1 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) ISSN (Print) 2313-4410, ISSN (Online) 2313-4402 © Global Society of Scientific Research and Researchers http://asrjetsjournal.org/ Soil Tests Analysis for Raft and Pile Foundations of a 5 Storey Building in Yenagoa, Bayelsa State, Nigeria Umeonyiagu. I. E.a*, Agboga. M. A.b*, Okeleke. J. N.c* aChukwuemeka Odumegwu Ojukwu University, Uli. Anambra State. Nigeria bGbogest Nigeria Limited, Benin City Edo State. Nigeria cPFD Consultants Services Asaba, Delta State, Nigeria aEmail: umeonyiaguikechukwu@yahoo.com bEmail: agbogamarcel@yahoo.com cEmail: perfectdesignconsultants@gmail.com Abstract 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). ------------------------------------------------------------------------ * Corresponding author. http://asrjetsjournal.org/ American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 2 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. Keywords: Raft; Pile; Foundations; Shear; Designs. 1. Introduction Foundations are appropriately described as a necessary evil. If a building is to be constructed on an outcrop of sound rock, no foundation is required. Hence, in contrast to the building itself which satisfies specific needs, appeals to the aesthetic sense, and fills its matters with pride, the foundation merely serve as a remedy for the deficiencies of whatever whimsical nature has provided for the support of the structure at the site which has been selected. On account of the fact that there is no glory attached to the foundations, and that the source of success or failures are hidden deep in the ground, building foundation have always been treated as step children; and their acts of revenge for lack of attention can be very embarrassing [15].The comments made by Terzaghi are very significant and should be taken seriously by all practicing architects and engineers. Since the substructures are as important as the superstructures, persons who are well qualified in the design of substructures should always be consulted [11]. All engineering construction resting on the earth are carried by some kind of interfacing element called a foundation. The term superstructure is commonly used to describe the engineered part of the system bringing load to the foundation, or substructure. The term superstructure has particular significance for buildings and bridges; however, foundation also may carry only machinery, support industrial equipment (pipes, towers, tanks), act as sign bases, and so on. For these reasons, it is better to describe a foundation as that part of engineered system that interfaces the load- carrying components to the ground. It is evident on the basis of this definition that a foundation is the most important part of the engineering system [2]. The function of any foundation is to safely sustain and transmit to the ground on which interests the combined dead, imposed and wind loads in such a manner as not to cause any settlement or other movement which would impair the stability or cause damage to any part of the building [8]. Research has shown that the two main types of foundation usually used in water-logged areas in which the soil is very weak and has a very low bearing capacity are raft and pile foundations and over the years, these foundations have imposed much concern and difficulties to engineers and clients in terms of their design and construction in water-logged areas [9] [1]. The aim is to design raft and pile foundations in a water logged area of Yenagoa for a five storey building and then compare both foundations and choose the one that is more effective in terms of safety and economy while taking into consideration the availability of materials. 2. Materials and Method 2.1 Materials Preliminary soil tests were carried out in order to determine the physical properties and the bearing capacity of the soil in accordance with BS1377 [7]. These tests were Dutch cone penetration tests, Borehole characteristics test involving standard penetration test, particle size distribution tests, direct shear test, triaxial tests and American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 3 consolidation tests. 