Some foundation work for a public housing project under construction in Kai Tak has been suspended after the soil at nearby Sung Wong Toi MTR station was found to have compressed to a depth of 20 millimetres.
According to a statement issued by the MTR Corporation (MTRC) on Wednesday, the railway company had requested the contractors of the housing project set up settlement monitoring checkpoints near its Kai Tak and Sung Wong Toi stations to ensure railway operations would not be affected by the construction work. In engineering, settlement refers to the downward movement of soil, typically because of stress changes.
During the construction of foundation work for a public housing project in Kai Tak, a settlement monitoring checkpoint set up near the Sung Wong Toi MTR station recorded 20 millimetres of settlement on Monday, a government statement said.
As 20 millimetres was the pre-set trigger level for suspension of works, the Housing Bureau suspended piling within 30 metres of the checkpoint.
The Buildings Department and the railway station deployed staff to inspect the area around the checkpoint and confirmed that “it is structurally safe,” according to the government statement.
Lam Sai-hung, the Secretary for Transport and Logistics, told the press after attending the Legislative Council meeting on Wednesday that: “Prior to the resumption of work at the site, the relevant departments, including the Hong Kong Housing Authority, the Buildings Department, the Electrical and Mechanical Services Department and the MTR Corporation Limited, will ensure that appropriate mitigation measures have been implemented at the site to ensure that the resumption of railway operation will continue to be safe.”
Ngai Hok-yan, a structural engineer, told HKFP that vibrations generated from piling at the nearby construction project might have caused the settlement.
“If the soil is loose, and there are vibrations, the soil will become packed and the density will increase. As a result, the volume of the soil will contract,” Ngai said.
Ngai said the construction team should have evaluated the area and assessed construction plans to estimate the situation of settlement. This incident could be due to erroneous calculation of data, he said. There could also be a difference between the actual condition of the soil and that of the evaluation.
He said there could be an alternative way to complete foundation work other than piling. The team may choose to drill a hole, put the rods in it and then pour cement.
Neither the MTRC nor the government said when work would resume.
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