Soil Mechanics Lecture 6 Flashcards
What is the range of capillary rise in soils (m) for sands?
0.1 -1.2
What is the range of capillary rise in soils (m) for silts?
0.75-7.5
What is the range of capillary rise (m) for clays?
7.5-23
What does the equation:
h1 = C/(e*D10)
e = void ration
D10 - effective size (mm)
C= constant (10-50 mm^2)
represent?
the variation of degree of saturation in the sand column
What does flow around a sheet pile mean?
On the side with the higher table the effective stresses will increase, on the other the effective stresses will decrease
What is bernoulis theory?
Shows that the total head, H, is made up from the elevation, pressure and velocity head
What is the definition of a state variable?
the physical consitions in which the soil exists
Give an example of a state variable
- Density
- Stress
- Fabric
How is stress in a soil induced?
The self weight of the material plus
What kind of pressure is found in soils, and what does it mean?
Hydrostatic, same in all directions
What is the definition of fabric?
The arrangement of particles and their orientation
What are useful bits of information when working out water pressur?
- Cannot sustain shear forces
- Incompressible
- Has a density of 1000
How do we calculate water pressure and what is it’s symbol in soil mechanics?
u = rho_w*g*z u = gamma_w*z
(measured in kNm^-2 or kPa)
**for no flow conditions
How do you calculate the dry self-weight of the soil?
sigma_z = gamma_d*z
= rho_d * g *z
where gamma_d and rho_d are the dry specific weight and the dry density
How do you calculate the self weight/ stress exerted by satruated soil?
theta_z = gamma_sat*z
= rho_satgz
