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  1. sgsibob

    Grouting in vertical fissures in rock

    Isn't the resultant fluid force on a vertical boundary limited by the volume of fluid available to exert the force? I am going to use an example of a fissure in rock but the same could be said of a retaining wall with a finite amount of flowable material behind it, for example a wall cut into...
  2. sgsibob

    Uncompacted rock fill

    Concretemasonry, Thanks muchly for the post. That is relevant to our issue, as I was referring to hard rock mining more so than coal stripping. The point is that thick, rapidly-placed rock fills adjust to the stresses induced by edge and point contact in complex ways and cannot be assessed...
  3. sgsibob

    Uncompacted rock fill

    Dick, Thanks for the information. Wow. 15 ft. That is just the kind of behavior that a lot of mine owners will swear will not happen. Sounds like a coal stripping operation. Terry West from Purdue has started studying settlements in subdivisions platted on top of old reclaimed strip mine...
  4. sgsibob

    Uncompacted rock fill

    Does anyone have any data on the compressibility or settlement of tall (>50 ft) end-dumped and uncompacted rock fill? This occurs in surface mining applications when waste dumps have to be used for some thing else. Information on the shear strength (related to some measure of particle...
  5. sgsibob

    Janbu vs Morgenstern-Price and Spencer in block stability

    Thank you for the replies. Not having gone through hand calculations of the Janbu vs M-P methods I will take your word for it. If Janbu generally results in lower safety factors because it leaves out resistive forces that are components of interslice shear, then that is good to know. On the...
  6. sgsibob

    Janbu vs Morgenstern-Price and Spencer in block stability

    Others performed the analyses...I believe the Janbu simplified method was used because runs attempted using the Janbu generalized option in the software return "no solution" so it seems that was not the Janbu model that was used. In one case the FOS using Janbu in the block failure mode was a...
  7. sgsibob

    Janbu vs Morgenstern-Price and Spencer in block stability

    We have compared stability analysis methods using SLOPE/W for a block failure geometry in a large rock slope. The problem is a tall slope at roughly 45 degrees which is backed by a fault zone which dips steeper than the slope, and various hypothetical inclined slip surfaces exiting the slope...
  8. sgsibob

    Soldier pile lagging top down installation

    DRC1 and PEInc, I thought the one-sided forming idea was to cast concrete in place against the lagging and soldier piles. 1. PEInc, why would this save any excavation and backfill, and why would it use more concrete? 2. DRC1, how would the formwork be braced in a tall wall application...
  9. sgsibob

    Consolidation settlement of stiff, unsaturated calcareous clays

    That's the kind of response that I was looking for. Given your experience, I think we will give Shelby tubes a try for the next round of drilling, but keep the ring sampler on standby. You mentioned that preconsolidation may not completely happen. I sincerely hope that will not be the case...
  10. sgsibob

    Consolidation settlement of stiff, unsaturated calcareous clays

    Yes, that may be part of the behavior, but the rate of consolidation (when it does occur) and the consolidation magnitudes are similar to that of ordinary pore-water dissipation. Comparing the consolidation signatures of the clays from below and above the water table demonstrates this. So my...
  11. sgsibob

    Soldier pile lagging top down installation

    DRC1, I am intrigued about the possibility of installing a cast-in-place lagging between piles. My question is how tall a lift is realistic, how long between successive lifts (in other words, what cure times have been used -- 3 days?), and whether the use of internal reinforcement is required...
  12. sgsibob

    Consolidation settlement of stiff, unsaturated calcareous clays

    I read the old thread on the expected consolidation of clays compacted wet vs dry of optimum and found it interesting but not determinative of a situation we have encountered. How would the expected consolidation parameters differ for an undersaturated stiff clay versus a saturated stiff clay...
  13. sgsibob

    Soldier pile lagging top down installation

    As usual, PEinc, you have answered the issue with clarity and detail. I am not trying to belabor this issue, in case you were wondering...My interest is permanent, long-term applications of top-down retaining walls for what would in LRFD terms be considered critical applications. In that...
  14. sgsibob

    Soldier pile lagging top down installation

    Can someone please enlighten me about the constructibiity pitfalls of top-down lagging of soldier pile walls? If, for example, a lift is excavated 5 ft with lagging in place, what keeps the lagging there -- earth pressure on the back side of the lagging? Suppose the wall is 50+ ft high -- is...
  15. sgsibob

    Core Drilling Equipment

    Try to contact Salisbury drilling in Spokane.
  16. sgsibob

    Should CPT shear values be supported by testing?

    Where I practice, the soil conditions are highly variable. We routinely have to deal with inhomogeneous sand-gravel-clay (SGC) mixtures having variable amounts of carbonate cementation. In those cases I believe the presence of coarser clasts (gravels) can throw off CPT values and if the soil...
  17. sgsibob

    Should CPT shear values be supported by testing?

    You mention basic (index) tests like Atterberg Limits, gradation and moisture. I agree that these should be part of a program for any major structure. More specifically, though, for critical structures, do you feel direct shear or triaxial tests are necessary to check the CPT correlations, or...
  18. sgsibob

    Should CPT shear values be supported by testing?

    I would like some opinions on whether the standard of practice is met if one relies exclusively on cone penetrometer (CPT) correlations to derive soil shear strength properties for design of critical facilities such as tall retaining walls, bridges, and large culverts, or whether such...
  19. sgsibob

    Modulus K-factor in COM624p for rock

    I made several runs. The deflections all turned out to occur in the sand anyway. It made little difference whether the rock was yielding or not.
  20. sgsibob

    Peak Particle Velocity variation in soil and rock

    The fact that the crack in the masonry was wider at the top than at the bottom points to settlement, not the lateral shifting more commonly associated with blasting damage. Lou Oriard wrote a prety good book on blast damage to structures, focusing on how to interpret the cause from the crack...

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