Terracon posted a new blog post about a unique hybrid soil nail and anchored soldier pile wall excavation support system for the Tower 12 Building project in Downtown Seattle. The project involves a 60-foot deep excavation for underground parking, but the west side of the excavation was adjacent to an existing 20-story building with three levels of below-grade parking. The hybrid system involved tightly spaced soil nails in the upper portion of the excavation wall and steeply-inclined, high-capacity ground anchors (200 kip) to support the lower portion. Check out more details on this interesting project from Terracon.
On March 21, 2008 a landslide caused the closure of Arizona State Route 87 between Payson and Phoenix near mile post 224. So far there are no official estimates as to the size, but based on aerial photos, it appears to be at least 50,000 sq-ft in plan. The offset at the head scarps was approximately 2-meters (6.6-ft) according to AZGS Geologists on site. It appears to have been a rotational slide as the toe of the landslide heaved the southbound roadway up by as much as 1-meter (3.3 ft). There was an existing soil-nail retaining wall on the slope that was destroyed by the slide as well. Lateral deformations can be seen in photos of the median barrier and the roadway striping. The deformations extended into the northbound lanes as well. More photos and links after the break. (Photo by ADOT)