Piling design intro
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Piling design Pile Design and Construction Rules of Thumb by Ruwan Rajapakse Chapter 1 and 3 ***pic in the slides are not my own creation but are credited, may be subjected to copyright.
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Piling design intro
- 1. Piling Design Toe Myint Naing Curtin Malaysia Intern KSI Engineering
- 2. Pile Design and Construction Rules of Thumb by Ruwan Rajapakse 2 Myanmar National Building Code 2016-Part 4
- 3. Site investigation and Soil Conditions Investigation of the site is a very important step in any geotechnical engineering project. 1. Steps 1.1 Literature survey 1.2 Site visit 1.3 Subsurface investigation program and sampling 1.4 Laboratory test program 3
- 4. Site investigation and Soil Conditions 4 1.1 Literature Survey • National Geological Surveys (The Department of Geological Survey & Mineral Exploration) • Adjacent Property Owners • Published Literature • Aerial Photographs
- 5. Site investigation and Soil Conditions Information • Groundwater information 5 ©Queeni Ou 1.1 Literature Survey
- 6. • Groundwater information • Utilities – gas and electrical utilities. • Hand Digging Prior to Drilling Site investigation and Soil Conditions 6 ©Win Htun Thant Information 1.1 Literature Survey
- 7. Site investigation and Soil Conditions 7 ©Aung Myo Min • Groundwater information • Utilities – gas and electrical utilities. • Hand Digging Prior to Drilling • Contaminants Information 1.1 Literature Survey
- 8. Site investigation and Soil Conditions 8 1.2 Site Visit Information • Surface soil characteristics 8
- 9. Site investigation and Soil Conditions Information • Surface soil characteristics • Water level in nearby streams, lakes and other surface water bodies 1.2 Site Visit 9 ©Queenie Ou
- 10. Site investigation and Soil Conditions 10 Information • Surface soil characteristics • Water level in nearby streams, lakes and other surface water bodies • Closeness to adjacent buildings 1.2 Site Visit 10
- 11. Site investigation and Soil Conditions 11 Information • Surface soil characteristics • Water level in nearby streams, lakes and other surface water bodies • Closeness to adjacent buildings • Stability of the ground surface 1.2 Site Visit 11
- 12. Site investigation and Soil Conditions 12 Information • Surface soil characteristics • Water level in nearby streams, lakes and other surface water bodies • Closeness to adjacent buildings • Stability of the ground surface • Overhead obstructions 1.2 Site Visit 12
- 13. Site investigation and Soil Conditions 13 The borehole spacing suggested by C.Q.H.P (minimum number of borings = 2 boreholes) is as follows: 1. One boring for every 2500 sq-ft (or) 250 sq-m of built-over area < 10,000 sq-ft (or) 1,000 sq-m. 2. One boring for every extra 5,000 sq-ft (or) 500 sq-m for large area projects >10,000 sqft (or) 1,000 sq-m. 3. Additional borings for irregular soil conditions. 1.3 Subsurface Investigation 13
- 14. Site investigation and Soil Conditions The following methods may be applied during the site investigation depending on the requirements of the proposed structures. 1. Open Trial Pit (Test Pits) Method 2. Auger Boring (Hand Auger Method) 3. Shell and Auger Boring 4. Wash Boring 5. Standard Penetration Test 6. Cone Penetration Test 7. Rotary Boring 8. Percussion Boring 1.3 Subsurface Investigation 14 ©Aung Myo Min
- 15. Site investigation and Soil Conditions 1.3 Subsurface Investigation 15 ©Qunnie Ou
- 16. Site investigation and Soil Conditions 16 1.3 Subsurface Investigation 16 Soil Exploration Methods Exploration Methods Direct Methods Semi Direct Methods Indirect Methods Test pits, Trial pits, Trenches Borings • Auger • Auger and shell • Wash boring • Percussion drilling • Rotary Drilling Sounding or penetration tests and geophysical methods
- 17. Site investigation and Soil Conditions 17 1.3 Subsurface Investigation 17 Test pits or trenches • Down to 15ft below the surface • Uneconomical at greater depths • Open type exploration • Soils are investigated in natural condition Fig. Excavated test pit
