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Recent content by Obregon

  1. Obregon

    MICROPILE PVC CASING PIPE

    Hello. Is there any functional problem by leaving a PVC casing pipe in place after grouting a micropile? Is it necessary for it to be withdrawn at all? Thank you for your response.
  2. Obregon

    Driven vs Grouted Soil Nails

    Good morning all. Does anybody have knowledge/experience on the construction of driven soil nailing walls as opossed to dirlled & grouted nails for temporary works? Savings, reliability? Thank you.
  3. Obregon

    Rectangular or Staggered Soil Nail Grid Pattern?

    Hello PEinc, thank you. According to some serious sources "Horizontal rows of soil nails should be staggered to improve the integral action between the soil nails and the ground." (Guide to Soil Nail Design and Construction - Hong Kong Geotechnical Engineering Office 2008). "Soil nails are...
  4. Obregon

    Rectangular or Staggered Soil Nail Grid Pattern?

    Hello. As far as I know, installing soil nails/ground anchors in a staggered grid pattern has advantages regarding load distribution along the facing. Nevertheless, the process can become more time consuming, particularly in slope stabilization as opossed to top-down wall construction. Do you...
  5. Obregon

    Performance of Anchors inside the Failure Wedge

    I thank you again PEinc "Therefore, I would be inclined to ignore it until someone researches the issue and obtains solid evidence of satisfactory performance" I believe this is the kind of rationale a wanted to hear, and you have made a point I could only have expected from a smart guy like...
  6. Obregon

    Performance of Anchors inside the Failure Wedge

    You are correct MTNClimber. In fact, considering this free length, the potential slide surface must had been located at around 8.50 m from the slope's surface.
  7. Obregon

    Performance of Anchors inside the Failure Wedge

    Thank you again for your kind attention PEinc, I sincerely appreciate it. I understand that, by following this approach, we wouldn't be able to get a minimum apparent free length value, i.e., at least 80 % of the design free length, based on elongation measurements during proof/performance...
  8. Obregon

    Performance of Anchors inside the Failure Wedge

    Good morning r13 jimstructures is right, please accept my apologies. Carlos R. Obregón www.sueloanclado.com
  9. Obregon

    Performance of Anchors inside the Failure Wedge

    I see your point PEinc, but remember that niether Mr. Schnabel nor myself are talking about long, low capacity soil nails, which btw we do employ, but tiebacks, i.e., prestressed full-length ground anchors with no unbonded length. I hope you can consider the fact that, as Mr. Schnabel has...
  10. Obregon

    Performance of Anchors inside the Failure Wedge

    That´s right. This is why he tells us his company don´t follow this design practice. Nevertheless, he actually acknowledges, as a fact, that the method has always been succesful with others who follow this approach, meaning that he knows about it and admits it. Interesting topic to take into...
  11. Obregon

    Performance of Anchors inside the Failure Wedge

    PEinc The 10 m-free length specified for that project was, of course, a result of an anchor design elaborated by a well-known geotech firm, and I believe the decision we made to shorten such length was, based on the results, the right one, being these kind of assertions encouraging: "While we...
  12. Obregon

    Performance of Anchors inside the Failure Wedge

    Case History A few years ago, we were engaged in a slope stability job requiring the installation of 500+ 60 ton-ground anchors in clayely soil (CL). For this project we were given the specs by an engineering firm working for the owner. As I can recall, for the upper anchors the...
  13. Obregon

    Performance of Anchors inside the Failure Wedge

    If the tieback is fully grouted, then as you stress the strand, the first few feet will progressiveley break the strand to grout bond and/or the grout to soil bond, essentially forming an unbonded length. What are your thoughts? Now, this is what Mr. Schnabel says: "For some tiebacks, it may...
  14. Obregon

    Performance of Anchors inside the Failure Wedge

    Good morning PEinc, thank you. In fact, I have a copy of the PTI and FHWA documents and I'm aware of their recommendations, rationale and generalized acceptance regarding this issue. Nevertheless, I don't know of any reported field tests talking about the inconvenience (with proof results) of...
  15. Obregon

    Performance of Anchors inside the Failure Wedge

    Hello. As you might know, some companies grout between the tendon and the soil in the failure wedge, and some government agencies require such grouting, the unbonded lentgth of the tendon being zero. Then, when these anchors are tested, some of the measured anchor capacity is from the soil...
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