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  1. ONENGINEER

    Soil Densification

    I am looking for different treatment methods to densify silt soils up to 10-15 m. I assume vibrofloation methods are only applicable to sands. but not for silt. Offshore methods would also be helpful. Thank you.
  2. ONENGINEER

    Soil Classification

    Can someone explain the difference between Modified Unified and Unified soil classification systems. What are the pros and cons of one against the other. Why some used the A line on Casagrande Chart and others use A and U line with little differences near the PI less than 4? My search did...
  3. ONENGINEER

    Beta method - pile capacity

    I realize the beta=tan(phi)*tan(delta) but decided not to use it to avoid correlate the SPT and phi values. The following formulations: beta=1.2-0.2SQRT(Z) beta=1.5-0.244SQRT(Z) are given in GEC 8 and am comparing with the CFEM beta values. I am trying to understand the differences. Seems...
  4. ONENGINEER

    N vs N(60)

    ...No Shelby but only SPT. Correlations are often through N-values, which I assume is the raw SPT obtained in the field. For example Beta= (N//15)* (1.2 - 0.11 sqrt(Z). or Phi= 0.3N + 27 or some other soil parameter-N value plots. Were these correlations meant for the raw SPT data or one...
  5. ONENGINEER

    Beta method - pile capacity

    geotechguy1- what is CFA manual? I could not readily find it. Thanks.
  6. ONENGINEER

    Beta method - pile capacity

    Thank you geotechguy1 for providing references on beta. The term I used like sandy clayey silt was meant to be either a clayey silt or sandy silt. My apology if sounded like a classification name. The point was if there are references for beta values that are not for purely silt or purely clay...
  7. ONENGINEER

    Beta method - pile capacity

    I am employing the beta method to calculate the ultimate load capacity of relatively long piles (35-40m). The soils encountered are predominantly clayey sandy silts, as well as sand. The Standard Penetration Tests (SPTs) conducted in the field often exceed 30 or are reported as refusal before...
  8. ONENGINEER

    Frequency of laboratory Testing along Boreholes

    Thanks EireChch to point out the friction angle vs coefficient of uniformity, I could not readily find BS8004 but saw the attached figure and wonder how widely it is used in practice without consideration of the soil compactness...
  9. ONENGINEER

    Frequency of laboratory Testing along Boreholes

    I understand the difficulties to answer a general question of this nature but thanks all and in particular geotechguy1 for your useful hints. While the moisture content is a useful data for fine grained soils, I am still interested to know how to utilize the moisture content test results in...
  10. ONENGINEER

    Frequency of laboratory Testing along Boreholes

    Hi, I have three 250ft boreholes with only SPTs every 5ft for a heavy foundation of 1000 m2. The soils are predominantly silt, some clayey silt and (silty) sand in a till context. The silts to me err on the sand type rather than clay. I will have some Atterberg limit tests to verify. Grain...
  11. ONENGINEER

    Call for innovation in Liquid Limit testing

    Albert Atterberg invented the test apparatus for liquid limit with a porcelain bowl in 1900 that was then upgraded to a metal bowl in 1932. These two great engineers still remain pioneers. The attached picture may indicate the state of the art of industry during Atterberg-Casagrande marvelous...
  12. ONENGINEER

    FoS and Geotechnical Resistance Factor

    Thank you. I do not recall having recent dialogues with structural engineers to know how they use the allowable bearing pressures given by a geotechnical engineer. It seems they multiply the allowable bearing pressure by the FoS used by the geotechnical engineer and then apply the LRFD method...
  13. ONENGINEER

    FoS and Geotechnical Resistance Factor

    Hi I understand well the concept and application of FoS. However, having gone through the Canadian Foundation Manual, I have a difficulty to understand the geotechnical resistance factor. For example, a resistance factor of 0.5 is recommended for vertical bearing resistance of shallow...
  14. ONENGINEER

    Soil Classification - Fine Materials

    Thank you for the helpful comments.
  15. ONENGINEER

    Soil Classification - Fine Materials

    Thanks, geotechguy1. That was relieving [dazed] and conveyed the message well. My gut feeling is that clays are sheet or needle minerals with surface chemistry rather than an assumed equivalent spherical grain in hydrometer's Stoke law measurements. As such Atterberg limit test might better...
  16. ONENGINEER

    Soil Classification - Fine Materials

    The fine soil materials classifications are unusually made based on A-line in Casagrande Chart. I have seen some engineers classify the fine soil based on the result of hydrometer test only and call it silty clay if the percentage of clay from hydrometer test is more than silt or clayey silt if...
  17. ONENGINEER

    Depth of Borehole Investigation

    Proceeding to the next stage, if the pile lengths (D) in the group are not all of the same lengths, how do they establish the equivalent raft at 2/3 D for settlement calculations. Would the D be: - the average length of all piles, - the length of perimeter piles or - the longest pile? Thank...
  18. ONENGINEER

    Depth of Borehole Investigation

    attachmenthttps://files.engineering.com/getfile.aspx?folder=c2443826-5776-4c89-aac0-bdc7c19efbf4&file=IMG_4172.jpeg
  19. ONENGINEER

    Depth of Borehole Investigation

    Thanks. I know realize that Look’s suggestion maybe come from the equivalent raft idea and that the 1.5B is the influencing zone below the raft as in the attached figure (if upload). The influencing bulb with a depth of 1.5B is understandable when we have end bearing poles and for settlement...
  20. ONENGINEER

    Depth of Borehole Investigation

    Thank you for all the valuable feedback. I assume if the building is 25m wide, for a prospective 40m pile at least one borehole should extend to 65m. I assume Burt Look has had the pile group effect in mind.

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