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 least opens the door to this technology for collapsing ground situations.
National Driller magazine recently republished a paper by authors from GRL Engineers Inc. and Pile Dynamics Inc. (PDI) describing a demonstration project for the Texas Department of Transportation involving thermal integrity profiling (TIP) of soil nails. TIP involves using the thermal energy created by curing concrete to determine the shape of a grout or concrete body and the position of reinforcement within a grouted or concreted hole. It has been used successfully for QC of drilled shafts and auger cast piles. It can be performed in open access ports by lowering a thermal probe down the hole, or by attaching thermal wire cables to the reinforcement with sensors spaced every 6 inches. This study used the thermal wire cables attached to two soil nail bars grouted into 6 inch diameter holes. The first nail had no deliberate defects, the second had two intentional soil inclusions attached to the bar prior to grouting. The TIP successfully identified the anomalies and it appears that the method shows potential for QC of the shape and diameter of a grout body around a soil nail. [Source: Read the article at National Driller. Image: National Driller]
GeoPrac sponsor Keynetix has released a video tutorial on how to create geology solids in AutoCAD using Civil 3D. This is a new and improved technique using the Civil 3D productivity pack 1. [Source: Keynetix YouTube Channel. Image: YouTube]
The International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE) is launching its first Webinar of the year on February 2. This upcoming webinar on Cone Penetration Testing will be given by CGS Member Prof. Peter Robertson (from Gregg Drilling - California USA). All ISSMGE webinars are offered free of charge in an effort to assist geotechnical engineers worldwide and to promote our profession. You are welcome to attend and highly encouraged to invite all geotechnical & civil engineers and students to participate. This Webinar will be launched on February 2 at 12 noon GMT (4:00 am PST and 7:00 am EST in Canada). lt will then be followed by a 2-day Q&A session that, like the webinar video, can also be viewed anytime later on the ISSMGE Website. Find more details about the webinar at the ISSMGE website. [Source: The Canadian Geotechnical Society. Image: ISSMGE]
Scholarship Applications for the 2015-2016 school year are now available on the ADSC website. Applications are due March 23, 2015. These $3,000 scholarships also include a trip to ADSC's annual conference with travel expenses paid. Applicants must be currently enrolled in an ABET or CEAB accredited engineering program or be a graduate from such a program, and must plan to enter or continue graduate school during the current academic year. [Source: Download the scholarship application form from ADSC - The International Association of Foundation Drilling. Image: ADSC]
Ray Roussy was a pioneer of the sonic drilling technique. In an interview with National Drilling Magazine, Roussy shares how the sonic drilling method began, what changes have occurred over time, and what some of the future challenges are for the method and how they will be faced by the drilling industry. [Source: National Driller Magazine . Image: National Driller]
2014 Seed Lecture: Developments in the Assessment of Liquefaction Potential and its Consequences, presented by W.D. Liam Finn, Ph.D.,P.Eng., Life.M.ASCE, Professor Emeritus, University of British Columbia at the 2014 Geo-Congress in Atlanta, GA, USA.
Economic times have been hard for federal, state and local transportation agencies as well as industry representatives since the recession started. Getting approval to travel for conferences or training classes has been difficult if not impossible. The Geotechnical Team at the FHWA and the National Highway Institute (NHI) has come up with a solution to that problem by offering training in an online virtual environment. In the near term they will be offering a tour of the virtual training venue and technology showcase and plan to have more demos in the coming months. They will offer the first training at the March 2015 International Foundation Congress and Equipment Expo (IFCEE) in San Antonio, Texas.
I like Hayward Baker's series of videos using animations to demonstrate different geotechnical construction methods. This video demonstrates how tangent pile shafts or secant pile shafts are constructed. Check out the video. Note: Hayward Baker is a sponsor of this website.
Underground metal mines can have extremely high temperatures, making it hazardous for employees to work there for more than a few minutes at a time. Researchers from my alma mater, the University of Arizona, are studying the possibility of using a common mining waste product, tailings, as aggregate in shotcrete with good insulation properties that will be used to coat rock surfaces that readily conduct heat. [Source: Arizona Engineer. Image: Arizona Engineer]