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.
USGS scientist Ken Hudnut fills us in on how science created the theoretical magnitude 7.8 earthquake behind the Great Southern California ShakeOut—the largest earthquake preparedness drill in U.S. history, coming Nov. 13—and what such an earthquake would do to downtown Los Angeles.
Seems like they did it right wiith this study. They had multiple teams independenlty come up with the ground shaking model, then had different structural engineers who are experts in seismic design of large buildings review the tall buildings in the L.A. area for the design earthquake. They say that buildings would likely come down in the 7.8 magnitude event. Click through to watch the video interview from the USGS.