Rideau街上出现一个大陷坑
- 主题发起人 月下独酌
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看来，比我猜想的可怕多了。
Ottawa sinkhole struck in unstable 'rock valley' flagged by engineers
Workers were 50 metres away from completing light rail tunnel under Rideau Street when collapse occurred
By Alistair Steele, CBC News Posted: Jun 09, 2016 5:00 AM ET Last Updated: Jun 09, 2016 7:10 AM ET
A 2011 geotechnical survey discovered a 'bedrock valley' filled with silty clay and loose stones in the vicinity of the sinkhole that swallowed part of Rideau Street in downtown Ottawa on Wednesday. (Jusin Tang/Canadian Press)
The sudden road collapse that left a gaping hole in the middle of a street in downtown Ottawa Wednesday morning occurred over a vein of sand, silt and fractured rock so unstable that workers completing the light rail tunnel below had to inch along cautiously for fear of causing a cave-in.
The sinkhole occurred in the same place engineers conducting a geotechnical survey for the light rail project in 2011 discovered a 120-metre wide "bedrock valley" stretching under Rideau Street, just east of Sussex Drive.
The updated geotechnical data report submitted by Golder Associates to Capital Transit Partners, and then presented to the city, describes the valley as a natural trench in the bedrock filled with between 15 and 37 metres of loose fill, silty clay and "glacial till," or broken, weathered rock.
Samples taken from boreholes in the vicinity of the sinkhole revealed the bedrock itself was also fractured, unlike the solid limestone found along the rest of the light rail tunnel's route, according to the report, which was obtained by CBC News.
'A bad area'
"Everybody knew that that was going to be a bad area, that special precautions would have to be taken," said a source familiar with the light rail project.
People close to the project simply referred to the area as "rock valley," the source said.
'Everybody knew that that was going to be a bad area, that special precautions would have to be taken.'- A source familiar with Ottawa's LRT project
At a news conference Wednesday afternoon, Steve Cripps, director of Ottawa's rail implementation office, said special precautions were taken on that section of the tunnel, where workers were carefully excavating the final 50 metres between the future Rideau station and Colonel By Drive when the sinkhole formed.
Workers used lighter, more agile tunnelling equipment and carefully reinforced the tunnel as they dug, Cripps said. The city and consortium Rideau Transit Group met regularly with a mining and tunnelling consultant brought in to provide advice on that stretch of tunnel, Cripps said.
"Certainly the city's been aware, and RTG's been aware for a number of years, about the soil conditions in that area, and they have taken extensive precautions to deal with the soil in that area," Cripps said, adding nearby buildings have been equipped with seismic monitors to detect any shift in ground conditions.
Rail official won't draw link
However, Cripps was unwilling to draw a direct link between those soil conditions and the sinkhole.
"We don't know if these soil conditions have caused this. It's really too early to speculate," Cripps said.
Steve Cripps, director of Ottawa's light rail implementation office, speaks at a news conference Wednesday afternoon. (CBC)
But another source familiar with the tunnelling project said everyone involved was well aware of the potential risk for failure near "rock valley."
"The worry was that there'd be pockets of disturbed material that didn't have the same strength as everything else," the source said. "That was the biggest challenge of the project, from my understanding … to construct the station underground, in soft soil."
Project officials haven't said whether shifting soil — or something else — caused the water main rupture that quickly filled the sinkhole with roiling, brown water Wednesday morning.
2014 sinkhole
Nor is it clear what sort of setback the sinkhole represents for the Confederation Line project, which is due to be completed in 2018.
"A lot of the focus was how tricky this would be, but it should be noted that they also almost finished it. This is the really sad part of the entire story," said the source familiar with the tunnelling project.
A sinkhole halted excavation near the LRT tunnel's east portal in 2014. It was filled with 700 cubic metres of concrete, then re-excavated, but the source said the void near Rideau Centre is much larger, and poses a greater challenge to fix.
The geotechnical report by Golder Associates only analyzed ground conditions, and didn't draw conclusions about the safety or viability of the tunnel in any one area.
还没关系，没做过bus把，比如三个86路，86 86b， 86c。要么不来，要么一下子全来。
downtown 附近还可以，车次还密集点
稍离开downtown，有的车半个小时一趟，中间转个车，加上schedule delay。冬天在寒风中站个个把小时试一下。。冻得都不想活了有木有
还有的车一个小时一趟，要人命啊。。。。
在渥太华，公共交通跟本发展不起来，还要继续修轻轨。。。。。。。修个地铁还靠谱些，就是没有钱。。。
downtown 附近还可以，车次还密集点
稍离开downtown，有的车半个小时一趟，中间转个车，加上schedule delay。冬天在寒风中站个个把小时试一下。。冻得都不想活了有木有
还有的车一个小时一趟，要人命啊。。。。
在渥太华，公共交通跟本发展不起来，还要继续修轻轨。。。。。。。修个地铁还靠谱些，就是没有钱。。。
跟bus schedule没关系，downtown那里交通整体不合理，下班时间堵成狗的节奏
跟bus schedule没关系，downtown那里交通整体不合理，下班时间堵成狗的节奏
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Ottawa Sinkhole Day 3: LRT tunnel below sinkhole is flooded, engineers discover
Matthew Pearson, Ottawa Citizen
More from Matthew Pearson, Ottawa Citizen
Published on: June 10, 2016 | Last Updated: June 10, 2016 8:24 PM EDT
As engineers on Friday ventured into the LRT tunnel far below Rideau Street to assess the damage caused by the massive sinkhole that opened up earlier this week, crews above them continued working around the clock to repair the damage at street level. (Jean Levac/Postmedia) Jean Levac / Ottawa Citizen
A 300-metre stretch of the LRT tunnel underneath Rideau Street, where a massive sinkhole opened up this week, is flooded, the city said Friday.
