Dip slopes and anchors suspected in freeway landslide
By
Taiwan News, Staff Writer
2010/04/27 00:00
A landslide destroys portions of a major highway outside of the northeastern port city of Keelung, northern Taiwan is shown in this aerial image made ...
A landslide destroys portions of a major highway outside of the northeastern port city of Keelung, northern Taiwan is shown in this aerial image made and released on Sunday by National Airborne Service. Fire fighters say that the slide has buried two vehicles but round the clock digging efforts still have not located them.
On the first working day after the landslide on the No.3 Freeway, traffic on roads near Keelung falls into chaos. Motorists traveling from Chinshan, W...
On the first working day after the landslide on the No.3 Freeway, traffic on roads near Keelung falls into chaos. Motorists traveling from Chinshan, Wanli and the Tawulun area of Keelung used the Sun Yat-sen Freeway, causing traffic jams on the Maichin Road near Patu at 7 a.m. yesterday.
A young man, right, waits for news of the rescue operation on the No.3 Freeway yesterday in the company of volunteers from the Buddhist Compassion Rel...
A young man, right, waits for news of the rescue operation on the No.3 Freeway yesterday in the company of volunteers from the Buddhist Compassion Relief Tzu Chi Foundation.
Excavators succeed in removing the steel cables from the overpass destroyed by the landslide on the No.3 Freeway near Keelung yesterday morning, but w...
Excavators succeed in removing the steel cables from the overpass destroyed by the landslide on the No.3 Freeway near Keelung yesterday morning, but work continued on the heaps of rocks spread over 300m.
Experts suspected the geological phenomenon of the dip slope was responsible for the unexpected landslides on the No.3 Freeway near Keelung.
Transportation Minister Mao Chi-kuo first brought up the topic during a visit to the disaster site Sunday evening. Initially, observers were unable to explain why landslides had occurred in the absence of an earthquake or heavy rain.
The hill next to the freeway had a dip slope leaning toward the road. The other side of such formations is steep and irregular, while the dip slope side tilts downward, making it easier for rocks to slide down, experts said.
National Taiwan University geology professor Liao Juei-tang also said the anchoring holding up the hill had rusted and loosened, becoming unable to stop the rocks from sliding down to cover the road.
The anchors or steel reinforcers were also identified as the possible source of the problem by government officials, including Lin Chao-chung, the director of the Central Geological Survey under the Ministry of Economic Affairs.
Faulty construction or wear on the anchors in the restraining walls might have contributed to the failure to prevent the rocks from covering the freeway, he told reporters.
Another theory looked for problems with the presence of the Hsinshan Dam just 1 kilometer away, but experts thought the water had no way of influencing the roadside hill.
The Ministry of Transportation said it was investigating the number of locations showing similar geological characteristics to the site of the landslide. Mao estimated the number of dip slopes next to major roads across Taiwan at about 20.
