PENGERTIAN TENTANG TANAH
• UKURAN PARTIKEL
BERUKURAN BESAR : quartz , feldspar
BERUKURAN SANGAT LEMBUT : clay minerals
KLASIFIKASI YANG DIDASARKAN
TEKSTUR / UKURAN DAN
PERMUKAAN BUTIRAN
• UKURAN PARTIKEL BIASANYA DIKAITKAN
DENGAN KANDUNGAN MINERALNYA, CONTOH
DENGAN KANDUNGAN MINERALNYA, CONTOH
Ukuran partikel kecil, biasanya mengandung
BEBERAPA STANDART KLASIFIKASI TANAH
• UNITED STATE DEPARTEMENT of AGRICULTURE
(USDA)
• AMERICAN ASOSIATION of STATE HIGWAY and
TRANSPORTATION OFFICIAL ( AASHTO )
TRANSPORTATION OFFICIAL ( AASHTO )
PROSEDUR ANALISA UKURAN
BUTIR
• Analisa dengan ayakan dipakai untuk ukuran partikel
> 75
µ
m
• Analisa Hydrometer dipakai untuk butiran lembut
Yakni analisa yang didasarkan Hukum Stoke’s , dimana
kecepatan mengendap butiran dianggap proporsional terhadap
diameter butiran
KURVA UKURAN BUTIR
2 0
4 0
6 0
8 0
1 0 0
%
F
in
e
r
0 .0 0 0 1
0 .0 0 1
0 .0 1
0 .1
1
1 0
1 0 0
0
2 0
P a r ti c l e s i ze ( m m )
W
Well graded
U
Uniform
P
Poorly graded
C
Well graded with some clay
•
CONTOH 1
•
TANAH A TERDIRI DARI ;
•
PASIR ; 30 %
•
LANAU ; 30 %
•
LEMPUNG ; 40 % ( BUTIRAN < 0,002 mm )
•
Plotkan dalam grafik ; Jenis tanah LEMPUNG TANAH LIAT
•
CONTOH 2
•
TANAH A TSB MENGANDUNG KERIKIL 20 % DAN
•
TANAH A TSB MENGANDUNG KERIKIL 20 % DAN
PASIR 10 %
MAKA HARUS DIADAKAN KOREKSI
%
50
20
100
100
40
;
%
5
,
37
20
100
100
30
;
%
5
,
12
20
100
100
10
;
=
−
=
−
=
−
x
Lempung
x
Lanau
x
Pasir
GRUP INDEX
• GI = (F-35)[0,2+0,005(LL-40)]
•
+ 0,01(F-15)(PI-10)
• F = persentase butir lolos ayakan no 200
• LL = batas cair ( Liquid Limit )
USDA
• PASIR 2 S/D 0,05 mm
• LANAU 0,05 S/D 0,002 mm
• LEMPUNG < 0,002 mm
CONTOH
• USDA HANYA MENGKLASIFIKASI BUTIR LOLOS NO 10
• JIKA ADA KANDUNGAN LEBIH BESAR , DIKOREKSI
• Tanah B dengan komposisi sbb
:
• 20 % kerikil, 10 % pasir, 30 % lanau 40 % lempung
••
• Pasir = ( 10 x 100 ) / ( 100 – 20 ) = 12,5 %
• Lanau = ( 30 x 100 ) / ( 100 – 20 ) = 37,5 %
• Lempung = ( 40 x 100 ) / ( 100 – 20 ) = 50,0 %
Atterberg Limits
• Analisa ukuran butir kurang cocok
• Analisa ukuran butir kurang cocok
Atterberg Limits
0
10
20
30
40
50
V
o
lu
m
e
Hubungan antara Kadar Air vs Volume
0
0
50
100
Moisture Content (%)
LL
Atterberg Limits
• Analisa saringan tidak bisa diterapkan
pada tanah berbutir lembut
10
20
30
40
50
V
o
lu
m
e
Kadar air >< volume saat proses pengeringan SL
-Shrinkage Limit
•
PL - Plastic Limit
•
LL - Liquid limit
0
0
50
100
Moisture Content (%)
LL
SL PL
Atterberg Limits
SL - Shrinkage Limit
PL - Plastic Limit
LL - Liquid limit
Moisture content
=
mass of water
Plasticity Index = LL - PL = PI or I
p
Moisture content
mass of water
mass of solids
=
BEBERAPA CONTOH
KLASIFIKASI TANAH
STANDART AAHSO
• 1. Well graded sand or gravel: may include
fines
• 2. Sands and Gravels with excess fines
• 3. Fine sands
• 4. Low compressibility silts
• 5. High compressibility silts
• 6. Low to medium compressibility clays
• 7. High compressibility clays
Unified Soil Classification
• SETIAP JENIS TANAH DIBERI TANDA DUA
• SETIAP JENIS TANAH DIBERI TANDA DUA
Unified Soil Classification
• Jenis tanah ditandai dengan dua huruf (contoh. SW).
