ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY & ENVIRONMENT AZOJETE March 2022. Vol. 18(1):15-22 Published by the Faculty of Engineering, University of Maiduguri, Maiduguri, Nigeria. Print ISSN: 1596-2490, Electronic ISSN: 2545-5818 www.azojete.com.ng Corresponding author’s e-mail address: ibrahimcivil73@gmail.com 15 ORIGINAL RESEARCH ARTICLE AN INVESTIGATION OF SOIL BEARING CAPACITY FOR BUILDING AND STRUCTURAL FOUNDATION DESIGN: A CASE STUDY OF POLO AREA, MAIDUGURI, NIGERIA I.S. Muhammad*, A.M Alkali and K. Bulu Department of Civil and Water Resources Engineering, University of Maiduguri, Maiduguri, Borno State. Nigeria *Corresponding author’s email address: ibrahimcivil73@gmail.com 1.0 Introduction The determination of soils shear strength parameters is very crucial to geotechnical and structural engineers as it forms the essential data required for estimating foundation bearing capacity, factor of safety for slope stability and pressures on earth retaining structures for effective and economical design. The stability and integrity of engineering structures erected on any soil depends on the shearing resistance offered by the foundation soil (Alkali et al., 2018). The shear strength of soils is generally depicted by the Mohr-Coulomb theory which says that the shear strength of soils varies linearly with the applied stress through two components known as the cohesion intercept and angle of shearing resistance (Garg, 2013). The tangent to the Mohr–Coulomb failure envelopes is represented by its slope and intercept. The slope expressed in degrees is the angle of shearing resistance and the intercept is the cohesion (Pravin and Karim 2016). The angle of shearing resistance represents the interlocking between the soil particles whereas cohesion is mainly due to the intermolecular bond between the adsorbed water surrounding each grain, especially in fine grained soils (Odeyemi et al., 2012). The attempt to investigate the bearing capacity of soils in this area through shear strength values came from the fact that most private, government, contractors and compromising engineers are reluctant toward soil investigation for structural design. On the contrary, they based their designs on arbitrary safe ARTICLE INFORMATION ABSTRACT The foundation of any structure is the back born of its stability against all kinds of deformation and this depends on the geotechnical behavior of the supporting soil. Clay soils usually posed serious threats to buildings due to shrink-swell behavior, settlements and low strength which is associated with their minerals. In this research, the safe bearing capacity of Polo soil have been investigated using direct shear laboratory analysis on twenty representative soil samples across virgin area where future development is approaching. Most of the soils were classified as lean clay with sand (CL) according to Unified Soil Classification System (USCS) although some were otherwise. The average natural moisture content of the soils at 1m depth is 8.38% with liquid limit and plasticity index of 30.2% and 15.7% respectively while that of 1.5m were 9.14%, 29.4% and 14.6% respectively. Results also revealed an average friction angle and cohesion of 21º and 18 kN/m2 at 1m and 22o and 19 kN/m2 at 1.5m depths respectively. Safe bearing capacity values ranges from 44.95 to 411.11 kN/m2 and 75.27 to 397.31 kN/m2 for 1m and 1.5m respectively using foundation widths of 0.5m, 1m and 2m. Foundation design carried out using the different safe bearing capacities and load combinations revealed that the pad footings analyzed with 1500 kN indicated that the minimum footing size that could be used is 1800mm×1800mm using 400kN/m2 safe bearing capacity. It also revealed that for a 100kN/m2 safe bearing capacity, the footing size is as much as 3500mm×3500mm which is very high and raft foundations were recommended for such situations. © 2022 Faculty of Engineering, University of Maiduguri, Nigeria. All rights reserved. Submitted 16 March, 2021 Revised 28 May, 2021 Accepted 