4.2.2 Perhitungan kapasitas daya dukung tiang dari hasil Standard Penetration
Test SPT
Perhitungan kapasitas daya dukung tiang pancang per lapisan dari data SPT memakai metode Meyerhoff yg diambil dari data BH-2
A. Daya dukung pondasi tiang pada tanah non kohesif Qp = 40 x N – SPT x
x A
p
400 x N – SPT
av
x A
p
N-SPT
av
= Meyerhoff
Qp = 40 x N – SPT x x A
p
400 x N – SPT
av
x A
p
= 40 x 40x 0.50.23 x 0.4
≤ 400 x 40 x 0.4
= 139.13 kN
≤ 640.000 kN Dimana :
Q
p
= Tahanan Ujung Ultimate kN A
p
= Luas Penampang Tiang Pancang m
2
N1 = Harga Rata-Rata dari Dasar ke 10D ke Atas N2 = Harga Rata-Rata dari Dasar ke 4D ke Bawah
B. Tahanan geser selimut tiang pada tanah non kohesif Q
s
= 2 x N – SPT x p x Li Q
s
= 2 x 40 x 0.8 x 0.5
= 32 kN = 3.2 Ton
Universitas Sumatera Utara
Dimana : Li = panjang lapisan tanah m
P = keliling tiang m
C. Daya dukung pondasi tiang pada tanah kohesif Q
p
= 9 x c
u
x A
p
Dimana : A
p
= luas penampang tiang m
2
C
u
= kohesi undrained kNm
2
D. Tahanan geser selimut tiang pada tanah kohesif
Q
s
= α x c
u
x p x Li
Dimana : α = kohefisien adhesi antara tanah dan tiang
c
u
= kohesi undrained kNm
2
p = keliling tiang m Li = panjang lapisan tanah m
Q
ult
= Q
ult
= = 143.82 ton
Q
ijin
=
Universitas Sumatera Utara
= 143.82 3 = 47.94 ton
Tabel 4.7. Perhitungan tahanan ujung berdasarkan data SPT BM. 1
Depth Soil
N Cu
α Skin Friction
End
Q
ult
Q
ijin
Ton Bearing
m Layer
kNm
2
Local Cumm
Ton Ton
Ton 0.00
1 1
0.000 1.00
0.000 0.000
0.000 0.000
0.000 0.50
3 16.889
1.00 0.676
0.676 0.608
1.284 0.428
1.00 4
26.889 1.00
1.076 1.751
0.968 2.719
0.906 1.50
5 35.111
1.00 1.404
3.156 1.264
4.420 1.473
2.00 7
46.444 1.00
1.858 5.013
1.672 6.685
2.228 2.50
2 8
54.889 1.00
2.196 7.209
1.976 9.185
3.062 3.00
9 62.444
1.00 2.498
9.707 2.248
11.955 3.985
3.50 10
69.556 1.00
2.782 12.489
2.504 14.993
4.998 4.00
12 76.667
1.00 3.067
15.556 2.760
18.316 6.105
4.50 12
81.111 1.00
3.244 18.800
2.920 21.720
7.240 5.00
12 76.889
1.00 3.076
21.876 2.768
24.644 8.215
5.50 10
65.778 1.00
2.631 24.507
2.368 26.875
8.958 6.00
8 52.444
1.00 2.098
26.604 1.888
28.492 9.497
6.50 9
57.333 1.00
2.293 28.898
2.064 30.962
10.321 7.00
8 55.111
1.00 2.204
31.102 1.984
33.086 11.029
7.50 3
8 53.333
1.00 2.133
33.236 1.920
35.156 11.719
8.00 8
51.333 1.00
2.053 35.289
1.848 37.137
12.379 8.50
7 49.556
1.00 1.982
37.271 1.784
39.055 13.018
9.00 8
54.000 1.00
2.160 39.431
1.944 41.375
13.792 9.50
4 9
58.889 1.00
2.356 41.787
2.120 43.907
14.636 10.00
10 64.222
1.00 2.569
44.356 2.312
46.668 15.556
10.50 11
70.000 1.00
2.800 47.156
2.520 49.676
16.559 11.00
12 76.667
1.00 3.067
50.222 2.760
52.982 17.661
11.50 13
83.333 1.00
3.333 53.556
3.000 56.556
18.852 12.00
5 14
- -
1.093 54.649
5.467 60.116
20.039 12.50
15 -
- 1.219
55.868 6.093
61.961 20.654
13.00 16
- -
1.317 57.185
6.587 63.772
21.257 13.50
18 -
- 1.448
58.633 7.240
65.873 21.958
14.00 19
- -
1.552 60.185
7.760 67.945
22.648 14.50
22 -
- 1.728
61.913 8.640
70.553 23.518
Universitas Sumatera Utara
15.00 25
- -
1.981 63.894
9.907 73.801
24.600 15.50
28 -
- 2.205
66.100 11.027
77.126 25.709
16.00 30
- -
2.435 68.534
12.173 80.708
26.903 16.50
6 33
- -
2.661 71.196