2.1.1 Site Description The proposed project site was situated along Tenbia Road, It located at about 2km from the proposed central processing facilities (CPF) are along the Crushed Rock Industries Road and about 500m of the Road. The area is topographically low lying seasonally flooded and located within dense vegetation 2.1.2 Field Work The coordinates of the test location are presented in table 2.1 Table 2.1: Co-ordinates of Boreholes and CPT Test Positions POINTS NORTHING EASTING BH 1 110932 425821 BH 2 110983 425224 BH 3 110953 425138 BH 4 111004 425075 CPT 1 110953 425832 CPT 2 110880 425821 CPT 3 110969 425582 CPT 4 110911 425229 CPT 5 111025 425201 CPT 6 110985 425170 CPT 7 110899 425170 CPT 8 111031 425130 CPT 9 110956 425111 CPT 10 111027 425090 CPT 11 110940 425069 CPT 12 111060 425058 LEGEND: Bore Hole, Cone Penetration Test 2.2 Methods 2.2.1 Cone Penetration Test The CPT data were acquired using mechanical static cone Penetrometer of the following specifications: cone base = 10cm2, apex angle = 60o and friction sleeve = 150cm2. A total of twelve (12) Nos. Dutch Cone Tests (CPT) was performed with a 10 Ton Dutch Cone Penetrometer machine up to the depths at which the machine capacity or anchorage strength could allow. The cone and the sleeve are pushed into the ground for 25cm then American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 4 the cone is pushed ahead of the sleeve for 3.5cm at a uniform rate of 2cm/sec.The Dutch Cone Penetrometer tests recorded resistance to penetration of the cone at intervals of 20cm by means of pressure gauges mounted on the hydraulic sounding head. 2.2.2 Bore Hole Characteristics/Standard Penetration Test Four (4) Boreholes were drilled. A light cable percussion rig was used for the drilling operation. Representative samples were collected at 0.75m intervals of depths and also at changes in soil type. Undisturbed samples of suspected critical soils were also obtained from the clay layers in the boreholes. Standard penetration tests were performed in sandy layers at I .5m intervals of depths in each of the Boreholes. The number of blows required to drive the standard sampling spoon 300mm penetration after an initial 150mm penetration represents the SPT (N) value. 2.2.3 Particle Size Distribution Tests Particle size analysis was carried out by wet sieving before dry sieving. Fine analysis was also carried out. Suspected soils were tested for organic content. The particle size analysis was carried out in accordance with BS1377 [7] — Methods of tests for soil for Civil Engineering purpose. 2.2.4 Direct Shear Tests Quick unconsolidated undrained shear box test was performed on the soil samples to determine undrained strength all the direct shear box tests were performed in accordance with BS1377 [7]. 2.2.5 Triaxial Tests Quick unconsolidated undrained triaxial test was performed on the soil sample in accordance with BS1377 [7]. 2.2.6 Consolidation Test One dimensional Oedometer test was carried out on the undisturbed clay samples in order to determine the consolidation characteristics. The consolidation test was carried out in accordance with BS1377 [7]. 2.3 Design Structural analysis and designs were carried out in accordance with BS 8110 – 1997[4], BS 6399 – 1984 [5], CP 1-3, 1972 and CP, 2004 [6]. For the purpose of estimation of forces and moments of the structure as well as the design of raft and pile foundations both at the serviceability and ultimate limit states, with the ultimate column axial load of 4138KN and serviceability column axial load of 2164KN [12,13,16]. 3. Results and Discussions 3.1 Cone Penetration Test Results American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 5 The Dutch Cone Penetrometer tests recorded resistance to penetration of the cone at intervals of 20cm by means of pressure gauges mounted on the hydraulic sounding head. The result are shown in fig. 3.1-3.12 Figure 3.1: ConePenetrometer Figure 3.2: ConePenetrometer Test 2 Figure 3.3: Cone Penetrometer Test 3 Figure 3.4: Cone Penetrometer Test 4 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 6 Figure 3.5: Cone Penetrometer Test 5 Figure 3.6: Cone Penetrometer Test 6 Figure 3.7: Cone Penetrometer Test 7 Figure 3.8: Cone Penetrometer Test 8 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 7 Figure 3.9: Cone Penetrometer Test 9 Figure 3.10: Cone Penetrometer Test Figure 3.11: Cone Penetrometer Test 11 Figure 3.12: Cone Penetrometer Test 12 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 8 3.2 Bore Hole Characteristics/Standard Penetration Test Results The results of the bore hole characteristics/standard penetration test are shown in figures 3.13 to 3.16. The tests showed that the top soil was dry grayish mottled clay, followed by soft silty/ sandy clay up to 6m depth. Below 6 to 7m was sand. The clay end bearing minimum pressure was 54kN/m2 and its maximum pressure was 68kN/m2. The sand end bearing minimum pressure was 416kN/m2 and its maximum bearing pressure - 697kN/m2. The clay skin friction ranged from 10 – 13kN/m2. The sand minimum skin friction was 77kN/m2 and the maximum was 129kN/m2. The allowable bearing capacity of the