Numerical analysis of the behaviour of a cut slope in stiff clays by finite difference method

This paper concerns the instability process occurring on a cut slope in stiff clays located at the north of the town of Lucera (Southern Italy). This unstable slope lies between a hospital at the top and an abandoned quarry at the toe, which was active until the end of the 1970s. A first landslide was triggered around 1980 and was characterized by a subsequent retrogressive activity This paper presents the results of a coupled elasto-plastic finite difference analysis of the slope behaviour carried out with FLAC(2D), outlining a possible interpretation of the landslide mechanism. The input data have been defined according to field surveys and laboratory investigations on the involved clays. The numerical results show that during the excavation stages the negative excess pore water pressures due to undrained unloading allowed for a temporary slope stability and that subsequently the process of pore pressure equalization caused the slope failure.