River wall stabilization

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Restoring slope stability (landslide prevention) based on dewatering mostly

Restoring slope stability (landslide prevention) by essentially dewatering

Groundwater is a major contributor to landslide initiation. Slope failures frequently occur when deep soil layers become saturated due to heavy rains, leaking water pipes or tanks. The problem is succesfully addressed by our innovative method of draining water away from these layers. Our system of subsurface drainpipes installed above the slip (sliding) surface using horizontal directional drilling creates an efficient and reliable solution that has been proven a success in a track record of slope stability projects.

We utilize our expertise by giving assistance to engineering and contractor companies around the world enabling them to meet the demands of water-induced landslide slope stabilization projects.

SYCONS' system for slope stability restoration (landslide prevention)

Adequate drainage of water is achieved by a system of drainpipes, vertical wells and collector shafts that all-in-all reduce water table level by up to 4 metres.

In high water table induced mass soil movements (landslides) there is a distinct surface of weakness that separates the sliding material from the more stable underlying material. This so called slip surface (sliding surface) is usually located at the top of a non-permeable clayrich soil layer that saturates in the upper few cm-s to the point of liquification resulting in drastic reduction of its shear strength. Decrease of resistance coupled with ground layers slanting in the slope's direction threaten slope stability. As soil conditions vary in every slope, subsurface drainage systems are always designed individually. The success of the drainpipe system therefore relies upon a top core quality geotechnical research carried out preceding the design and installation.

The network of self-cleaning drainpipes is installed right above the sliding surface using mainly the no-dig technology of horizontal directional drilling (HDD). When installing pipes in great depths or under great surface obstacles no-dig technology has several benefits over open cut techniques reducing environmental, economic and social costs. Moreover, in ground masses subject to ongoing movements open cut constructions are impossible due to high danger concerns. Using HDD single span drainpipes of 150 metres can be installed in a maximum depth of  25 metres.

The design of drainpipe perforation (the decreasing slot size towards the outer perimeter) makes clogging virtually impossible and therefore under regular maintainance ensures a life expectancy of at least 50 years.

Water in the drainpipes is gravity transferred first into prebuilt collector shafts and later to natural or artificial reservoirs (lakes, rivers, sea, etc.).

Soil permeability above the slip surface may necessiate the construction of additional filtering surfaces. When the sliding material is of highly permeable silty sand (containing minimal amount of clay) water easily penetrates to the slip surface (sliding surface) and is collected by the drainpipes. However in low permeability soil additional gravel filled wells are a demand to increase filtering performance of the drainpipes. Low permeability may be due to clayrich layers that trap water. The drainpipes pass through the wells collecting water from their bottom.

Download landslide prevention brochure



See our most important references in slope stabilization:

  • Municipality of Ercsi, Hungary - Danube riverbank stabilization.Complete slope stabilization system, installation of subsurface drainage system coupled with gabions retaining walls.
    2000-2001 and 2003. - Municipal government
  • Municipality of Rácalmás, Hungary - Danube riverbank stabilization.Complete slope stabilization system, installation of our innovative subsurface drainage system with self-cleaning drain pipes, gravel filled wells and collector shafts.
    2003-2004 - Municipal government
  • Municipality of Dunaújváros, Hungary - Danube riverbank stabilization.Stabilization of the riverbank, excavation of the sliding mass, reinforcement with soil nails and recultivation with quality soil.
    2010 - Municipal government

More references