soil ranged from 64kN/m2 to 71kN/m2 for a shallow depth of 1m – 2m and 177kN/m2 – 517kN/m2 for a deep depth of 10m – 20m. The soil water quality is shown in table 3.1 Table 3.1: Water Quality Borehole No Temperature (oC) pH Sulphate (mg/I) Chloride (mg/I) 1 27.6 6.1 142 10.4 2 27.6 5.9 145 8.9 3 27.5 6.0 144 11.5 4 27.4 6.0 140 11.2 Soil Water Quality Figure 3.13: Bore Hole No.1 Characteristics With Ground Water Depth 9.5m Figure 3.14: Bore Hole No.1 Characteristics With Ground Water Depth 8.5m American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 9 3.3 Particle Size Analysis The results of the particle size analysis are summarized in Table 3.1 and presented below in figs. 3.17 to 3.32. The sands classify as poor graded material (mfc). Organic matters identified were mainly root fibers varying from 0% to 3% in content. Figure 3.15: Bore Hole No.1 Characteristics With Ground Water Depth 9.0m Figure 3.16: Bore Hole No.1 Characteristics With Ground Water Depth 9.2m Figure 3.17: Bore Hole No. Particles Size Distribution At Depth 2m Figure 3.18: Bore Hole No. Particles Size Distribution At Depth 3.25m American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 10 Figure 3.19: Bore Hole No. Particles Size Distribution At Depth 4m Figure 3.20: Bore Hole No. Particles Size Distribution At Depth 6.2m Figure 3.21: Bore Hole No. Particles Size Distribution At Depth 6.75m Figure 3.22: Bore Hole No. Particles Size Distribution At Depth 7.5m American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 11 Figure 3.25: Bore Hole No. Particles Size Distribution At Depth 12.75m Figure 3.26: Bore Hole No. Particles Size Distribution At Depth 16m Figure 3.27: Bore Hole No. Particles Size Distribution At Depth 15m Figure 3.28: Bore Hole No. Particles Size Distribution At Depth 15.25m American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 12 3.4 Shear Box Test Results The results from the shear box test are shown in Table 3.2 (soil characteristics) and table 3.3 (summary of soil properties). The direct shear tests graphs are shown Table 3.2: Soil Characteristics (Shear/ Consolidation Test Result) BH NO Depth (m) Moisture content (%) Bulk unit weight (KN/m3) Dry unit weight (KN/m3) Friction (Degree) Cohesion (Direct shear) (KN/m2) Compression Index Coeff. Of consolidation (Cm2/Sec) Coeff of Vol. Comp (m2/kN) 1. 4.5 41 17.76 12.60 7 17 0.17 1.1x10-3 6.2x10-4 16.0 17 18.21 15.56 44 0 - - - 2. 3.0 38 16.22 11.75 5 19 0.13 1.4x10-3 5.0x10-4 11.0 20 17.72 14.77 43 0 - - - 3 4.0 43 15.52 10.85 2 20 0.41 0.28x10-3 7.8x10 -4 14.0 22 18.87 15.47 43 0 - - - 4. 2.0 44 15.29 10.62 3 19 0.17 1.0x10-3 6.1x10-4 12.0 21 18.36 15.17 44 0 - - - Figure 3.31: Bore Hole No. Particles Size Distribution at Depth 25.25m Figure 3.32: Bore Hole No. Particles Size Distribution at Depth 27.25m American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 13 Table 3.3: Summary of Soil Properties (Shear/ Consolidation Test Result) Clay Silty Sand Minimum Maximum Average Minimum Maximum Average Friction (degrees) 2 7 4 43 44 44 Cohesion (kN/m2) 17 20 19 0 0 0 Bulk density (kN/m3) 15.29 17.76 16.20 17.21 18.87 18.16 Dry density(kN/m3) 10.62 12.6 11.46 14.77 15.56 15.24 Moisture content (%) 38 41 42 17 22 20 Liquid limit (%) 36 65 45 - - - Plasticity Index (%) 14 34 20 - - - Compression index 0.13 0.41 0.22 - - - Coeff of Comp (m2/kN) 5.0x10-4 7.8x 10-4 6.3x10-4 - - - Coeff Of consol (cm2/sec) 0.28x10-3 1.4x10-3 0.95x10-3 - - - Specific gravity 2.58 2.61 2.60 2.61 2.62 2.62 %Passing200 25 30 28 1 5 3 Coeff Of curvature 0.07 1.3 0.8 Coeff Of uniformity 0.38 4.0 2.8 Figure 3.34: Shear Box Test For BoreholeNo.2 Figure 3.33: Shear Box Test For Borehole No.1 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 14 3.3 Triaxial Test Results The results obtained are presented against their corresponding soil layers in each of the Boreholes. The data were analyzed following Mohr — Coulomb failure criterion, as shown in figs. 3.37 to 3.40. Figure 3.37: Triaxial Test for Borehole No.1 Figure 3.38: Triaxial Test for Borehole No.2 Figure 3.35: Shear Box Test For BoreholeNo.3 Figure 3.36: Shear Box Test For BoreholeNo.4 American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 15 3.4 Consolidation Test Results The void ratio versus load curves of the consolidation test are shown Figs. 3.41 to 3.44. Figure 3.39: Triaxial Test for BoreholeNo.3 Figure 3.40: Triaxial Test for BoreholeNo.4 Figure 3.41: Borehole 1. Consolidation test at depth, 4.5m Figure 3.42: Borehole 2. Consolidation test at depth, 3m American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 16 3.5 Quantities and Cost Analysis of Raft Foundation The quantities and cost analysis