For a wind farm near Lawton, OK, many of the foundations consist of rock sockets 19 feet in diameter, 20 feet deep. The rock was blasted to presplit the holes and facilitate excavation. The bedrock in the area was so shallow that blasting was needed to construct the access roads, removing the high spots and providing material to fill in the low. In areas where the bedrock was deeper, spread footings were used. [Source: National Driller. Image: National Driller]
The latest information to come out of the collapse of a subway tunnel excavation in Cologne, Germany is that investigators are evaluating the ground anchors or tiebacks that were holding open the subway tunnel excavation. There doesn’t appear to be much information available to the public yet, and the New Civil Engineer article mostly quoted academics saying an anchor failure “could” have caused the collapse. Apparently at the time of the collapse, the excavation had reached the bottom depth after the slurry walls had been constructed along with the ground anchor system. Crews were supposedly working on the base slab which would have undoubtedly stiffened up the whole system. For what its worth, an anonymous comment left at the bottom of that article indicated that after half of the debris had been excavated, the diaphragm walls were still intact and without apparent displacement. So what other theories have been floated? Read on for more info. (Image Credit: New Civil Engineer)
Arizona DOT is undertaking a project to remove hazardous rock formations above Highway 77 between the towns of Globe and Winkelman, AZ (east of Phoenix). On November 29/30, The blasting work inadvertently dislodged an 18 […]
Recently, URETEK ICR was asked to review a project involving lifting and stabilization of 10 precast transformer pads at a wind farm located in South Dakota.
The pads had settled to varying degrees with 8 of the 10 having settled 1 (±0.5) inch and requiring only stabilization and the two remaining, with settlement in excess of 3.5 inches, requiring lift and stabilization.
[Editor] Click through for more on this interesting project by GeoPrac.net sponsor, URETEK ICR! [/Editor]
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