Wednesday, October 31, 2012

Repairing Lateral house basement failures

Repairing lateral house basement failures can be conducted inside or out.

In general, the wall failed due to lateral pressure. The repair must be stronger than the old wall. When the failure was caused by impact or vertical load, the old wall was too weak, even though it served until it failed.

The steps to repair are to unload the wall, straighten, add stiffeners, water proof, and backfill. The design must account for the lateral pressure, construction lateral pressures, surcharge loading, and hydrostatic. Unreinforced concrete wall, frequently used in residential cannot be numerically justified when backfill, hydrostatic, construction and surcharge are placed on them. In short, when we do the calculations, they fail often. In reality, they fail often.

It is a simple design of a beam column problem that the code ignores by using a defective prescriptive method which ignores surcharge, hydrostatic and construction loads. It also assumes back fill soils can be compacted without providing lateral pressure on the walls. In an effort to save money, the code is allowed to stand. The reason is the code is effectively controlled by home builders, who are aware of the cost and issue, and can gently lay in fill against the basement and allow settlement to occur. Repairs cannot allow the time for settlements. As a result, repairs must be considerably stronger that the original construction.  

Monday, October 29, 2012

Procrastination verses Exhaustion

Procrastination verses Exhaustion

When we set out a list of stuff we should do today, and at the end of the day, it is not done, was it procrastination or exhaustion that stopped us, or just delusion of how much we could do in a day? It is difficult to to know along with the other stuff that comes up during the day.

When I was a young engineer, working for a testing firm, doing the dispatching, and engineering, I would start out with a pile of "engineering" to do in the morning. I would work all day, and toward the end of the day, the pile was bigger, not because I had not been working, but more was added, and I had been busy doing dispatching, and I felt it was up to me to do it all, a belief the company tried to foster in all the employees. They easily got 1.5 times the proper amount of work from us. Some of us believed the crap about how the company would look after us when the economy slowed, as it surely would. Those who got laid off after Trudeau's national energy policy came into effect know where the companies loyalty lies, with the boss man's bank account. The company and Trudeau emotionally, spiritually and motivationally destroyed many of us. No wonder there is such hatred of Liberals in Alberta.

Some of us never recovered to what we had been. Resentments, and distrust of companies, of promoter employers, kept us from performing our best for others. Companies need to be run by promoters, over optimistic, positive sorts, who can stay motivated and positive even when they as losing, just ahead of the bankruptcy trustee. Yet, at the same time, not defrauding the employees. Yes, not remitting employee deductions, and selling leased cars, and then leasing those same cars back are both forms of fraud. Producing fraudulent test results, pressing us to do likewise, and invoicing the clients is client fraud, and demoralizes the employees. Creating other companies to syphon of money for non-existent services - tax and society fraud. Running parallel companies with different ownership, one with Dick sole ownership, and all employees paid by the other, is theft from the other shareholders. We saw all those, along with theft of supplies, ordering stuff to steal for personal use, all by the share holders, who happened to be "management".

Billy and Dick, may you rot or burn, where ever you are.       

Now that I got past that rant, when I do not get my "today" list done, was the list just a delusion of what I would have time for, exhaustion, or procrastination. Did I do other more enjoyable things instead? Were those thing important and urgent? Or just important, or just urgent? We should not be doing unimportant and un-urgent things, that is just procrastination by displacement.

Important things may only be important to us, not to others. Rest and relaxation is important, and even needed, perhaps not just when it is convenient, but when it is needed. Ugly necessity. We can only do so much, and what we can do often declines with time, especially after retirement.

It is all over when the heart stops beating. Until then, we do what we do. Thank you for reading this. Please feel free to post your own thoughts or opinions on this subject or any other.

Monday, October 22, 2012

The future, retirement

Cut from the web --- not intended as humor 

The better solution then, according to a just-published IBM patent filing (US29228426A1), might be to find a way to suck knowledge out of the experts then inject it into younger, stronger, cheaper employees, possibly even in other countries.

