# PERMEABILITAS Yulvi Zaika.

## Presentasi berjudul: "PERMEABILITAS Yulvi Zaika."— Transcript presentasi:

PERMEABILITAS Yulvi Zaika

SIKLUS HIDROLOGI

Muka Air Tanah

AQUIFER

Dari mana datangnya air tanah

Kemana air tanah mengalir?

Interaksi air tanah dan air permukaan

Aliran Shallow, unconfined aquifers often follow the same flow patterns as the watershed above them, as seen in the illustration at right. Deeper, confined aquifers may be part of a different flow system.

Bagaimana mengeluarkan air tanah?

UKURAN BUTIRAN TANAH

Porositas

TANAH

BATUAN

Permeabilitas Kemampuan air mengalir melewati tanah

KOEFISIEN PERMEABILITAS
Soil Permeability Coefficient, k (cm/sec) Relative Permeability Coarse gravel >10-1 High Sand, clean Medium Sand, dirty Low Silt Very Low Clay <10-7 Impervious

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

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

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

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 A Soil B Porous Stone Porous Stone L

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 A Soil B ZA Porous Stone Porous Stone ZB L Datum

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

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

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

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 Pore Water Pressure Effective Stress Total Stress Pore Water Pressure Effective Stress Buoyancy Ws u1 = s1 = s1 = u2 = s2 = s2 = s3 = u3 = s3 = s4 = u4 = s4 = s5 = u5 = s5 =

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

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

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

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 Total Stress Pore Water Pressure Effective Stress Buoyancy - Seepage Force Ws Seepage Force Total Stress Pore Water Pressure Effective Stress

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

PERCOBAAN LABORATORIUM
Figure 1 is a sketch of the apparatus used to determine the coefficient of permeability in the laboratory. The soil sample should be as close to un- disturbed as possible. While performing the test, one has to maintain a constant water level at the top by adding water at a rate of q for some time interval of t. Then and Q is the volume of water collected in time t from the outlet.  The cross- sectional area of the specimen is indicated by A.

PERCOBAAN LAPANGAN