Study of design and construction methods of bored piles
- 1. Group Members 1. Sachittra Ranasinghe 2. Mohamed Siyath 3. Sahl Buhary 4. Mohamed Juhry 5. Mohamed Hiyas
- 2. 1. Introduction 2. Literature Review 3. Methodology 4. Data Collection & Analysis 5. Conclusion & Recommendations
- 3. Aims and Objectives of Research 1. To determine various type of piles in used and identify most suitable type for Qatar construction industry. 2. To analyse construction method used for cast in situ friction piles. 3. To compare the design results which computer aided design and manual design.
- 4. Foundations provide support for structures, transferring their load to layers of soil or rock that have sufficient bearing capacity and suitable settlement capacity Here Pile foundations are deep foundations They are formed by long & circular elements typically made from steel or reinforced concrete, or sometimes timber.
- 5. Pile foundation is required when the soil bearing capacity is not sufficient (soft soil) for the structure to withstand. This is due to the soil condition. pile foundation transferring structure load to rocky or hard layer of soil
- 6. History of case The first recorded use of drilled deep foundations was in the 1920s, where piles were originally termed Chicago caissons. Weaker top soils in areas such as Chicago, Cleveland, London called for an alternative foundation to traditional methods
- 8. Purpose of Literature Review To define current state of the arts in pile design and construction from previous research and To assess classification of pile, construction methodology & design methodology
- 9. Why bored piles are used Commonly used as foundation to support heavily loaded structures such as high rise buildings, Hydraulic Structure and bridges in view of it low noise, low vibration and flexibility of sizes to suit different loading conditions and subsoil conditions Required to be carried on tall buildings or massive industrial complexes, which require foundations and can bear the load of thousands of tons, most probably in unstable or difficult soil conditions.
- 10. Classification of Piles 1. Classification based on materials Timber piles Concrete piles Steel Piles Composite piles 2. Classification based on the function End bearing piles :-Piles which transfer structural load to a hard and relatively incompressible stratum such as rock or dense sand are known as end bearing piles. These piles derive the required bearing capacity from end bearing at tip of the pile.
- 11. Classification of Piles Friction piles:- These are piles which derive carrying capacity from skin friction or adhesion between the pile surface and surrounding soil. Tension pile: These piles are also called as uplift piles. Generally it can be used to anchor down the structures which are subjected to uplift pressure due to hydrostatic force.
- 13. Classification of Piles 3. Classification based on method of installation Bored piles:- Bored piles are constructed in pre-bored holes either using a casing or by circulating stabilizing agent like bentonite slurry. The borehole is filled with concrete after placing or lowering reinforcement. The main advantage in bored piles is no damage due to handling and driving which is common in driven piles. The different types of bored piles are: small diameter piles up to 600mm diameter: Large diameter pile greater than 600mm; Under-reamed piles generally 300 to 450mm diameter.
- 14. Classification of Piles 3. Classification based on method of installation Driven piles:- Driven piles may be of concrete, steel or timber. These piles are driven into the soil strata by the impact of a hammer. Generally boring is not used in these cases. When pile is driven into granular soils it densifies the soil and increases stiffness (strength) of soil.
- 15. Classification of Piles 3. Classification based on method of installation Cast-in-Place Piles:- These piles are formed by driving a tube with a closed end into the soil strata, and then filling the tube with freshly prepared concrete. The tube may or may not be withdrawn afterwards.
- 16. Design methodology What are the various capacities of pile commonly used in practice? ◦ Axial capacity ◦ Lateral capacity ◦ Tension capacity
- 17. How to estimate the capacity of a Pile? What are the approaches? Field approach ◦ In this approach the pile is loaded to the desired level and its capacity is estimated. Theoretical Approach ◦ In this approach the pile capacity is calculated using some formulae into which soil data is fed for obtaining the capacity.
- 18. Load Tests On a Single Pile The load tests are categorized as Stress tests:- •Maintained load test •Constant rate of penetration test •Lateral load test •Dynamic load test •Cyclic load test Strain tests:- •Low strain integrity testing •High strain integrity testing
- 19. Pile load tests are usually carried out for the following main reasons: ◦ To obtain back figured soil data that will enable other piles tobe designed ◦ To confirm pile lengths and hence contract costs before the client is committed to over all job costs ◦ To counter check results from geotechnical and pile driving formulae ◦ To determine the load-settlement behavior of the pile, especially in the region of anticipated working load, that the data can be used for prediction of group settlement. ◦ To verify the structural soundness of the pile.
- 23. The purpose if this chapter is to examine the research methodologies available for this study. The outline research methodology includes; Literature review of book, articles and journals on design and construction methods of bored piles in the industry.
