Tuesday January 1, 2013
Vital to have regular maintenance of slope, says expert
PETALING JAYA: It is safe to stay above an anchored slope but regular maintenance is required to ensure the slope's safety, said engineer and geo-technical consultant Dr Gue See Sew.
He said such slope would be safe if it was maintained every six months.
“An anchored slope is used for steep slopes that is strengthened by ground anchors in the rock or soil behind it. The anchors need to be restressed (tightening the anchor) consistently to maintain the carrying capacity of the ground anchors.
“If the carrying capacity is reduced without re-stressing, the safety of the slope is reduced in time. This is when landslides can occur,” he said yesterday.
Dr Gue, who is past president of the Institution of Engineers Malaysia (IEM) and Fellow of Academy of Sciences Malaysia, said anchored slopes were sometimes used at highways when there was a dedicated team to conduct the necessary maintenance.
“Anchored slopes are usually not used for hillside development for residential, commercial and resorts now due to the regular maintenance needed,” he said.
Dr Gue, who is from G&P Professionals Sdn Bhd, added that a passive system would involve the use of soil nail slope, whereby minimal maintenance is required such as cleaning the drainage and checking of cracks.
On the issue of the wall collapse in the Bukit Setiawangsa area, Dr Gue, who visited the site on Sunday, said he did not attribute the cause of the landslide to a water drainage problem.
“I found that the water was flowing away from the slope. However, a detailed investigation should be conducted on the wall's failure,” he said.
Meanwhile, IEM Geotechnical Engineering Technical Division chairman Liew Shaw Shon said if the areas with anchored slope had been designed with proper design practices and executed with good construction practices under supervision of a slope designer, there was no problem for buildings or structures to be built over it.
However, he said the use of prestressing ground anchors for residential development were losing favour worldwide while it was discouraged by the local authorities due to the high maintenance needed.
“According to CERUN 1( Guidelines on Slope Maintenance in Malaysia) published by Slope Unit of the Public Works Department, inspection for high risk slopes must be conducted at least once a year,” he said.
“If there are no specific design life requirements, normal design life span for the slope is 50 years with proper maintenance as specified in codes of practice,” he said.