Pa2 = 1/2 Ka* γ’ * H1^2 = 1/2 x 1/3 x (20 – 10) x 2^2 = 20/3 kN
Pa3 = 1/2 * γ air * H1^2 = 1/2 x 10 x 2^2 = 20 kN
Pp = 1/2 * γ * Kp * H2^2 = 1/2 * 20 * 3 * 0.3^2 = 2.7 kN
Jarak beban terhadap titik putar asumsi, o,
Y1 = 1/2 * H1 = 1/2 x 2 = 1 m
Y2 = Y3 = 1/3 * H1 = 1/3 x 2 = 2/3 m
Yp = 1/3 * H2 = 1/3 x 0.3 = 0.1 m
Momen terhadap ujung dinding penahan, o,
Mp1 = Pa1 * Y1 = 20/3 x 1 = 6.67 kNm →
Mp2 = Pa2 * Y2 = 20/3 x 2/3 = 4.45 kNm →
Mp3 = Pa3 * Y3 = 20 x 2/3 = 13.33 kNm →
Mpp =Pp * Yp = 2.7 x 0.1 = 0.27 kNm ←
ΣPa = 33.33 kN ΣMp (1-3) = 24.45 kNm
[ΣMb / ΣMp] ≥ 1.5 (Safety factor)
[31.50 / 24.45] = 1.29 < 1.5 … ( Penampang dinding penahan tanah harus diperbesar)
Baca juga: Pekerjaan Pondasi Batu Kali Lengkap Dengan Gambar
Revisi Ukuran Dinding dengan merubah b1=
Berat dinding (gunakan berat jenis, γb = 25 kN/m3)
W1 = b1 * H1 * γb = 0.8 x 2.0 x 25 x 1 m= 40 kN
W2 = 1/2 * b1 * H1 * γb =1/2 x 0.6 x 2.0 x 25 x 1 m = 15 kN
Jarak beban terhadap titik putar asumsi, o,