30 May, 2021 Keywords: Shearing strength bearing capacity foundation design http://www.azojete.com.ng/ mailto:ibrahimcivil73@gmail.com mailto:ibrahimcivil73@gmail.com Arid Zone Journal of Engineering, Technology and Environment, March, 2022; Vol. 18(1):15-22. ISSN 1596-2490; e-ISSN 2545-5818; www.azojete.com.ng Corresponding author’s e-mail address: ibrahimcivil73@gmail.com 22 bearing value which may sometimes lead to unsatisfactory or uneconomical design causing serious infrastructural damage. Lack of data for proper foundation design has led to continuous distress in buildings erected on Polo soils due its clayey nature. Presently, there is no published material covering this subject in the study area. This study, therefore, aimed toward investigating the type and bearing capacity of Polo soil, Maiduguri, for structural/foundation design purposes. With the results from this work, an engineer can easily compare and locate the category of soil type and possible safe bearing value based on knowledge and experience. However, this will be after obtaining preliminary laboratory results of soil index properties such as soil particles size distribution, moisture contents, Atterberg limits, and bulk and dry densities of a given sample which are by far cheaper and non-cumbersome compared to shear strength parameters which require equipment such as direct shear or triaxial machine. Otuaga, 2015, investigated the shear strength parameters of soils across zones of Owo Local Government Area of Ondo State, Nigeria, using triaxial and direct shear box methods. The study recommends a safe bearing capacity of 139.01 kN/m2 be adopted for foundation design. Similar investigations were carried out by Egbe et al., 2011, Oluwapelumi 2013 and Surendra and Gurcharan, 2014. These investigations address soils from Calabar south, Nigeria; lateritic soil in Akure, Nigeria and soils from Sirsa, India, respectively. Researchers have developed model equations using soil index properties and recommended its usage following the soil type. This work will, however, concentrate on soils from Polo area of Maiduguri by computing their safe bearing capacities. This is due to increasing number of defective houses in the area resulting from swelling and shrinking behavior of the clay soil which is predominant. This will be sound and more useful in computing new bearing capacities of samples collected across the area since they lie within same formation rather than model equations which do not always give good correlation. Using similarities in index properties and classification of soils in the location, one can use the information provided in this study to compute new bearing capacities based on knowledge and experience. 2. Materials and Methods 2.1 Materials The tools used for collecting the disturbed samples include sterilized digger and shovel, measuring tape, digital weighing balance, mobile phone with google map application and polythene bags. 2.1.1 Soil Samples The soil samples used in this study were collected from Polo area of Maiduguri, Borno State, Nigeria. Soil samples were dug at a depth of 1m and 1.5m respectively. Virgin area where development is rapidly approaching was used to collect the samples. The area is located at latitude 11046’ 41’’ N and longitude 130 08’ 29’’ E. The samples are collected at the interval of 200m from the last cluster of buildings in the area to the west where future development is expected. A total of twenty (20) samples were obtained from ten (10) different pits. Soil samples were then taken into polythene bags to avoid loss of moisture and further subjected to laboratory analysis. file:///C:/user/Downloads/azojete143/www.azojete.com.ng mailto:ibrahimcivil73@gmail.com Muhammad et al: An Investigation of Soil Bearing Capacity for Building and Structural Foundation Design: A Case Study of Polo Area, Maiduguri, Nigeria. AZOJETE, 18(1):15-22. