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Recent content by Mccoy

  1. Mccoy

    A Non-serous Question

    My mind has become so lazy in calculations that I always use a spreadsheet, even when simply adding figures. My answer consequently is that I use the automatic pi() function when needed.
  2. Mccoy

    Calculating the values of rock springs in Finite Element Software

    I've been using the approximate solutions from Gazetas you cite and the rigorous solutions from Pais & Kausel. The hypothesis is that the foundation is rigid but it is shown that a nonrigid foundation is an acceptable approximation. What happens in the presence of a rock mass which is not...
  3. Mccoy

    Slide 2 - Surficial Failure Surface

    That's exactly the same thing I do, I examine visually the graphical output of all critical surfaces within the lower FOS range and decide which ones are realistic and which ones look more like a potential result of surface erosion rather than of a potential sliding surface.
  4. Mccoy

    Footing on bedrock, rotational stiffness / degree of fixity

    My attention was caught by the 'rotational stiffness' since it is rarely considered. The stiffness of bedrock (which bedrock?) is usually very large in translational stiffness, so much so that to all practical purposes we can assume a fixed constraint (especially if the bedrock exhibits few...
  5. Mccoy

    UCS Test and Young's Modulus

    I myself do not waste time at all with anomalous values. If a parameter goes outside the known range, from literature or professional practice, I simply discard it as garbage, unless extensively justified with valid technical reasonings. I'm utterly horrified that the university guys cited by...
  6. Mccoy

    How do I determine the spring constant for a pile?

    It also depends on the software. I've been working mainly with a FEM-based software. The procedure is to discretize piles in finite-length cylinders. The reaction of each cylinder is modeled by 3 Winkler springs, horizontal, torsional and vertical (all applied to the lateral surface). The Base...
  7. Mccoy

    Bearing Capacity in Relation to Shear Capacity

    My first impression is the same as your impression, that is the report appears to state the obvious since if the soil stress exceeds the shear capacity, a rupture or shear plane is formed which will compromise the stability of the foundation.
  8. Mccoy

    mat foundations sliding resistance: Adhesion or Friction?

    Those loads act in a very short time span so the undrained condition should be used. Please note that, in analogy to the drained condition, probably we should not use peak Cu (also defined Su), but rather the remolded Cu, sometimes called Cu,r. the remolded quantity is often calculated by an...
  9. Mccoy

    Where is Oldestguy?

    Kudos to Oldestguy for having kept his professional interests awake for so long...
  10. Mccoy

    Slopes and probability of failure

    This is a slope in a statistically homogeneous soil with a small scale of fluctuation (SOF) of its strength (described by Su or phi, according to the soil type and rupture model used). The elementary soil volumes are small and the light ones represent smaller strength whereas the darker ones...
  11. Mccoy

    Slopes and probability of failure

    Just about that, if we simplify considering a single statistically homogeneous layer, if each CPT is considered a random sampling/§resampling through the layer, then after conversion for example from Qc to Su in your example we would have 10 values of Su average, and one corresponding values of...
  12. Mccoy

    Residual strength: internal friction angle

    AS stated above, phi_cs, which is phi at the critical state (also called phi_cv or constant volume)for prevalently sandy soil, is usually 30° or above. There is a discussion on this topic almost 10 years old.... https://www.eng-tips.com/viewthread.cfm?qid=348077
  13. Mccoy

    Slopes and probability of failure

    This thread has been inspired by the practical issues posed in this other thread: https://www.eng-tips.com/viewthread.cfm?qid=493211 The issue was basically that Pf, or Pof = Probability of failure, sometimes, or often, seems to be high in relation to the FS, the minimum Factor of safety of the...
  14. Mccoy

    Site class based on Rock data

    I do agree with Eirechch as above. Also, If you can extrapolate safely to 30 m of depth, then you should also have reliable numbers for Vs of each rock, by reliable I mean citing sources. In my experience, a weathered shale may have a 400 m/s cautious Vs, whereas a hard shale may have from 600...
  15. Mccoy

    Passive soil bearing notations

    I don't know if you guys agree but I believe that the concept of passive pressure can also be modeled by Winkler-like springs (for example, the p-y model in piles) so in such models a horizontal modulus of subgrade reaction with relevant units (pressure/length) may be envisaged. In this case...
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