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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The site for the new Harrison County Hospital, approximately 25-miles west of Louisville, Kentucky had 15 sinkholes formed by limestone dissolution, a geomorphologic process referred to as Karst topography.  There were a number of geotechnical engineering and geological engineering challenges associated with the characterization, excavation, backfilling, foundation engineering and other mitigation measures as described by Peggy Hagerty Duffy, P.E. in her article entitled “Karst and Complications” in the August 2008 issue of Civil Engineering Magazine (Duffy, 2008b).

Mitigation measures for the sinkholes included use of graded filters with geotextiles, careful inspection of rock socket foundations along with pilot holes and careful geotechnical inspection throughout the construction process. One particularly interesting aspect of the project is that several of the sinkholes were used as drainage facilities to receive surface water runoff. Read on for a summary of this interesting article. (Photo of sinkhole in Karst Topography being used as a drainage feature, from Duffy (2008b), Civil Engineering Magazine)

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Tropical Storm Agatha that hammered Guatemala over the weekend also was likely a catalyst in the final collapse of a massive 100-ft wide by at least 200-ft deep sinkhole in Guatemala City. The sinkhole swallowed […]