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng Corresponding author’s e-mail address: ibrahimcivil73@gmail.com 21 Figure 1. Google map of the study area 2.2 Methods 2.2.1 Index Properties All tests were carried out on the twenty (20) soil samples in accordance with specifications outlined in British Standard (BS) 1377 (1990). Bulk and dry densities were determined using the following relations: Bulk density (ρ) = 𝑀2− 𝑀1 V (1) where: M1 is the mass of mold and base plate, M2 is the mass of mold, baseplate and compacted soil, V is the volume of the mold (cm3) Dry density (ρd) = 100𝜌 100+𝑤 (2) where: w is the moisture content of the soil (%) 2.2.2 Direct Shear Test Direct shear test was carried out using shear box with the specimens (60mm x 60mm). Specimen with plain grid plate at the bottom of the specimen and plain grid plate at the top of the specimen was fitted into position in the shear box housing and assembly placed on the load frame. The serrations of the grid plates were kept at right angle to the direction of shear. The loading pad was kept on the top grid plate. The required normal stress was applied, and the rate of longitudinal displacement/shear stress application adjusted so that no drainage can occur in the sample during the test (1.25 mm/min). The upper part of the shear box was raised such that a gap of about 1mm was left between the two parts of the box. The test was conducted by applying horizontal shear load to failure or to 20 percent longitudinal displacement whichever occurs first. The test was repeated on identical specimens. http://www.azojete.com.ng/ mailto:ibrahimcivil73@gmail.com Arid Zone Journal of Engineering, Technology and Environment, March, 2022; Vol. 18(1):15-22. ISSN 1596-2490; e-ISSN 2545-5818; www.azojete.com.ng Corresponding author’s e-mail address: ibrahimcivil73@gmail.com 22 2.2.3 Computation of Soil Bearing Capacity The bearing capacity of the various samples were computed using the formula proposed by Terzaghi. qult = c .N c +γD f N q + 0 .5BγN γ (3) where: γ = Unit weight of foundation soil in KN/m³, D f = depth of the foundation (m), c,ϕ = Strength parameters of the soil below foundation level in KN/m² and degrees respectively, B = Width of foundation in (m), Nc Nγ Nq = Bearing capacity coefficients dependent on the angle of internal friction. Safe bearing capacity of the soils, qsafe, was determined using: qsafe = Qult/ FS (4) where: FS is the factor of safety 3. Results and Discussion Geotechnical properties like particles size distribution, bulk and dry densities, Atterberg limits and natural moisture content of soils collected in Polo were determined. Shear strength parameters of the soils mainly friction angle and cohesion were also assessed. Most of the soils were classified as clay. Tables 1 and 2 below represents the data obtained for different soils from laboratory analysis. 3.1 Index properties and classification The index properties of Polo soils at 1m and 1.5m depths are presented in Tables1 and 2. The average natural moisture content of the soils at 1m depth is 8.38% with liquid limit and plasticity index of 30.2% and 15.7% respectively. All the soils at this depth are classified according to Unified Soil Classification System (USCS) as Lean Clays with sand (CL) with the exception of samples SD, SF and SG which falls within the class of Sandy Clay (SC), Sandy Clay (SC) and Silty Sand (SM) respectively. The index properties at 1.5m revealed that samples SA and SG were Silty Clay (ML) and SC while the remaining belongs to CL as well. The average natural moisture content, liquid limit and plasticity index are 9.14%, 29.4% and 14.6% respectively. The low Atterberg limits values also indicate low compressive strength which is as reported elsewhere (Ezenwaka et al., 2014). Table 1: Index properties of Polo soils at 1m depth Parameters/Sample SA SB SC SD SE SF SG SH SI SJ Natural moisture content (%) 23.0 13.2 15.0 3.9 3.5 2.9 2.9 9.9 6.9 2.6 Liquid limit (%) 34 36 34 22 33 29 29 37 26 22 Plastic limit (%) 18 20 15 11 10 13 24 15 09 10 Plasticity index (%) 16 16 19 11 23 16 05 22 17 12 % Fine 77 75 68 67.7 76 48 35 79 56 68 % Coarse 23 25 32 32.3 24 52 65 21 44 32 USCS CL CL CL SC CL SC SM CL CL CL Bulk unit weight (KN/m3) 11.7 16.9 17.8 15.4 15.7 15.4 15.5 14.6 14.5 15.8 Dry unit weight (KN/m3) 15.6 14.9 15.4 14.9 14.6 14.9 14.9 13.3 13.6 14.6 USCS (ASTM, 1992) file:///C:/user/Downloads/azojete143/www.azojete.com.ng mailto:ibrahimcivil73@gmail.com Muhammad et al: An Investigation of Soil Bearing Capacity for Building and Structural Foundation Design: A Case Study of Polo Area, Maiduguri, Nigeria. AZOJETE, 18(1):15-22. