Nama: Shema LestariKelas: SI-3BMata Kuliah: Mekanika Tanah

3. Dinding penahan tanah, tinggi H = 5,0 m dibelakang dinding ditimbun dengan bahan pasir = 20 kN/m3, = 30,c = 0 kN/m2 dan diatas permukaan timbunan bekerja beban lajur (Strip Load) q = 4 t/m berjarak m1 = 3 m dari permukaan dinding belakang dan panjang beban lajur m2 = 4 m. untuk lebih jelasnya lihat gambar dibawah.Diminta gambarkan garis distribusi tekanan, resultan dan letak resultan pada sisi dinding tembok belakang.

Penyelesaian:

BEBAN LAJUR (STRIP LOAD)

m1 = 3 mm2 = 4 m q 4 t/m2

Bahan urug pasir P1 = 20 kN/m3 + P2H = 5 m

= 30oPa P3 C = 0 kN/m2 P4Ya P5 ka H

Perhitungan tekanan tanah akibat timbunan dibelakang dindingk = = 0.333P = = = 8.3250y = = x 5 = 1.667

z (m) (KN/m)k (KN/m)

0200.3330.000

1200.3336.667

2200.33313.333

3200.33320.000

4200.33326.667

5200.33333.333

Perhitungan tekanan tanah beban lajur (strip load) setiap interval z = 1 mUntuk z = 1 m== tan( )= 71.565= 1.249 rad== tan= 81.870= 1.429 rad= = = 78.6901 = 1.373 rad= - = 10.305= 0.180 rad= ( sin cos 2)

= (0.180 (sin 0.180 x cos (2x1.373)) = 0.878 rad

Tabel:Perhitungan tekanan tanah akibat beban jalur (strip load) setiap interval z =1m

zHqmm

(m)(m)(t/m)(m)(m)(rad)(rad)(rad)(rad)t/m

054340.0000.0000.0000.0000.000

154341.2491.4290.1801.3730.878

254340.9831.2920.3101.1901.351

354340.7851.1660.3811.0301.414

454340.6441.0520.4080.8961.261

554340.5400.9510.4100.7851.044

JUMLAH5.949

Perhitungan tekanan total dan jaraknya dari dasar akibat beban jalur= == 30.964= = = 54.462Pt= = = 5.222 t/mR1 = ( m1 + m2 )2 ( 90 - ) = ( 3 + 4 )2 ( 90 - 54.462) = 1741.362R2 = (m1 )2 ( 90 - ) = (3)2 ( 90 - 30.964) = 531.324Z = Z = Z = 2.227 m

Perhitungan komponen tekanan tanah akibat beban lajurP1 = = 0.439 t y1 = 4 += 4.333 mP2 = = 1.1145 t y2 = 3 + = 3.465 mP3 = = 1.3825 t y3 = 2 + = 2.496 mP4 = = 1.3375 t y4 = 1 + = 1.490 mP5 = = 1.1525 t y5 = = 0.484 m

RT = P1+P2+P3+P4+P5+PA = 0.439 + 1.1145 + 1.3825 + 1.3375 + 1.1525 + 8.3250 = 13.751 tYt = = Yt = 1.865 m

H=5mR= 13,751 t/my