As crews at street level continued working around the clock to fill in the hole and repair damaged utilities, engineers ventured into the tunnel two dozen metres underground where excavation had been underway at the time of Wednesday’s road collapse, which swallowed a minivan and one piece of construction equipment, and caused huge headaches for transit users and businesses in the area.
There were no injuries and no cause has been established, though many wonder if it could be connected to the LRT digging.
“Over the next several days, water will be pumped out to allow teams to better assess the impact and plan the path forward,” city manager Steve Kanellakos wrote in a late-afternoon memo sent to Mayor Jim Watson and city councillors.
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It was the first confirmation that the sinkhole, which was estimated to be about five metres deep, has affected the tunnel.
Earlier Friday, Kanellakos told Postmedia in an interview that engineers believed there would be no permanent damage to the tunnel, which is a key part of the $2.1-billion Confederation LRT line set to open in 2018.
“It’s just a question of getting out some of the water, some of the debris that might have come in,” said Kanellakos, who added he’d had a productive meeting with RTG officials Thursday.
“They are focused on getting back to work,” he said, noting it’s still early to know when crews might return to their jobs at that location. RTG is working on a “tunnel reinstallment plan.”
Elsewhere underground, work continues in the three downtown stations, including Rideau, which is just east of the sinkhole site. Crews were down to the final 50 metres of tunnelling at the time of Wednesday’s road collapse.
RTG officials don’t fear the timeline for opening the LRT line will be delayed, Kanellakos said.
No one from RTG was available for an interview, but the company is supplying the city with regular updates, said spokeswoman Kathryn Keyes.
Meanwhile, workers at street level focused on repairing the damaged infrastructure after they had poured several thousand cubic metres of concrete into the hole and waited for it to set.
Rideau Transit Group, which is building the LRT, is coordinating the repair work with various city departments and the utility companies.
Pipes located deepest in the ground used to move sewage and stormwater were to be fixed first, followed by water and utilities, including power, natural gas and telephone, which are located closer to the surface, Kanellakos said.
Matthew Pearson, Ottawa CitizenMore from Matthew Pearson, Ottawa Citizen
Published on: June 10, 2016 | Last Updated: June 10, 2016 8:24 PM EDT
As engineers on Friday ventured into the LRT tunnel far below Rideau Street to assess the damage caused by the massive sinkhole that opened up earlier this week, crews above them continued working around the clock to repair the damage at street level. (Jean Levac/Postmedia) Jean Levac / Ottawa Citizen
A 300-metre stretch of the LRT tunnel underneath Rideau Street, where a massive sinkhole opened up this week, is flooded, the city said Friday.
As crews at street level continued working around the clock to fill in the hole and repair damaged utilities, engineers ventured into the tunnel two dozen metres underground where excavation had been underway at the time of Wednesday’s road collapse, which swallowed a minivan and one piece of construction equipment, and caused huge headaches for transit users and businesses in the area.
There were no injuries and no cause has been established, though many wonder if it could be connected to the LRT digging.
“Over the next several days, water will be pumped out to allow teams to better assess the impact and plan the path forward,” city manager Steve Kanellakos wrote in a late-afternoon memo sent to Mayor Jim Watson and city councillors.
Advertisement
It was the first confirmation that the sinkhole, which was estimated to be about five metres deep, has affected the tunnel.
Earlier Friday, Kanellakos told Postmedia in an interview that engineers believed there would be no permanent damage to the tunnel, which is a key part of the $2.1-billion Confederation LRT line set to open in 2018.
“It’s just a question of getting out some of the water, some of the debris that might have come in,” said Kanellakos, who added he’d had a productive meeting with RTG officials Thursday.
“They are focused on getting back to work,” he said, noting it’s still early to know when crews might return to their jobs at that location. RTG is working on a “tunnel reinstallment plan.”
Elsewhere underground, work continues in the three downtown stations, including Rideau, which is just east of the sinkhole site. Crews were down to the final 50 metres of tunnelling at the time of Wednesday’s road collapse.
RTG officials don’t fear the timeline for opening the LRT line will be delayed, Kanellakos said.
No one from RTG was available for an interview, but the company is supplying the city with regular updates, said spokeswoman Kathryn Keyes.
Meanwhile, workers at street level focused on repairing the damaged infrastructure after they had poured several thousand cubic metres of concrete into the hole and waited for it to set.
Rideau Transit Group, which is building the LRT, is coordinating the repair work with various city departments and the utility companies.
Pipes located deepest in the ground used to move sewage and stormwater were to be fixed first, followed by water and utilities, including power, natural gas and telephone, which are located closer to the surface, Kanellakos said.
