PERFORMANCE OF REPAIRED SLOPE USING A GEONET OR GEOPIPE DRAIN TO LOWER GROUND-WATER TABLE
A 70 m long by 5 m high slope with gradient of 1(v):2(H) was cut into a medium-stiff residual soil of undrained shear strength better than 60kPa, with drained strength parameters of about c = 10kPa, and o = 22 degrees, to form the bank for an effluent pond used for irrigation of a racetrack turfing. Both drained and undrained slope stability analysis indicates stable slopes under reasonable ground-water (GW) levels expected in the cut slope. However, after a period of intense rainfall during construction, the slope suffered a shallow slip of about 1 m to 1.5 m depth over a 30m stretch of the slope length with a vertical scarp near the top of the cut slope. This paper examines the cause of slope failure, and the strategy adopted for a permanent repair of the slope by providing internal geosynthetic drains beneath the re-compacted slope, using a GEONET or closely spaced geo-pipe inclusions in the slope. For design, the GEONET or geo-pipe drains used must have adequate factored transmissivity to conduct expected heavy rainfall condition of 150 mm/h on the racetrack, it is demonstrated by the Finite Element Method (FEM) analysis, that GEONET must be provided to at least as far back as the mid-depth of the slope (about 4 m depth) to produce sufficient GW lowering to give stable slopes. The construction method of the slope repair to avoid further failure is described briefly, and the performance of the sub-soil drains in enhancing slope stability is demonstrated in the field project.
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Availability:
- Find a library where document is available. Order URL: http://worldcat.org/isbn/0803128606
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Corporate Authors:
American Society for Testing and Materials (ASTM)
100 Barr Harbor Drive, P.O. Box C700
West Conshohocken, PA United States 19428-2957 -
Authors:
- Tan, Siew-Ann
- Chew, Soon-Hoe
- Karunaratne, G-P
- Wong, Swee-Fong
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Conference:
- Testing and Performance of Geosynthetics in Subsurface Drainage
- Location: Seattle, Washington
- Date: 1999-6-29 to 1999-6-29
- Publication Date: 2000-3
Language
- English
Media Info
- Features: Figures; References; Tables;
- Pagination: p. 3-14
Subject/Index Terms
- TRT Terms: Drain pipe; Finite element method; Geosynthetics; Groundwater; Lowering; Piping systems; Shear strength; Slope failure; Slope stability
- Subject Areas: Geotechnology; Highways; Hydraulics and Hydrology; I26: Water Run-off - Freeze-thaw;
Filing Info
- Accession Number: 00801020
- Record Type: Publication
- ISBN: 0803128606
- Report/Paper Numbers: STP 1390
- Files: TRIS
- Created Date: Oct 16 2000 12:00AM