Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations MintJulep on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  • Users: MTSOE
  • Order by date
  1. MTSOE

    Ultimate vs. Allowable Passive Pressure - which to use with a safety factor

    I would inquire of the geotechnical engineer whether or not the ultimate passive pressure they provided has already been factored (reduced). I approach cantilever pile designs like this by comparing resisting moment to overturning moment. I set the embedment depth such that the ratio of the...
  2. MTSOE

    Lateral earth pressure at rest for a standing cliff

    I don't know where this project is but the soil properties you have assigned are very strange to me. They are not indicative of a deep open cut that has remained standing for 10 years. Were these values provided in a geotechnical report?
  3. MTSOE

    Stepped excavation - forces on soldier pile

    Applying the resultant toe reaction to the top of the lower soldier pile wall seems reasonable to me. However, I am concerned about what appears to be a very shallow toe embedment for the existing wall. You show lagging behind the back of your lower soldier pile wall. This means that for the...
  4. MTSOE

    Negative Cohesion Component Value for Active Pressure

    I personally would never assume zero earth pressure unless I'm building against a very competent rock. I would ask others in your area what a safe assumption but not overly conservative equivalent K value would be. Unfortunately, geotechnical engineers can often be reluctant to give realistic...
  5. MTSOE

    Negative Cohesion Component Value for Active Pressure

    I disagree that Ka=1 implies that is neither clay nor granular. To me, Ka=1 implies that the friction angle equals zero. For me, using a friction angle of zero and an undrained shear strength puts bounds to the problem. Undrained shear strength is the cohesion intercept which corresponds to...
  6. MTSOE

    Negative Cohesion Component Value for Active Pressure

    Also, in my experience/local area of practice, when I get a theoretically negative pressure, I use a K value of 0.2 (this is just a made up, safe value). This is specific to my area. Ask around to see what is common practice where yoy are.
  7. MTSOE

    Negative Cohesion Component Value for Active Pressure

    Yes, it is fairly common to get calculate negative active earth pressure for cohesive soils (at least in my area). A mathematically negative value would seem to imply that the soil is pulling away from your wall (whatever that might be). Instinctively, we know this isn't happening. Rather the...
  8. MTSOE

    Using Equipment next to an existing retaining wall

    When you say the slab has been supporting a live load for 20 years, do you mean a vehicular live load? What is the purpose of this slab? I would definitely be at ease about putting a skid steer on this slab if I knew the area was used for ploughs to stockpile snow or garbage trucks to pick up...
  9. MTSOE

    Auger cast pile with no rebars

    It is absolutely possible. Whether it is appropriate depends entirely on the loads which they must resist. I assume when you say only axial load, you mean only compressive axial load. If that's the case, I would research "rigid inclusions". This would usually fall under the heading of ground...
  10. MTSOE

    Piled Foundation Question

    I have no idea what the access is like on this slope, what kind of loads you need to resist, or how remote this site is. However, there are many smaller drill rigs that can handle slopes better than the large, top-heavy drills often used on large infrastructure projects. Look up smaller drill...
  11. MTSOE

    Underpinning

    Try to get your hands on a copy of Underpinning by Prentis and White. The Foundation Engineering Handbook by Winterkorn and Fang also has a good chapter on underpinning written by White.
  12. MTSOE

    Guidelines for designing foundation anchoring to rock

    Are you describing micropiles and/or tiedowns? If so, check out some FHWA publications: https://www.fhwa.dot.gov/engineering/geotech/foundations/
  13. MTSOE

    Soldier pile and lagging next to adjacent building

    Hmmm. 4ft is pretty tight pile spacing and should give the soil lots of opportunity to arch (unless the contractor does something silly like open all of the bays and chip away all of the soil behind the pipes all at once). But keep in mind, if your intent is to lag behind pipe piles, you will...
  14. MTSOE

    Soldier pile and lagging next to adjacent building

    In my experience, it is best to avoid lagging within the influence of adjacent buildings and construct a tanget or secant wall as you previously suggested to your client (however, based on your sketch, it doesn't look like you have clearance for a tangent or secant wall). This is not for...
  15. MTSOE

    Deawatering and shoring

    In my area, the sequence is to drill the soldier piles, drill the dewatering wells, draw down the water, then excavate. I suppose in some areas, it may be preferable to draw down the water and then drill the soldier piles, but where I am the contractors are content to drill in wet ground with...
  16. MTSOE

    Brace brace detail

    Here are some things to consider: 1. Has a specialty contractor already been selected to construct this support of excavation system? If so, ask them what detail they like. 2. What are you using for the struts? W/HP shapes? Pipes? This will influence the detail. 3. Consider...
  17. MTSOE

    Two sided Soldier Pile Lagging Wall

    For Stage 1, I would expose the entire pile web (without disturbing the soil/fill behind the outside of the back flange) and install the lagging against the inside face of the back flange. A piece of steel angle could then be welded to the web of the pile to sandwich the lagging in place. The...
  18. MTSOE

    Can Torque applied be converted reliably into Anchor lock off load?

    I'm not suggesting that you yield any of the anchors. Basically, you apply a tensile load to the anchor with a hydraulic jack until the nut is just barely lifted off the bearing plate/pile/wall/whatever it's bearing against. This point can usually be surmised by an abrupt reduction in gain of...
  19. MTSOE

    Can Torque applied be converted reliably into Anchor lock off load?

    Sorry. I should have said until the increase in hydraulic pressure abruptly slows.
  20. MTSOE

    Can Torque applied be converted reliably into Anchor lock off load?

    I imagine your contractor would be reluctant to re-stress all the anchors using a hydraulic jack, but perhaps you could do a do a lift-off test of a single anchor. Basically, mount the jack on the anchor and extend the ram until the hydraulic pressure abruptly increases. This pressure can then...

Part and Inventory Search

Back
Top