Prepared for Office, Chief of Engineers, U.S. Army, Washington, D.C. and the Panama Canal Company

This report was previously submitted (April 1978) by the author to the University of Illinois in partial fulfillment or requirements for the degree of Doctor of Philosophy in Civil Engineering. The reported work was conducted as an adjunct study to a long-term and broad effort entitled 'Study of Clay Shale Slopes Along the Panama Canal' conducted by personnel of the U.S. Army Engineer Waterways Experiment Station under the author's supervision. The work consists of a documentation of a case history in which the occurrence and nature of initial failures or 'breaks' were described and pin-pointed with respect to time, location, and extent; the geological setting and groundwater conditions were described; physical tests, with emphasis on laboratory determination of strength parameters, were conducted; and back analyses were conducted along nine cross sections constructed through six initial breaks to compare the required field strength parameters with parameters determined in laboratory tests. Important results and conclusions from this Supplemental Report as well as Reports 1, 2, and 3 of the series will be presented in Report 4, which summarizes the overall study.

Developments in Geotechnical Engineering, Vol. 14B: Rockslides and Avalanches, 2: Engineering Sites focuses on initiatives to offer a foundation for studies of mass movement phenomena in the Western Hemisphere. The selection first takes a look at the contributions of Josef Stini to engineering, geology, and slope movement investigations, the concept of Karl Terzhagi on rockslides, and the contributions of Laurits Bjerrum to the mechanics of rockslides. Concerns cover stability of hard rock slopes, influence of geological details, relation between slide process and remedial treatment, water pressure in pores and fractures, slope creep, rockslides, and avalanches, and early warning of an impending slide. The publication then examines rock slope movements with hydroelectric power projects in Mexico, Bighorn Reservoir slides in Montana, U.S.A., rock avalanche and wave at Chungar, Peru, and wedge rockslides in Libby Dam and Lake Koocanusa in Montana. The text examines Hogarth Pit slope failure in Ontario, Canada, pit slope performance in shale in Wyoming U.S.A., Twin Buttes pit slope failure in Arizona, U.S.A., and the Prime Mine slope failure in Arizona, U.S.A. Discussions focus on stability analyses, description of slope failures, cause of failure, remedial actions, geotechnical properties of tertiary shales, and subsequent slope performance. The selection is a valuable source of data for researchers interested in rockslides and avalanches.

This report compares various laboratory procedures and equipment used for determining the residual strength of clay shales. The effects of testing apparatus, specimen type, normal load, and rate of displacement on the residual strength of various clay shales were evaluated by relations between residual strength and Atterberg limits, grain size, and mineralogy were examined. (Modified author abstract).