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8/10/2019 SOFT SOILS Preloading & VD (Paulus Rahardjo - Sesi 6)
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Rekayasa Tanah Lunak
PERBAIKAN TANAH LUNAK DENGAN
PRELOADING DAN VERTICAL DRAIN
Prof. PAULUS P. RAHARDJO, Ph.D Parahyangan Catholic University,Bandung – Indonesia
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Metode PreloadingTujuan : - Meningkatkan kuat geser tanah dasar
- Mengurangi sifat kemampatan tanah- Mengurangi resiko settlement dikemudian hari
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KONSEP
PRELOADING DAN VERTICAL DRAINS
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MENINGKATKAN
KUAT GESER TANAH DASAR
hGww nn
1
Gs = berat jenis tanah
= penurunan tanah permukaan
h = tebal lapisan lunak
hS
C
GwS u
c
nu
434.0
.1
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8/10/2019 SOFT SOILS Preloading & VD (Paulus Rahardjo - Sesi 6)
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Prinsip
Preloading dan Vertical Drain
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SAND DRAINS / GRAVEL DRAINS
dan PREFABRICATED VERTICAL DRAINS
8/10/2019 SOFT SOILS Preloading & VD (Paulus Rahardjo - Sesi 6)
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Alat Pemancang PVD
Metode Pemasangan Prefebricated Vertical Drain
1. MENGGELAR LAPISAN PASIR SEBAGAISAND BLANKET ALTERNATIF LAIN DENGANPREFABRICATED HORIZONTAL DRAIN
2. MEMASANG VERTICAL DRAINS (PVD)3. MELAKUKAN PENIMBUNAN DAN SURCHARG4. MEMONITOR SETTLEMENT DAN TEKANAN
AIR PORI EKSES5. MEMINDAHKAN SURCHARGE6. MELAKUKAN PERAPIHAN LAHAN SIAP
DIBANGUN
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CARA Pemasangan Prefebricated Vertical Drain
Pemasangan Sepatu Pelat
Pemancangan Mandrel
Ke Dalam Tanah
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Metode Pemasangan Prefebricated Vertical Drain
Pencabutan Mandrel
Dari Dalam Tanah
Pemotongan
Ujung Atas PVD
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Metode Pemasangan Prefebricated Vertical Drain
Sambungan Antar Ujung Rol Material PVD
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DASAR-2 UNTUK DESAIN
c
o
o
c
o
c
o
s f
p
p p
e
C
p
p
e
hC s log
1log
1
1. PERHITUNGAN SETTLEMENT KONSOLIDASI
2. PERHITUNGAN WAKTU KONSOLIDASI
s = U . Sf
3. PERANCANGAN PRELOAD DAN VERTICAL DRAINS
- tinggi preload ditentukan dari stabilitas dan ketersediaanmaterial timbunan
- kedalaman vertical drain ditentukan dari tebal lapisantanah lunak
- jarak vertical drains ditentukan dari batasan waktu
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Perhitungan derajat konsolidasi
vertikal dan radial1 – U = (1 – Uh) (1 – Uv)
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Nomogram desain
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LOKASI PROYEK DAN KONDISI GEOLOGI
Mahakam river deltaicsoils
Alluvial type withconsiderable thickness,where the soil consist ofmud deposited in afluviatile, deltaic andcoastal environtment
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HASIL PENYELIDIKAN TANAH
Void Ratios and Shear Strength
g vs Depth
0
5
10
15
20
25
30
35
40
45
50
1.00 1.50 2.00g (t/m3)
D e p t h
SC 2 SC 1
e initial vs Depth
0
5
10
15
20
25
30
35
40
45
50
0 2 3
e initial
D e p t h
SC 1 SC 2
Su vs Depth
0
5
10
15
20
25
30
35
40
45
50
0 20 40 60 80
Su (kPa)
D e p t h
S C1 S C2
Su / v' vs Depth
0
5
10
15
20
25
30
35
40
45
50
0.0 0.2 0.4 0.6 0.8
Su / v '
D e p t h
SC1 SC2
8/10/2019 SOFT SOILS Preloading & VD (Paulus Rahardjo - Sesi 6)
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HASIL PENYELIDIKAN TANAH
Water Content, Plasticity andCompressibility
wn vs Depth
0
5
10
15
20
25
30
35
40
45
50
0 50 100 150
wn (%)
D e p t h
SC1 SC2
Plastic Limit
0
10
20
30
40
50
60
0 25 50 75 100
(%)
D e p t h ( m )
SC1 SC2
Liquid Limit
0
10
20
30
40
50
60
0 50 100 150
(%)
D e p t h ( m )
SC1 SC2
Cc vs Depth
0
5
10
15
20
25
30
35
40
45
50
0.0 0.5 1.0 1.5 2.0
Cc
D e p t h
SC 1 SC 2
E50 vs Depth
0
5
10
15
20
25
30
35
40
45
50
0 20 40 60 80
E50
D e p t h
