A Model Study on Pile Behavior under Inclined Compressive Loads in Cohesionless Soil Serin Issac M Tech Student, Department of Civil Engineering Saintgits College of Engineering, Kottayam Kerala, India Swapna Thomas Assistant Professor, Department of Civil Engineering Saintgits College of Engineering, Kottayam Kerala, India Abstract— Pile foundations are extensively used to support various structures built on loose/ soft soils where shallow foundations would undergo excessive settlements or have low bearing capacity. Piles are slender, having high length to width ratio, and are mainly designed to resist axial loads. However, some structures such as high rise buildings, offshore structures, tall chimneys, earth retaining walls are subjected to horizontal or lateral pressure caused by wind force, wave force, traffic movement, earthquake etc. Thus, piles are used as foundation to transmit vertical and lateral loads to the surrounding soil media. In many cases, they may be subjected to inclined compressive loading conditions also. These loads cause lateral and vertical displacements and rotation of the pile cap. These overall behaviors of the piles are estimated from the available conventional theoretical approaches. There are limited experimental studies available on behavior of vertical piles subjected to inclined compressive loads. This paper is an attempt to study the behavior of single pile in cohesionless soil, subjected to varying inclined load until failure with the angle of applied load varying from 0º to 90º from the vertical axis of the pile, through an experimental model study on model mild steel and concrete piles driven into dry river sand. Axial and lateral load carrying capacities of both piles of various slenderness ratios (10, 15, and 20) are found through the load – settlement diagrams and are compared. The effects of vertical and lateral components of inclined loads on horizontal and vertical displacement of the pile head are discussed. Also, the effects of pile material on the lateral load capacity of piles are studied. Keywords— Bearing Capacity, Cohesionless soil, Inclined Loads, Lateral loads, Model tests, Pile foundation I. INTRODUCTION Pile foundations are generally adopted, when the soil conditions are poor. The purpose of a pile foundation is to transmit the loads of the superstructure to the deep underlying firm soil while preventing excessive structural deformations. Pile foundations of offshore structures, transmission towers, wind energy converters, are often subjected to inclined loads and moment from usual structural dead load and horizontal loads generated by wind, waves, earth pressure etc. For proper functioning of such structures, two criteria must be satisfied: (1) A pile should be safe against ultimate failure, (2) Normal deflection at working loads should be within the permissible limit. For design of such piles, a quantitative estimate of allowable inclined compressive load is needed. If a vertical pile is subjected to an inclined and eccentric load, the ultimate bearing capacity in the direction of the applied load is intermediate between that of ultimate lateral load and ultimate vertical load. When load acts vertical, it is resisted by pile through skin friction and base resistance but when load acts with inclination, the deficiency in the base resistance and to some extent in the shaft friction leads to decrease in carrying capacity of single pile. Analysis of piles subjected to inclined loading action is complicated due to large number of variables involved. Further, experimental studies on behavior of single pile subjected to inclined compressive loads are limited. The effect of angle of inclination of compressive load on horizontal deflection and vertical displacement of vertical piles of different length to diameter ratio are also rarely tested. A number of model tests have been conducted by Sharma and Pise (1994) and some other methods of analysis have been proposed by Meyerhof and Adams (1968), Chattopadhyay and Pise (1986), Rao and Kumar (1994), for the piles or anchors separately and that too in homogeneous media. The comparative study by Lianyang Zang et al. (2005) has shown that these studies produced significantly different ultimate resistance values of single as well as pile group. Behavior of vertical and batter piles subjected to inclined oblique loads have been reported by researchers like Madhusudan Reddy. K et al. (2011), Muthukkumaran et al. (2015) etc. Salini U. and Girish M. S (2009), Alice Johny and C. Prabha (2014), Jerin Wiba, V. Jeyanthi Vineetha (2014) studied the lateral load analysis results of single piles in cohesionless soils for range of soils. Their studies captured both the short pile and long pile behaviour observed for loose sands from dry state to submerged condition. The present work involves separate analysis of axial and lateral pile capacities. An attempt is made here to study the behavior of single model steel and concrete piles in cohesionless soil, subjected to varying inclined load until failure with the angle of applied load varying from 0º to 90º from the vertical axis of the pile, through an experimental model study. II. EXPERIMENTAL INVESTIGATION A. Foundation medium The foundation medium used for the study is dry sand obtained from the river Bharathapuzha in Palakkad district, Kerala, India. The physical properties of sand were determined using various laboratory experiments such as specific gravity test, density test, sieve analysis and direct shear test. The results obtained are shown in Table 1. International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 www.ijert.org IJERTV4IS110160 (This work is licensed under a Creative Commons Attribution 4.0 International License.) Vol. 4 Issue 11, November-2015 166