Proceedings of Indian Geotechnical Conference December 15-17, 2011, Kochi (Paper No. Q-087) GRAVILOFT RETAINING WALL: A CASE STUDY R. J. Balwan, HOD, Govt. Polytechnic, Kolhapur, [email protected] Ajitkumar Kumbhar, Manager, C.E.C.M., M V M Ltd, Pune, [email protected] ABSTRACT: Earth retaining structures cost is major cost in any infrastructural developmental project. Saving in earth retaining structure influences the project cost. The use of gravity wall coupled with loft gives excellent combination, resulting into about 40% cost saving. This has further advantages as no new material required, reduced foundation width, uniform foundation pressure, no skilled labour required, speedy construction, material saving, etc. An attempt has been made to work out the cost of construction of “Graviloft wall” and “RCC Cantilever and Gravity wall”. The comparison clearly indicates a considerable reduction in the cost of construction. INTRODUCTION ‘Retaining Structure’ is an indispensable feature of any civil construction projects. Traditionally, Gravity Retaining wall, Cantilever Retaining wall, Counterfort Retaining wall, Buttress Retaining wall and Reinforced Earth walls are adopted to retain soil at a slope steeper than that it would naturally assume. It is noticed that the cost of earth retaining structure is major one and therefore any saving in earth retaining structure influences the project cost. GRAVILOFT TECHNOLOGY Gravity retaining wall have limitations due to their bulky section and higher cost. RCC cantilever retaining wall also not cost effective for more height. The Graviloft technology is essentially a marriage of Gravity Wall and R.C.C. wall effected by the provision of a loft. In this concept the good points of the gravity walls and R.C.C. walls are brought together so as to save the resources. In this innovation, time tested materials are used and the retaining wall which is essentially gravity structure provided with reinforced loft, which is built into it. The placement, geometric configuration and the design of the loft is through optimization. CASE STUDY The site under consideration is Mahindra Vehicle Manufacturers Ltd., Chakan Industrial Area, Pune. This type of wall is extensively used at different locations within the site area. For the present study a wall of 6.0m height is considered for cost comparison. The cost worked out for Cantilever wall section, Gravity wall section and Graviloft wall section. Cantilever R.C.C. Wall The total height of wall is 6.0m and base width of 4.2m. The section is shown in Fig.1. The cost worked out per running meter length of wall in rupees as : Item Qty. Rate Amount Excavation 28.8 m 3 659 18979.2 PCC 0.44 m 3 4761 2094.84 RCC 4.68 m 3 5615 26278.2 Reinforcement 281 Kg 48.39 13598.71 Total = 60950.95 Gravity Wall The total height of wall is 6.0m and base width of 4.1m. The section is shown in Fig.2. The cost worked out per running meter length of PCC wall in rupees as : Item Qty. Rate Amount Excavation 28.2 m 3 659 18583.8 PCC 0.41 m 3 4761 1952 Plum concret 10.85 m 3 3485 37812.2 Total = 58348.06 Graviloft Wall The total height of wall is 6.0m and base width of 1.8m. The section is shown in Fig.3. The cost worked out per running meter length of PCC wall in rupees as : Item Qty. Rate Amount Excavation 12. m 3 659 7908 PCC 3.85 m 3 4761 18329.8 RCC loft 0.84 m 3 5615 4716.6 Reinforcement 22.46 Kg 48.39 1086.9 Total = 32041.38 For comparison PCC of M15 grade, RCC Concrete M20 grade considered. However, items like disposing excavated material, back filling, shuttering, expansion joint and weep holes are not considered. 1068