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng Corresponding author’s e-mail address: ibrahimcivil73@gmail.com 21 Table 2: Index properties of Polo soils at 1.5m depth Parameter/Sample SA SB SC SD SE SF SG SH SI SJ Natural moisture content (%) 17.3 13.9 17.3 5.1 5.9 8.9 3.1 9.1 3.3 7.5 Liquid limit (%) 25.0 38.0 28.0 26.0 48.0 27.0 24.0 24.0 21.0 33.0 Plastic limit (%) 21 16.0 13.0 10.0 18.0 14.0 8.0 15.0 10.0 23.0 Plasticity index (%) 4.0 22.0 15.0 16.0 30.0 13.0 16.0 9.0 11.0 10.0 % Fine 74.0 80.0 78.0 73.5 59.0 63.0 47.0 60.0 60.0 71.0 % Coarse 26.0 20.0 22.0 26.5 41.0 37.0 53.0 40.0 40.0 29.0 USCS ML CL CL CL CL CL SC CL CL CL Bulk unit weight (KN/m3) 17.5 15.6 18.5 16.0 15.7 15.3 15.4 14.6 14.6 15.5 Dry unit weight (KN/m3) 14.9 13.7 15.8 14.5 14.42 13.9 14.8 13.4 13.5 15.0 USCS (ASTM, 1992) 3.2 Computation of Soil Bearing Capacities The bearing capacities (Tables 3 and 4) were computed using foundation widths of 0.5m, 1.0m and 2.0m for all the soils. The average friction angle and cohesion of soils at 1m depth were 21o and 18 kN/m2 while that of 1.5m were 22o and 19 kN/m2 respectively. The safe bearing capacities at 1m depth ranges between 44.95 – 90.32 kN/m2 for samples SA to SC and this is due to low friction angles of 6o,13o and 5o respectively. The value increases between 135.18 – 411.11 kN/m2 for samples SD – SJ for the various widths investigated as a result of increase in angle of shearing resistance value. The same values at 1.5m depth revealed an increasing trend with the exception of sample SF which has a value little below that of 1m depth following the decline in friction angle value observed. This occurred as a result of additional increase in cohesion value of the soil when compared to that of SF at 1m depth. Table 3: Bearing capacities for shallow foundations at 1m depth Parameter/Sample SA SB SC SD SE SF SG SH SI SJ Depth (m) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Width (m) 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 ThUnit weight (KN/m3) 11.7 16.9 17.8 15.4 15.7 15.4 15.5 14.6 14.5 15.8 Angle of friction (o) 6.0 13 5.0 29 24 29 33 18 25 25 Cohesion (kN/m2) 18 20 16 14 22 17 9.0 24 18 22 Ultimate bearing capacity (kN/m2) 145.87 146.28 147.09 258.80 262.85 270.95 134.84 135.25 136.07 715.25 775.95 897.36 612.32 639.95 695.20 800.22 860.93 982.34 883.69 1000.23 1233.32 405.53 414.75 433.18 565.87 595.91 655.96 666.75 699.46 764.88 Safe bearing capacity (kN/m2) 48.62 48.76 49.03 86.27 87.62 90.32 44.95 45.08 45.36 238.41 258.65 299.12 204.11 213.32 231.73 266.74 286.98 327.45 294.56 333.41 411.11 135.18 138.25 144.38 188.62 198.64 218.65 222.25 233.15 254.96 http://www.azojete.com.ng/ mailto:ibrahimcivil73@gmail.com Arid Zone Journal of Engineering, Technology and Environment, March, 2022; Vol. 18(1):15-22. ISSN 1596-2490; e-ISSN 2545-5818; www.azojete.com.ng Corresponding author’s e-mail address: ibrahimcivil73@gmail.com 22 Table 4: Bearing capacities for shallow foundations at 1.5m depth Parameter/Sample SA SB SC SD SE SF SG SH SI SJ Depth (m) 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Width (m) 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 0.5 1.0 2.0 Unit weight (KN/m3) 17.5 15.6 18.5 16.0 15.7 15.3 15.4 14.6 14.6 15.5 Angle of friction (o) 29.0 12.0 9.0 29.0 27.0 21.0 29.0 21.0 22.0 19.0 Cohesion (kN/m2) 4.0 22.0 20.0 19.0 19 20.0 17.0 25.0 24.0 23.0 Ultimate bearing capacity (kN/m2) 620.87 689.70 827.35 280.69 283.70 289.71 225.83 227.57 230.89 1002.98 1066.00 1192.05 823.27 868.15 957.92 501.85 518.22 550.95 928.93 989.59 1110.93 