52. The use of geogrids in landslide control works: case history from Valtellina

Following rainstorms in July 1987, several landslides fell along the Adda River, diverting the stream and threatening people and civil works in the area.

La Boscaccia slide, 200 meters wide and 160 meters long, had a volume of 1,1 million cubic meters. The main scarp after the slide was 50 meters high and 125 meters wide. The materials involved were gravelly and silty sands, belonging to a fluvial fan due to a tributary of the Adda River.

The local Authority (Lombardia Region - Public Works Board) carried out various control works, namely:

- a rockfill cliff 5 meters high, 160 meters long, to prevent bank erosion;

- a check dam 50 meters wide to control bottom erosion;

- 630 meters of drainage trenches to drain the surface water;

- 5 geogrid-reinforced embankments, 20-meters high altogether, for slope stabilization.

The paper will describe the procedure followed during design and-construction of the geogrid-reinforced embankments.

Particular attention will be devoted to the existing relationships between the-layout of the geogridreinforced embankments and the stability of the slope.

The stability analysis, has been carried out making use of limit equilibrium methods, modified to take into due account the geogrid effects.

• 1. INTRODUCTION

• 2. LA BOSCACCIA: A CASE HISTORY

• 3. MITIGATIVE MEASURES

• 4. THE GEOGRID REINFORCED EMBANKMENTS

• 5. CONCLUSIONS

• REFERENCES