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TOPIC 2 STEADY STATE FLOW THROUGH SOIL

TOPIC 2 STEADY STATE FLOW THROUGH SOIL. Course : S0705 – Soil Mechanic Year : 2008. CONTENT. PERMEABILITY / CAPILARITY (SESSION 7 : F2F) SEEPAGE (SESSION 8 : F2F) FLOW NET / JARINGAN ALIRAN (SESSION 9 – 10 : F2F). SESSION 7 PERMEABILITY / CAPILARITY. INTRODUCTION. DEFINITION :

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TOPIC 2 STEADY STATE FLOW THROUGH SOIL

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  1. TOPIC 2 STEADY STATE FLOW THROUGH SOIL Course : S0705 – Soil Mechanic Year : 2008

  2. CONTENT • PERMEABILITY / CAPILARITY (SESSION 7 : F2F) • SEEPAGE (SESSION 8 : F2F) • FLOW NET / JARINGAN ALIRAN (SESSION 9 – 10 : F2F)

  3. SESSION 7PERMEABILITY / CAPILARITY

  4. INTRODUCTION • DEFINITION : THE VELOCITY OR THE CAPABILITY OF WATER/FLUDI PASS THROUGH POROUS MEDIA • NOTATION : k • UNIT : m/s, cm/s • PURPOSE : • To evaluate the seepage through dam • To evaluate the uplift force or seepage force under hydraulic structure for stability analysis • To control seepage velocity • To determine the consolidation time rate

  5. DETERMINATION OF PERMEABILITY COEFFICIENT • LABORATORY • CONSTANT HEAD (TINGGI KONSTAN) • FALLING HEAD (TINGGI JATUH) • FIELD • UNCONFINED AQUIFER (AKIFER BEBAS) • CONFINED AQUIFER (AKIFER TERKEKANG ) • INCONSTANT WATER HEIGHT (TINGGI AIR TIDAK TETAP)

  6. CONSTANT HEAD (TINGGI KONSTAN) • SUITABLE FOR SANDY SOIL, SAND OR GRAVEL WHICH HAVE BIG VOID RATIO VALUE • BASIC EQUATION :

  7. FALLING HEAD (TINGGI JATUH) • MORE ECONOMICAL FOR LONG TERM TEST • BASIC EQUATION :

  8. UNCONFINED AQUIFER (AKIFER BEBAS)

  9. UNCONFINED AQUIFER (AKIFER BEBAS) Q

  10. CONFINED AQUIFER (AKIFER TERKEKANG )

  11. CONFINED AQUIFER (AKIFER TERKEKANG )

  12. INCONSTANT WATER HEIGHT (TINGGI AIR TIDAK TETAP) 2r y L y

  13. RANGE OF k VALUE Cm/s

  14. RANGE OF k VALUE C is coefficient of soil roughness (published by Hazen), the value range from 40 to 150 i.e. as follow :

  15. EQUIVALENT COEFFICIENT OF PERMEABILITY OF LAYERED SOIL • Equivalent Coefficient of Vertical Permeability (kv’) • Equivalent Coefficient of Horizontal Permeability (kh’)

  16. Equivalent Coefficient of Vertical Permeability (kv’) Basic Concept • qin = qout • v constant

  17. Equivalent Coefficient of Vertical Permeability (kv’)

  18. EXAMPLE 1 q = 1 ft3/hr Question : Find the permeability coefficient of sand in ft/min

  19. EXAMPLE 1 SECTION 1 SECTION 2 TOTAL

  20. EXAMPLE 1 k = 4 ft/hour = 6,67x10-2 ft/min

  21. Section 1 Section 2 EXAMPLE 2 q • Questions : • determine h • determine q in cc/sec

  22. EXAMPLE 2 Determination of h Section 2 Section 1 h = 38.33 cm

  23. EXAMPLE 2 Determination of water flow rate or q = 0.15 cc/s

  24. SESSION 8SEEPAGE

  25. INTRODUCTION • DEFINITION VOLUME OF WATER/FLUID FLOW IN OR FLOW OUT AT A MEDIA OR CERTAIN SOIL MASS • PURPOSE • TO DETERMINE THE INFLUENCE OF SEEPAGE TO THE STABILITY OF STRUCTURE OR DAM • TO ESTIMATE THE FLOW VELOCITY AND FLOW RATE AT DEWATERING WORK

  26. WATER FLOW EQUATION • BASIC OF THEORY • DARCY LAW • BERNOULLI LAW • CONTINUITY EQUATION = constant energy

  27. WATER FLOW EQUATION Inflow water per time unit: Outflow water per time unit:

  28. CONTINUITY EQUATION WATER FLOW EQUATION qinflow = qoutflow

  29. WATER FLOW EQUATION STEADY STATE CONDITION: WATER FLOW VELOCITY :

  30. LAPLACE EQUATION WATER FLOW EQUATION HOMOGEN SOIL k constant at x,y,z direction ISOTROPY SOIL kx = ky = kz = k TWO DIMENSION

  31. WATER FLOW EQUATION • SEEPAGE SOLUTION • CLOSED FORM SOLUTION • MODEL SOLUTIONS • APPROXIMATE SOLUTIONS • NUMERICAL SOLUTIONS • GRAPHICAL SOLUTIONS  FLOW NET

  32. SESSION 9-10FLOW NET / JARINGAN ALIRAN

  33. DEFINITION Combination of 2 line group which perpendicular each other i.e. : • Flow Line A bundle of line or points which defined flow direction • Equipotential Line The position of point which have same total head

  34. FLOW NET / JARINGAN ALIRAN

  35. FLOW NET / JARINGAN ALIRAN

  36. FLOW NET / JARINGAN ALIRAN

  37. FLOW NET / JARINGAN ALIRAN

  38. FLOW NET / JARINGAN ALIRAN • GUIDANCE OF FLOW NET DRAWING • The water surface of upper stream and lower stream is equipotential line • The interface line of water and soil is equipotential line • The flow line perpendicular with equipotential line • The impermeable surface of boundary line is flow line • The shape area formed by flow line and equipotential line is square

  39. FLOW NET / JARINGAN ALIRAN

  40. FLOW NET / JARINGAN ALIRAN

  41. FLOW NET / JARINGAN ALIRAN

  42. q a b h+h h a = b FLOW NET / JARINGAN ALIRAN

  43. Sheet Piling 4,50 m 8,60 m Datum 0,5 m D C B A 6,0 m E k = 1,5 x 10-6 m/s EXAMPLE 3

  44. EXAMPLE 3

  45. EXAMPLE 3 Nd = 12 Nf = 4,3 H = 4,0 m

  46. EXAMPLE 3

  47. EXAMPLE 4 5 m 15 m 12 m k = 2,5 x 10-5 m/s

  48. EXAMPLE 4 Nd = 15 Nf = 4,7 H = 4,0 m

  49. EXAMPLE 4

  50. H h2 L h1 SEEPAGE FORCE / GAYA REMBESAN

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