• Prosedurnya sbb :
• Coarse grained (>50% lebih besar 75
µ
m)
• Huruf S jika > 50% butiran kasar adalah pasir
• Huruf G jika > 50% butiran kasar adalah Gravel
• Suffix tergantung prosentase kandungan butir halus
• Jika % butir halus < 5% suffix nya W atau P
• Jika % butir halus > 12% suffix nya M atau C
Unified Soil Classification
Untuk menentukan jenis W atau P, hitung C
u
dan C
c
C
D
D
u
=
6 0
1 0
C
D
D
D
c
=
×
30
2
60
10
(
)
X % dari tanah berukuran lebih kecil
dari Dx
Contoh ; D10 adalah berapa ukuran
terbesar butiran , dimana prosentase
terbesar butiran , dimana prosentase
yang lolos saringan sebesar 10 %
Cu = Koefisien keseragaman
Unified Soil Classification
2 0
4 0
6 0
8 0
1 0 0
%
F
in
e
r
0 . 0 0 0 1
0 . 0 0 1
0 . 0 1
0 . 1
1
1 0
1 0 0
0
2 0
P a r t i c l e s i z e ( m m )
D
90
= 3 mm
Unified Soil Classification
C
D
D
u
=
6 0
1 0
C
D
D
D
c
=
×
30
2
60
10
(
)
If prefix is G then suffix is W if C
u
> 4 and C
c
is between 1
and 3 otherwise use P
If prefix is S then suffix is W if C
u
> 6 and C
c
is between 1 and
3 otherwise use P
Unified Soil Classification
40
50
60
in
d
e
x
CH
"A
" l
in
e
Comparing soils at equal liquid limit
Toughness and dry strength increase
with increasing plasticity index
Coarse grained soils
To determine M or C use plasticity chart
0
10
20
30
40
50
60
70
80
90
100
Liquid limit
0
10
20
30
P
la
st
ic
it
y
OH
or
MH
CL
OL
ML
or
CL
ML
Plasticity chart
for laboratory classification of fine grained soils
Below A-line use suffix M - Silt
Above A-line use suffix C - Clay
Unified Soil Classification
– Tanah berbutir halus (> 50% lebih kecil 75
µ
m)
– Kedua huruf ditentukan dari plasticity chart
40
50
60
n
d
ex
CH
"A
" l
in
e
Comparing soils at equal liquid limit
Toughness and dry strength increase
with increasing plasticity index
0
10
20
30
40
50
60
70
80
90
100
Liquid limit
0
10
20
30
P
la
st
ic
it
y
in
CH
OH
or
MH
CL
OL
ML
or
CL
ML
Plasticity chart
Give typical names: indicate ap-proximate percentages of sand and gravel: maximum size: angularity, surface condition, and hardness of the coarse grains: local or geological name and other pertinent descriptive information and symbol in parentheses.
