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  1. cchamberlain

    Jacking Pit Design

    I used a FS of 3 on the passive resistance as a check. I used a FS 1.5 for the cofferdam portion (inward loads)which controlled the length of the sheets. I then checked with FS of 3 and it worked. If it wouldn't have worked I would have reduced the FS for the Jacking loads and not tried to...
  2. cchamberlain

    Jacking Pit Design

    I assume you are talking about soldier pile with lagging. If so I would think you could use the full height of the soldier pile and lagging system to provide passive resistance. I used the full height of my sheets even though the concrete block was not full height. Do you have poor soils. My...
  3. cchamberlain

    Jacking Pit Design

    800 kips. That's getting up there. Contractor is just building my pit. Not sure when jacking is going to start. Have you heard of anymore deflection or any signs of distress? The jacking contractor that I am working with just gave me the size of the reaction plates he will be using, but I...
  4. cchamberlain

    Jacking Pit Design

    Sorry, I was using pipe inadvertently. I know what you meant though. 90 kips is very, very low compared to your design loads.
  5. cchamberlain

    Jacking Pit Design

    Intuitavely the friction factor seems high, but not unreasonable. I did not try to verify it with any references. I am curious how they were able to put the 100' of pipe in. Is there a long open distance to get this much pipe in or am I misunderstanding something. My contractor can only get...
  6. cchamberlain

    Jacking Pit Design

    PEinc, I checked the bending and shear above and below the thrust block for the passive soil pressure diagram. This is the max pressure that can devlop even though the actual pressure will be different and may never reach close to that. I checked both the drained and cohesive states, but the...
  7. cchamberlain

    Jacking Pit Design

    PEinc, I am coming up with 30" thrust block with #6 at 4" on the face near the sheeting. Two-way shear controlled, if it is even possible as a failure mode. I checked bending about the reaction plate which is only 26" by 80" but my thrust block is 19.75' (full width) by 8' tall which is below...
  8. cchamberlain

    Jacking Pit Design

    Thanks for the info. What was the trapezodal distribution based on? Was it the force applied to the reaction wall? If so what limits did you use to transition? End of concrete? Did you check the cantilever setion based on the trapezodal pressure or triangular (passive) pressure? I assume you...
  9. cchamberlain

    Jacking Pit Design

    The pit will be somewhat like a cofferdam. Sheet pile on 4 sides because the flow line will be down approximately 20'. So I will have about 20' of retained height, so I was really looking for some insight with how to balance the apparent earth pressures with the jacking force (which I am told...
  10. cchamberlain

    Jacking Pit Design

    I am a structural engineer with knowledge of geotechnical engineering. I would not consider myself an expert, but have designed many retaining wall systems for both permanent and temporary applications. I was recently asked by a Contractor to design a jacking/receiving pit for a culvert boring...

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