A dramatic hole swallowed up a part of a Bangkok central road on September 24, forcing Thailand’s mass traffic authority to detain the construction of the metro extension of the city’s $ 2.2 million purple and order emergency stabilization.
In a technical update of September 25, The agency stated that soil and water are infiltrated through a gap at the station’s station interface at Vajira Hospital, disassociating 6.30 meters. Twin tunnels.
The collapse was exacerbated by the rupture of a 1.2 m of water that accelerated the loss of the soil and triggered the failure of the pavement. The authority stated that “the subsidence was observed before there was a complete failure of the pavement” and pledged to restore traffic before moving to long -term structural repairs.
Authorities said that no deaths or injuries did not occur, and the morning time limiting traffic to Samsen Road. The rupture of the water led to flooding and service interruptions located; A nearby police station was evacuated and sealed until the inspections were completed.
Local media reported that officials described the compliance with the size of about 30 square meters and said that the crews were oriented to a reopening of October 8 in Samsen Road, using sprayed concrete stabilization layers, sanded cement and crushed cement filling.
Police have launched an investigation into the incident, according to the Bangkok PostWith local sale outlets reported that the area was declared a disaster to speed up the response.
Bangkok is on top of thick layers of soft Holocene clay than the older Pleistocene and Pliocene overdrops, a geological profile that contributes to generalized land subsidence and complicates underground construction.
The Vajira Hospital, which was directly facing the site, had suspended outpatient services for two days, but “hospitalized services continued without IBRNTERRUPTION,” a statement said after the road failure. Normal operations resumed on September 26.
Purple line extension
Work on the southern extension of the purple line, divided into six civil working contracts, to obtain in March 2022. Aecom, called project designer, assures that the 14.3 miles plan is expected to end in 2027.
Bangkok is on top of thick layers of soft Holocene clay than the older Pleistocene and Pliocene overdrops, a geological profile that contributes to generalized land subsidence and complicates underground construction. Image courtesy of Researchgate
The planning of the line was formed with the early support of the Asian Development Bank, which provided technical assistance from 2017 for due diligence due to engineering, hiring, environment and resettlement problems.
While Thailand finally decreased its funding, the bank’s work resulted in recommendations on multimodal integration and harmonization of rates that fueled the government transport policy. The joint company contractor CKST-PL is responsible for the Vajira Hospital’s segment, with PMCSC-1 as owner engineer.
According to ThailandOne in English daily in Bangkok, the project is now more than 60% complete.
The line will connect Tao Poon a Rat Burana with a high, underground track designed to relieve congestion in the dense central districts of the capital.
The railway agency reported that about 500 square meters of sand bags were placed on a diaphragm wall to block the entrances before the area was finished off with a concrete mat of 3 to 4 m thick and refilling to stabilize the road.
The political scrutiny has intensified when the former Deputy Governor Samart Ratchapolsit accused the agency of “trying to avoid responsibility” and demanded accounts, citing the alleged contractor links to political leaders.
The collapse comes from difficulties that contractors have in underground construction in Bangkok soft alluvial soils and high levels of groundwater, where strong seasonal rains can further destabilize the ground. The Japan International Cooperation Agency previously identified as the main challenges of expanding the city’s mass traffic system.
An equal reviewed study published in Sustainability In 2022 he came to a similar conclusion, warning that “groundwater pumping has induced long -term settlement in the Bangkok Metropolitan Region, with registered subsidence rates reaching 10 cm per year during the maximum extraction in the 1980’s” and that monitoring lagoons continue to leave vulnerable underground works.
The incident also highlights the vulnerability of the station’s interfaces -the impact of cascading of the ruptures of utility and confidence in the sand bag and mass concrete as methods of emergency stabilization.
With the contractor and traffic agency under pressure to reopen the road, the questions about the long -term impacts are kept on the purple line delivery schedule and if the control and supervision were adequate before the collapse.
