Boy, I wish I never said "a simple poking stick does better than both." I have used a manual static cone since 1984 in Florida and the Midwest very successfully and I swear by it. Geo Durham makes it.
Mayne's paper indicates that due to the small Poisson's ratio, the difference between the two is so small that it can practically be neglected. Clyde Baker was a forensic investigator on the project addressed in Mayne's paper and said during a talk up here in Chicago that the original engineers...
When would one be used rather than the other? Say the depth to rock is 100 ft (H) and the footing is 25 ft wide (B), I would use the Young's Modulus. If B=100 ft and H=25 ft, I would use the constrained modulus. Does anyone have any references or guidance when to choose between the two when...
JAE,
The geology of the Chicago area is very well mapped and based on the shallow borings and a geologic review, we will recommned a site class but always recommend a deep boring be drilled from a CYA standpoint.
No to your question JackTrades. Be careful about driving them to "refusal." Overdriving can damage them via "brooming." With a 15000 ft-lb hammmer, generally 3 blows on the last inch will get you a 40-50 ultimate capacity pile and there is no need to drive it harder.
We found the opposite is true. In downtown Chicago, it is better to quickly drive a larger vibro for a shorter duration than a smaller vibro for a longer duration when it comes to the human perception issue (got less complaints).
We drill the borings to normal depths and provide a site class based on those and our knowledge of local geology. We also add a qualifier stating that a 100 ft deep boring is recommended to confirm our assumption.
Does anybody know how to estimate a vertical spring constant in kips per inch for the tip of a micropile embedded a couple of ft into very hard dolomite?
If you are just starting on a new project, ask others if they have done something similar and get the report to use as a "go by" but don't plagerize anything. I have saved portions of several hundred of my old reports so if I have a similar job I have a starting point and don't have to...
150 tons is correct and that provides a FS=1 since only 145 tons will make it thru the fill/peat and then another 5 tons must be deducted due to the long-term downdrag load of 5 tons.
