LANDSLIDES AND STABILITY OF COASTAL CLIFFS OF COXS-BAZAR AREA, BANGLADESH

Successive applications of two-dimensional circular slip limit equilib rium analysis of slices have been made to the three sections of the Co x's Bazar Coastal Cliff. These three sections have been found to be st able (S), quasistable (QS), and unstable (U) with factors of safety (F s) of 1.269 +/- 0.01, 1.13 +/- 0.0504, and 1.01 +/- 0.058, respectivel y. In the quasistable and unstable sections, the slopes suffered shall ow slidings with slip circles parallel to the surface of slopes. The m ain causes of these slidings are steepness of slopes, lack of vegetati on cover, erosion of toe accumulations by run-off water and waves duri ng high tides. The influence of the slope geometry and the material's strength properties of slopes on safety factors are evaluated. The ste eper cliffs reach an unstable condition faster than the more gentle cl iffs as their heights change by an equal amount. Again, the high cliff s reach an unstable condition faster than the lower cliffs as slope in clinations change by an equal amount. The safety factor increases with a corresponding increase of friction angle (phi(0)) and vice versa.