PROBABILISTIC BACK ANALYSIS AND THEIR RELIABILTY OF PLANE FAILURE: A CASE STUDY FROM TRABZON-GUMUSHANE HIGHWAY, NE TURKEY

This study discusses the prior information of input data from both laboratory tests and deterministic back calculation methods that are to be considered by probabilistic back analysis method. For this purpose, the failure based on discontinuity surface, plane failure, occurred at natural slope on the Trabzon highway, NE Turkey, in May 2008. In order to obtain the shear strength parameters of the sliding surface, the deterministic back analyses with a comparison with laboratory derived shear-box test and considering these value and water condition as input parameters, the probabilistic back analyses were performed. A measure of the reliability of the back calculated shear strength parameters were able to develop. For this, the probabilistic stability analysis for the failure conditions obtained by the deterministic and probabilistic back analysis were performed and standard deviation of the safety factor and slope failure probability were obtained the landslide investigated.. In this analysis, Monte Carlo method was applied. These analyses clearly reveal that the result of the probabilistic back analyses is a more representative according to the deterministic back analyses for at the failure condition of the landslide investigated. And the shear strength parameters obtained by the comparison laboratory derived shear-box test results and deterministic back analyses can be used as a input parameter for the probabilistic back analysis.