FIELD JACKING TESTS OF FOUNDATION ROCK MORROW POINT DAMSITE - CURECANTI UNIT, COLORADO RIVER STORAGE PROJECT,
BUREAU OF RECLAMATION DENVER COLO
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Field jacking tests were conducted at Morrow Point Dam to determine the in-situ characteristic of the foundation rock beneath the Bureaus first double curvature thin arch dam. The basic test procedures consisted of applying loads of known intensity to the rock inside tunnels driven in both abutments and measuring the resulting rock deformation. Load is applied to the rock by two jacks, 3 feet apart, each having a capacity of 200 tons. Loads were applied first vertically and then horizontally at the same tunnel location during a test series. Loads of 200, 400, and 600 psi were applied to the rock each for a period of approximately 1 week utilizing automatic controls to maintain the load. The data, when properly analyzed and carefully correlated with the results of laboratory core sample investigations and field seismic studies, should provide the basis for a reliable prediction of foundation deformations under the dam structure. The influence of joints and fissures were apparent in these tests, indicating the importance of performing site tests in every instance where a major structure is planned on a rock foundation.