Centrifuge modeling of two dimensional slope failure

Slope failures occurred frequently resulting in great loss of lives and properties. It is known that slopes performed differently with respect to different slope angles, heights and soil properties. In this study, the centrifuge facility was used to simulate slope failure under two dimensional (2-D) conditions. A total of 34 tests were conducted under different tests.; The first series of 26 tests were conducted to investigate the slope failure under increasing gravity. Clean Nevada sand and its mixtures with different percentages of fines (up to 30%) were used. The slope models were compacted at optimum water content and maximum dry unit weight. The slope angles were 60, 75 and 90 degrees, and the heights were 10, 15 and 20 cm. The test results showed a normalized behavior of slope failure surface with height and the agreement was more satisfactory for steep slopes. Based on log-spiral analysis, the strength parameters (cohesion and angle of internal friction) were obtained. These back-analyzed strength parameters agreed well with the parameters obtained from the triaxial compression tests. A better agreement was seen with the strength parameters obtained from plane strain compression tests.; The other 8 tests were conducted to simulate rainfall-induced slope failure. Sand with 15% fines soil with optimum water content and maximum dry unit weight was used to construct the slope models. The models with the 15-cm slope height and 60-degree slope angle were selected for the rainfall tests. The tests were conducted under 80-g and 60-g centrifugal field, which were below the gravity at failure for the case without rainfall (97.73 g). The rainfall intensities were simulated using four different set of nozzles. The normalized failure surfaces obtained from the tests of different rainfall intensities were identical and also close to that obtained from 2-D slope failure tests without rainfall. The rainfall intensity-duration threshold curve and the accumulative rainfall that triggered the failure of the tests showed a similar trend to those reported for the field.