SC 1 SC 2
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Initial Condition of Site
Site Preparation and Reclamation
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MENGGELAR GEOTEKSTIL, MENGGELAR PASIR
DAN MEMASANG PVD
Reclamation Program
Soil Improvement by Geotextile,Preloading and the Use of Vertical Drains
INVESTIGASI DAN HASIL REKAMAN
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INVESTIGASI DAN HASIL REKAMAN
SP-1 - SP-24 Fill Thickness
0
1
2
3
4
5
6
0 50 100 150 200 250
Time (day)
F i l l T h i c k n e s s ( m )
SP-1 - SP-24 Settlement
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 50 100 150 200 250
Time (day)
S e t t l e m e n t ( m )
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Geotechnical Investigation Program
CPTU BEFORE ANDDURINGRECLAMATION WORKS
ill
j
i
i i j
T T 77
< -
D e p t h i n m t o
r e f e r e n c e l e v e l
0123456789
10111213141516171819202122232425
262728293031323334353637383940
0 2 4 6 8 10
SoilBehaviour Type
after Robertson,1986S l eeveresi stance, fs(M Pa) P orepressure, u2(MPa) Pore pressure ratio,Bq
0123456789
10111213141516171819202122232425
262728293031323334353637383940
0 0.05 0.1
0123456789
10111213141516171819202122232425
262728293031323334353637383940
0 0 .2 0 .4 0 .6 0 .8 1
0123456789
10111213141516171819202122232425
262728293031323334353637383940
0 1 2 3 4 5 6 7 8 9 10
0123456789
10111213141516171819202122232425
262728293031323334353637383940
0 0.2 0.4 0 .6 0.8 1 -----------
Cone resistance,qc(MPa) Friction r atio,FR(%)
0123456789
10111213141516171819202122232425
262728293031323334353637383940
(8) Sand to siltysand
(9) Sand
(3) Clays
(3) Clays
(1) Sensitive, finegrained
(1) Sensitive, finegrained
(5) Clayeysilt to siltyclay
(6) Sandysilt to clayeysilt
(6) Sandysilt to clayeysilt
(6) Sandysilt to clayeysilt(6) Sandysilt to clayeysilt
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UJI CPT-U SEBELUM DIMULAI PENIMBUNAN
fs (kg/cm2)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
0 0.5 1
SC 2 SC 1
qc (kg/cm2)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
0 10 20 30 40
SC 2 SC 1
u (kg/cm2)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
-2 0 2 4 6 8 10
SC 2 SC 1
OCR
Lunne et all, 1997
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
0 1 2
SC 2 SC 1
K0
Kulhawy and
Mayne, 1990
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
0 1 2
SC 2 SC 1
Su (kg/cm2)
Campanella et all,
1980
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
0 0 .1 0 .2 0 .3 0 .4 0 .5
SC 2 SC 1
8/10/2019 SOFT SOILS Preloading & VD (Paulus Rahardjo - Sesi 6)
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PTu were conducted during the period of waiting time before fill removal
Typical CPTu test result during reclamation
< - D e p t h i n m t o
r e f e r e n c e l e v e l
0
123456789
1011121314151617181920212223242526272829
3031323334353637383940
0 2 4 6 8 10
Soil Behaviour Type
after Robertson,1986Sleeve resistance,fs(MPa) Pore pressure,u2(MPa) Pore pressure ratio,Bq
0
123456789
1011121314151617181920212223242526272829
3031323334353637383940
0 0.05 0.1
0
123456789
1011121314151617181920212223242526272829
3031323334353637383940
0 0.2 0 .4 0 .6 0 .8 1
0
123456789
1011121314151617181920212223242526272829
3031323334353637383940
0 1 2 3 4 5 6 7 8 9 10
0
123456789
1011121314151617181920212223242526272829
3031323334353637383940
0 0.2 0 .4 0 .6 0 .8 1
Cone resistance,qc(MPa) Friction ratio,FR(%)
0123456789
1011121314
151617181920212223242526272829
3031323334353637383940
(8) Sand to silty sand
(9) Sand
(3) Clays
(3) Clays
(1) Sensitive, fine grained
(1) Sensitive, fine grained
(5) Clayey silt to silty clay
(6) Sandy silt to clayey silt
(6) Sandy silt to clayey silt
(6) Sandy silt to clayey silt(6) Sandy silt to clayey silt
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PTu were conducted during the period of waiting time before removal
Comparison of Old and New CPTu test results
The Comparison of qc Value of Soft Soil
Before and After Preload
0
10
20
30
40
50
60
