Description
In the context of landslide mitigation, it is always necessary and beneficial to prevent the infiltration of surface water into the ground in or close to existing or potential landslides. Good surface drainage is therefore necessary in these areas to avoid rises in piezometric levels in the unstable mass, reducing effective stress and consequently shear strength on the slip surface.
Impervious membranes are normally used as a short term, temporary or emergency measure.
Impervious facing is normally used as a permanent measure as part of landslide remediation or as a preventive measure on excavated slopes (see section 1).
Vegetation may be considered to provide partial impermeabilization through the canopy storage effects (see fact sheet 3.5).
Design methods
will be updated
Functional suitability criteria
Type of movement |
||
| Descriptor | Rating | Notes |
|---|---|---|
| Fall | 1 | Most suited to all types of slides. In spreads, only useful as remediation, not as a preventive measure. |
| Topple | 0 | |
| Slide | 7 | |
| Spread | 5 | |
| Flow | 0 | |
Material type |
||
| Descriptor | Rating | Notes |
|---|---|---|
| Earth | 8 | Mainly applicable to landsliding involving earth and only to a lesser extent in debris. Applicability in rock limited by typical slope geometry and failure mode, but note that in deep seated rock slides tension cracks propagating through the surface cover would also benefit. |
| Debris | 7 | |
| Rock | 2 | |
Depth of movement |
||
| Descriptor | Rating | Notes |
|---|---|---|
| Surficial (< 0.5 m) | 8 | Typically applicable to landslides of any depth, but relative effectiveness decreases with increasing depth of movement. |
| Shallow (0.5 to 3 m) | 8 | |
| Medium (3 to 8 m) | 7 | |
| Deep (8 to 15 m) | 3 | |
| Very deep (> 15 m) | 0 | |
Rate of movement |
||
| Descriptor | Rating | Notes |
|---|---|---|
| Moderate to fast | 1 | Can be carried out without special difficulty when the rate of movement is slow (5 cm/day) or less, but may be disrupted and will rquire additional maintenance or reconstruction as a result of continued movement. May be applicable, with special precautions and limited effectiveness due to continuous disruption, to moderately fast movements. |
| Slow | 6 | |
| Very slow | 8 | |
| Extremely slow | 8 | |
Ground water conditions |
||
| Descriptor | Rating | Notes |
|---|---|---|
| Artesian | 6 | Applicable irrespective of groundwater conditions. Effects on groundwater levels only indirect through reduced infiltration. Potential difficulties in carrying out in areas of high or artesian groundwater levels, depending on the depth of local excavation required. |
| High | 6 | |
| Low | 8 | |
| Absent | 8 | |
Surface water |
||
| Descriptor | Rating | Notes |
|---|---|---|
| Rain | 9 | Water courses should be diverted. |
| Snowmelt | 9 | |
| Localized | 8 | |
| Stream | 3 | |
| Torrent | 1 | |
| River | 1 | |
Reliability and feasibility criteria
| Criteria | Rating | Notes |
|---|---|---|
| Reliability | 8 | Effects on stability only indirect. The reliability in the long term may be impaired by further movement or poor maintenance. |
| Feasibility and Manageability | 10 | Simple technique. Potential benefits and limits of applicability are well established. |
Urgency and consequence suitability
| Criteria | Rating | Notes |
|---|---|---|
| Timeliness of implementation | 10 | Easily implemented with widely available equipment. |
| Environmental suitability | 6 | will be updated |
| Economic suitability (cost) | 10 | Low, where applicable. |
References
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Edil T.B. (1992). “Landslide cases in the Great Lakes: Issues and Approaches”. In Transportation Research Record 1343, TRB, National Research Council, Washington, D.C., 87-94.
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Gedney D.S., Weber W.G. ( 1978). “Design and construction of soil slopes”. In: Landslides: analysis and control, Special Report 176, Chapter 8, R.L. Shuster, R.J. Krizek (eds.), TRB, National research Council, Washington D.C., 172-191.
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Millet R.A., Lawton G.M., Repetto P.C., Varga V.K. (1992). “Stabilization of Tablachaca Dam”. In: Proc. of a Specialty Conference on Stability and Performance of Slopes and Embankments, Berkeley, California, R.B. Seed, Boulanger R.W. (eds.), Geotechnical Special Publication 31, ASCE, 1365-1381.
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Kelly J.M.H., Martin P.L. (1985). “Construction works on or near landslides”. In: Landslides in the South Wales Coal Field, Polythecnic of Wales, C.S. Morgan (eds.), 85-106.
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Kropp A., Thomas M. (1992). “Partial landslide repair by buttress fill”. In: Transportation Research Record 1343, TRB, National Research Council, Washington, D.C., 108-113.
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Holtz R.D., Shuster R.L., (1996). “Stabilization of soil slopes”. In: Landslides: Investigation and Mitigation, Special Report 247, chapter 17, A.K. Turner and R.L. Shuster (eds.), Transportation Research Board, Washington.
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Turner A.K., Schuster R.L. (eds.). (1996). “Landslides: Investigation and Mitigation”. Special Report 247, Transportation Research Board, Washington.