573.82 589.44 620.68 603.45 621.93 658.88 473.47 485.22 508.73 Safe bearing capacity (kN/m2) 206.96 229.90 275.78 93.56 94.56 96.57 75.27 75.86 76.96 334.32 355.33 397.35 274.42 289.38 319.31 200.74 207.29 220.38 309.64 329.86 370.31 191.27 196.48 206.89 201.15 207.31 219.63 157.82 161.74 169.58 3.3 Foundation Design The foundation design based on different safe bearings capacities and column load combinations has been analyzed using Prota Structure software and the results is presented in Table 5. The analysis was carried out using average bearing capacities of 100, 150, 200, 250, 300, 350 and 400 kN/m2 respectively. For each safe bearing capacity, a column loads of 200, 500 and 1500 kN were used to analyzed its punching shear capacity and settlement using different pad footing sizes. The results show that for all the safe bearing capacities, footings subjected to 200 and 500 kN column loads can be constructed as singly reinforced section with sizes between 700 mm × 700 mm to 2000 mm × 2000 mm depending on the safe bearing capacity used. This is due to the low load intensity acting on the footing as well as the fair average safe bearing capacity of the soils. Furthermore, the pad footings analyzed with 1500 kN indicated that the minimum footing size that could be used is 1800 mm × 1800 mm using 400 kN/m2 safe bearing capacity. It was also observed that for a 100 kN/m2 safe bearing capacity, the footing size is as much as 3500 mm × 3500 mm, which is very high. As a result, raft foundations were recommended for such situations in order to accommodate the high load intensity of the structure under single footing (raft) instead of larger footings covering almost the entire foundation area. Table 5: Foundation analysis and design using different safe bearing capacities, column loads and footing sizes Foundation Type Column Load (KN) Safe Bearing Capacity (KN/m2) Foundation Size (m) Punching Shear Capacity (N/mm2) Settlement (mm) Rebar (mm2) Factor of Safety Remark/Comment PSS USS Pad Footing 200 500 1500 100 1300×1300 2000×2000 3500×3500 0.11 0.29 0.3 0.36 0.36 0.36 19 22 34 380.64 1035.90 3355.09 2 2 2 Singly Reinforced Section Singly Reinforced Section Raft Foundation Recommended Pad Footing 200 500 1500 150 1000×1000 1700×1700 2900×2900 0.06 0.23 0.31 0.36 0.36 0.36 16 24 32 319.44 824.18 2927.91 2 2 2 Singly Reinforced Section Singly Reinforced Section Raft Foundation Recommended file:///C:/user/Downloads/azojete143/www.azojete.com.ng mailto:ibrahimcivil73@gmail.com Muhammad et al: An Investigation of Soil Bearing Capacity for Building and Structural Foundation Design: A Case Study of Polo Area, Maiduguri, Nigeria. AZOJETE, 18(1):15-22. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng Corresponding author’s e-mail address: ibrahimcivil73@gmail.com 21 Pad Footing 200 500 1500 200 900×900 1500×1500 2400×2400 0.03 0.33 0.33 0.36 0.36 0.36 24 23 32 261.36 838.30 2550.24 2 2 2 Singly Reinforced Section Singly Reinforced Section Raft Foundation Recommended Pad Footing 200 500 1500 250 800×800 1300×1300 2400×2400 0.09 0.25 0.28 0.36 0.36 0.36 24 25 36 232.40 679.34 2273.98 2 2 2 Singly Reinforced Section Singly Reinforced Section Raft Foundation Recommended Pad Footing 200 500 1500 300 800×800 1200×1200 2000×2000 0.09 0.20 0.35 0.36 0.36 0.36 23 25 38 232.30 601.70 2279.20 2 2 2 Singly Reinforced Section Singly Reinforced Section Raft Foundation Recommended Pad Footing 200 500 1500 350 750×750 1100×1100 1900×1900 0.14 0.13 0.32 0.36 0.36 0.36 24 23 35 217.80 525.40 525.40 2 2 2 Singly Reinforced Section Singly Reinforced Section Raft Foundation Recommended Pad Footing 200 500 1500 400 700×700 1000×1000 1800×1800 0.19 0.05 0.27 0.36 0.36 0.36 22 24 33 203.30 450.40 1978.0 2 2 2 Singly Reinforced Section Singly Reinforced Section Raft Foundation Recommended 3.4 Conclusion and Recommendation The index properties and shearing strength parameters of Polo soil for bearing capacity values was investigated. The results indicated that most of the soils are classified as lean clay