ANALYSIS AND DESIGN OF REINFORCED CONCRETE STEPPED CANTILEVER RETAINING WALL

Abstract

A retaining wall is one of the most important types of retaining structures. It is extensively used in variety of situations such as highway engineering, railway engineering, bridge engineering and irrigation engineering. Reinforced concrete retaining walls have a vertical or inclined stem cast with base slab. These are considered suitable up to a height of 6m.It resists lateral earth pressure by cantilever action of stem, toe slab and heel slab. The tendency of wall to slide forward due to lateral earth pressure should be investigated and a factor of safety of 1.5 shall be provided against sliding. Cantilever retaining walls are found best up to a height of 6m.For greater heights earth pressure due to retained fill will be higher due to lever arm effect, higher moments are produced at base, which leads to higher section for stability design as well as structural design. This proves to be an uneconomical design. As an alternative to this, one may go for counter fort retaining wall, which demands greater base area as well as steel. As a solution to this difficulty, a new approach that is to minimize effect of forces coming from retained fill , short reinforced concrete members in the form of cantilever steps are cast along the stem on the retaining face. Addition of these steps would counterbalance the locally appearing forces and will result into lesser moment and shear forces along the stem. Also it will reduce the bending action that is pressure below the base. The objectives of the study are 1) To reduce the stresses on the retaining face of the cantilever retaining wall, it is proposed to introduce reinforced concrete steps along the stem. 2) Decide the most economical location of step along length and also along height of wall from number of trials. 3) Decide cross section of the R. C. step as per the stresses due to frictional forces in step. 4) Stability analysis of Cantilever retaining wall with steps for unit width will be done. Check for minimum and maximum stresses will be observed. 5) Cost comparison shall be carried out for these three different alternatives to give most economical retaining wall type.