Indian Geotechnical Conference IGC2016 15-17 December 2016, IIT Madras, Chennai, India 1 EXPERIMENTAL STUDY OF LATERAL LOAD-DISPLACEMENT BEHAVIOR OF PILES IN SAND Amanpreet Kaur 1 Ashish Hans 2 Amit Kumar 3 1 Associate Professor , 2,3 Undergraduate Student, Department of Civil Engineering, Rayat Bahra Institute of Engineering and Nano Technology, Hoshiarpur, Punjab – 146104. E-mail addresses: 1 preetaman_79@yahoo.com, 2 ashishhans6@gmail.com, 3 kumar124.ak@gmail.com ABSTRACT: Pile foundations are often subjected to lateral forces in addition to vertical loads. The lateral forces acting on piles may arise due to wind pressure, seismic waves, wave action in offshore structures and lateral earth pressure in earth retaining structures. Lateral displacement at the pile head is an important criterion for a successful design of pile that supports lateral load. In this paper, results observed from model tests conducted on laterally loaded piles embedded in medium dense sand are presented. The effect of variation in pile embedment length to diameter (L/D) ratio and flexural stiffness on lateral load carrying capacity of single pile was studied by varying pile embedment length and pile diameter. Stainless steel pipes have been used as model piles. The piles were kept free headed with floating tips. Various value of pile length to diameter ratio (L/D = 10, 15, 20, 25, 30 and 35) were employed in the model testing. Pile group tests were also performed for comparison with single pile. The observed results are presented in the form of lateral load displacement curves and design charts are prepared for lateral load displacement response of piles in cohesionless soils. Keywords: Lateral displacement, Lateral load, Model pile, Pile group. 1 INTRODUCTION Pile foundations are normaly used to transfer loads at greater depths when provision of shallow foundations is not feasible. These foundations are often subjected to lateral loads in addition to axial loads. Lateral loads on the pile foundations may occur due to various reasons in different conditions like earth retaining structures, harbors and offshore structures, high rise bulidings etc. For laterally loaded piles, not only the ultimate loads but also the lateral deflection is required to be known to find the working loads for design as well as to check the serviceability limits.Several analytical methods have been developed for predicting the lateral resistance of pile foundations using subgrade reaction approach [Matlock and Reese (1960)] or elastic continuum approach [Phanikanth and Choudhury (2013)] including finite element method. Also lot of experimental testing has been performed to study the pile behavior in cohesionless soils [Uncuoğlu and Laman, (2011)]. However most of the analytical methods require enormous computation time and resources. In the present work, a parametric study was carried out including model tests on laterally loaded piles in cohesionless soil in which the load displacement behavior of model piles of hollow steel circular sections embedded in medium dense sand was studied.The objectives of this study were to analyse the lateral load displacement behavior of a free head flexible pile in medium dense sand and to study the effect of variation in length to diameter (L/D) ratio on the lateral load carrying capacity of single piles. Effect of variation in flexural stiffness(EI) of the pile on lateral load capacity was also studied by changing the diameter of pile keeping other parameters constant. Comparison was also made between single pile and pile group of same L/D ratio to check the effiecieny of a 2 x 2 pile group in medium dense sand. Design charts were prepared on basis of observed results. 2 MODEL TEST AND INSTRUMENTATION 2.1 Model Test The schematic diagram of the model test arrangement is shown in Figure1. The model tests were conducted in a testing tank with internal dimensions of 0.62 m x 0.62m and 0.95m in depth. The thickness of the soil below the pile tip was kept at least seven times the pile diameter to minimize the influence of base of the testing tank. Steel pipes of external diameter 19.05mm and 25.4mm having wall thickness 0.5mm were used as model piles. Bending test of model piles was conducted to find modulus of elasticity, E which was found to be 0.87 x 10 5 N/mm 2 . Flexural rigidity (EI) of the piles was 109 x 10 6 Nmm 2 and 263.8 x 10 6 Nmm 2 for 19.05mm and 25.4mm diameter piles respectively. The dimensions of the model piles were determined by dimensional analysis using Buckingham’s Pi theorem including variables lateral displacement y, pile diameter D, pile length L, moment of inertia I, lateral load P and