# Relationship between soil suction and angle of repose

1. Sep 13, 2011

### ausineng

I am writing a report for my civil engineering subject. and i have few questions.

is there any relationship between angle of repose and total soil suction.
is there any relationship between angle of repose and particle size distribution.
is there any relationship between angle of repose and electrical conductivity of water.
is there any relationship between angle of repose and shear strength.

i have tried looking online, but i havent found anything solid to include in the report.
thanks

2. Sep 14, 2011

### Studiot

Welcome to Physics Forums, ausineng.

Civil Engineering is an intensely practical subject. Have you done any experiments/made any measurements to test any of these relationships?

Any civ eng course will not have left you totally adrift to answer these questions ( which are pretty fundamental) so what is your basis to proceed on?

3. Sep 14, 2011

### ausineng

hello
the tests we have done are shear test, compression test, total suction test, electrical conductivity of water, ph test of water, sieving analysis, density measurement, gravimetric water content, and angle of repose.

i actually need to know how angle of repose is related to each one of the tests.

thanks

4. Sep 14, 2011

### Studiot

Presumabably you have been told the difference between granular or cohesionless soils and those with cohesion?

The angle of repose is related to the shear in the material as is is the angle of the failure plane.

If ff is a failure plane at angle $\varphi$ to the horizontal then the stresses on that plane are related as follows

$\tau$ff = c + $\sigma$fftan($\varphi$)

Obviously for cohesionless soils, c = 0.

Normally a tau v sigma plot is a straight(ish) line with slope given by tan($\varphi$).

This plot is called the Mohr envelope.

You will have noticed that phi is affected by void ratio.

go well