Reliability of Deteriorating Slopes

Abstract

The effect of deterioration on the reliability of slopes of various service periods has seldom been considered explicitly in the current reliability approach in slope engineering. Constant annual failure probabilities, that are commonly used in practice to evaluate reliability of a slope over a given expected service period, may not be capable of capturing the deteriorating characteristics of slopes. This paper presents a procedure to model probabilistically the deteriorating effect on the failure probability with time. Past performance of geotechnical systems of similar nature is systematically analyzed to evaluate the failure probabilities for systems of different ages and for different expected service periods. The method was applied to the stability performance of soil cut slopes in Hong Kong. Through this exercise, the reliability of slopes of different ages for different future service periods can be reasonably estimated. As such, a planner can benchmark a design standard and plan a slope improvement program in a more effective and defensible way.