Effective Stress in Soil

I'm studying our of Goswami's All-in-One Civil Engineering PE Breadth and Depth book and I'm having a problem following one of the soil compaction examples. You are given the below failure data for a saturated cohesionless soil.

Pore water pressure: 12.0psi

Verticle Total Stress: 36.5psi

Horizontal Total Stress: 15.5psi

Q: Under undrained conditions, what is the effective friction angle?

The first part of the solution shows:

Verticle effective stress = 36.5 - 10 = 26.5psi

Horizontal effective stress = 15.5 - 10 = 5.5psi

Where does this 10psi come from?

Any help would be great, this stuff is rather new to me.

Thanks.

chotovec said:

I'm studying our of Goswami's All-in-One Civil Engineering PE Breadth and Depth book and I'm having a problem following one of the soil compaction examples. You are given the below failure data for a saturated cohesionless soil.
Pore water pressure: 12.0psi

Verticle Total Stress: 36.5psi

Horizontal Total Stress: 15.5psi

Q: Under undrained conditions, what is the effective friction angle?

The first part of the solution shows:

Verticle effective stress = 36.5 - 10 = 26.5psi

Horizontal effective stress = 15.5 - 10 = 5.5psi

Where does this 10psi come from?

Any help would be great, this stuff is rather new to me.

Thanks.

Click to expand...

The given value for pore water pressure (12psi) is actually 10psi. 12psi is a typo error.

The procedure is correct.

Samuel,

To those who don't have that book like myself. Is the answer 41 degrees? Thanks.

djgint said:

Samuel,
To those who don't have that book like myself. Is the answer 41 degrees? Thanks.

Click to expand...

Yeah the answer is 41 degrees, assuming the pore water pressure is 10psi versus 12psi thats shown in the book.

Thanks for everyone's help.

Samuel said:

chotovec said:

I'm studying our of Goswami's All-in-One Civil Engineering PE Breadth and Depth book and I'm having a problem following one of the soil compaction examples. You are given the below failure data for a saturated cohesionless soil.
Pore water pressure: 12.0psi

Verticle Total Stress: 36.5psi

Horizontal Total Stress: 15.5psi

Q: Under undrained conditions, what is the effective friction angle?

The first part of the solution shows:

Verticle effective stress = 36.5 - 10 = 26.5psi

Horizontal effective stress = 15.5 - 10 = 5.5psi

Where does this 10psi come from?

Any help would be great, this stuff is rather new to me.

Thanks.

Click to expand...

The given value for pore water pressure (12psi) is actually 10psi. 12psi is a typo error.

The procedure is correct.

Click to expand...

Does anyone know if there is a consolidates list of typo's in this book?

chotovec said:

Samuel said:

chotovec said:

I'm studying our of Goswami's All-in-One Civil Engineering PE Breadth and Depth book and I'm having a problem following one of the soil compaction examples. You are given the below failure data for a saturated cohesionless soil.
Pore water pressure: 12.0psi

Verticle Total Stress: 36.5psi

Horizontal Total Stress: 15.5psi

Q: Under undrained conditions, what is the effective friction angle?

The first part of the solution shows:

Verticle effective stress = 36.5 - 10 = 26.5psi

Horizontal effective stress = 15.5 - 10 = 5.5psi

Where does this 10psi come from?

Any help would be great, this stuff is rather new to me.

Thanks.

Click to expand...

The given value for pore water pressure (12psi) is actually 10psi. 12psi is a typo error.

The procedure is correct.

Click to expand...

Does anyone know if there is a consolidates list of typo's in this book?

Click to expand...

See the attached errata file:

THANK YOU!