IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 __________________________________________________________________________________________ Volume: 03 Special Issue: 06 | May-2014 | RRDCE - 2014, Available @ http://www.ijret.org 110 PERFORMANCE OF SQUARE FOOTING RESTING ON LATERALLY CONFINED SAND A. Krishna 1 , B. Viswanath 2 , Nikita Keshav 3 1 Asst. Professor, Department of Civil Engineering, University Visvesvaraya College of Engineering, Bangalore, Karnataka, India, 2 Asst. Professor, Department of Civil Engineering, University Visvesvaraya College of Engineering, Bangalore, Karnataka, India 3 Former ME Student, Department of Civil Engineering, University Visvesvaraya College of Engineering, Bangalore, Karnataka, India Abstract The load carrying capacity of a model square footing resting on sand has been studied. Footing is confined laterally with the help of mild steel plates welded to form a hollow box of different depths. The effect of embedment depth of footing on the load carrying capacity and settlement values has been studied. Varying depth of confinement, relative density, embedment depth of footing ratio was utilized. Based on the results obtained, load versus settlement curves are plotted and it is observed that, as the depth of confinement increases, the load carrying capacity of the footing also increases. Keywords: Sand, Mild steel Hollow Box and Relative Density ----------------------------------------------------------------------***------------------------------------------------------------------------ 1. INTRODUCTION A shallow foundation is one that is located at, or slightly below, the surface of the ground. A typical foundation of this type is seen in the shallow footings, either of plain or reinforced concrete, which may support a building. Footings are generally square or rectangular. Long continuous or strip footings are also used, particularly beneath basement or retaining walls. Another type of shallow foundation is the raft or mat; it may cover a large area, perhaps the entire area occupied by a structure. India has seen increasing growth in infrastructure development in the last decade. The decreasing availability of good construction sites is forcing engineers to utilize even the poorest sites with weak subsoil conditions. The poor ground conditions pose the problem of low shear strength leading to low bearing capacity as well as high compressibility resulting excessive settlements occurring over long periods of time. The presence of large deposits of weak soil of varying nature has necessitated the development & application of various ground improvement techniques. The confinement material can be of different types. One such common type used in improving the bearing capacity of soil or sand is cellular confinement systems. Cellular Confinement Systems (CCS, also known as geocells) are widely used in construction for erosion control, soil stabilization on flat ground and steep slopes, channel protection, and structural reinforcement for load support and earth retention. Typical cellular confinement systems are made with ultrasonically- welded high-density polyethylene (HDPE) or Novel Polymeric Alloy (NPA) strips that are expanded on-site to form a honeycomb-like structure which may be filled with sand, soil, rock or concrete. Laboratory plate loading tests on geocells showed that the performance of geocell-reinforced bases depends on the elastic modulus of the geocell. The geocell with a higher elastic modulus had a higher bearing capacity and stiffness of the reinforced base. Geocells made from NPA were found significantly better in ultimate bearing capacity, stiffness, and reinforcement relative to geocells made from HDPE. The effect of sand confinement on the behaviour of shallow foundations has been investigated through loading confined sand specimens, testing foundation models resting on laterally or vertically confined sand. Much literature is available is this; some of them are listed below. Centrifuge tests were conducted Kutter, B.L., Abhari, A., and Cheney, J.A in 1988, on concentric loading of circular footings on dense sand. Results concluded that except for 1-g test, all three methods of determining the strength parameters appear to yield adequate predictions of bearing capacity. De Beer’s method and the newly proposed c-ф method give excellent agreement between predicted and measured bearing capacities. Experimental study concerning a method of improving the bearing capacity of strip footing resting on sand subgrades utilizing vertical nonextensible reinforcement were studied by M.A.Mahamoud and F.M.Abdrabbo in 1989. Results concluded that utilizing nonextensible reinforcing elements installed along each side of a strip footing was found