Aerial footage shows work crews clearing mud and debris following flash floods that left nearly 200 vehicles stuck in up to 5ft (1.5 metres) of mud. The Leona Valley, about 20 miles north of Los Angeles, saw extensive downpours on Thursday, with 3.58 inches (9 cm) of rainfall during a 30 minute period. Elsewhere in southern California, several roads were washed out and there were reports of motorists having to be rescued from torrential flooding
Since March of 2003, the FHWA’s Geotechnical Engineering Circular Number 7 (GEC No. 7) has been the standard reference document for design and construction of soil nail retaining walls in roadway applications, and really in all applications. The FHWA has released an updated version of this manual as of February of 2015. This new version is still called GEC No. 7, but now titled “Soil Nail Walls Reference Manual.” You can download the document from the FHWA’s Geotechnical Engineering website.
I am still in the process of working through the manual, but one of the major changes is the addition of the implementation of the Load and Resistance Factor Design (LRFD) platform. This will have an implication on all future soil nail walls for roadway projects.
The manual also appears to have removed example problems solved using SNAILZ software (by CalTrans) in favor of the FHWA’s own Soil Nail Analysis Program (SNAP) 2 software. I guess we’re going to have to get familiar with that software as well. I’m strongly considering looking into SNAIL Plus by DeepExcav, a commercial product. I’ve seen demos before, and have been very impressed.
Finally, I was very curious to see what they would say about hollow bar soil nails. They review some of the work done in the last 5 years or so done by the FHWA and ADSC. If I understood correctly, it appears that they are saying that because of the uncertainties regarding damage to corrosion protection during installation, they are still not recommending hollow bar nails for roadway applications, except if the ground conditions are non-aggressive and if you use sacrificial steel. I suppose that at […]
A large landslide occurred in northwest Washington at about 10:37 am PDT on Saturday, March 22, 2014. Multiple casualties are confirmed as a direct result of the landslide and many people remain missing. Landslide debris covered about 30 houses and 0.8 miles of State Route 530.
The landslide occurred in an area of known landslide activity, but this time the slide was much larger, traveled much further, and had greater destructive force than previously experienced. Precipitation in the area in February and March was 150 to 200% of the long-term average, and likely contributed to landslide initiation.
The slide took place along the edge of a plateau about 600 feet high composed of glacial sediments. The volume of the slide is estimated to be about 10 million cubic yards, and it traveled about 0.7 miles from the toe of the slope. This travel distance is about three times longer than expected based on published information regarding previous slides of this height and volume worldwide. If the landslide had behaved in the expected range, it would have likely blocked the river and possibly destroyed a few houses. Instead it led to tragic loss of life and destruction of property.
Flow also dammed and temporarily blocked the upper part of the North Fork Stillaguamish River. A pool of water formed behind the debris dam, which flooded houses and other structures. There were initial fears that the debris dam would […]
The Kennecott Copper Bingham Canyon Mine sits quiet after a landslide on April 11, 2013, in Bingham Canyon, Utah. Kennecott has suspended mining inside one of the world’s deepest open pits as geologists assess a landslide the company says it anticipated for months.
The Salt Lake Tribune reports:
“We started noticing movement in that part of the mine in February,” Rio Tinto-Kennecott spokesman Kyle Bennett said, indicating at that time the mine’s wall was slipping a fraction of an inch each day.
As the slipping continued and began to accelerate in the following weeks, Kennecott moved workers out of the area, utility lines were rerouted and the modular building that housed the mine monitoring equipment was relocated to safer ground. Kennecott also closed its visitors center for the rest of the year.
Bennett said the company has not yet determined the exact size of the slide. He said mining experts would be evaluating the slide area and its impact on future operations.