- 24. There are two types of reserch strategies, Qualitative and Quantitative. Qualitative data is data in the form of descriptive accounts of observations or data which is classified by type. Quantitative data is data which can be expressed numerically or classified by some numerical value.
- 25. Here our research methodologies based on Qualitative strategies, The state of the art has been defined through literature review, for the design approach & data collection has been used previous case of pile design in qatar project
- 26. 4. Data Collection & Analysis
- 27. 1.Pile Capacity: • Toe load-carrying capacity of a pile depends on the properties of the soil in which it is embedded. 2 Negative shaft resistance or down drag Force: • Negative friction is downward drag acting on a pile due to the downward movement of the surrounding compressible soil relative to the pile. Bore Pile Design considerations
- 28. Design Phase 1. Drawings and Calculations • Structural Engineer pile layout drawing. • Make sure it includes pile reference numbers and the amount of load each pile will be subjected to. • Ensure calculations demonstrate how the load amount figure was generated for each pile. Design Steps
- 29. 2. Site Investigation Report • Conduct a geotechnical site investigation(Soil Investigation report base on bore holes) along and beneath the piles. • Ensure investigations extend to at least 3 times the pile diameter or a minimum of 5 meters in accordance with BS codes and guidelines. 3. Factor of Safety • This will be determined based on the design, site investigation and pile load testing. • It should have a factor of safety rating of between 2 and 3 in accordance with BS8004 guideline. 4. Testing • Testing needs to be carried out to ensure the foundations meet the design requirements. There are two types of testing available which are: • Static load testing • Dynamic load testing. Design Steps
- 30. Testing for pile design Load Tests On a Single Pile The load tests are categorized as Stress tests • Maintained load test (Static vertical load test) • Constant rate of penetration test • Lateral load test • Dynamic load test • Cyclic load test • Low strain integrity testing • High strain integrity testing.
- 31. Type of Pile Designing methods 1- Manually • By human hand and mind using standard codes & base on given manual data to be calculated all the requirements of design criteria until unless achieved the best suitable pile design for given structure.
- 32. Type of Pile Designing methods • Pile design software used for the analysis of modelling the shoring of excavations in stratified soil using sheet pile walls. Calculation methods are based on the British Steel Piling Handbook and the US Steel Sheet Piling Design Manual as we as per base on given data. 2-Computerized
- 33. Software of Pile Design 1- FOXTA V3 2- GGU-AXPILE 3- Pile - GEO5 4- RSPile 5- sap20000 6- SHAFT v2012 7- VERSAT-2D 8- McTrans
- 34. CONCLUSIONS Bored pile is usually ignored due to doubts in cleaning. If it is not possible for the case of the dry hole and the inspection of the base, the basic resistance with the corresponding mobilizing factor can be considered. For the design of bored piles in the ground, the two common methods, namely semi-empirical and simplified methods of soil mechanics, are mostly used to determine the final piling capacity. The use of load transfer method is important to optimize the pile design for value engineering and also provide settlement performance.
- 35. CONCLUSIONS The use of the load transfer method is important in order to optimize the pile design for value engineering and also provide settlement performance. For rock socket pile design, design approach and charts with consideration of socket roughness, rock strength, rock mass stiffness and socket geometry are presented and discussed. For the design of rock socket, the design approach and the tables are presented and discussed, taking into account the roughness of the bushings, the rock thickness, the rock resistance and the geometry of the bushes. Instrumentation test pile is used for design optimization and value engineering if there are enough pile points for the project to justify the testing cost.
- 36. Recommendations The results of this research indicates that improvements in designing friction piles are important to benefit from the advantages involved in the design. The following items provide the required recommendations to be implemented: The collected data from this project should be planned into a central database. Creating a database will be the most effective way to view and use the data that have been collected in an effort to calibrate regional Load Resistance Factor Design (LRFD) resistance factors. Incorporating the effects of pile setup into design would provide the ability to reduce pile lengths and pile sizes which may not be considered.
- 37. Recommendations A standardized pile driving record needs to be kept during the installation of all piles in the projects. The information in this document should fully describe the project, location of the pile with respect to the structure, pile length, and blow count per foot during installation. Even though the data collected in a pile driving record are simple, they can be used to generally evaluate the consistency in the subsurface in the location of the piles. The pile driving records should be made part of the “as built” plans of record. Additional research grade static pile load tests should be performed in ongoing construction projects to increase the reliability and validity of the current data sets collected. Pile setup is an important factor in piles friction into clay deposits. Incorporating the effects of pile setup into design would provide the ability to reduce pile lengths and pile sizes that may not be considered.
- 38. Thanks you.