fernley. If you haven't already located or used it, an excellent discussion of the means/methods, and analyses pertaining to protecting a slope with natural materials can be found in Donald Gray's books on biotechnical slope stability. One is published in 1982 and the newer version can be...
From soil science, the percentage of gravel in a soil matrix causes a proportional increase in the bulk density of the soil while causing a proportional decrease in the saturated hydraulic conductivity. Hope this helps.
jbeitia - the reason the formula "blows up" is that you are analyzing a marginally stable situation to begin with. A slope with a friction angle of 33 degrees means that once the slope angle reaches 33 degrees the slope has an approximate facator of safety of 1.0. This is just for the static...
CarlB: It's been a busy month. Thanks for your comments. To respond to your questions, the sidewalk exhibited jacking by one end lifting up. Much of the sections return to nearly their original positions in summer. Over the years the cycles have resulted in typical uneven edges and cracking...
Thanks DRC1. We are considering a shoulder ballast 2-1/2" minus crushed stone with 0-2 percent passing #100 sieve for the base. I appreciate the recommendation for additional reinforcing in the sidewalk. There is plenty of crushed basalt available in the area of the site so that sounds like...
Definitions and geogrid systems aside, the essentials of the site are similar to what occurs in Western Washington and Oregon: Thick deposits of saturated orgainc soil right where we want to put roads and buildings. Based on the described problem, I do not believe full removal of all the...
We have been asked to evaluate the cause (and possible repair) of a sidewalk that has been damaged by frost heave or frost jacking. The soil below the slab consists of alluvial gravel with sand and silt. Silt content is less than 10 percent. However, the water table is reported by the client...
As a follow up, I did manage to contact the correct people at Triggs and they have provided me with an updated spreadsheet that works with newer versions of excel. If anyone is interested in the contacts I will gladly provide them. Regards to all! :-)
We use a dynamic cone penetrometer to test shallow soil strength via correlation to the Standard Penetration Test. The manufacturer's spreadsheet provided to us for this use is an old Lotus 123 version, the macros of which do not work in Excel. My question is, has anyone developed a working...
Thanks to all for the comments and advise. I just wanted to follow up with you all on the project. We ended up coring the concrete pier in an area the structural engineer deemed to have the most severe environmental degredation - that was below and just above the seasonal high water level...
ZiggyMan76: In my experience, timber walls are mostly constructed as timber cribs, that is they have a 3-D cellular box structure forming pockets within which can be placed fill. The combination of timber facing and "rock-filled boxes" creates a stable mass that can be designed to resist the...
May I suggest "Rock Slope Engineering", 3rd Revised Edition by Evert Hoek and John W. Bray. This 1973 volume is an oldie but a goodie. If there are more recent versions I am not aware of them. Refer to chapter 5, "Shear Strength of Rock" for an in depth discussion of the nature and...
Is there a good resource for evaluating the structural capacity of a 64-year old reinforced concrete bridge pier? So far, we have identified the following issues: 1)are there discontinuities (cracks, fractures, cold joints, etc.,) where corrosion of reinforcing steel could have compromised the...
That approach (sidewall testing) would certainly allow tests in "undisturbed" conditions. It seems like it would work best for silty sands and finer grained soils. Gravel soils may be more problematic. We will try using this method. Thanks for the idea.
Thank you for your responses, rchanke, BigH, and Focht3. Yes, we are taking standard counts in the test pits and moisture samples from the test and keeping track of the correlations with moisture. The typical test pit we use this in is about 4 to 5 feet deep, and about 3 feet wide. We have...
My question for the honorable forum is this: Does anyone have an opinion regarding the reliability of using a nuclear density probe device to obtain indications of density within a soil exploration test pit? We typically use them in ours within the upper 4 to 5 feet but have not heard of any...
MRM Brings up a good point, to wit, is an unlicensed person liable for dispensing engineering advise. In my state the Board of Professional Engineering Examiners has weighed in on this topic. They are clear that they only have jurisdiction over their licencees. In other words, the...
You can use a commercially available software product called SRW Wall available from the National Masonry Concrete Association to evaluate the internal stability of large facing blocks and geogrid. The program (and some others as well) allow you to input the size and characteristics of the...
RDK- I agree with you on the matter of protecting the public of course. I sense that the ideal of "noble public service" is assumed in your response and I believe as you do that we as engineers should seek opportunities to have some positive influence in our communities. However, I...
