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Unformatted text preview: Steady State Flow Flow of water through soil There are 2 main issues • Quantity of water flowing • Pore water pressures Flow through a Dam Unsaturated Soil Flow of water ′ = ′ = ′ = ′ = ′ = ′ = σ σ σ σ σ σ σ σ σ σ σ σ xx xx w yz yz yy yy w zx zx zz zz w xy xy u u u ; ; ; Soil behaviour is governed by Effective Stress When water flows pore water pressures change. This can be important when considering stability of retaining walls, earth dams, and other soil constructions P z(P) Datum Definition of Head at a Point h P u P z P w w ( ) ( ) ( ) = + γ (1) Note z is measured vertically up from the datum 1. Calculation of head at P Choose datum at the top of the impermeable layer 2 m 5 m X P Impermeable stratum 1 m 1m Example: Static water table 1. Calculation of head at P Choose datum at the top of the impermeable layer 2 m 5 m X P Impermeable stratum 1 m 1m Example: Static water table P w u w ( ) = 4 γ 1. Calculation of head at P Choose datum at the top of the impermeable layer 2 m 5 m X P Impermeable stratum 1 m 1m Example: Static water table P z P ( ) = 1 w u w ( ) = 4 γ 1. Calculation of head at P Choose datum at the top of the impermeable layer 2 m 5 m X P Impermeable stratum 1 m 1m Example: Static water table P z P thus h P m w w ( ) ( ) = = + = 1 4 1 5 w u w ( ) = 4 γ γ γ 2. Calculation of head at X Choose datum at the top of the impermeable layer Example: Static water table 2 m 5 m X P Impermeable stratum 1 m 1m u X w w ( ) = γ 2. Calculation of head at X Choose datum at the top of the impermeable layer Example: Static water table 2 m 5 m X P Impermeable stratum 1 m 1m u X z X w w ( ) ( ) = = γ 4 2. Calculation of head at X Choose datum at the top of the impermeable layer Example: Static water table 2 m 5 m X P Impermeable stratum 1 m 1m u X z X thus h X m w w w w ( ) ( ) ( ) = = = + = γ γ γ 4 4 5 The heads at P and X are identical does this imply that the head is constant throughout the region below a static water table?...
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This note was uploaded on 08/30/2011 for the course CIVL 2410 taught by Professor Dairey during the Three '11 term at University of Sydney.
 Three '11
 DAirey
 Steady State

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