Drawing Flow Nets in Geotechnical Engineering

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  • Опубліковано 7 січ 2025

КОМЕНТАРІ • 43

  • @Leeshixo
    @Leeshixo Місяць тому +1

    Best video ever! Thank you kind sir ❤

  • @roboarmy357
    @roboarmy357 Рік тому +3

    Thank you for this video, this makes so much more sense! You are the best!

  • @katsuragrey
    @katsuragrey 3 роки тому +2

    Welcome back sir, thank you so much for the upload!

  • @nathancommissariat3518
    @nathancommissariat3518 Рік тому +1

    thanks for the video! About to start learning about this in class on Monday :)

  • @mathiaspedersen1965
    @mathiaspedersen1965 2 роки тому +4

    Great video got a exam in this tomorrow, you answered some question my book couldnt :D

  • @loganwashere24
    @loganwashere24 24 дні тому +1

    Is the reason we use the flow tube and number of drop ratio here because we do not have a length given to us? Otherwise it would just be delta_h/delta_L correct?

    • @EngineeringEconomicsGuy
      @EngineeringEconomicsGuy  24 дні тому

      ...no, not really, but I'm glad you're thinking about it! The path the water follows through the flow net has a different length along each flow-path. The trick to understanding a flow net is to realize that the volume of flow per unit time through each of the flow channels (tubes) is the same. Notice that the tubes are smaller and shorter near the middle, and long and large near the outside. The equipotential lines show how the "difference" in total head is distributed between the two sides of the problem... I hope this helps. The flow through the soil can also be described by a partial differential equation, and the flow net is a kind of visual representation of the solution(s) to that equation. Hope this helps!

  • @MrRICHARDGOMEZ
    @MrRICHARDGOMEZ Рік тому

    Thank you For sharing your knowledge. Very helpful.

  • @vanskis7618
    @vanskis7618 2 місяці тому +1

    so drawing the flow nets is arbitrary? I can draw one with more drops or less drops?

    • @EngineeringEconomicsGuy
      @EngineeringEconomicsGuy  2 місяці тому +1

      Yes. As long as you follow the rules for drawing the flow lines and potential lines, the 'ratio' of the number of flow channels to number of potential drops should be approximately the same.

  • @adithyasundar2017
    @adithyasundar2017 2 роки тому

    Thank you very much for the video, But how can you predict water goes in a particular path in soil, At 5:12 you said that "water is going to go down then around the tip of sheet and go up" why does that happen

    • @EngineeringEconomicsGuy
      @EngineeringEconomicsGuy  2 роки тому

      Thank you for the question. Water is 'driven' (i.e. - flows) from regions of high-pressure to low-pressure. The difference in the elevation of the watertable on either side of the sheetpile wall creates this pressure difference. The flow net is a way to predict the path that the water will follow. The flow net method is based on the assumptions that water does not 'cross-over' itself - it only flows in continuous 'parallel' paths. It is also based on the assumption that the flow into an 'element' of the flow nets equals the flow out of the same element. These assumptions come from the french mathematician Laplace - you can read more in any textbook or on the internet, if you are interested.

  • @sethaho2747
    @sethaho2747 2 роки тому +2

    Super helpful, thank you!!!

  • @khashayarsamiee
    @khashayarsamiee Рік тому +1

    Thank you for the video. at the end we found the seepage rate but how can we compare it to allowable rate ? how can we use it for proof of safety ?

    • @EngineeringEconomicsGuy
      @EngineeringEconomicsGuy  Рік тому

      Good question. There is not typically an allowable seepage rate, therefore we are not able to calculate a 'factor of safety' in the same sense we would for bearing capacity, or other geotechnical calculations. We would use the calculated seepage rate for something like selecting the capacity of de-watering pumps for a project - i.e. we would supply pumps that could keep up with the seepage we anticipate - and we might size the pumps 3-4 times what the calculations suggest. This would be the closest thing I could think of to a 'factor of safety' for seepage. Hope this helps!

  • @omarDababa23
    @omarDababa23 Рік тому +2

    thank you so much ❤️,
    so basically Nf= is most of the times given and it is no of channels? and Nd is basically up to us?

    • @EngineeringEconomicsGuy
      @EngineeringEconomicsGuy  Рік тому +2

      Yes, Nf is the number of flow channels; it is not usually given, but drawing the flow net with 3-4 channels usually works out. Fractional channels are also possible. The number of Nd will be determined by how well you follow the rules for drawing the flow net. Don't over think it - just draw!

  • @niksugden1096
    @niksugden1096 2 роки тому +1

    How do I know how many equipotential lines to draw. Do I need to calculate each one?

    • @EngineeringEconomicsGuy
      @EngineeringEconomicsGuy  2 роки тому +2

      Believe it or not, any number of equipotential lines will work! BUT, you must follow the rules for drawing the flow lines and equipotential lines. If you follow the rules, the RATIO of the number of flow channels to number of equipotential drops should always be about the same regardless of how many lines you draw. Hope this makes sense. Thanks for the question.

  • @lewisgilmour3434
    @lewisgilmour3434 8 місяців тому +1

    very good helpful video

  • @mohsenbodaghi8044
    @mohsenbodaghi8044 Рік тому

    thanks man that was great

  • @arifhossainshah6346
    @arifhossainshah6346 Рік тому +1

    Thank you

  • @oliverd8524
    @oliverd8524 Рік тому +1

    thanks that was beast

  • @lisho6806
    @lisho6806 3 роки тому +1

    Thank you sir

  • @jamescavalari3977
    @jamescavalari3977 Рік тому

    So you can get a different answer by just choosing to draw a different number of lines? I don't buy it. lol I could easily see 2 or 3 people legitimately following the super-vague rules of drawing a flow net, and getting 2 or 3 different ratios of Nf to Nd.

    • @EngineeringEconomicsGuy
      @EngineeringEconomicsGuy  Рік тому +1

      This is a common observation made by students. If you follow the rules perfectly, everyone should get a value of Nf/Nd within +/- 10-15%. This kind of accuracy is well within the acceptable limits for geotechnical engineering. In fact, there is probably more uncertainty and assumptions in the value of the hydraulic gradient! Think about drawing twice as many flow channels...if you follow the "rules" you will need twice as many equipotential lines...and you'll get the same ratio!