- 18. Site investigation and Soil Conditions 18 1.3 Subsurface Investigation 18 Soil sampling Sieve analysis • Disturbed Samples • Split spoon sampler –depth known • Auger sampler-depth unknown • SPT Atterberg limit tests Soil identification
- 19. Site investigation and Soil Conditions 19 1.3 Subsurface Investigation 19 Soil sampling • Undisturbed Samples • Thin-wall sampler (Shelby Tube)-sample taken by pushing the tube into soil and sealed to prevent moisture loss Unconfined compressive testsConsolidation test
- 20. Site investigation and Soil Conditions 1.3 Subsurface Investigation 20 Required Soil sampling
- 21. Site investigation and Soil Conditions 1.3 Subsurface Investigation 21 Complete detailed descriptions must be included on each sample bag as follows: 1. Location (GPS), Project name 2. Sample No. 3. Depth from where to where 4. Collector’s name 5. Date of sampling 6. Investigation and Sampling Method Boring Log
- 22. 1.3 Subsurface Investigation Depth of Boring Site investigation and Soil Conditions 22 CQHP suggested the following depth specifications. 1. Shallow foundations: depth =1.5 x min: (B or L) (Limit to 30ft or 10 m minimum) 2. Deep foundations: min depth = 15 𝑆0.7 (ft) or 5 𝑆0.7 (m) (Limit to 3 consecutive SPT values ≥ 50) 22
- 23. Site investigation and Soil Conditions 23 • Grain Size analysis (i) Dry – sieve analysis to 75 microns (No. 200 Sieve) (ii) Wet – sieve analysis for soil less than 75 microns (No. 200 Sieve) – Pipette method – Hydrometer analysis • Test for determination of water content and dry unit weight of soil • Test for determination of specific gravity • Test for determination of consistency of soil • Shear strength tests 23 1.4 Laboratory test program Laboratory Test
- 24. 1.4 Laboratory test program Site investigation and Soil Conditions 24 • Compaction test • California Bearing Ratio (CBR) Test • Permeability tests • Consolidation tests • Dispersibility tests • Vane shear test • Swelling pressure test • Free swell test • Linear shrinkage test Laboratory Test
- 25. 1.5 Soil Types Site investigation and Soil Conditions 2525 Soil Classification for Geotechnical Engineering
- 26. 1.5 Soil Types Site investigation and Soil Conditions 2626 Strength of soils For sand, by friction angle ( Ø )
- 27. 1.5 Soil Types Site investigation and Soil Conditions 2727 For sand, by friction angle ( Ø ) Strength of soils For clay, by cohesion ( c )
- 28. 1.5 Soil Types Site investigation and Soil Conditions 2828 Strength of soils For clay, by cohesion ( c ) For silt, frictional material behave as sands clayey silt and silty clays behave as clays For sand, by friction angle ( Ø )
- 29. Young’s elastic modulus 1.6 Design Parameters Site investigation and Soil Conditions 2929 Sandy Soils Friction angle ( Ø ) Triaxial test Most engineers use standard penetration test (SPT) on site and use correlations back to obtain the friction angle of a soil. Poisson’s ration Foundation Selection The strength of sandy soils comes mainly from friction between Particles.
- 30. 1.6 Design Parameters Site investigation and Soil Conditions 3030 Sandy Soils SPT — N (Standard Penetration Test Value) and Friction Angle
- 31. 1.6 Design Parameters Site investigation and Soil Conditions 3131 Sandy Soils SPT — N (Standard Penetration Test Value) and Friction Angle
- 32. 1.6 Design Parameters Site investigation and Soil Conditions 3232 Clay Soils The strength of clayey soils is developed through cohesion between clay particles. Friction is a mechanical process, whereas cohesion is an electrochemical process. Undisturbed samples – Shelby tube sampler Unconfined compressive testsConsolidation test
- 33. 1.6 Selection of Foundation Type Shallow Foundation Site investigation and Soil Conditions 33 • Soil below the footing is strong • Cheapest 33 Mat/raft Foundation • Building load is distributed in a large area Pile Foundation • When bearing soil is at a greater depth • Building loads are transferred to the bearing soil stratum Caissons • Simply larger piles, instead of a pile group, one large caisson can be utilized.
