Static and dynamic centrifuge modelling of landslide stabilization with large-diameter shafts

This paper presents the results of a series of static and dynamic centrifuge tests carried out to investigate the stabilisation of shallow landslides by rigid shafts. The experimental campaign was aimed at creating a database on the basis of which calibrating an advanced numerical model to be used as a tool for design. The centrifuge models reproduced a shallow landslide on a rock slope 32° steep, reinforced by 3.5 m diameter shafts. Three models were tested, both under static and dynamic loading conditions: the unreinforced landslide and the landslide reinforced with one or three aligned piers. During the tests one model shafts was instrumented with strain gauges to measure bending moments. In the static tests, the shallow landslide was triggered by a displacement-controlled piston which pushed down the top of the slope through a rigid slab which imposed uniform displacements along the slope direction. During the tests the displacements of the sliding mass were monitored through a series of potentiometers. The effect of the insertion of one or three pier was estimated comparing the displacement field of the landslide with and without the reinforcing shafts. In the dynamic tests a real, properly-scaled time history was applied to the models using a one-degree-of-freedom shaking table installed in the centrifuge. Five accelerometers were embedded into the physical models to measure the seismic excitation and response. The reinforced slope resulted stable under the earthquake loading while the test results clearly showed evidence of ground amplification within the soil mass.