Analysis and design of retaining wall having reinforced cohesive frictional backfill SATYENDRA MITTAL 1 , K. G. GARG 2 and SWAMI SARAN 1 1 Department of Civil Engineering, Indian Institute of Technology, Roorkeee 247667, India 2 Central Building Research Institute, Roorkeee 247667, India (Received 27 May 2004; revised 7 October 2004; accepted 20 October 2004) Abstract. The case of a rigid wall with inclined back face retaining reinforced cohesive- frictional backfill subjected to uniformly distributed surcharge load has been analyzed using limit equilibrium approach. The analysis considers the stability of an element of the failure wedge, which is assumed to develop in the reinforced earth mass adjoining the back face of wall. The non-dimensional charts have been developed for computing the lateral earth pres- sure on wall and the height of its point of application above the base of wall. The theoretical findings have been verified by model tests on a rigid wall retaining a dry cohesive-frictional soil reinforced by geogrid strips. Experimental results are in good agreement with the theoretical predictions. A design example has been included to illustrate the design procedure. Key words. cohesive-frictional soil, geogrid, inclined backface, retaining wall, uniform surcharge. 1. Introduction Construction of reinforced earth wall is becoming popular in many countries. In this type of wall the reinforcing strips are connected to the wall (Figure l). The length of such strips lies generally in the range of 0.8–1.2 times the height of wall. The lateral thrust on the wall facing is almost eliminated due to the development of soil-rein- forcement interface friction and bearing. However, there may be locations where the space behind the wall is limited and may not permit the use of designed length of reinforcing elements (Figure 2). Such situations can conceivably arise on narrow hill roads on unstable slopes. Any attempt to increase the space, behind wall facing, to accommodate the reinforcing strips may seriously undermine the stability of the hill slope and also that of road located up the slope. In such circumstances a retaining wall with reinforced backfill may appear more appropriate. This technique consists of a rigid wall retaining backfill reinforced by reinforcing elements not tied/con- nected to the wall backface (Figure 3) and is considered appropriate and acceptable to Indian conditions. In this type of construction, the earth pressure on the wall is reduced significantly. The reinforcing material can even be bamboo strips. Hence there are economic benefits due to elimination of fixtures, use of cheaper reinforcing materials and a significant reduction in the level of skilled labour requirement. Some studies on the performance of rigid wall with reinforced backfill are reported in the literature. Talwar (1981), Garg (1988) and Khan (1991) developed analytical Geotechnical and Geological Engineering (2006) 24: 499–522 Ó Springer 2006 DOI 10.1007/s10706-004-5153-9