ABSTRACT
Mastering a lot of landslides through deep dewatering drainage by one or more lines of drains, being pumped either by siphoning pipes or by electropneumatic pumps®, it has appeared to us that water tests were not reliable for different reasons. In order to study the feasibility of such dewatering scheme, there is always a preliminary geotechnical and hydrogeological study with borings, samplings, laboratory tests and water tests on site and in the laboratory. Vertical drains, either drained by siphoning pipes® or electropneumatic pumps®, have allowed the stabilization of more than too hundred lanslides he hereabove proposed formulae of the permeability and of the flow coming out of the drains should lead to an improvement in the design of the scheme of drains, these formulea having to be adjusted to the further experience of new works.
