MEKANIKA TANAH 1
description
Transcript of MEKANIKA TANAH 1
MEKANIKA TANAH 1PERTEMUAN III
Determination of Permeabilty Coefficient
Oleh :Arwan Apriyono
PROGRAM STUDI TEKNIK SIPIL JURUSAN TEKNIK FAKULTAS SAINS DAN TEKNIK UNSOED
TAHUN 2010
Introduction
LABORATORYCONSTANT HEAD (TINGGI KONSTAN)FALLING HEAD (TINGGI JATUH)
FIELDUNCONFINED AQUIFER (AKIFER BEBAS)CONFINED AQUIFER (AKIFER TERKEKANG )INCONSTANT WATER HEIGHT (TINGGI AIR
TIDAK TETAP)
Bina Nusantara
SUITABLE FOR SANDY SOIL, SAND OR GRAVEL WHICH HAVE BIG VOID RATIO VALUE
BASIC EQUATION :
A.h.tQ.Lk
.tLhk. A. A.(k.i).t A.v.t Q
Lab Test
CONSTANT HEAD (TINGGI KONSTAN)
Bina Nusantara
Lab Test
FALLING HEAD (TINGGI JATUH) MORE ECONOMICAL FOR LONG TERM TEST Suitable For Clayed Soil that have low k BASIC EQUATION :
LhkA
dtdha
qqLhkAikAq
dtdhaq
keluarmasuk
keluar
masuk
..-
....
-
dtdh-v
Field Test
UNCONFINED AQUIFER (AKIFER BEBAS)
Field Test
2122
1
2
1
2
21
22
.
ln.
ln
.....2..
hhrrQ
k
rrhhkhr
drdhkQ
UNCONFINED AQUIFER (AKIFER BEBAS)
Field Test
CONFINED AQUIFER (AKIFER TERKEKANG )
Field Test
CONFINED AQUIFER (AKIFER TERKEKANG )
21o
2
1
hh.h..2rrlog.Q.3,2
k
Layered Soil
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 (h1 and h2) = 15 and 19 ft at distances
from the well (r1 and r2) of 60 and 180 ft, respectively. Thickness of aquifer = 20 ft
Coefficient of permeability of the soil in the aquifer?
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
2.0 m
2.5 m
Kx = 1.2 x 10-3 cm/sKy = 2.4 x 10-4 cm/s
Kx = 2.8 x 10-4 cm/sKy = 3.1 x 10-5 cm/s
Kx = 5.5 x 10-5 cm/sKy = 4.7 x 10-6 cm/s
Example
13