The 12 th International Conference of International Association for Computer Methods and Advances in Geomechanics (IACMAG) 1-6 October, 2008 Goa, India An Analytical Approach to Lateral Capacity of Rigid Pile in Layered Soil Using Kinematics and Hyperbolic Model V. Padmavathi, M. R. Madhav, E. Saibaba Reddy Geotechnical Engineering, J. N. T. U. College of Engineering, Kukatpally, Hyderabad, Andhra Pradesh, India. Keywords: Layered, Kinematics, Hyperbolic, Lateral, Pile ABSTRACT: In this paper, an approach based on kinematics and non-linear subgrade (hyperbolic) response has been developed to study the load-displacement response of a single rigid free-head pile in layered sands. The analysis carried out in non-dimensional terms, allows general qualitative conclusions to be drawn from the results. A soil system consisting of any number of layers may be analysed with this technique, but results for only a two layer system are presented in this paper. 1 Introduction The lateral load capacity of a pile is important for the design of the superstructures. The ultimate lateral capacity of a rigid pile depends on the ultimate resistance offered by the surrounding soil, the pile flexibility, pile head and tip conditions, etc. Several methods are currently available for the prediction of the ultimate lateral capacity of single pile in cohesionless soils. (Matlock and Reese, 1960, Broms, 1964, Reese et al., 1974, Poulos and Davis, 1980, Meyerhof et al., 1981, Meyerhof and Sastry, 1985, Prakash and Kumar, 1996, Prasad and Chari, 1999, Patra and Pise, 2001, Shen and Teh, 2004, Zhang et al., 2005, Padmavathi et al., 2007). Except for the last, all the above studies consider only the fully plastic state of the soil with no consideration of the kinematics of pile movement. Therefore, the predictions based on most of these methods result not only in different ultimate capacities, but also differ from the actual values, because the ultimate capacity of a laterally loaded pile is dependent on the kinematics and the non-linear response of the soil. Information about the lateral behaviour of piles in layered soil profiles is very limited. Poulos (1985) gave dimensionless solutions for ultimate lateral capacity of a pile in two layered cohesive soil profile. Davisson & Gill (1963), Lee and Karunaratne (1987), Reese et al. (1981), Georgiadis (1983), Lam and Law (1996), Yang et al. (2005) presented work on laterally loaded piles in layered soils. The prediction of the ultimate lateral load capacity of a single rigid free-head pile in a two layer cohesionless soil system based on kinematics and non-linear subgrade reaction is presented in this paper. The analysis can easily be extended to multi-layered systems. The analysis quantifies the effect of stiffening of the surficial or upper soil deposit has, in reducing lateral deflections of a laterally loaded pile. 2 Statement of the Problem A rigid pile of embedded length, L, and diameter, d, is acted upon (Fig. 1(a)) by a lateral force, H, at an eccentricity, e, creating a moment, M (= H.e) at ground level. The pile is embedded in a two layered soil system. The depths of upper and lower layers are L 1 and L 2 respectively. Modulus of subgrade reactions, k s1 and k s2, unit weight of the soils, γ 1 and γ 2 , angle of internal friction of the soils, φ 1 and φ 2 are respectively the properties of the two layers. The pile is unrestrained and rotates through an angle, θ, about a point ‘O’ at depth, z 0 , from the ground surface. For rigid pile failure, two situations may arise, the point of rotation may lie (i) in the lower layer, i.e. z 0 > L 1 (Fig. 1(b)) or (ii) in the upper layer, i.e. z 0 < L 1 (Fig. 1(c)). In both the cases the displacements vary linearly with the depth. The lateral response of the soil on to the pile is represented by a non-linear Winkler type response with 3086