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Daya Dukung (Bearing Capacity)

Tanah kuat. b atuan ( rock ). Daya Dukung (Bearing Capacity). Tanah kuat. b atuan ( rock ). P onda s i Dangkal. ~ untuk melimpahkan beban ke lapisan di bawahnya. ~ utamanya untuk tanah kuat atau beban ringan. maximum service load. ultimate capacity. safe load. Elastic.

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Daya Dukung (Bearing Capacity)

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  1. Tanah kuat batuan(rock) Daya Dukung (Bearing Capacity)

  2. Tanah kuat batuan(rock) Pondasi Dangkal ~ untuk melimpahkan beban ke lapisan di bawahnya ~ utamanya untuk tanah kuat atau beban ringan

  3. maximum service load ultimate capacity safe load Elastic maximum tolerable settlement Plastic Ultimate Limit State Plunging Failure Serviceability Limit State Footing Performance Vertical Load Vertical movement Maximum allowable load = min [safe load, max service load ]

  4. Limit States Serviceability Ultimate

  5. Allowable Safe Bearing Pressure qb = qs = f.qu / y qa < qs(settlement) F / A Ultimate Bearing Capacity qu = Ffail / A Bearing Pressure Definitions F Plan Area, A

  6. Soil Heave Foundation Failure Force Rotational Failure Resistance

  7. Pola Keruntuhan General Failure Local Shear Failure Punching Shear Failure

  8. General Failure Local Shear Failure Punching Shear Failure

  9. q Soil Failure Lines Settlement passive rigid radial shear log spiral FOUNDATION FAILURE1.Generalized Shear Failure

  10. Perhitungan Daya Dukung Untuk menghitung daya dukung dapat dilakukan dengan analisisis berdasarkan : • Data Uji Laboratorium: Teori Terzaghi Teori Meyerhof Teori Brinch Hansen Teori Vesic • Data Uji Lapangan : Plate Bearing Test Cone Penetration Test/CPT (Sondir Standard Penetration Test/SPT

  11. Aplikasi Teori Daya Dukung

  12. Daya Dukung Terzaghi Anggapan-anggapan: • Tanah homogen isotropik • Mode keruntuhan pondasi adalah adalah general shear failure • Pondasi adalah strip dengan permukaan bawah kasar • Bidang keruntuhan geser diatas permukaan tanah diabaikan • Permukaan tanah adalah horizontal • Tidak terdapat gaya horizontal, momen dan eksentrisitas • Pondasi terletak pada kedalaman D<B • Daerah elastis mempunyai sudut batas yang lurus dengan bid. horizontal

  13. Keseimbangan Gaya Keseimbangan gaya-gaya yang bekeja pada baji tanah (soil wedge) adalah: Qu.(2b).1 = - W + 2.CsinΦ + 2.Pp

  14. Strip footing

  15. Faktor Daya Dukung Tanah Menurut Terzaghi dan Berbagai NilaiNyang Berbeda

  16. Terzaghi Bearing Equation applies to strip footing Nc, Nqand Nare functions of f, and are usually given in graphical form c, f and g' refer to soil properties in the failure zone below the footing p'ois the effective overburden pressure at the founding level shear strength contribution above footing level is ignored : conservative for deeper footings qu nett = c.Nc + p'o (Nq - 1) + 0.5B'N

  17. Terzaghi Bearing Equation qu nett = c.Nc + p'o (Nq - 1) + 0.5B'N Overburden p'o = 'oD B Failure Zone (depth  2B) Soil unit weight : ' (total or effective as applicable) Generalized soil strength : c,  (drainage as applicable) Adopt weighted average values !

  18. Bearing Capacity Factors

  19. Faktor daya dukung Terzaghi

  20. Faktor daya dukung Terzaghi

  21. Faktor Daya Dukung Bearing capacity factors

  22. Rumus Umum Daya Dukung Secara umum daya dukung dapat ditulis sbb: qu = c.c Nc + q. D.Nq + .0,5  B.N dimana: c, q,  = faktor koreksi yang tergantung pada bentuk,kedalaman,kemiringan: beban, muka tanah, dasar pondasi

  23. Ng = 250 Nc Nq N g Nq = 33 Nc = 10 46o 35o 14o Faktor Daya Dukung 1000 100 Bearing Capacity Factor 10 1 0.1 0 10 20 30 40 50 Friction Angle (deg)

  24. Bearing Capacity Factors for soil cohesion, surcharge and weight • functions of friction angle, f • determine by equation or from graph • Correction factors for footing shape (s), footing depth (d) and load inclination (i ). • determine from appropriate equations f Df c B soil density, g, (kN/m3) Persamaan Daya Dukung Meyerhof qu = c.Ncscdcic + q.Nqsqdqiq + 0.5gBNgsgdgig qu = c.Ncscdcic + q.Nqsqdqiq + 0.5gBNgsgdgig qu = c.Ncscdcic + q.Nqsqdqiq + 0.5gBNgsgdgig qu = c.Ncscdcic + q.Nqsqdqiq + 0.5gBNgsgdgig qu = c.Ncscdcic + q.Nqsqdqiq + 0.5gBNgsgdgig qu = c.Ncscdcic + q.Nqsqdqiq + 0.5gBNgsgdgig qu = c.Ncscdcic + q.Nqsqdqiq + 0.5gBNgsgdgig q = g.Df

  25. Faktor daya dukung Meyerhof

  26. Faktor daya dukung Hansen

  27. Faktor daya dukung Vesic

  28. Pengaruh Muka air

  29. M P P e Pondasi dengan Beban Momen e = M P ekivalen eksentrisitas beban

  30. 2e L' = L- 2e Cara Meyerhof menentukan eksentrisitas beban L e B P

  31. L 2e2 e1 B e2 B' = B- 2e2 2e1 L' = L- 2e1 Eksentrisitas 2 arah P

  32. Daya Dukung Berdasar Data Uji Lapangan (In Situ Test) • Plate Bearing Test (Uji Pembebanan Pelat) • Standard Penetration Test (SPT) • Cone Penetration Test/CPT (Sondir)

  33. Plate Load Tests

  34. Plate Bearing Test(Uji Pembebanan Pelat) • Tanah dengan kekuatan konstan B < 4 Bp • Tanah Dengan Kekuatan Meningkat Secara Linear Thd Kedalaman B < 4 Bp • Ekstrapolasi Hasil Uji Penurunan Terzaghi & Peck.

  35. Standard Penetration Test (SPT) • PONDASI TELAPAK (FOOTING) MEYERHOF (1956,1974) Dimana : qa,1 = daya dukung ijin utk penurunan 1 inchi Kd = 1+0,33 D/B≤1,33 Nn = SPT yang dikoreksi F = faktor tergantung energi pukulan SPT • PONDASI PELAT (MAT/RAFT)

  36. Cone Penetration Test/CPT (Sondir) SCHMERTMANN (1978) • DAYA DUKUNG BATAS PADA TANAH NON KOHESIF MENERUS : qu = 28 – 0,0052(300-qc)1,5 BUJUR SANGKAR : qu = 48 – 0,0090(300-qc)1,5 • DAYA DUKUNG BATAS PADA TANAH KOHESIF MENERUS : qu = 2 + 0,28 qc BUJUR SANGKAR : qu = 5 + 0,34 qc qu dan qc dalam tsf atau kg/cm2

  37. Belajar Jangan tunggu sampai menit terakhir.

  38. Exams My mama always said, “Exam is like a box of chocolates; you never know what you are gonna get”

  39. TERIMA KASIH

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