13.307 84.502
28.167 17.00
36 -
- 2.848
74.044 14.240
88.284 29.428
17.50 38
- -
3.011 77.054
15.053 92.108
30.703 18.00
39 -
- 3.136
80.190 15.680
95.870 31.957
18.50 40
- -
3.200 83.390
16.000 99.390
33.130 19.00
40 -
- 3.200
86.590 16.000
102.590 34.197
19.50 40
- -
3.200 89.790
16.000 105.790
35.263 20.00
40 -
- 3.200
92.990 16.000
108.990 36.330
20.50
7 40
- -
3.200 96.190
16.000 112.190
37.397 21.00
40 -
- 3.200
99.390 16.000
115.390 38.463
21.50 40
- -
3.200 102.590
16.000 118.590
39.530 22.00
40 -
- 3.200
105.790 16.000
121.790 40.597
22.50 40
- -
3.200 108.990
16.000 124.990
41.663 23.00
40 -
- 3.200
112.190 16.000
128.190 42.730
23.50 40
- -
3.200 115.390
16.000 131.390
43.797 24.00
40 -
- 3.200
118.590 16.000
134.590 44.863
24.50 40
- -
3.200 121.790
16.000 137.790
45.930
Tabel 4.8. Perhitungan tahanan ujung berdasarkan data SPT BM. 2
Depth Soil
N Cu
α Skin Friction
End
Q
ult
Q
ijin
Ton Bearing
m Layer
kNm
2
Local Cumm
Ton Ton
Ton 0.00
1 1
0.000 1.00
0.000 0.000
0.000 0.000
0.000 0.50
6 41.333
1.00 1.653
1.653 1.488
3.141 1.047
1.00 8
55.778 1.00
2.231 3.884
2.008 5.892
1.964 1.50
12 77.111
1.00 3.084
6.969 2.776
9.745 3.248
2.00
2 16
105.111 1.00
4.204 11.173
3.784 14.957
4.986 2.50
19 126.667
1.00 5.067
16.240 4.560
20.800 6.933
3.00 22
144.444 1.00
5.778 22.018
5.200 27.218
9.073 3.50
25 167.556
1.00 6.702
28.720 6.032
34.752 11.584
4.00 28
184.667 1.00
7.387 36.107
6.648 42.755
14.252 4.50
31 209.778
1.00 8.391
44.498 7.552
52.050 17.350
5.00 38
251.556 1.00
10.062 54.560
9.056 63.616
21.205 5.50
40 266.667
1.00 10.667
65.227 9.600
74.827 24.942
Universitas Sumatera Utara
6.00 3
40 -
- 3.200
68.427 13.913
82.340 27.447
6.50 40
- -
3.200 71.627
13.913 85.540
28.513 7.00
40 -
- 3.200
74.827 13.913
88.740 29.580
7.50
4 40
- -
3.224 78.051
14.017 92.068
30.689 8.00
33 -
- 2.653
80.704 11.536
92.240 30.747
8.50 27
- -
2.139 82.843
9.299 92.141
30.714 9.00
25 -
- 2.029
84.872 8.823
93.695 31.232
9.50 24
- -
1.944 86.816
8.452 95.268
31.756 10.00
24 -
- 1.923
88.739 8.359
97.098 32.366
10.50 24
- -
1.928 90.667
8.383 99.049
33.016 11.00
24 -
- 1.896
92.563 8.243
100.806 33.602
11.50 23
- -
1.848 94.411
8.035 102.445
34.148 12.00
22 -
- 1.776
96.187 7.722
103.908 34.636
12.50 22
- -
1.755 97.941
7.629 105.570
35.190 13.00
26 -
- 2.053
99.995 8.928
108.922 36.307
13.50 29
- -
2.285 102.280
9.936 112.216
37.405 14.00
31 -
- 2.485
104.765 10.806
115.571 38.524
14.50 34
- -
2.741 107.507
11.919 119.426
39.809 15.00
40 -
- 3.200
110.707 13.913
124.620 41.540
15.50
5 40
- -
3.200 113.907
13.913 127.820
42.607 16.00
40 -
- 3.200
117.107 13.913
131.020 43.673
16.50 40
- -
3.200 120.307
13.913 134.220
44.740 17.00
40 -
- 3.200
123.507 13.913
137.420 45.807
17.50 40
- -
3.200 126.707
13.913 140.620
46.873 18.00
40 -
- 3.200
129.907 13.913
143.820 47.940
18.50 40
- -
3.200 133.107
13.913 147.020
49.007 19.00
40 -
- 3.200
136.307 13.913
150.220 50.073
19.50 40
- -
3.200 139.507
13.913 153.420
51.140 20.00
40 -
- 3.200
142.707 13.913
156.620 52.207
4.2.3 Perhitungan kapasitas daya dukung tiang pada saat pemancangan berdasarkan bacaan manometer
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