Karteikarten
Geotech 2 Permeability
Karten in diesem Stapel (15)
- 1What is the definition of soil permeability?The permeability of a soil is the rate at which water flows through the soil
- 2What are the factors which affect the water flow through soil?1. The cross sectional area it flows through
2. The hydraulic gradient existing across the soil mass
3. The Coefficient of permeability "k" - 3What is Darcy's Lawq=A.k.i
A= Area of cross section m2
k= Co-efficient of permeability m/s
i= hydraulic gradient = head loss/length of flow path
q= flow through cross section Area m3/s - 4What is the procedure for test Constant Head Permeameter (Gravels & Coarse Sands)1. Allow water to flow through sample under constant head until a steady flow is achieved. It is usual to test a sample at three different flow rates.
2. Once steady flow rate is achieved, determine the rate by measuring the time t required to collect a predetermined volume Q.
3. At the same time measure the Difference in head h over the measured sample length L - 5Draw the constant head permeater test
- 6What calculations are done for the constant head permeameter test?From Darcys Law q = A.k.i
Flow rate q = Volume Q /Time t = Q/t
Hydraulic gradient i = Head loss h / Sample length L
Q/t = A.k.(h/L)
Coefficient of permeability
k = Q .L/t. h. A - 7Draw the falling head permeameter test.
- 8For the Consolidation test what is the formula for the coefficient of permeability?k = Mv. Cv.w .g
Mv is co-efficient of Volume Compressibility in m2/kN.
Cv .is co-efficient of consolidation in m2/year
w .g is density of water in kN/m3 this formula will give k in units of m/yr - 9What are the 2 general types of field permeability test in common use1. Pump Tests
2. Soakage tests - 10What is the field testing procedure for Wells1. Measure depth of pump well and determine static water level in each of the observation wells.
2. Start pumping from well, and measure water level in each observation well until steady state
conditions are reached.
3. Once steady state conditions are reached measure flow rate from bore and the water level in
each pair of observation wells.
4. Determine k value for each pair of observation wells using the methods unconfined or confined aquifer and average. - 11Draw the diagram for an unconfined flow pump test
- 12Draw the diagram for the confined flow pump test
- 13What is heave and boilWhen the pore water pressure in a granular soil exceeds the downward pressure due to the weight of the soil above. The overlying soil will be pushed up and boiling will occur id sufficient volume of water is available.
- 14What is the critical hydrualic gradient?desity of subsoil x gravity
- 15What is piping in a soil?Erosion of soil subject to upward flow of groundwater where hydraulic gradient reaches critical values and the soil liquifies.
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- Beschreibung
- Diploma Geotechnical Engineering 2 Karteikarten am Geotech 2 Permeability, erstellt von Pauline Leota am 14/05/2015.
- Erstellt von
- Pauline Leota
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