For undisturbed soils add infor-mation on stratification, degree of compactness, cementation, moisture conditions and drain-age characteristics. Example: Well graded gravels,
gravel-sand mixtures, little or no fines
Poorly graded gravels, gravel-sand mixtures, little or no fines
Silty gravels, poorly
graded gravel-sand-silt mixtures Clayey gravels, poorly graded gravel-sand-clay mixtures Well graded sands, gravelly sands, little or no fines Poorly graded sands, gravelly sands, little or no fines Silty sands, poorly graded sand-silt mixtures Clayey sands, poorly graded sand-clay mixtures GW GP GM GC SW SP SM SC Wide range of grain size and substantial amounts of all intermediate particle sizes
Predominantly one size or a range of sizes with some intermediate sizes missing
Non-plastic fines (for identification procedures see ML below) Plastic fines (for identification pro-cedures see CL below)
Wide range in grain sizes and sub-stantial amounts of all intermediate particle sizes
Predominantely one size or a range of sizes with some intermediate sizes missing Non-plastic fines (for identification pro-cedures, see ML below)
Plastic fines (for identification pro-cedures, see CL below)
Field identification procedures
(Excluding particles larger than 75mm and basing fractions on estimated weights)
Group symbols
1
Typical names Information required for
describing soils Laboratory classification criteria C =D Greater than 4 D ----60 10 U C = (D ) Between 1 and 3 D x D ---30 10 c 2 60
Not meeting all gradation requirements for GW Atterberg limits below
"A" line or PI less than 4 Atterberg limits above "A" line with PI greater than 7
Above "A" line with PI between 4 and 7 are borderline cases requiring use of dual symbols
Not meeting all gradation requirements for SW
C =D Greater than 6 D ----60 10 U C = (D ) Between 1 and 3 D x D ---30 10 c 2 60
Atterberg limits below "A" line or PI less than 4 Atterberg limits above "A"
Above "A" line with PI between 4 and 7 are borderline cases requiring use of dual
e te rm in e p er ce n ta g e s o f g ra v el an d sa n d fr o m g ra in si ze cu rv e th e fr ac ti o n s a s g iv e n u n d e r fi e ld id en ti fi ca ti o n e p en d in g o n p er ce n ta g es o f fi n e s (f ra ct io n sm al le r th an .0 7 5 m m ev e si ze ) co a rs e g ra in e d so il s ar e c la ss if ie d as fo ll o w s ss th an 5 % o re th an 1 2 % % to 1 2 % G W , G P, S W , S P G M , G C , S M , S C B o rd el in e ca se re q u ir in g u se o f d u al sy m b o ls sm al le st p ar ti cl e v is ib le to th e n a k ed e y e C o a rs e g ra in ed so il s M o re th a n h a lf o f m a te ri a l is la rg er th a n .0 7 5 m m si ev e si ze S a n d s M o re th a n h a lf o f c o a rs e fr a c ti o n is sm a ll er th a n 2 .3 6 m m G ra ve ls M o re th a n h a lf o f co a rs e fr a ct io n is la rg e r th a n 2 .3 6 m m S a n d s w it h fi n es a p p re ci a b le o u n t o f fi n es ) C le a n sa n d s (l it tl e o r n o fi n es ) G ra ve ls w it h fi n es (a p re c ia b le a m o u n t o f fi n es ) C le a n g ra v el s (l it tl e o r n o fi n es )
Unified soil classification (including identification and description)
Silty sand, gravelly; about 20% hard angular gravel particles 12.5mm maximum size; rounded and subangular sand grains coarse to fine, about 15% non-plastic lines with low dry strength; well compacted and moist in places; alluvial sand; sand-clay mixtures
cedures, see CL below)
ML CL,CI OL MH CH OH Pt Dry strength crushing character-istics None to slight Medium to high Slight to medium Slight to medium High to very high Medium to high
Readily identified by colour, odour spongy feel and frequently by fibrous texture Dilatency (reaction to shaking) Quick to slow None to very slow Slow Slow to none None None to very high Toughness (consistency near plastic limit) None Medium Slight Slight to medium High Slight to medium
Inorganic silts and very fine sands, rock flour, silty or clayey fine sands with slight plasticity Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays Organic silts and organic silt-clays of low plasticity inorganic silts, micaceous or dictomaceous fine sandy or silty soils, elastic silts Inorganic clays of high plasticity, fat clays Organic clays of medium to high plasticity
Peat and other highly organic soils
Give typical name; indicate degree and character of plasticity, amount and maximum size of coarse grains: colour in wet con-dition, odour if any, local or geological name, and other pert-inent descriptive information, and symbol in parentheses For undisturbed soils add infor-mation on structure, stratif-ication, consistency and undis-turbed and remoulded states, moisture and drainage conditions Example
Clayey silt, brown: slightly plastic: small percentage of fine sand: numerous vertical root holes: firm and dry in places; loess; (ML)
Atterberg limits above "A" line with PI greater than 7
requiring use of dual symbols D e U se g ra in si ze c u rv e in id en ti fy in g t D e si e L e M o 5 % T h e .0 7 5 m m si ev e si ze is a b o u t th e F in e g ra in ed so il s M o re th a n h a lf o f m a te ri a l is sm a ll er th a n .0 7 5 m m si ev e si ze S il ts a n d c la y s li q u id li m it g re a te r th a n 5 0 S il ts a n d cl a ys li q u id li m it le ss th a n 5 0 M f S (ap a m o
Identification procedure on fraction smaller than .425mm sieve size
Highly organic soils
moist in places; alluvial sand; (SM) 0 10 20 30 40 50 60 70 80 90 100 Liquid limit 0 10 20 30 40 50 60 P la st ic it y in d e x CH OH or MH OL ML or CL "A" l ine
Comparing soils at equal liquid limit Toughness and dry strength increase with increasing plasticity index
Plasticity chart
for laboratory classification of fine grained soils CI
CL-ML
