanics, edited by Parker D. Trask, is the third volume on the series. It contains the following papers: Some engineering studies of rock movement in the Niagara area; Rock mechanics in the investigation and construction of T.1 Underground Power Station, Snowy Mountains, Australia; Importance of geological information as a factor in tunnel-lining design; and Effect of the elastic properties of rocks on civil-engineering design.