0 0.5 1 1.5 2
qc (MPa)
D e p t h ( m )
CPTU SC-1 PCPT-01
The Comparison of fs Value of Soft Soil
Before and After Preload
0
10
20
30
40
50
60
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04
fs (MPa)
D e p t h ( m )
CPTU SC-1 PCPT-01
The Comparison of u2 Value o f Soft Soil
Before and After Preload
0
10
20
30
40
50
60
0 0.2 0.4 0.6 0.8 1
u2 (MPa)
D e p t h ( m )
CPTU SC-1 PCPT-01
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Determination of the degree of consolidation of Reclaimed
Site on deep soft Mahakam deltaic soils using CPTu
Higher qc and fs may be due to increased shear strength
UNDERSTANDING THE MEASUREMENT OF CPTu ON RECLAIMED SITE
Response from CPTU
qc =‘higher’ tip resistance
f s = ‘higher’ friction
u2 = ‘higher’ pore pressure
u1
u2
u3
u2
up = excess pore pressure due
to cone penetration
u = residual excess pore pressure
u0 = hydrostatic pore water pressure
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Determination of the degree of consolidation of Reclaimed
Site on deep soft Mahakam deltaic soils using CPTu
UNDERSTANDING THE MEASUREMENT OF CPTu ON RECLAIMED SITE
u1
u2
u3
u2
up = excess pore pressure due
to cone penetration
u = residual excess pore pressure
u0 = hydrostatic pore water pressure
ui
Log time
uf = u0
ui
Log time
u0
uf
ReclaimedSite
UnreclaimedSite
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Determination of the degree of consolidation of Reclaimed
Site on deep soft Mahakam deltaic soils using CPTu
UNDERSTANDING THE MEASUREMENT OF CPTu ON RECLAIMED SITE
Dissipation Curve At 9.825 m
140
160
180
200
220
240
0.01 0.1 1 10 100 1000
Time (Min.)
P o r e p r e s s u r e ( K P a )
Log time
u due to cone
penetration
u50
t50
ui
u100
uf
u50
u0
u residual excess pore
pressure
u50 = (ui-uf )/2
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Degree of Consolidation interpreted by Method ofextrapolation of dissipation test
Dissipation Curve at 8.38 m t50 = 59.95 Minute
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
1 10 100 1000 10000
Log Time (Min.)
E x c e s s P o r e W a t e r P
r e s s u r e ( M P a )
Measured Extrapolated t50 u0
Excess Pore Pressure Due
To Insertion Of CPTu Cone
Excess Pore Pressure
Due To Fill Material
Hydrostatic Pore Water Pressure
U [%] = 1-(ut/ui)
U [%] = 1-(ut/p)
p = pressures dueto fill placement
8/10/2019 SOFT SOILS Preloading & VD (Paulus Rahardjo - Sesi 6)
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ASAOKA 9.825 m, PIK
100
125
150
175
200
225
250
100110120130140150160170180190200210220230240250
ut[KPa]
u t +
t [ K P a ]
Depth = 9.82 m
u0 = 68 kPa
uf = 117 kPa
ut = 117-68 = 49 kPa
= 64.6 kPa
U = 24.54 %
Dissipation Curve At 9.825 m
140
160
180
200
220
240
0.01 0.1 1 10 100 1000
Time (Min.)
P o r e p r e s s u r e ( K
P a )
uf = 117 Kpa
EXAMPLE OFCALCULATION
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PTu were conducted during the period of waiting time before removal
Degree of Consolidation interpreted empiricalcorrelations
OCR vs Depth
0
10
20
30
40
50
60
0.00 1.00 2.00 3.00 4.00 5.00
OCR
D e p t h ( m )
SC-1
SC-2CPTu k=0.413
best fit the value of k=0.413
'.
0
0
v
vt qk OCR
Powell, 1988
k = 0.2-0.5
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CONCLUSIONSSite Characterization of the deltaic soils using CPTu is best
It is concluded that the site is homogeneous deep soft clayswith increasing strength vs depth
The CPTu conducted before and after fill placement givevery clear understanding of the soft ground response. Thechanges in strength and pore pressure are identified.
A simple technique is developed and can be used to predictthe degree of consolidation by extrapolation of thedissipation test results. In general the degree ofconsolidation of the reclaimed site achieved before removalwas 85%
Next Challenge : CAN CPTU PREDICTS
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Next Challenge : CAN CPTU PREDICTSWHEN THE MUD ERUPTIONS IN EASTJAVA WILL STOP?
THANK YOU !
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