One dimensional flow of water through soil Flashcards
How can water flow through earth embankments?
Its hard for water to flow through impervious soil, however there are weak points where water can easily flow through
What is seepage?
The flow of eroded material due to the action of water.
What happens if solids escape the soil through the flow of water?
The density goes down and mass slowly reduces which means less resistance and more susceptible to collapse.
What can you use to divert water away through soil.
- French drains
What is shotcrete?
Shotcrete is a method of applying concrete projected at high velocity primarily on to a vertical or overhead surface
How can you increase slope stability?
- Use design frames
- Shotcrete
- Use built-in-drainage layers
What can alter the degree of saturation and strength of soil?
Changes in environmental conditions
How roads designed to be stable?
- Fill gap from natural level of soil to level of road
What are used in conjunction with roads to transport water?
Outlet pipes to transport water higher elevation to a lower elevation
What are the outlet pipes used by roads called?
Collector pipes
What do you do when you have water above the base of an excavation?
- Install pumps in bore holes and sucks water out which will have a temporary effect
- Reduce water level
What can boreholes also be used for?
Checking dryness is at right depth
How can multiple boreholes be used?
Little bore holes connected to a bigger pipe
How does water flow in terms of energy?
Water flows from zones of high mechanical energy to zones of low mechanical energy
What is the hydraulic gradient?
∆h/l
What are the 3 component of energy?
- Elevation head
- Pressure head
- Velocity head -> assumed to be negligible
What is the difference in height of water called between two points?
Head loss
What is the total head?
h = h_z+h_p
What is static liquefaction?
Caused by a sudden loss of effective stress accompanied by vast deformations and a rapid build-up of pore water pressure that can cause soils to behave like liquids
What is static liquefaction known as or like?
Quick condition - flow of water through the soil
How do you determine the critical effective stress?
𝜎’_c = z𝛾’-iz𝛾_w=0
- i = h/H_2
What is the critical hydraulic gradient?
i_c=𝛾’/𝛾_w
What does upward seepage do?
Upward seepage reduces the vertical effective stresses in the
soil
How can flow rate be calculated?
q = vA = v_sA_v