- 34. 1.6 Selection of Foundation Type Site investigation and Soil Conditions 3434 Foundation Selection Criteria
- 35. 1.6 Selection of Foundation Type Site investigation and Soil Conditions 3535 Foundation Selection Criteria
- 36. 1.6 Selection of Foundation Type Site investigation and Soil Conditions 3636 Foundation Selection Criteria
- 37. 2.0 Scenarios Selection of Pile Type 3737 2.1 Case 1 Granular soil with boulders underlain by medium -stiff clay. Pile type If rock layer is shallow If rock layer is deep Timber piles Pipe piles H piles Caissons
- 38. 2.0 Scenarios Selection of Pile Type 3838 2.2 Case 2 Pile ends in medium stiff clay soil rock Floating or friction pile
- 39. 2.0 Scenarios Selection of Pile Type 3939 2.3 Case 3 Pile ends in medium stiff clay with groundwater present Pile type If rock layer is shallow Timber piles Pipe piles H piles
- 41. Any Question?
Hinweis der Redaktion
- Published Literature: general information such as soil types, depth to bedrock, and depth to groundwater by conducting a literature survey on published scientific articles. Aerial Photographs: Google earth
- Hand digging the first 6 ft prior to drilling boreholes is an effective way to avoid utilities.
- Hand digging the first 6 ft prior to drilling boreholes is an effective way to avoid utilities.
- Contaminant soil
- Contaminant soil
- Contaminant soil
- Contaminant soil
- Contaminant soil
- Contaminant soil
- Contaminant soil Committee for Quality control of High-rise building construction Projects
- Contaminant soil Committee for Quality control of High-rise building construction Projects
- Contaminant soil Committee for Quality control of High-rise building construction Projects
- Contaminant soil Committee for Quality control of High-rise building construction Projects
- Contaminant soil Committee for Quality control of High-rise building construction Projects
- Atterberg limit tests – liquid limit test and plastic limit test Split spoon samples are obtained during boring construction. They are adequate for sieve analysis, soil identification, and 6 Pile Design and Construction Rules of Thumb Atterberg limit tests.
- Split spoon samples are not enough to conduct unconfined compressive tests, consolidation tests, and triaxial tests. Shelby tube samples are obtained when clay soils are encountered. Shelby tubes have a larger diameter, and Shelby tube samples can be used to conduct consolidation tests and unconfined compressive strength tests.
- Contaminant soil Committee for Quality control of High-rise building construction Projects
- Contaminant soil Committee for Quality control of High-rise building construction Projects
- Sowers (1979) suggested specified depth criteria as follows: Minimum depth of borings = 10 S0.7 (ft) or 3 S0.7 ( m) (for narrow and light buildings) Minimum depth of borings = 20 S0.7 (ft) or 6 S0.7 ( m) (for wide and heavy buildings) Where, S = the number of stories in the building The Committee for Quality control of High-rise building construction Project (CQHP) suggested the following depth specifications. 1. Shallow foundations specified depth as 1.5 times lesser dimension (B < L) (Limit to 30ft (or) 10 m minimum) 2. Deep foundations: Minimum depth of boring = 15 S0.7 (ft) or 5 S0.7 (m) (Limit to 3 consecutive SPT values ≥ 50)
- Standard Penetration Test
- CBR - for determining the Relative Bearing Ratio & expansion characteristics under known surcharge weight of base, sub-base and sub grade soils for the design of roads, payments & runways. The CBR test is used extensively in selection of materials & control of sub-grades. Permeability tests-To determine the permeability of a given soil sample using a falling or constant head permeameter. Dispersibility test-soils that are dislodged easily and rapidly in flowing water are called dispersive soils Vane shear test-shear strength and sensitivity of clay Swelling pressure test-The objective of a swelling pressure test on soil is to determine the swelling pressure of expansive soil when it is not allowed to undergo any volume change. The volume change is arrested or the soil is not allowed to swell in order to test this. Linear shrinkage test- This test covers the determination of the linear shrinkage of a disturbed soil sample. It is a tedious and expensive test that is done only on soils (other than sands) when the dispersion percentage is >50 or volume expansion tests fail to saturate or shrink. This test is performed on dispersive soils only. (sand, silt and clay)
- For geotechnical engineering purposes, soils can be classified as sands, clays, and silts.