with sand (CL) according to USCS although there exist sandy clay (SC), silty clay (ML) and Silty sand (SM). The average natural moisture contents of the soils at 1m and 1.5m were 8.38% and 9.14% respectively. The average liquid limit and plasticity index values ranges from 30.2% to 15.75% and 29.4% to 14.6% respectively which is an indicative of low compressive strength. The minimum and maximum safe bearing capacities observed for 1m and 1.5m depths were 44.95 to 411.11 kN/m2 and 75.27 to 397.31 kN/m2 respectively. Sample SA, SD and SF were also observed to have possessed heterogeneity between the depths investigated. Due to different safe bearing capacities and load combinations, the foundation design conducted revealed that certain foundations will be singly reinforced section while other will call for raft. It is, therefore, recommended that a minimum of index properties test of soil in the study area be carried out to compare e the possible corresponding shear strength parameters based on the information provided above before foundation design in the study area. This could be achieved by comparing parameters such as % fines and coarse, plasticity index, bulk density and soil type obtained in the laboratory with the ones provided here, this will however require knowledge and experience. It is also our conviction that this will mitigate blind assumption of bearing values during design as some soils misbehave within short spans, a typical example being some samples with safe bearing capacity less than 50 kN/m2. References Alkali, AM., Muhammad, IS. and Bulu, K. 2018. Structural Integrity Assessment of an Uncompleted Reinforced Concrete Structure in Maiduguri, Nigeria. Arid Zone Journal of Engineering, Technology and Environment, 14(3): 404-410. http://www.azojete.com.ng/ mailto:ibrahimcivil73@gmail.com Arid Zone Journal of Engineering, Technology and Environment, March, 2022; Vol. 18(1):15-22. ISSN 1596-2490; e-ISSN 2545-5818; www.azojete.com.ng Corresponding author’s e-mail address: ibrahimcivil73@gmail.com 22 ASTM 1992. Annual Book of Standards. Philadelphia: American Society for Testing and Materials, vol. 4, 1-8. British Standard Institute. 1990.Methods of testing soils for civil engineering purposes. BS 1377, London, 1-30. Ezenwaka, KC., Ugboaja, A., Ahaneku, CV. and Ede, TA. 2014. Geotechnical Investigation for Design and Construction of Civil Infrastructures in Port Harcourt City of Rivers State, Southern Nigeria. The International Journal of Engineering and Science, 3(8): 74-82. Garg, SK. 2013. Soil Mechanics and Foundation Engineering. Ninth Revised Edition, ew Delhi Khanna publishers., 212-253. Pravin, SD. and Karim, CM. 2016. New Approach for Determination of bearing Capacity of Soil using Direct Shear Test. International Journal of Innovation in Engineering and Technology, 7(4): 426-430. Odeyemi, SO., Kaigama, WB., Adeyemi, AO. and Amototo, IO. 2012. Determination of the Ultimate Bearing Capacity of Soils in Offa Community. Epistemics in Science, Engineering and Technology, 2(4): 168-174. Otuaga, PM. 2015. Determination of Bearing Capacity for Building and Structural Design in Owo Local Government Area, Ondo State, Nigeria. European Journal of Engineering and Technology, 3(4): 1-10. Egbe, JG., Ewa, DE., Ubi, SE., Ikwa, GB. and Tumenayo, OO. 2017. Application of Multilinear Regression Analysis in Modeling of Soil Properties for Geotechnical Civil Engineering Works in Calabar South. Nigerian Journal of Technology (NIJOTECH), 36(4): 1059 – 1065. Oluwapelumi, OO. 2013. Predictive Shear Strength Models for Tropical Lateritic Soils. Hindawi Publishing Corporation Journal of Engineering, 2013, Article ID 595626, http://dx.doi.org/10.1155/2013/595626, 1-8. Surendra, R. and Gurcharan D. 2014. Statistical Models for the Prediction of Shear Strength Parameters at Sirs., India International Journal of Civil and Structural Engineering, 4(4): 483-498 file:///C:/user/Downloads/azojete143/www.azojete.com.ng mailto:ibrahimcivil73@gmail.com http://dx.doi.org/10.1155/2013/595626