CASE HISTORY

Reinforcement of Poor Draining Backfill at JKR Road Reserve, Kulim, Kedah

Authority : JKR, Kedah
Client : Barisan Kemajuan Sdn Bhd 
Consultant : Perunding Timur
Completion : April 1994

Conventionally, the use of poor draining backfills for reinforced soil structures has been avoided whenever possible. However, the use of poor draining backfills can be considered with Nehemiah Wall system because of the enhancement in pullout resistance provided by the anchor blocks.

In a housing project in Kulim, Nehemiah Wall system was adopted to reinforce poor draining backfill. Due to the JKR road reserve boundary, Nehemiah Wall was constructed to retain a 3m high slope upon which the housing project was situated. The backfill material available on site comprised cohesive frictional residual soil with 36% silt and clay. This backfill material, though makes for poor draining, complied to the specification stipulated for use with Nehemiah Wall. Dissipation of pore water pressure in the backfill was provided for through drainage blanket incorporated behind the facing panels. French drains were also incorporated at several locations along the height of wall. These drains were laid perpendicularly to the facing at 3m horizontal spacing.

The construction of the whole wall extended 170m long with average height of 4.5m. On site pullout tests on the reinforcing elements and vertical checks on the wall were carried out which showed that the wall is in excellent condition.

Apart from providing structurally stable and aesthetically pleasing structure, the use of Nehemiah Wall in this housing project with poor draining backfill resulted in tremendous cost savings.

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