Back experience of deep drainage for landslide stabilization through lines of siphon drains and electro-pneumatics drains: A French railway slope stabilization example

摘要

The prime trigger for landslips is high standing groundwater levels within the slope. Drainagetechniques which lower the standing groundwater level within the unstable soil mass are a proven method ofstabilising landslips. The field of technique are important to lower and maintain the groundwater levels withinslopes but techniques using one or more lines of vertical or inclined drainage wells could have advantage assiphon and electro-pneumatic often used in Europe. Back experience is presented for a case in France wherethe construction in 1995 for the high-speed railway line from Lyon to the Mediterranean included significantearthworks. In 2000 in the southern area of Lyon,a landslide 30 m in depth and 300 m width occurred. To solvethe problem,600,000 m3 of material was removed from the slope to reduce the movement at the upslope part ofthe railway. However on completion of these works slow ground movement continued over a 150 m length withgroundwater levels being near ground surface. After further studies,the Railway Agency in 2006 have chosen toinstall about 47 electro-pneumatic drains wells to lower groundwater to 10 to 15 m depth. Details of the design,monitoring and geological context are described.