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

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Presentasi berjudul: "SIVA 1 Daya Dukung (Bearing Capacity) batuan (rock) Tanah kuat."— Transcript presentasi:

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2 SIVA 1 Daya Dukung (Bearing Capacity) batuan (rock) Tanah kuat

3 SIVA Copyright  2001 2 batuan (rock) Tanah kuat Pondasi Dangkal ~ untuk melimpahkan beban ke lapisan di bawahnya ~ utamanya untuk tanah kuat atau beban ringan

4 SIVA Copyright  2001 Footing Performance Vertical Load Vertical movement Elastic Plastic PlungingFailure Serviceability Limit State maximum tolerable settlement maximum service load ultimatecapacity safe load Ultimate Limit State Maximum allowable load = min [safe load, max service load ]

5 SIVA Copyright  2001 4 Limit States ServiceabilityServiceabilityUltimateUltimate

6 SIVA Copyright  2001 Bearing Pressure Definitions FF Plan Area, A Bearing Pressure qb =qb =qb =qb = F / A Ultimate Bearing Capacity qu =qu =qu =qu = F fail / A Safe q s = .q u /  Allowable q a < q s (settlement)

7 SIVA Copyright  2001 Foundation Failure Force Rotational Failure Soil Heave Resistance

8 SIVA Copyright  2001 7 Pola Keruntuhan General Failure Local Shear Failure Punching Shear Failure

9 SIVA Copyright  2001 8 General Failure Local Shear Failure Punching Shear Failure

10 SIVA Copyright  2001 FOUNDATION FAILURE 1.Generalized Shear Failure Soil Failure Lines rigid radialshearpassive log spiral Settlement q

11 SIVA Copyright  2001 2. Local Shear Failure Medium dense or firm soils minor surface heave only Settlement q

12 SIVA Copyright  2001 3. Punching Shear Failure Loose or Soft Soils No surface heave Settlement q

13 SIVA Copyright  2001 12 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

14 SIVA Copyright  2001 13 Aplikasi Teori Daya Dukung KEMIRINGAN TERZAGHIMEYERHOFHANSENVESIC BEBAN 0  MUKA TANAH 0  DASAR PONDASI 0 

15 SIVA Copyright  2001 14 Daya Dukung Terzaghi Anggapan-anggapan: 1.Tanah homogen isotropik 2.Mode keruntuhan pondasi adalah adalah general shear failure 3.Pondasi adalah strip dengan permukaan bawah kasar 4.Bidang keruntuhan geser diatas permukaan tanah diabaikan 5.Permukaan tanah adalah horizontal 6.Tidak terdapat gaya horizontal, momen dan eksentrisitas 7.Pondasi terletak pada kedalaman D { "@context": "http://schema.org", "@type": "ImageObject", "contentUrl": "http://images.slideplayer.info/10/2762843/slides/slide_15.jpg", "name": "SIVA Copyright  2001 14 Daya Dukung Terzaghi Anggapan-anggapan: 1.Tanah homogen isotropik 2.Mode keruntuhan pondasi adalah adalah general shear failure 3.Pondasi adalah strip dengan permukaan bawah kasar 4.Bidang keruntuhan geser diatas permukaan tanah diabaikan 5.Permukaan tanah adalah horizontal 6.Tidak terdapat gaya horizontal, momen dan eksentrisitas 7.Pondasi terletak pada kedalaman D

16 SIVA Copyright  2001 15 Keseimbangan Gaya Keseimbangan gaya-gaya yang bekeja pada baji tanah (soil wedge) adalah: Q u.(2b).1 = - W + 2.CsinΦ + 2.P p

17 SIVA Copyright  2001 16 Strip footing

18 SIVA Copyright  2001 17 Faktor Daya Dukung Tanah Menurut Terzaghi dan Berbagai Nilai N  yang Berbeda

19 SIVA Copyright  2001 Terzaghi Bearing Equation  applies to strip footing  N c, N q and N  are functions of , and are usually given in graphical form  c,  and  ' refer to soil properties in the failure zone below the footing  p' o is the effective overburden pressure at the founding level  shear strength contribution above footing level is ignored : conservative for deeper footings q u nett = c.N c + p' o (N q - 1) + 0.5B  'N 

20 SIVA Copyright  2001 Terzaghi Bearing Equation B q u nett = c.N c + p' o (N q - 1) + 0.5B  'N  p' o =  ' o D Generalized soil strength : c,  (drainage as applicable) Soil unit weight :  ' (total or effective as applicable) Overburden Failure Zone (depth  2B) Adopt weighted average values !

