Geo problems

[Ambrug20]

I know it may be too early to start studying for some people and some are anxiously waiting for the result. I wish everyone, who is waiting, best news. But I am on the other side of the moon and trying to make myself ready for October. I am study now. And I do need help with some geotechnical.

Please, see attached file and try if possible to answer the questions I added to the problem.

Thank you in advance, guys.

Buy the way these problems are form PPI Civil PE Sample Examination morning solution, second edition.

 

[PE_2009]

I know it may be too early to start studying for some people and some are anxiously waiting for the result. I wish everyone, who is waiting, best news. But I am on the other side of the moon and trying to make myself ready for October. I am study now. And I do need help with some geotechnical.Please, see attached file and try if possible to answer the questions I added to the problem.

Thank you in advance, guys.

Buy the way these problems are form PPI Civil PE Sample Examination morning solution, second edition.

Did you check Errata?

For question 13, following is correction per Errata

correction Second Column, Problem 13 illustration. "γ = 19 kN/m3" should be "γsat = 19 kN/m3".

For problem 14, effective specific weight is used, only if water table is given

I hope that it helps

Good luck!

 

[Ambrug20]

I know it may be too early to start studying for some people and some are anxiously waiting for the result. I wish everyone, who is waiting, best news. But I am on the other side of the moon and trying to make myself ready for October. I am study now. And I do need help with some geotechnical.Please, see attached file and try if possible to answer the questions I added to the problem.

Thank you in advance, guys.

Buy the way these problems are form PPI Civil PE Sample Examination morning solution, second edition.

Did you check Errata?

For question 13, following is correction per Errata

correction Second Column, Problem 13 illustration. "γ = 19 kN/m3" should be "γsat = 19 kN/m3".

For problem 14, effective specific weight is used, only if water table is given

I hope that it helps

Good luck!

yes, it helps. That basically what I thought, that water table should be given, but wasn't sure if I correct. But, you see, problem #13 doesn't tell me where is water level, Where did you check for Errata?

I have two more problems to ask (easy for somebody who knows geo), do you mind to answer? I would need to remove previous attachment and add the other one.

 

[PE_2009]

I know it may be too early to start studying for some people and some are anxiously waiting for the result. I wish everyone, who is waiting, best news. But I am on the other side of the moon and trying to make myself ready for October. I am study now. And I do need help with some geotechnical.Please, see attached file and try if possible to answer the questions I added to the problem.

Thank you in advance, guys.

Buy the way these problems are form PPI Civil PE Sample Examination morning solution, second edition.

Did you check Errata?

For question 13, following is correction per Errata

correction Second Column, Problem 13 illustration. "γ = 19 kN/m3" should be "γsat = 19 kN/m3".

For problem 14, effective specific weight is used, only if water table is given

I hope that it helps

Good luck!

yes, it helps. That basically what I thought, that water table should be given, but wasn't sure if I correct. But, you see, problem #13 doesn't tell me where is water level, Where did you check for Errata?

I have two more problems to ask (easy for somebody who knows geo), do you mind to answer? I would need to remove previous attachment and add the other one.

There is no Errata for slope stability problem. You should take effective specific weight, only if water table is given per my knowledge.

You can post more problems......will try to answer

 

[Ambrug20]

I know it may be too early to start studying for some people and some are anxiously waiting for the result. I wish everyone, who is waiting, best news. But I am on the other side of the moon and trying to make myself ready for October. I am study now. And I do need help with some geotechnical.Please, see attached file and try if possible to answer the questions I added to the problem.

Thank you in advance, guys.

Buy the way these problems are form PPI Civil PE Sample Examination morning solution, second edition.

Did you check Errata?

For question 13, following is correction per Errata

correction Second Column, Problem 13 illustration. "γ = 19 kN/m3" should be "γsat = 19 kN/m3".

For problem 14, effective specific weight is used, only if water table is given

I hope that it helps

Good luck!

yes, it helps. That basically what I thought, that water table should be given, but wasn't sure if I correct. But, you see, problem #13 doesn't tell me where is water level, Where did you check for Errata?

I have two more problems to ask (easy for somebody who knows geo), do you mind to answer? I would need to remove previous attachment and add the other one.

There is no Errata for slope stability problem. You should take effective specific weight, only if water table is given per my knowledge.

You can post more problems......will try to answer

Thank you for your quick replay, PE_2009.

Here are two more problems i'd like to understand. My quetions are at the end of each problem

 

[PE_2009]

I know it may be too early to start studying for some people and some are anxiously waiting for the result. I wish everyone, who is waiting, best news. But I am on the other side of the moon and trying to make myself ready for October. I am study now. And I do need help with some geotechnical.Please, see attached file and try if possible to answer the questions I added to the problem.

