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Recent content by jdmm

  1. jdmm

    Liquefaction - effect of liq. zone below 40 feet of dense fill

    Practically, I think that you are right. Over 40 feet of dense soil, liquefaction at depth will be relatively insignificant at the surface. The only way I can think of justifying this mathematically is to using something like SIGMA (finite element for soils) to model the static condition of a...
  2. jdmm

    Stone Columns

    Work with your local contractor. They are very good at providing information not only on what is best for them but what materials, locally, are the best. They are often happy to help by knowing about the job and by having a bit of inside information about the tender.
  3. jdmm

    Settlement of Driven Piles

    I haven't checked it but I suspect that this is a rule of thumb for end bearing piles of a particular type. This would be the elastic shortening of the pile. Please check your sources when dealing with 'rule of thumb'. There is often a good reason but you should know how it is derived. If...
  4. jdmm

    Open question: Are we doing less lab testing?

    As the world becomes more experienced they become more confident and require less testing be as the world becomes more litigious the engineers become more cautious and require more testing to confirm their opinions. It is a shame but this has been brought on by a legal sensitive system and...
  5. jdmm

    Daylight basemetn Foundation wall sliding

    This isn't an easy question to answer because there are so many varibles. You suggest that the horizontal force is due to an undifferentiated force equal to 12 feet of soil. Is this really true or is there some passive resistance. If there is a 12 foot horizontal force there is also a...
  6. jdmm

    Post testing of concrete footings

    You guys obviously don't deal in the world of building inspection. This is the most common problem in small foundation inspection. It isn't so much a question of geotechnical engineering as a legal question of who will be responsible. Municipalities (Cities) do inspections and in doing so...
  7. jdmm

    Calculating desiccation shrinkage

    I can't tell you of an experience where the recommendations were verified but I once had to do the same thing for a heavy clay (bentonitic) where they wanted to raise the temperature to 100C to remove dry-cleaning contaminants. I took a simple approach and took samples of the material, measured...
  8. jdmm

    Heave

    50 m2 is not very big so that there will be edge effects. There are probably a number of closed form solutions to this problem that date back to the 60's but with all of the new programs available, if it is important to know this then it is worth purchasing a finite element program. We used...
  9. jdmm

    shear wall anchored footing on rock

    I would think that it is either the frictional component and the lockoff OR the capacity of the tie-down anchor or the combined effect. Remember that you would not only rely upon the friction but the tension in the anchor itself. If this does not provide sufficient capacity, and the rock is...
  10. jdmm

    MSE Wall Cosmetic Remedy

    You might want to go to a forum on concrete but if you think that you would like to replace the panel, it is probably do-able. I have had many cases of arching around vertical panels that have been removed and have excavated behind MSE walls to depths of 10 feet at the back of the...
  11. jdmm

    Soil Friction Angle

    When I started in the early 1970's I asked the same questions and got just about the same answers. THECORKSTER dispite the tone, got it right. Experience is the guide and is, without doubt, the most valuable experience. You should have someone in your place of work who can pass on that...
  12. jdmm

    Geogrid with Boulder Retaining Wall?

    I started designing shot rock (not round rock) walls in the early 1980's. The rocks were 2 to 4 feet in size. The base width of the wall constructed of rocks, carefully placed in a brickwork fashon was designed as a gravity wall. The backfill was always fine shot rock in the minus 12 inch...
  13. jdmm

    Reduced bin pressure using geosynthetic reinforcement

    patucci is right. In order for geogrid to work you need to mobilize the active condition. One appoach would be to essentially build a wall using wrapped geogrid behind the bin wall and once it was completed, backfill the space. A second appoach could be to use in-extensible reinforcement such...
  14. jdmm

    Preloading

    If you exceed the preconsolidation pressure and cause settlement then you essentially change the soil to a stiffer one. This would make the unload flatter than the loading curve. If you load below the preconsolidation pressure then I would agree that the load-unload slope should be similar...
  15. jdmm

    Slope stabilisation using sheet piles

    If this isn't too late: A method imployed by Dr. RM Hardy and attributed to him is to align the sheet piles parallel to the direction of movement. This is counter intuitive but the purpose is to effectively increase the shear strength of the soil by providing shear resistance on the sides of...
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