21 SIVA Copyright  2001 20 Bearing Capacity Factors

22 SIVA Copyright  2001 21 Faktor daya dukung Terzaghi

23 SIVA Copyright  2001 22 Faktor daya dukung Terzaghi

24 SIVA Copyright  2001 23 Faktor Daya Dukung Bearing capacity factors

25 SIVA Copyright  2001 24 Rumus Umum Daya Dukung Secara umum daya dukung dapat ditulis sbb: q u =  c.c N c +  q.  D.N q +  .0,5  B.N  dimana:  c,  q,   = faktor koreksi yang tergantung pada bentuk,kedalaman,kemiringan: beban, muka tanah, dasar pondasi

26 SIVA Copyright  2001 Faktor Daya Dukung 1000 100 10 1 0.1 01020304050 Bearing Capacity Factor Friction Angle (deg) Nc 14 o N c = 10 Nq 35 o N q = 33 N 46 o N  = 250

27 SIVA Copyright  2001 Persamaan Daya Dukung Meyerhof q u = c.N c s c d c i c + q.N q s q d q i q + 0.5  BN  s  d  i  c  soil density, , (kN/m 3 ) q u = c.N c s c d c i c + q.N q s q d q i q + 0.5  BN  s  d  i  B DfDfDfDf q = .D f q u = c.N c s c d c i c + q.N q s q d q i q + 0.5  BN  s  d  i  Bearing Capacity Factors for soil cohesion, surcharge and weight Bearing Capacity Factors for soil cohesion, surcharge and weight functions of friction angle,  functions of friction angle,  determine by equation or from graph determine by equation or from graph q u = c.N c s c d c i c + q.N q s q d q i q + 0.5  BN  s  d  i  Correction factors for footing shape (s), footing depth (d) and load inclination (i ). Correction factors for footing shape (s), footing depth (d) and load inclination (i ). determine from appropriate equations determine from appropriate equations

28 SIVA Copyright  2001 27 Faktor daya dukung Meyerhof

29 SIVA Copyright  2001 28 Faktor daya dukung Hansen

30 SIVA Copyright  2001 29 Faktor daya dukung Vesic

31 SIVA Copyright  2001 30 Pengaruh Muka air

32 SIVA Copyright  2001 Pondasi dengan Beban Momen P M e P e = M P ekivalen eksentrisitas beban

33 SIVA Copyright  2001 Cara Meyerhof menentukan eksentrisitas beban P e L 2e2e LL- 2e L' = L- 2e B

34 SIVA Copyright  2001 Eksentrisitas 2 arah P e1e1e1e1 L 2e12e12e12e1 LL- 2e 1 L' = L- 2e 1 B e2e2e2e2 2e22e22e22e2 BB- 2e 2 B' = B- 2e 2

35 SIVA Copyright  2001 34 Daya Dukung Berdasar Data Uji Lapangan (In Situ Test) Plate Bearing Test (Uji Pembebanan Pelat) Standard Penetration Test (SPT) Cone Penetration Test/CPT (Sondir)

36 SIVA Copyright  2001 35 Plate Load Tests

37 SIVA Copyright  2001 36 Plate Bearing Test (Uji Pembebanan Pelat) Tanah dengan kekuatan konstan B < 4 B p Tanah Dengan Kekuatan Meningkat Secara Linear Thd Kedalaman B < 4 B p Ekstrapolasi Hasil Uji Penurunan Terzaghi & Peck.

38 SIVA Copyright  2001 37 Standard Penetration Test (SPT) PONDASI TELAPAK (FOOTING) MEYERHOF (1956,1974) Dimana : q a,1 = daya dukung ijin utk penurunan 1 inchi K d = 1+0,33 D/B≤1,33 N n = SPT yang dikoreksi F = faktor tergantung energi pukulan SPT PONDASI PELAT (MAT/RAFT)

39 SIVA Copyright  2001 38 Cone Penetration Test/CPT (Sondir) SCHMERTMANN (1978) DAYA DUKUNG BATAS PADA TANAH NON KOHESIF MENERUS : q u = 28 – 0,0052(300-q c ) 1,5 BUJUR SANGKAR : q u = 48 – 0,0090(300-q c ) 1,5 DAYA DUKUNG BATAS PADA TANAH KOHESIF MENERUS : q u = 2 + 0,28 q c BUJUR SANGKAR : q u = 5 + 0,34 q c q u dan q c dalam tsf atau kg/cm 2

40 SIVA Copyright  2001 39 Belajar Jangan tunggu sampai menit terakhir.

41 SIVA Copyright  2001 40 Exams My mama always said, “Exam is like a box of chocolates; you never know what you are gonna get”

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