Johannasburg Sinkhole Opens after Tunnel Collapse

A massive sinkhole more than 300-ft in diameter and with depths to bedrock of up to 350-ft is located under a future I-4 traffic interchange in an Orlando suburb. A massive $9 million stabilization project is underway to prepare the site for the eventual TI construction. The size of the Maitland Sinkhole is on par with the largest sinkholes to form in central Florida in recent times. There is not a void present, instead it is infilled with a compressible sand deposit. (Image from FDOT)

The mitigation method includes drilling over 300 grout injection holes, and performing grouting operations to infill cracks in the limestone bedrock. Then in the same holes, compaction grouting will be used as a method of ground improvement to densify the sand in place. Once the grouting is complete, the site will be surcharged to compress any remaining weak layers. Click through for a subsurface profile and location map. Via ASCE SmartBrief.

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It takes planning and good leadership to decide on an effective solution to problems associated with a building asset. Recently, a large wholesale warehouse facility in Cincinnati began to experience large sinkholes across a significant portion of their customer parking lot. Unable to determine the problem at that time, store management was forced to close a portion of the parking lot, inconveniencing their customers. This particular parking lot is unusual in that a drainage system is located directly under the parking lot, consisting of a network of pipes spanning 250 feet in length and 12” in diameter. Joint separations in the underground drainage piping had caused enough soil erosion to create sinkholes in the asphalt. Engineers were concerned that other unknown sinkholes could cave in anytime, resulting in further costly damage, and potentially posing safety hazards to customers.

[Editor] Click through for the rest of the article. [/Editor]

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The City of Vancouver is suing a developer, excavation contractor and their consulting engineer for the costs of repairs, overtime for city employees and lost revenue from parking meters etc stemming from an apparent failure of a shoring system that formed a 30-meter sinkhole. No mention of the developer’s name or the engineer, but the contractor was Matcon Excavation and Shoring. The site will be the future home of high-rise condominiums…if the City lifts it’s stop work order.

The failure of the shoring caused a break inf a 20-cm water main ultimately flooding the site. It also necessitated the closure of the adjacent street. Of course this invites the whole chicken or the egg scenario. The defendants will probably argue that the water line failed first causing the failure of the shoring, but of course the City Engineer, Tom Timm was not shy about fingering the shoring as being deficient.

"It’s some kind of a failure of the shoring system . . . either a design issue or the way it was put in place."

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