Effect of Adjacent Axle Loads on Uplift of Rails on Geocell-Stone Column Improved Tensionless Foundation
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ORIGINAL PAPER
Effect of Adjacent Axle Loads on Uplift of Rails on GeocellStone Column Improved Tensionless Foundation Shashank Bhatra . Priti Maheshwari
Received: 26 November 2019 / Accepted: 28 August 2020 Ó Springer Nature Switzerland AG 2020
Abstract Rails resting over tensionless or unilateral foundation (responds to compressive forces only) has an uplift tendency ahead and behind the applied load. The presence of train of loads on such foundations may result in greater upward deflection of the rail. The current study investigates this possibility for rails on geocell-stone column improved tensionless foundations. Lumped parameter modelling approach has been used to idealize the rail on reinforced foundation. Granular layer has been placed between two infinite beams, one representing the rail and other the geocell with infill soil, and modelled as Pasternak shear layer. Stone columns and soft foundation soil beneath the beams have been idealized by Winkler springs of different stiffnesses. Mathematical model in the form of governing differential equations has been developed with due consideration to damping in the system. Finite difference method in combination with Gauss– Seidel iterative scheme has been used to arrive at their solution based on employed loading and the boundary conditions. Effect of adjacent axle loads and inclusion of stone columns on the response of the rail has been S. Bhatra Department of Civil Engineering, NIT Uttarakhand, Srinagar (Garhwal) 246 174, India e-mail: [email protected] P. Maheshwari (&) Department of Civil Engineering, Indian Institute of Technology Roorkee, Roorkee 247667, India e-mail: [email protected]
investigated. Influence of variations in input parameters of soil-foundation system has been studied in detail and presented in the form of non-dimensional charts along with a sensitivity study. Keywords Geocell Stone columns Moving loads Double beam model Tensionless foundation
1 Introduction Lack of proper ground due to rapid expansion of urban areas has led to increased use of ground improvement techniques in railroads and highways during the last few decades. Soil-reinforcement using prefabricated vertical drains (PVD), stone columns and geosynthetics in various forms like geocell, geotextile etc. has become widely popular in the field of transportation geotechnics on account of their environmental feasibility and simple application. Inclusion of geocell layer reduces differential deformations of ground and its performance has been found to be superior as compared to other available geosynthetic reinforcements (Dash et al. 2004; Latha et al. 2010). It behaves as a stiffer reinforcement with finite flexural stiffness and supports even distribution of loads (Raymond 2002; Indraratna et al. 2015). For application of geocell mattress in railways and roadways, several numerical and experimental studies
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Geotech Geol Eng
have been carried out in the past (Cowland and Wong 1993; Fakher and J
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