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  1. muuddfun

    Weights of Switchgear and Transformers

    I am working on geotechnical investigations for 3 solar farms of about 500 acres each out in the desert. The electrical engineers for the project have not yet been chosen by the client. So I hope you guys can help with some basic questions so I can complete a preliminary report for possible...
  2. muuddfun

    Steel Tank Partially on Fill

    What you should do is blow out the back half of the excavation, and then you will have 20 feet of fill under the entire tank. You are talking about 3,000 yards or so additional grading, that is not very much money to fix your problem.
  3. muuddfun

    ground response spectrum usage

    For all projects we include the site class, S1, Ss, Sds, Sd1 in our reports. For many projects like those requiring review by DSA or OSHPOD we are required to generate a site specific spectrum analysis, and provide the full ground spectrum in the report for the structural engineers. Do you use...
  4. muuddfun

    ground response spectrum usage

    What usage do you generally make of the ground response spectrums that are prepared by the geotechnical engineers? Do you use the whole spectrum or just the Sa at the fundamental period? Would different modes of the structural response contribute more or less response back to the base of a...
  5. muuddfun

    Siesmic Bearing Capacity with Liquefied Ground

    FixedEarth The pga is about 0.6. The liquefaction analysis was done following professor Seeds 2003 procedures. It checks fairly well also following Idriss and Boulanger, in spite of Professor Seed ripping Idriss and Boulanger to shreds (but that's a whole other story). I am not sure I agree...
  6. muuddfun

    Siesmic Bearing Capacity with Liquefied Ground

    In Depth: I suspect that bearing failure may be the dominant failure mechanism. I do not believe that the general bearing capacity equation from Terzagi is valid for this case however. As i understand it, that is only valid for the general shear case. I suspect that the footing will fail in...
  7. muuddfun

    Siesmic Bearing Capacity with Liquefied Ground

    What do you consider to be the bearing capacity of ground that has liquefied? I am checking a design for a large amusement park ride that was submitted to a city I review for. The ride is 300 feet tall. The ride was designed with a spread footing that is a hexagon that is 60 foot wide, with...
  8. muuddfun

    Maximum swelling pressure behind retaining walls

    What would be the maximum pressure that a retaining wall would see from an expansive backfill? If you backfill a wall with a highly expansive clayey soil, say with an EI above 120, would the maximum swelling pressure against the wall top out at the at rest pressure? Or could it go as high as...
  9. muuddfun

    STP Borings in compacted fill

    Sounds like a classic case of "hydrocollapse". Your lift hights were to much, and the soil was not completly compacted. Once it was inundated it collapsed. Also not completing the removal as specified probably contributed as well. There is no reason to blame the EOR for using a finer grained...
  10. muuddfun

    The 10/50 Seismic Acceleration

    Ask the goetech what he is getting at. It may be that he is giving you something for Ss and S1 that he recommends you use instead of SDs and SD1. If that is the case then they may be higher or more conservative values than what you would get if you use 2 in 50 for Ss and S1 then reduce them by...
  11. muuddfun

    Seismic Lateral Pressures on Retaining Walls

    Look at the following reference, it will explain a lot about where the loads come from. It also shows that the inverted triangular distribution is incorrect. PEER 2007/06 - Development of Improved Procedures for Seismic Design of Buried and Partially Buried Structures Linda Al Atik, Nicholas...
  12. muuddfun

    Needing Help in Duncan & Chang (Hyperbolic) Constitutive Model

    I don't know much about the specific values you are using, but my guess would be that the actual behaviour may be a cross between the elastic-perfectly plastic, and the hyperbolic. You might try to plug the values for one into the other and try to get upper and lower bounds of the settlement in...
  13. muuddfun

    Needing Help in Duncan & Chang (Hyperbolic) Constitutive Model

    I agree with dgillete on this one. You are compacting the clay during construction close enough to the ZAV line so that it would not take significantly more pressure to close the gap in density and basically eliminate most all of the air voids, once that has occured then clasical consolidation...
  14. muuddfun

    Field Density Test Results Don't Match Observed Soil Behavior

    Have you tried compacting dry of optimum, maybe 2 percent down? Have you tried to take larger sand cones, or ring tests? How sharp or flat is you curve? What is your EI? Is something weird going on with the expansiveness?
  15. muuddfun

    Pile Driving Next to 3rd Rail Power

    Some kind of barrier or shielding might work. My concern that I expressed to the contractor the other day was that he might not have enough room to construct a barrier. I was thinking of something like a k rail to anchor the bottom and then building some kind of screen wall above that. Does...
  16. muuddfun

    Pile Driving Next to 3rd Rail Power

    dgillette This is California. Ron Thats what I am hoping they have in their back pocket if we press them hard enough. Vulcanhammer Thats what I need to find out from the pile sub, we have been using a swinging leads so far on this job. Hopefully he has a fixed leads rig that might help...
  17. muuddfun

    Pile Driving Next to 3rd Rail Power

    We have had many problems with the pile installation on this project. After several hundred piles we have a procedure that works, I am very reluctant to change what we have spent million of dollars to find out the hard way, works. I started managing this project about a year and a half ago just...
  18. muuddfun

    Pile Driving Next to 3rd Rail Power

    Just came from a meeting about how to proceed in the rail yard. The rail company is thinking that if you can drive piles with zero clearance next to a building then why not next to the third rail. Some how they think we can possition the drilling rigs and cranes in such a way as they won't go...
  19. muuddfun

    Pile Driving Next to 3rd Rail Power

    Well that is what I have been telling them, but somehow the rail road thinks it can be done safely. I am not sure what planet they are on right now. Hopefully I will find out more tomarow. Thanks
  20. muuddfun

    Pile Driving Next to 3rd Rail Power

    How close to active 3rd rail power have any of you driven piles? We are driving piles for a bridge bent located between two rail tracks. The rail people do not want to shut off power to two tracks at the same time. They only want to allow one to be taken out of service. We will be maybe...

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