contoh perhitungan standar geotekstil untuk perkuatan timbunan

SLOPE REINFORCEMENT USING G EOSYNTHETIC STANDAR BINA MARGA NO. 003/BM/2009 1 Soil fill parameters, parameters, load and geosynthetic geosynthetic material material ɣ soil fill 12.3 12.3 kN/m3 kN/m3 ɸ 23 c' 4.2 kN/m2

2 Checking slope stability without reinforcement

Traffic Load Ka q H FS Radius of slip No. Irisan n 1 2 3 4 5 6 total

0.44 10 7

kN/m2 m

0.68 19

m

(1)

(2)

c'

ɸ

ɣ soil fill

Wn

αn

(kN/m2)

( )

o

(kN/m3)

(kN/m) 11.8 31.9 46.5 39.3 24.6 8.3

( ) 59 53 48 44 39 36

4.2

23

12.3

(3)

(4)

s in αn co s α n ta n α n

o

0.86 0.80 0.74 0.69 0.63 0.59

0.52 0.60 0.67 0.72 0.78 0.81

1.66 1.33 1.11 0.97 0.81 0.73

(5) bn

h

(m) 2.1 1.8 1.6 1.4 1.3 1.3

(m) 1.8 3.2 4.4 5.4 6.2 7.0

c'bn

(6) (7) Wn sin Wn tan ɸ αn

(kN/m) (kN/m) 8.7 10.1 7.4 25.4 6.6 34.6 6.0 27.3 5.6 15.5 5.5 4.9 117.8

(kN/m) 5.0 13.5 19.7 16.7 10.4 3.5

(8) qKaH cotgα

(9) ma n

(kN/m) 4.8 10.6 17.3 24.4 33.7 42.2

2.6 2.2 1.9 1.7 1.5 1.4

(10)

(11)

(5+7) (10)/(9) (kN/m) 13.7 20.9 26.3 22.7 16.1 9.0

(kN/m) 5.2 9.7 14.0 13.3 10.5 6.3 58.9

(12) L (m) 16.36 15.33 14.3 13.27 12.24 11.21

Mslide (kN.m)

Mresist (kN.m)

(1+8x12) 271.1 651.3 912.5 845.4 713.6 566.5 3960.5

(10x12) 223.5 320.0 375.9 301.1 196.7 100.8 1518.0

3 Calculating Tensile Strength needed (Ts) FKr 1.3 Fku 0.68 Mresist 1518.0 kN.m Mslide 3960.5 k N.m Height from slide center point to top fill Ts max

8.79

m

129.2 kN

Distributing tensile strength Ts max to each zone (Ts zona) Zone factor Ts zone Unit 1 (bawah) 0.5 64.6 kN 2 (tengah) 0.33 43.1 kN 3 (atas) 0.17 21.5 kN Determining tensile strength per geosynthetic layer in each zone Zona Ts zona N Ts max 1 (bawah) 64.6 2 32.3 2 (tengah) 43.1 2 21.5 3 (atas) 21.5 2 10.8 Length of geotextile needed Zona Ts max Le 3 1 (bawah) 32.3 1.5 2 2 (tengah) 21.5 1.42 1 3 (atas) 10.8 1.25

F* 0.282983 0.282983 0.282983

α 0.6 0.6 0.6

σv 96 67 39

C 2 2 2

FKpo 1.52 1.51 1.53

status OK OK OK

4 Calculation check using Schmertmann curve

Checking Ts max using Schmertmann curve H 7 q 10 ɣs 12.3 H' 7.81301 K 0.32 Ts max cek 120.133 cukup mendekati Ts max dari langkah 4

Checking Le/H value using Schmertmann curve Le/H 0.78 H L zona 1 5.75 4.5 zona 2 3.45 2.7 zona 3 1.15 0.9

5 Conclusion Geotextile Tensile Strength (Ts) used Tensile Strength needed (Ts max) Check Recommended geotextile length Length of geotextile used Height between geotextile layer

16 10.8 OK 0.9 1.25 1

kN kN m m m

(from Schmertmann curve)

11.21 m

18.88 m

8.78 m

1.03 m 1.03 m 1.03 m 1.03 m 1.03 m zona 3 (atas)

1.04 m 59°

zona 2 (tengah)

53°

Ts min 7.3 kN, L min 1,25 m 1.81 m 3.22 m 4.39 m 5.38 m 6.23 m 7.01 m Ts min 14.5 kN, L min 1,4 m

48°

Ts min 21.8 kN, L min 1,5 m

zona 1 (bawah)

44°

39° 36°