ABSTRACT
This paper presents the analysis of a case of major surface movement, the underlying causes and the mode of reconstruction work. This landslide occurred at the building site of a storehouse in a cutting made into a hillside in Budapest. During excavation, soon after the natural support at the toe was undercut, a mass of 12 000 m3 of soil began to move. An attempt was made to block the movements by the construction of buttress drains but rainy weather still reactivated the movement of the earth mass. Then, to stop the movement, 3 m high stabilizing berm was placed before the toe of the sliding mass. The designer would have liked to add nine new stone ribs to the retaining structure, but stability analysis proved that not even such a solution could have resisted the sliding action. Eventually an anchored slurry trench wall 8 m deep was constructed to support the back face of the excavation.
The paper describes the results of ground investigations, the design of the stone ribs, the stability analysis of the hillside and the causes of ground movements.
In addition it calls attention to the potential risk of underestimating the inherent danger of constructing on sliding-prone hillsides – on the part of both the designer and the contractor – because unfavourable conditions (awkward underground conditions, or/and a rainy period during construction) may trigger the movement of earth masses with the outcome of significant economic losses.
Finally a brief review is given of the effect of moisture content increase on shear strength.