- Standard Penetration Test
- Standard Penetration Test
- Standard Penetration Test
- The most important design parameter for sandy soils is the friction angle. The bearing capacity of shallow foundations, pile capacity, and skin friction of piles depend largely on the friction angle (). The strength of sandy soils comes mainly from friction between particles. The friction angle of a sandy soil can be obtained by conducting a triaxial test. There are correlations between friction angle and standard penetration test (SPT) values. Many engineers use SPT and friction angle correlations to obtain the friction angle of a soil. To predict the settlement of a pile or a shallow foundation, one needs to use Young’s elastic modulus and Poisson’s ratio.
- Standard Penetration Test
- Dry bulk density = mass of soil/ volume as a whole
- Cohesion of a soil is obtained by using an unconfined compressive strength test. To conduct an unconfined compressive strength test, one needs to obtain a Shelby tube sample. Settlement of clay soils depends on consolidation parameters. These parameters are obtained by conducting consolidation tests.
- Standard Penetration Test
- a shallow foundation, mat foundation, pile group, and a caisson. The geotechnical engineer needs to investigate the feasibility of designing a shallow foundation owing to its cheapness and ease of construction. In the above situation, it is clear that a weak soil layer just below the new fill may not be enough to support the shallow foundation. Settlement in weak soil due to loading of the footing also needs to be computed.
- In this situation, one needs to be careful of the second weak layer of soil below the bearing stratum. Piles could fail due to punching into a weak stratum below.
- The engineer needs to consider negative skin friction due to new fill layer. Negative skin friction would reduce the capacity of piles. Due to the new load of the added fill material, weak soil layer 1 will consolidate and settle, and the settling soil will drag down piles with it. This is known as negative skin friction or down drag.
- End bearing piles Timber piles are not suitable for the situation given above owing to the existence of boulders in upper layers. The obvious choice is to drive piles all the way to the rock. The piles can be designed as end bearing piles. If the decision is taken to drive piles to the rock for the above configuration, H-piles are ideal. Unlike timber piles or pipe piles, H-piles can go through boulders. On the other hand, the rock may be too far for the piles to be driven. If the rock is too deep for piles, a number of alternatives can be envisioned. 1. Drive large-diameter pipe piles and place them in medium-stiff clay. 2. Construct a caisson and place it in the medium-stiff clay. In the first case, driving large-diameter pipe piles through boulders could be problematic. It is possible to excavate and remove boulders if the boulders are mostly at shallower depths. In the case of H-piles, one has to be extra careful not to damage the piles. Caissons placed in the medium-stiff clay is a good alternative. Settlement of caissons needs to be computed.
- Friction piles Piles cannot be placed in soft clay, but they can be placed in medium-stiff clay. In this situation, piles need to be designed as friction piles. Pile capacity comes mainly from end bearing and skin friction. End bearing piles, as the name indicates, obtain their capacity mainly from the end bearing, while friction piles obtain their capacity from skin friction. If the piles were placed in the medium-stiff clay, stresses would reach the soft clay layer below. The engineer needs to make sure that settlement due to compression of soft clay is within acceptable limits. Friction piles work on a different principle. The pile transfers the load of the building to the soil across the full height of the pile, by friction. In other words, the entire surface of the pile, which is cylindrical in shape, works to transfer the forces to the soil. To visualize how this works, imagine you are pushing a solid metal rod of say 4mm diameter into a tub of frozen ice cream. Once you have pushed it in, it is strong enough to support some load. The greater the embedment depth in the ice cream, the more load it can support. This is very similar to how a friction pile works. In a friction pile, the amount of load a pile can support is directly proportionate to its length.
- Timber Piles: Timber piles can be placed in the medium-stiff clay. In this situation, soft clay in upper layers may not pose a problem for driving. Timber piles above groundwater should be protected. Microbes need two ingredients to thrive: oxygen and moisture. Pipe Piles: Pipe piles can also be used in this situation. Pipe piles cost more than timber piles. One of the main advantages of pipe piles over timber piles is that they can be driven hard. At the same time, large-diameter pipe piles may be readily available, and higher loads can be accommodated by few piles. H-Piles: H-piles are ideal candidates for end bearing piles. The above situation calls for friction piles. Hence, H-piles may not be suitable for the above situation.