Soil Tests Analysis for Raft and Pile Foundations of a 5 Storey Building in Yenagoa, Bayelsa State, Nigeria
This work involved the designs and analyses of the foundation of a 5-storey building in Yenagoa, a water-logged area of Bayelsa State, (Nigeria), using both raft and pile foundations. Preliminary soil tests were carried out in order to determine the physical properties and the bearing capacity of the soil. These tests were Dutch cone penetrometer tests, Borehole characteristics test involving standard penetration test, particle size distribution tests, direct shear test, triaxial tests and consolidation tests. The Dutch cone penetrometer tests recorded resistance to cone penetration of 345-355kg/cm2. The Borehole characteristic tests showed that the top soil was dry grayish mottled clay, followed by soft silty/sandy clay up to about 6m depth. Below 6-7m depth was sand. The clay end bearing minimum pressure was 54kN/m2 and maximum pressure was 68kN/m2. Sand end bearing minimum pressure was 416kN/m2 and maximum was 697kN/m2. The clay skin friction ranged from 10kN/m2 to 13kN/m2. The sand minimum skin friction was 77kN/m2 and the maximum skin friction was 129kN/m2.The allowable bearing capacity of the soil ranging from 64kN/m2to 71kN/m2 for a shallow depth of 1m – 2m and 177kN/m2 to 517 kN/m2 for a deep depth of 10m to 20m. The pile sizes ranged from 305mm to 500mm. Design of the structural elements (superstructure) as well as the design of the foundations (Raft and Pile) were executed with ultimate column axial load of 4138 kN and serviceability column axial load of 2164 kN. The cost analysis was also performed. From the cost analysis, the cost of the raft foundation was N78,884,505.00 (Seventy Eight Million, eight Hundred and eighty four Thousand, five Hundred and five Naira only) while the cost of the pile foundation was N117,551,700.00 (One Hundred and seventeen Million, five Hundred and Fifty one Thousand, Seven Hundred Naira only).
This showed that the cost of the pile foundation was greater than that of the raft foundation by 39%. It is recommended that raft foundation be used on the area in order to minimize cost.
Balla, A, (1962)., “Bearing Capacity Of Foundations”, JSMFD. Proc. ASC
Bowles, J. E., (1996) Foundation Engineering and Design, (Fifth Edition), McGraw-Hill, 1996.
Bowles J. E. Foundation Analysis and Design (1997), (Fifth Edition) McGraw-Hill International Editions.
British Standards 8110. (1997) Code Of Practice for Design and Construction Part 1, 2 and 3 Publish By: British Standard Board
British Standards 6399. (1984): Designs Loading for Buildings, Part: Code of Practice for Dead and Imposed Loads, Published By: British Standards Institution, London.
British Standard 8004. (1986)Code of Practice for Foundations (Formerly CP (2004) published by: British Standards Institution Board, London.
British Standards,1377. (1990) Method of test for soil for civil engineering purposes, published by: British Standard Board.
Chudley, R. and Greeno R. (1998), Buildings Construction Handbook, (Sixth Edition, Elsevier publisher, London.
Jha, J. and Sinha, S.K (2009) Construction And Foundation Engineering (Seventh Edition) Khanna Publishers, New Delhi.
Murthy V.N.S. (2007), Advanced Foundation Engineering – Geotechnical Engineering Series (first Edition), Statish Kumar Jain: New Delhi
Murthy V.N.S. (2007), Textbook of Soil Mechanics and Foundation Engineering-Geotechnical Engineering Series (First Edition), Statish Kumar Jain: New Delhi, Pvt.
NainanP.K. (2014) Design of Foundation Systems principles and practies” (Sixth Edition) Narosa Publishing house.
Oyenuga V.O. (2009), Design & Construction of Foundation (A Partised Approach) (Second Edition) Asros Limited.
The Royal Institution of Chartered Surveyors and the Construction Confederation, (1998) Building and Engineering Standard Method of Measurement, Published by Construction Confederation.
Terzaghi, K (1951). “The Influence Of Modern Soil Studies On The Design And Construction Of Foundation” Bldg. Research congr., London, 1951, div. 1, par III
Tomlinson M. J. (1994), Pile Design and construction Practice (Form Edition) E &FnSpon
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