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  1. Doctormo

    slope stability programs for mac computers

    Also Geo-Tec B by Interstudio Italy
  2. Doctormo

    slope stability programs for mac computers

    MobiSlope (iPad), MacSlope (MAC)
  3. Doctormo

    Lateral Pressure due to Point Load Equation Discrepancies

    Sorry, I see you did provide some data in the original post. The H.Y. Fang plot is the most correct based on the lateral loading being 2X the calculated load as noted in the Fang text. The other plot is incorrect and not representative of the point loading and Boussinesq distribution. There is...
  4. Doctormo

    Lateral Pressure due to Point Load Equation Discrepancies

    Please provide the example you are modeling. What is Q load and and Q offset distance from the wall that is represented by the curves. If you are using Poisson's ratio, what is the value? Most simplified equations assume 0.50 in the general Boussinesq so that the term (1 - 2u) goes to zero and...
  5. Doctormo

    Active vs at rest for vehicle surcharge

    The 2' of roadway surcharge for retaining walls comes from AASHTO whereas building codes and design guides typically use 250 psf. The 2' of soil surcharge would only be accurate if the load was from trucks carrying the backfill material, haha. Seriously, the weight of backfill varies from 100...
  6. Doctormo

    Flex MSE vs. Rockery wall

    Rockery is a gravity wall system, FlexMSE is a MSE wall or reinforced steepened slope system. The excavation, backfill, and construction requirements are considerably different. It would really have a lot to do with the height of the walls you are considering. I suspect that the "rocks" in a...
  7. Doctormo

    Active vs at rest for vehicle surcharge

    Hello fattdad, We're heading back to the discussions about Bousinesseq, 2 X Bousinesseq, and trial wedge surcharge loads. There are lots of conflicting theory on the treatment of surcharges, how, when and where. Bowles discusses this relative to Spangler's testing as I recall. AASHTO...
  8. Doctormo

    3 Single Precast Box Culverts

    310' of fill might require a conservative analysis?
  9. Doctormo

    Soil - Wall Friction Angle

    There are charts for estimating various friction angles of dissimilar materials (NAVFAC, AASHTO) as it is not practical to actually test for these. Using 1/2 - 2/3 of soil phi angle for a concrete wall interface is customary but then this would not apply to a Rankine form of earth pressure...
  10. Doctormo

    Conventional MSE Wall Design Responsibility

    (also not intended to derail the conversation that appears to have stopped) fattdad - 50 states and probably about that many different approaches. Sometimes it is a funding issue when money becomes available and a project is pushed forward on a D-B basis ahead of the engineering thus minimal...
  11. Doctormo

    Conventional MSE Wall Design Responsibility

    fattdad - Your observation is consistent with the DOT market. However, there are some DOT's and and many transit agencies that attempt to push all soil stability responsibility onto the wall designer via the contract specifications which is why all bid documents have to be reviewed. I have been...
  12. Doctormo

    Conventional MSE Wall Design Responsibility

    ps: As a side issue, the NCMA Design Manual 3rd edition "attempts" to define responsibilities of the parties in a construction project (generally private sector projects). While this is good in concept, the plans and specification of a project govern responsibilities as well as legal precedence...
  13. Doctormo

    Conventional MSE Wall Design Responsibility

    In the US, the majority of MSE walls with panels and steel reinforcement are for state and federal transportation departments who determine what kinds of retaining walls are required at a location prior to bidding based on geotechnical, structural, aesthetic, and cost requirements. In most...
  14. Doctormo

    Books on the history of geotech and how it’s devloped over time?

    From a quick internet search: http://aashtoresource.org/docs/default-source/newsletter/three-musketeers-in-soils-testing-atterberg-casagrande-and-terzaghi---printer-friendly.pdf?sfvrsn=0 Seems to be a nice summary of the "beginning" and I am sure there are many like it.
  15. Doctormo

    Safe distance for loading beyond crest of a slope

    The crane is usually a couple of isolated point or strip loads of finite length so modeling as continuous line or strip load in a conventional slope stability program would tend to be overly conservative. A 3D slope stability modeling would probably be more appropriate for a crane on surface...
  16. Doctormo

    Extruded Geogrids versus Coated Polyester Knit Geogrids

    High strength polyester soil reinforcement is a low creep product with well defined design values. Polypropylene is a high creep product so ultimate strength has to be factored down quite a bit to obtain a safe load capacity Depends on what you want to do with the materials, wall or slope...
  17. Doctormo

    minimum required compaction degree for reinforced fill

    This has always been a controversial issue and varies on a regional level in the US. The fact that MSE is involved should not alter the density requirements as it tends to be a soil strength and consolidation issue related to the function(s) of the structure. What does the MSE structure support...
  18. Doctormo

    Retaining wall displacement

    If you can create an accurate static analysis model of the wall, you should be able to calculate the additional seismic force required to drop the sliding FS to 1.0. You could compare that to the expected pseudo-static force from the design PGA or As acceleration. If the structure can handle the...
  19. Doctormo

    Retaining wall displacement

    In my opinion, this is pretty much voodoo engineering when trying to predict retaining wall movement due to a seismic event. What are you going to do with this information that will most probably not be correct? Richards & Elms has some good discussion on the concepts of the seismic event and...
  20. Doctormo

    When is Slope Stablity Analysis Required or Not Required

    The reply sent itself somehow... geotechguy1 - I totally agree about lack of borings where needed and the owner's propensity to rearrange sites after the geotechnical investigation seeking out the swampy area to build a wall and drive lane. On the legal front, experience tells me that notes...

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