Thank you in advance, guys.

Buy the way these problems are form PPI Civil PE Sample Examination morning solution, second edition.

Did you check Errata?

For question 13, following is correction per Errata

correction Second Column, Problem 13 illustration. "γ = 19 kN/m3" should be "γsat = 19 kN/m3".

For problem 14, effective specific weight is used, only if water table is given

I hope that it helps

Good luck!

yes, it helps. That basically what I thought, that water table should be given, but wasn't sure if I correct. But, you see, problem #13 doesn't tell me where is water level, Where did you check for Errata?

I have two more problems to ask (easy for somebody who knows geo), do you mind to answer? I would need to remove previous attachment and add the other one.

There is no Errata for slope stability problem. You should take effective specific weight, only if water table is given per my knowledge.

You can post more problems......will try to answer

Thank you for your quick replay, PE_2009.

Here are two more problems i'd like to understand. My quetions are at the end of each problem

If you are taking depth section of Geotech, you need geotechnical reference book (or books). You can browse this forum & you will find suggested books by various authors like Das, Coduto etc. You will find explanation of how to draw flow nets in those books. However, it will be highly unlikely in P.E. exam that they will ask you problem to make flow nets.

For your second problem as well, you need to study details of Mohr's circle from reference book.

Good luck!

 

[Phalanx]

Thank you for your quick replay, PE_2009. Here are two more problems i'd like to understand. My quetions are at the end of each problem

I don't think you need to worry about drawing a flow net during the morning exam, but here are the steps that I know.

1) Draw your flow channels - the two lines that go from the front of the dam to the back.

2) Draw the equipotential drops (I think that's what they're called). These lines should cross the flow lines at a right angle (90 degrees).

3) A good flow net allows a circle to be drawn in each "square". The circle should touch each side of the square once. If the circle touches only 2 or 3 sides of the square, you need to adjust the spacing of the vertical lines or flow lines or both.

The CERM may go into more depth. Most importantly, know how to use the equation for Q that is shown in the solution. If a problem similar to this shows up on the exam, the flow net will likely be provided in the problem statement. This will insure that all examinees who solve the problem correctly will calculate the same answer.

For the second question:

Graphing the data points is pretty easy. Use a ruler to draw a simple graph and plot the points. Draw a best-fit line through the data points. The slope of the line is phi, and the cohesion of the soil is where the line crosses the verical axis. Because a sandy soil is used, there is no cohesion.

With no cohesion, phi = arctan(105/150) ~ 35 degrees

The vertical leg of the interior triangle is 105 kpa, and the horizontal leg is 105 * tan(35) = 73.5 kpa

The center of the circle is located at 150 kpa + 73.5 kpa = 223 kpa

The radius of the circle = sqrt( (105)^2 + (73.5)^2) = 128 kpa.

The principle stresses = 223 + 128 = 351 kpa and 223 - 128 = 95 kpa

 

[Ambrug20]

Thank you for your quick replay, PE_2009. Here are two more problems i'd like to understand. My quetions are at the end of each problem

I don't think you need to worry about drawing a flow net during the morning exam, but here are the steps that I know.

1) Draw your flow channels - the two lines that go from the front of the dam to the back.

2) Draw the equipotential drops (I think that's what they're called). These lines should cross the flow lines at a right angle (90 degrees).

3) A good flow net allows a circle to be drawn in each "square". The circle should touch each side of the square once. If the circle touches only 2 or 3 sides of the square, you need to adjust the spacing of the vertical lines or flow lines or both.

The CERM may go into more depth. Most importantly, know how to use the equation for Q that is shown in the solution. If a problem similar to this shows up on the exam, the flow net will likely be provided in the problem statement. This will insure that all examinees who solve the problem correctly will calculate the same answer.

For the second question:

Graphing the data points is pretty easy. Use a ruler to draw a simple graph and plot the points. Draw a best-fit line through the data points. The slope of the line is phi, and the cohesion of the soil is where the line crosses the verical axis. Because a sandy soil is used, there is no cohesion.

With no cohesion, phi = arctan(105/150) ~ 35 degrees

The vertical leg of the interior triangle is 105 kpa, and the horizontal leg is 105 * tan(35) = 73.5 kpa

The center of the circle is located at 150 kpa + 73.5 kpa = 223 kpa

The radius of the circle = sqrt( (105)^2 + (73.5)^2) = 128 kpa.

The principle stresses = 223 + 128 = 351 kpa and 223 - 128 = 95 kpa

thanks a lot