Information derived from shear and sliding friction tests on Morrow Point foundation rock can be used to determine sliding resistanoa between surfaces of jointed rock and on a concrete-rock interface. All of these field and laboratory tests to augment previous data from triaxial tests on rock cores were performed on 15- by 15- by 8-in. specimens of the dominant foundation rock, a mica schist (Type II) and a micaceous quartzite (Type III) and of concrete-on-rock. Laboratory rock samples were encased in concrete and oriented so foliation would be perpendicular to normal load and parallel to shearing load, thereby testing the weakest foliation condition. In the field, specimens were prepared in the floor of the power plant exploratory tunnel by removing loose rock, roughly shaping by line drilling, and then chipping and bush-hammering the block to etact dimensions. The concrete-on-rock specimen was made by casting a concrete block on the sheared surface of a lower block of Type II rock. A special apparatus to fit the 5,000,000-lb testing machine was designed and built for the laboratory tests. Good correlation obtained between field and laboratory direct shear tests shows that laboratory tests of large specimens can be substituted with confidence when field tests are not feasible. The number and repeatability of the sliding friction tests indicate that they can be used to estimate sliding resistance.
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