Once again we confuse “Expert” with “Expert System”. These two things are almost diametrically opposed.

Experts understand exceptions, learn and focus on the unusual

Expert Systems codify knowledge and focuses on the common.

In fact the economic incentives for expert systems reward handling the common cases first and returns tend to decrease as the more uncommon cases are added. IBM isn’t reproducing and storing real experts, just finding a way to stamp out repeatable workers and miss labelling them.

And don’t forget: IBM perfected the step-by-step manual (repair, maintenance, and training), railroad tracks and all.

What we’re talking about, then, is a possible revolution in workplace training, one where a lifetime of experience would ideally be sucked from the mind of an experienced worker to be injected into a trainee and then the older worker discarded.

But I am an expert with experience. Every thing I learned came from books, then I tried to use that and then I started to learn what was really being done. Mind you, that was dirt and people acting like construction workers, doing what they had previously done with a twist. 

But is all that information worth anything? or is it all just smoke that will blow away? Does anyone care? Does anyone want the information? I doubt it. 

Wednesday, October 17, 2012

What Needs A geotechnical Investigation

What needs a geotechnical investigation? I will answer that by saying that for rational design of a foundation, we must know what the soil is verses depth and how strong it is for the depth of the foundation. Houses in a known subdivision, here, imply a competent soil at 5 feet down, so we could design piles adjacent without much risk.

Where there is no basement and foundations adjacent to look at, we need a geotechnical investigation or at least a few testholes to verify the soils are suitable. I personally would not plan an outhouse without a testhole. For an outhouse a hand auger hole would be suitable, but for a duplex, 4-  24 foot deep macro core holes with moistures and pocket pen readings ever two feet would be suitable. One in each corner, for information.

Peat, topsoil, fill, garbage, or a good lot have different values and issues. With organic materials, there is also outgassing to consider.

Negligence is such an ugly thing to be involved in, I think I will just decline to be involved, unless we know what the soils are.

Monday, October 15, 2012

Slope Instability

When we look at a big river bank and see some small movements occurring, we get a feeling that this may be a progressive failure starting. So what should we do with respect to the top of bank setbacks? The City of Edmonton has a Top of Bank Policy that requires a geotechnical engineer to provide an opinion on the slope, and have created a concept of a like of stability at some point behind the top scarp.

The first way of  providing a estimate of the required setback is to use a mature slope angle concept. That is to say that the soils are uniform along the portions of length of the river, and for that portion, the slopes should be all the same. AKA, take the longest natural distance from the river and use that as a setback from the river. OK. First approximation, OK. Expect issues. I will add to that, from any daylight, a maximum of 2.5h:1v for clays, to address sharp top scarps.

Geologically, there are two methods of producing a slope, erosion or bank slumping and toe erosion. Eroded slopes have undisturbed material at there face on the upper portions, while slumped banks have disturbed material everywhere below the top scarp. It has the shape produced by heads and minor scarps, flank scarps, fault zones, and a run out toe. It is even worse it the run out toe has been eroded by a river or ran into a river, on the outside of a bend.

A bit of erosion and channelling through general slump features shows the age. Sharpe features suggests newer, round features suggest older. Existing fresh movements suggest the hill is not stable. Repairs to the hill to prevent erosion, and provide roadway support often reduce the factor of safety on the overall hill. The city does not like to to slope analysis unless necessary, as if these show an inadequate slope, it could not allow develop above the slope without liability. As a result, the City does little short term fixes, but never address the actual cause.

Instead it put the responsibility on the home owner to find a geotechnical engineer to say it is ok to build. This one gets nervious with progressive failures, as the model to to complete failure time is not good, and before failure there is sometime considerable creep, and resulting house movements.

Thursday, October 11, 2012

Client Education

Educating of clients to the reality of geotechnical / foundation engineering is an ongoing time consuming issue. Many of our clients are non engineers, often professional, well educated people. But they are often unaware of the basic principals. There expectations may exceed the engineering expected performance of the foundations.

