Freezing soil movements

As soil freezes, the moisture changes from water to ice, it expands by 9.08 percent. Water density goes from essentially 1.0 to 0.9167 gm/cc on the old metric system notation, gm/ml now. When a saturated soil freezes, the free water expands. The attached plastic water depends on the temperature drop whether it freezes or not. If we have a silty sand at 30 percent moisture saturated. Gs=2.65, 1 cubic metre is composed of 1476 kg solids, 443 kg of water. If the free water was 25% (25/30) of the total water 369 liters, that new volume after freezing is 402.7 liters, or expansion of 33.7 liters. Since the only way soil can expand is upwards, that is 0.0337 of the depth of freezing from phase change only.

As freezing is occurring, water is drawn to the freezing front by thermodynamic forces. This can produce ice lensing, in addition to phase change. The amount of heave can be considerable, 150 to 300 mm in a season is not uncommon, I have often seen 100 in addition to phase change. For these to happen, all you need is a frost susceptible soil, a lower source of water, and a freezing front. These often show up around water line leaks and frequently cause water line failures as these start to mellow in spring, driving the frost front down further.

When a trench is insulated and drained, through a wet sandy silt deposit, you are designing in a seasonal settlement over the trench, in addition to any line settlement.

How many people with ADHD does it take to change a lite bulb?
           Look, ... there goes a rabbit. 

Long term vs residual

Long term soil strength for slope analysis is akin to residual strength that we see with direct shear tests. Beyond a specific shear displacement, the shear strength drops to some residual value and remains at that level. This reduced level has a phi angle, as can be seen in the unit force vs unit perpendicular loading across the shear surface. Note that there is no such thing as shear strain, there is no distance to use for nominalization.

Slope failures start the rupture surface at the bottom toe, and the shear strength of the soil drops to residual once the displacement is adequate. The individual slices of simple shear analysis assumes that there is uniform distribution of the shear stress along the circle of analysis, which is oversimplification. The rupture surface starts at the toe, and later at the scarp, and proceed to where the dramatic happens. This may take years or days.

Flows, where excessively wet materials, loess, or liquafication occur, may happen seemingly instantly, with no warning. The hill is sitting there, and then it fails. Slopes and life around loess and liquifying soils is dangerous. As is life over carst formations, liquid mining (Fort Saskatchewan), and old coal mine workings. Ever geotechnical investigation should check these parameters.

All silts should be checked for loess condition. The first simple test is a "rolled down from natural moisture" plastic limit is conducted, and the results compared to a dried then plastic limit. Even a small difference is in question. Sensitivity is the second sign. Often in drilling, the material is observed as wet and soft, yet cone penetration shows a firm of hard condition. The data does not match, sensitivity is high, now what?          

Risk Bumpers

We engineers, from time to time, make a recommendation to do something, not to do something, to wait a period of time before building, or whatever.

Along come the owner, contractor, general engineer, and in the words of Dino, "you geotechnials are too conservative" and try to ignore our recommendations. I no longer care if you do not follow my recommendations. You may receiver a letter like this;

Our recommendations are not binding on you. If you wish to assume greater risk of movement, which is in fact the total risk, you may do so.

Engineered fill suffers from movement from a number of sources:
- time dependent elastic and plastic movements, compaction and consolidation of the underlying soils,
- stress changes and moisture changes in the engineered fill
- swelling or shrinkage brought about by changes in the water table changes due to a new moisture regime

If anyone thinks they can estimate these for the first year, which are the large portions of movements, just have at it and accept the risk.  Anyone who is risk adverse will wait the first year, which will account for something like 50% of the movements.

In summary, you can do as you like, but all movements are your problem.

Service, Robert

But I reflect - what does it matter?
On the brain of scholar, sot and swine;
(on his replete and arid mine)
with equal zest the worm doth dine.

Seneca

We are born unequal, we die equal. 

.... (but don't let the modern human rights activists or modern culture and government in on that fact)

We are all returned, the question is, in which order?

(Demetrius quoted by Seneca) The utterances of the unenlightened are as noises emanating from the belly. It does not mater whether they come from above or lower.

Seneca

Life we receive is not short but we make it so. We are not ill provided but use what we have wastefully.

Enough

Just add a few wolves

Video Of The Day http://biggeekdad.com/2014/02/yellowstone-wolves/

Multi-Chem / Halliburton

Wednesday evening, we were at the public information meeting for  Multi-Chem / Halliburton - Nisku Blend Facility.

After thinking about the presentation, the attitude of Multi-Chem / Halliburton is similar to that of Monsanto. Your life quality is not my concern. Anything that leaves our plant will meet Environment regulations. We will generally meet that, and anything less that that is not our concern. You adjacent land owners are just not our concern.

Much of the regulations can be meet by blowing more air through the monitor. Dilution with clean air. All else is not Multi-Chem / Halliburton concern.

There attitude seems to be "we have complied with the regulations, it is not our concern. " or "If anything go's wrong, whatever fault was committed is not our concern, we are not responsible" This may clear their legal responsible, but what about moral responsibility?   

Putting a chemical plant within a populated area is just not moral, even if it is legal. 

More mis picks

 Blue eyed grass

 butterfly on thistle, Brasseau dam

 Frosty Mountain Ash

Wood Pecker. The big pecker wood kept moving, and would not hold his head still.

 Flower,

 One of the lily family, wild, high country of BC.

 Crab apple, from front driveway, flowers last about 1 day.

N. Saskatchewan, at Devon. Forty years ago, I harvested Gold eye trout from this very spot, and fried they just to the left of here. Onions, butter, cast iron pan, over wood fire. The concrete bridge was not there then, only that old truss thing, one step up from a Bailey.