Slope Management

and

Landslip Preventative Measures

Development of the Hong Kong System

Major Landslide at Maracas, Trinidad - Late December 2002.

Prevention of Landslides•Database of Slopes

•Type of Slope

•Condition•Consequences

•Cut Slopes

•Fill Slopes

•Retaining Walls

•Hybrids: Cut/Retaining Wall / Fill/Retaining Wall

•“Natural” Slopes - slopes where there has been no anthropogenic activity, or where such activity is causes small changes to the geometry of the slope so that the Factor of Safety is largely unaffected.

Development of Slope Registration Scheme

Began in late 1970’s based on geographic map area

e.g. 11SW-A

followed by a code

C - Cut Slope : F - Fill Slope

R - Retaining Wall : N - Natural Slope

CR - Cut Slope with Retaining Wall

FR - Fill Slope with Retaining Wall

followed by a number

i.e. 11SW-A/R188

refers to Retaining wall 188 in Map area 11SW-A

1 2 3 4

5 6 7 8

9 10 11 12

13 14 15 16

NW NE

SW SE

A B

C D

Map Referencing

Scheme

11SW-A

Hong Kong Slope Catalogue

Some recent Landslides in Trinidad

•There is NO proactive system in place

•Everything is Reactive

Landslide at Maracas

December 2002

December 2004 – note the slide is much more

extensive

December 9th

Landslide

3 km beyond Las Cuevas as seen on TV

half of road blocked

Landslide 11th December 2004 at

approximately 13:00

1 km before Las Cuevas

half of road blocked

Slope before failure at Couva

Slope after Landslide

Slide by Derek Gay, UWI

Could we improve on Hong Kong System?

• A unique number code irrespective of feature type

• Allow for more codes e.g. NRF - natural-retaining-fill

• Or RC as well as CR?

• What about including a code for stability

e.g. L – Landslide

S - Stable

P – Preventative Works done etc

43D-1a/RCN-002/L

Retaining wall beneath cut slope then natural in area 43D-1a

Reference number 002 - landslide has occured

Best way to record information

• Map Reference

• need to have a good map at time of recording

• GPS – convert to Map Reference• need to have GPS (software needs to be written to convert to Map reference)

• Chainage –

•Most roads in Trinidad have chainage markers at 25 m intervals

•Easy to record

•Needs some thought to convert to GPS and hence Map Reference

•Most simple method for basic recording