Clay soils are about like sponges that have very sensitive pressure displacement curves that change with changes in moisture content, pressure, and time. Any foundation placed on soils will move in a response to pressure, and changes in pressure, as well as time and changers in moisture. Place two similar footings on similar soils, the one with a greater load will move more. Place an identical footing with similar loads on different soils, and we can expect different movements. Place two similar footings with similar load at different elevations within a site, we can expect different movements.

The differential movement between different unconnected foundations is the part that causes issues. Perimeter strip footings are usually tied together with a foundation wall, and some reinforcement. But was it enough and put in correctly? The interior footings are expected to move differently, and adjustable columns are now required so that the main floor can be maintained in a straight line. Adjustment must be maintained, and the structure must be build such that adjustment can be made.

Note that engineered fill is not addressed in any useful way in the building code. The building code, part 9, was developed for traditional housing, and many of the new bigger house exceed traditional; hence, the building code prescriptive portion may not be adequate to address all the issues. But the building code has an escape clause, something like; "if the code is not adequate, consider engineering the project as per the remainder of the code". How useful is that?

There are standards, but first is the standard suitable? Secondly, was the standard followed? Following an unsuitable standard will lead to problems.

Saturday, October 6, 2012

Political / Media Crap

These two men, with their famous political last names, have been friends all their lives just as their fathers were – Romeo LeBlanc, the former governor-general, and Pierre Trudeau, the former prime minister. In fact, Mr. Trudeau was an honorary pallbearer at Romeo LeBlanc’s funeral; Mr. LeBlanc was an honorary pallbearer at Pierre Trudeau’s.  

Friday, October 5, 2012

Different Approaches

There are frequently different approaches to the same problem. In engineering, we frequently see different approaches, due to the time of training, place, history, or whatever. Friction in soils, for example, relative to the shear stress, may be expressed as a change in friction angle or as an absolute ratio. The numbers to get the same effect are not the same.

In cohesionless soils, a change in friction angle is more traditional, but when it comes to soil acting on a surface, it is easier to understand and work with a absolute number. This absolute term of reference make life easier, but more confusing to those who training has only included friction as a change in angle.

Neither is more correct than the other, as long as one is used, and the meaning is clear. Using alpha or delta is not clear, as the nomenclature changes textbook to textbook.

The problem with university is there is too much to learn in the allotted time. Additional time would and is just filled with the professors choice of material. It takes time to absorb and learn to the point of understanding, and there is just to much material in some fields. Specialization is forced on us, even if we know a bit about many subjects.

Some of us have worked our entire lives around the field we wanted to be in, only occasionally doing the sort of projects we really wanted to do. We were forced to learn more and more around our chosen field, until we find we are generalists, no expertise in any one subfield, but generalist in the area, doing the work, and having opinions on the various methods. These opinions put us at odds with the academics.

Oh well, life goes on. We are all just learning. It is the first time through life.



Monday, October 1, 2012

Hand Calculated vs Computer

It has become apparent to me that use of the computer has become a impediment to good engineering. I started in this business with a slide rule and a Curtiss, and if you know both, you will know how I was trained. Cancel out, do the simple, and then approximate, and finally work out the mantissa. Then those expensive hand held calculators...  worth a weeks pay.
We drew graphs by hand, and remembered the values of the results.
Now the young cannot divide by three and multiply by ten on paper. Draw a graph, one minutes work, without a computer, forget it.
I feel for the next generation, when a problem arises, the young will flail for days to find a solution.
For some of these problems, I have simple numerical solution, which I learned at Uni, that produce an approximate solution. Some of them are as reliable as modern computer solutions. In one case, one of the new wonderful computer programs actually uses crappy approximate method, but provides "calibration" questions to "evaluate" parameters that are listed in the formula found in a 1923 publication. Mind you, the computer is quick at raising a number to the 0.564.