Thanks for the responses.
I feel "snake oil" is appropriate, but I should have asked if anyone knows of testing such as CBR, Atterberg Limits or UCS over a period of time which indicates the improvement, or lack thereof, when using polymers with and without traditional additives such as lime or...
We are looking at an "ionic polymerisation" additive to stabilise and "waterproof" soil subgrade materials. The distributor claims the polymer links together and forms a bond which increases the density of the material, while reducing the porosity of the soil matrix making it resistant to water...
Thanks for responses.
born2drill and PEinc, Using an Obermann 600 and agree completely re bells and whistles and that it's not a colloidal mixer. I should have added that we are using a high speed shear mixer in the agitator tank after batching in the Obermann.
For anchors I'm not concerned...
We are engaged in heated discussions about the need, or otherwise, of using true colloidal grouts (cement and water) for grouting soil or rock anchors and for deep mixing in soils.
One view is that it is not necessary, the opposing view is that it is essential.We are using an Obermann twin bowl...
Rockmynci: the piles were drilled in very stiff to hard residual clays of medium plasticity, grading to weathered rock at depth. The rock is a slightly metamorphosed sandstone/siltstone, varying from extremely low to low strength. Typically all piles were founded above the water table.
Rockmynci; thanks for the information. I tend to agree with BigH. However, one should certainly consider time to drill and time to pour. Over many years, I have found that for bored piles, 600 and 750mm diameter holes are the quickest to drill, 9oo next, then 600 and less; with 1200 diameter...
Big H and PSlem, Thanks for the comments. I await with bated breathe further posts. My collegue mumbled something about Poisson's ratio, but I have my doubts.
PSlem, could you elucidate? Do you mean that you noted very little differece for various diameters? This seems counter intuitive.
Has anyone observed a reduction in shaft adhesion for increasing diameters of bored piles in similar subsurface condition?
In a recent project, shaft adhesions were developed from in-situ and laboratory testing. These values were confirmed/modified based on a number of CAPWAP analyses undertaken...
DirtPlayer,
Assumming we are not looking at partially saturated soils, which seems to be a new kid on the block, low strength cohesive materials are probably best considered as undrained for "normal" construction times. We tend to use vane shears to assess Su, applying Bjerrum's correction for...
Some late thoughts...
Probably the best method of assessing residual strength is to use a ring shear device. I would guess around 22-25 deg with c'=0. I don't think there is anyway to get "better" values. Residual strength is residual strength.
However, the method of testing will certainly...
PEinc, Agreed - apparent pressure diagrams are conservative envelopes, widely used before PCs. Soil-structure interaction analyses must be carried out for multi-propped walls and should be used for single props. You commented "..people who specialize in the design and building of shoring walls...
We do a lot of work in soft clays and over the past 25 years a large testing data base has been collected. It suggests Su ranges from around 10 to 30kPa, phi' between 20 to 28 deg and c' between 1 and 5 kPa.
While I agree with dgilllete et. al. that for "stronger" soils, the difference between...
geodan, a very good reference is Cone Penetration Testing in Geotechnical Practice, T. Lunne, P.K. Robertson and J.J.M. Powell, 1997, reprinted by Routledge in the USA and Canada. Two warning comments:- Prediction of Cv only within one order of magnitude. Permeability from CPT dissapation is...
A very late reply; but...I do not understand how you can:- calculate settlements without some knowledge of stress history
assess overburden pressure without densities,
assess c' and phi' without strength testing,
classify soils (to the extent that different people logging the soils, call them...
