1 / 20

Datum

Seepage Through Porous Media. W.T. Impervious Soil. ) h = h A - h B. pervious Soil. W.T. h A = total head. Impervious Soil. h B = total head. Datum. W.T. Impervious Soil. ) h = h A - h B. D h. W.T. q = v . A = k i A = k A. Water In. h A. L. Impervious Soil. h B. Datum.

salvatore
Download Presentation

Datum

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Seepage Through Porous Media W.T. Impervious Soil )h = hA - hB pervious Soil W.T. hA = total head Impervious Soil hB= total head Datum

  2. W.T. Impervious Soil )h = hA - hB Dh W.T. q = v . A = k i A = k A Water In hA L Impervious Soil hB Datum Head Loss or Head Difference or Energy Loss )h =hA - hB i = Hydraulic Gradient hA Pressure Head (q) Water out Total Head Pressure Head hB A Soil Total Head B Elevation Head L = Drainage Path ZA Elevation Head ZB Datum

  3. Bernouli’s Equation: Total Energy = Elevation Energy + Pressure Energy + Velocity Energy or Total Head = Elevation Head + Pressure Head + Velocity Head htotal = Z + P + V2 Darcy’s Law: v % i v = discharge velocity & i = hydraulic gradient v = k i k = coefficient of permeability v = k )h/L Rate of Discharge = Q = v.A = k ()h/L).A g 2 g

  4. To determine the rate of flow, two parameters are needed * k = coefficient of permeability * i = hydraulic gradient k can be determined using 1- Laboratory Testing [constant head test & falling head test] 2- Field Testing [pumping from wells] 3- Empirical Equations i can be determined 1- from the head loss 2- flow net

  5. Seepage Through Porous Media Water In L = Drainage Path Head Loss or Head Difference or Energy Loss i = Hydraulic Gradient )h =hA - hB hA Water out hB Datum Soil B A Porous Stone Porous Stone L

  6. Seepage Through Porous Media Water In L = Drainage Path Head Loss or Head Difference or Energy Loss i = Hydraulic Gradient )h =hA - hB hA Water out hB B Soil A Porous Stone ZA Porous Stone ZB L Datum

  7. Ws Ws Ws Ws Ws Buoyancy No Seepage Piezometer In Flow 3 ft D Out Flow 2 ft C u = 6 x 62.4 4 ft 14 ft B 12 ft u = 14 x 62.4 8 ft A 3 ft 3 ft Datum

  8. Upward Seepage Ws Ws Ws Ws Ws Buoyancy + Seepage Force In Flow Piezometer 3 ft Du D Out Flow 2 ft C u = 6 x 62.4 + Du 4 ft 17 ft B 12 ft u = 17 x 62.4 8 ft A 3 ft 3 ft Datum

  9. Seepage Force Ws Ws Ws Ws Ws Buoyancy - Seepage Force Downward Seepage Piezometer 3 ft In Flow D 2 ft C Out Flow u = 6 x 62.4 - Du 4 ft B 12 ft u = 17 x 62.4 10 ft 8 ft A 3 ft 3 ft Datum

  10. Ws Ws Ws Ws Ws Buoyancy No Seepage 1 1 g1 =110 pcf W.T. 3 ft 2 2 4 ft 3 3 - 6 ft = 4 4 12 ft 5 5 Total Stress Effective Stress Pore Water Pressure Effective Stress Pore Water Pressure Total Stress s1 = u1 = s1 = s2 = u2 = s2 = s3 = u3 = s3 = s4 = u4 = s4 = s5 = u5 = s5 =

  11. Ws Ws Ws Ws Ws Buoyancy No Seepage W.T. 1 g1 =110 pcf 3 ft 4 ft 2 - 6 ft = 3 12 ft 4 Effective Stress Total Stress Pore Water Pressure

  12. Ws Ws Ws Ws Ws Buoyancy No Seepage W.T. 1 3 ft 2 g1 =110 pcf 3 ft 4 ft 3 - 6 ft = 4 12 ft 5 Effective Stress Total Stress Pore Water Pressure

  13. Ws Ws Ws Ws Ws Buoyancy + Seepage Force Upward Seepage 1 5 ft g1 =110 pcf W.T. 3 ft 2 4 ft 3 - = 6 ft 4 12 ft 54 4 Pore Water Pressure Total Stress Effective Stress Pore Water Pressure Effective Stress Total Stress

  14. Seepage Force Ws Ws Ws Ws Ws Buoyancy - Seepage Force Downward Seepage g1 =110 pcf W.T. 3 ft 1 1 3 ft 4 ft 2 2 - = 6 ft 3 3 12 ft 4 4 Pore Water Pressure Total Stress Effective Stress Effective Stress Total Stress Pore Water Pressure

  15. g1 =110 pcf W.T. 3 ft W.T. 3 ft 4 ft 4 ft 6 ft 6 ft 12 ft 12 ft

  16. Dh q = A k i = A k L Equipotential Lines Flow Lines

  17. Principles of the Flow Net Equipotential Lines Flow Lines Flow Lines Flow Element

  18. Principles of the Flow Net )h = head loss = one drop Pressure Head Piezometer Total Head = Elevation head + Pressure head 1 2 3 Flow Lines Flow Lines 4 5 Flow Element Elevation Head Equipotential Lines Total heads along this line are the same Datum

  19. Ws Ws Ws Ws Ws Buoyancy + Seepage Force In Flow )h )h )h 3 in )h )h )h )h )h Out Flow 2 in 8 Feff = *(soil + * (water - ( - )h) * (water 7 14 in 6 u = [14 - (3. )h)].(water 5 4 3 2 2 1

  20. Seepage Through Porous Media IN qx(in) = dz . dy kx (Mh/Mx) qx(in) = dx . dz ky (Mh/My) OUT qx (out) = dz . dy kx (Mh/Mx + M2h/Mx2 dx ) qx (out) = dx . dz ky (Mh/My + M2h/My2 dy ) Equating q in and q out Direction of Flow Two sets of curves Rate of Discharge = qout Rate of Discharge = qin Z dy X dZ Y Rate of Discharge = qin Rate of Discharge = qout dx Rate of Discharge = qin (Rate of Discharge)in = (Rate of Discharge)out Rate of Discharge = qin IN

More Related