3 ms·

IANAE (No An Engineer), but I think he mentions both the issues of piles wandering off-course, and of unanticipated piling problems causing major budget & sched

IANAE (No An Engineer), but I think he mentions both the issues of piles wandering off-course, and of unanticipated piling problems causing major budget & scheduling issues. From a structural PoV, an extremely long piling in soft-ish soil will start having problems with lateral deflection - which it is too thin (relative to length) to resist. Then there's the case of "we think we finally hit bedrock...but what if it's just a big boulder?". I can imagine cases of pilings running into large underground caverns, or penetrating strata containing water / gas / petroleum under pressure. Edit: From a quick search... In some locations, bedrock may not start until >1000' below the surface. And here's a very quick & simple intro to the fact that "bedrock starts at depth D" is usually too simplistic: https://education.nationalgeographic.org/resource/bedrock/ https://education.nationalgeographic.org/resource/bedrock/

adolph 2y ago
> I can imagine cases of pilings running into large underground caverns Example being the Lake Peigneur disaster. https://64parishes.org/entry/lake-peigneur-drilling-accident https://64parishes.org/entry/lake-peigneur-drilling-accident On the morning of November 20, 1980, the crew drilling near the salt mining operations reported that the tip of their drill shaft was stuck. After the crew removed the tip, they heard strange noises and abandoned the platform in the nick of time. A giant mud crater began sucking down barges, rigs, and almost some fishermen who escaped with moments to spare.
- trilbyglens 2y ago
  [flagged]
  - adolph 2y ago
    In 1980 south Louisiana, “those schmucks” were likely staunch Democrats, following their forebears since the Republican association with reconstruction efforts after the American civil war.
    - adolph 2y ago
      Goodness, so much hate of honest history. Louisiana is where “vote for the crook, it’s important” actually happened. https://en.wikipedia.org/wiki/1991_Louisiana_gubernatorial_election https://en.wikipedia.org/wiki/1991_Louisiana_gubernatorial_e...
  - kortilla 2y ago
    That’s at will employment. Works exactly the same fucking way in California where “those schmucks” certainly aren’t voting R.
beerandt 2y ago
>Then there's the case of "we think we finally hit bedrock...but what if it's just a big boulder?" Doesn't matter. There's two types of pile support: noncohesive and cohesive. Which can be thought of as end (bearing) resistance and side (friction) resistance. Most people only think of end resistance. Most end resistance piles aren't driven to bedrock or even a boulder, but a strata of soil with sufficient strength. Usually a layer of sand under silt or clay, but a boulder could do it. Here's the catch- if it's a one-off, then adjacent piles won't hit it, and you'll see the anomaly. Mitigation may or may not be required. If it's not, then you've hit a strong (noncohesive) layer of boulders. Either way- it goes back to the point: each pile is resistance tested. And you know now not only the insitu soil strength, but also that of each layer to reach that depth. Also side note- the act of driving and then post-drive settling both build addl strength. Eg, The force used to drive the pile, applied a few months later, usually won't be sufficient to drive it any further.

adolph 2y ago

> I can imagine cases of pilings running into large underground caverns Example being the Lake Peigneur disaster. https://64parishes.org/entry/lake-peigneur-drilling-accident https://64parishes.org/entry/lake-peigneur-drilling-accident On the morning of November 20, 1980, the crew drilling near the salt mining operations reported that the tip of their drill shaft was stuck. After the crew removed the tip, they heard strange noises and abandoned the platform in the nick of time. A giant mud crater began sucking down barges, rigs, and almost some fishermen who escaped with moments to spare.

trilbyglens 2y ago
[flagged]
- adolph 2y ago
  In 1980 south Louisiana, “those schmucks” were likely staunch Democrats, following their forebears since the Republican association with reconstruction efforts after the American civil war.
  - adolph 2y ago
    Goodness, so much hate of honest history. Louisiana is where “vote for the crook, it’s important” actually happened. https://en.wikipedia.org/wiki/1991_Louisiana_gubernatorial_election https://en.wikipedia.org/wiki/1991_Louisiana_gubernatorial_e...
- kortilla 2y ago
  That’s at will employment. Works exactly the same fucking way in California where “those schmucks” certainly aren’t voting R.

beerandt 2y ago

>Then there's the case of "we think we finally hit bedrock...but what if it's just a big boulder?" Doesn't matter. There's two types of pile support: noncohesive and cohesive. Which can be thought of as end (bearing) resistance and side (friction) resistance. Most people only think of end resistance. Most end resistance piles aren't driven to bedrock or even a boulder, but a strata of soil with sufficient strength. Usually a layer of sand under silt or clay, but a boulder could do it. Here's the catch- if it's a one-off, then adjacent piles won't hit it, and you'll see the anomaly. Mitigation may or may not be required. If it's not, then you've hit a strong (noncohesive) layer of boulders. Either way- it goes back to the point: each pile is resistance tested. And you know now not only the insitu soil strength, but also that of each layer to reach that depth. Also side note- the act of driving and then post-drive settling both build addl strength. Eg, The force used to drive the pile, applied a few months later, usually won't be sufficient to drive it any further.