MEKANIKA TANAH 1 PERTEMUAN III Determination of Permeabilty

MEKANIKA TANAH 1 PERTEMUAN III Determination of Permeabilty Coefficient Oleh : Arwan Apriyono PROGRAM STUDI TEKNIK SIPIL JURUSAN TEKNIK FAKULTAS SAINS DAN TEKNIK UNSOED TAHUN 2010

Introduction � 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)

Lab Test CONSTANT HEAD (TINGGI KONSTAN) � SUITABLE FOR SANDY SOIL, SAND OR GRAVEL WHICH HAVE BIG VOID RATIO VALUE � BASIC EQUATION : Bina Nusantara

Lab Test FALLING HEAD (TINGGI JATUH) � MORE ECONOMICAL FOR LONG TERM TEST � Suitable For Clayed Soil that have low k � BASIC EQUATION : Bina Nusantara

Field Test UNCONFINED AQUIFER (AKIFER BEBAS)

Field Test CONFINED AQUIFER (AKIFER TERKEKANG )

Layered Soil

Example � A pumping test was performed in a well penetrating a confined aquifer to evaluate the coefficient of permeability of the soil in the aquifer. � When equilibrium flow was reached, the following data were obtained: � Equilibrium discharge of water from the well = 200 gal/min. � Water levels (h 1 and h 2) = 15 and 19 ft at distances from the well (r 1 and r 2) of 60 and 180 ft, respectively. � Thickness of aquifer = 20 ft � Coefficient of permeability of the soil in the aquifer?

Example � A nonhomogeneous soil consisting of layers of soil with different permeabilities. � Average coefficient of permeability in the horizontal direction and vertical direction 1. 5 m Kx = 1. 2 x 10 -3 cm/s Ky = 2. 4 x 10 -4 cm/s 2. 0 m Kx = 2. 8 x 10 -4 cm/s Ky = 3. 1 x 10 -5 cm/s 2. 5 m Kx = 5. 5 x 10 -5 cm/s Ky = 4. 7 x 10 -6 cm/s

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