of the raft foundation based on Building and Engineering Standard Method of Measurement (BESMM3), 1998. Is presented in table 3.4. Figure 3.43: Borehole 3. Consolidation test at depth, 3.75m Figure 3.44: Borehole 4. Consolidation test at depth, 2m American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 17 Table 3.4: Bills of Quantities for the Raft Foundation S/N Description Qty Unit Rate (N) Amount (N) A. B. C. D. E. F. Element No. 1 Excavation and Filling Excavate foundation starting from the top level to a depth not exceeding 5.00metres. Remove surplus excavated materials from site. In Situ Concrete Plain in situ concrete (1:2:4-19mm aggregate) for building. In Situ Concrete Reinforced concrete raft foundation with thin form thickness of 600mm mix ratio (1:1:2). Form Work Sawn form work at the edges of bed 600mm. Reinforcement 12mm diameter high tensile reinforcement to BS 4449. 5240 5240 629 629 286 63 m3 m3 m3 m3 m Ton 2,000.00 1,000.00 25,000.00 30,000.00 850.00 390,000.00 10,480,000.00 5,240,000.00 15,725,000.00 18,870,000.00 243,100.00 24,570,000.00 SUB TOTAL 75,128,100.00 ADD 5% Contingencies 3,756,405.00 GRAND TOTAL 78,884,505.00 3.6 Quantities and Cost Analysis of Pile Foundation The quantities and cost analysis of the pile foundation based on Building and Engineering Standard Method of measurement (BESMM3), [14] 1998. American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 18 Table 3.5: Bills of Quantities for the Pile Foundation S/N Description Qty Unit Rate (N) Amount (N) A. B. C. D. E. Element No. 1 Concrete Work In Situ Concrete Reinforced concrete pile foundation with 6 piles in a cap, each pile is 15m deep. 36 numbers of pile caps. Concrete mix (1:1:2). Form Work Sawn form work to reinforced concrete pile foundation to vertical sides of pile cap 36 numbers. Reinforcement 16mm diameter high tensile reinforcement to BS 4449. 12mm diameter high tensile reinforcement to BS 4449. Pilling 6 pile in a cap, 15m deep. 250 720 15 12 36 m3 m3 Ton Ton Nr 30,000.00 850.00 390,000.00 390,000.00 2,592,000.00 7,500,000.00 612,000.00 5,850,000.00 4,680,000.00 93,312,000.00 SUB TOTAL 111,954,000.00 ADD 5% Contingencies 5,597,700.00 GRAND TOTAL 117,551,700.00 4. Limitations The limitations of the research include: 1. Difficulty in obtaining permission from the local community leaders before carrying out soil American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 19 investigation. 2. It also involves a lot of financial implications to get suitable equipment to work on swampy environment 4. Conclusion 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. References [1]Balla, A, (1962)., “Bearing Capacity Of Foundations”, JSMFD. Proc. ASC [2]Bowles, J. E., (1996) Foundation Engineering and Design, (Fifth Edition), McGraw-Hill, 1996. [3]Bowles J. E. Foundation Analysis and Design (1997), (Fifth Edition) McGraw-Hill International Editions. [4]British Standards 8110. (1997) Code Of Practice for Design and Construction Part 1, 2 and 3 Publish By: British Standard Board [5]British Standards 6399. (1984): Designs Loading for Buildings, Part: Code of Practice for Dead and Imposed Loads, Published By: British Standards Institution, London. [6]British Standard 8004. (1986)Code of Practice for Foundations (Formerly CP (2004) published by: British Standards Institution Board, London. [7]British Standards,1377. (1990) Method of test for soil for civil engineering purposes, published by: British Standard Board. [8]Chudley, R. and Greeno R. (1998), Buildings Construction Handbook, (Sixth Edition, Elsevier publisher, London. [9]Jha, J. and Sinha, S.K (2009) Construction And Foundation Engineering (Seventh Edition) Khanna Publishers, New Delhi. [10]Murthy V.N.S. (2007), Advanced Foundation Engineering – Geotechnical Engineering Series (first Edition), Statish Kumar Jain: New Delhi [11]Murthy V.N.S. (2007), Textbook of Soil Mechanics and Foundation Engineering-Geotechnical American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS) (2019) Volume 52, No 1, pp 1-20 20 Engineering Series (First Edition), Statish Kumar Jain: New Delhi, Pvt. [12]NainanP.K. (2014) Design of Foundation Systems principles and practies” (Sixth Edition) Narosa Publishing house. [13]Oyenuga V.O. (2009), Design & Construction of Foundation (A Partised Approach) (Second Edition) Asros Limited. [14]The Royal Institution of Chartered Surveyors and the Construction Confederation, (1998) Building and Engineering Standard Method of Measurement, Published by Construction Confederation. [15]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 [16]Tomlinson M. J. (1994), Pile Design and construction Practice (Form Edition) E &FnSpon