DIFFERENT TYPES OF RETAINING WALLS AND THEIR BRIEF NARRATIVES

GRAVITY WALLS :-- This is a simplest type of retaining wall.These walls consists of mass of concrete or masonry.Main function of mass of concrete or masonry is to provide dead weight to give stability against thrust of retained earth .The unit stresses in concrete or masonry are very low and these walls are so proportioned that there are no tensile stresses developed .Because of massive construction these retaining walls are more resistant to destructive agencies than other walls .(2) SEMI -GRAVITY WALLS :--  Gravity retaining walls require greater toe to give sufficient base width so that no tension is developed at the base .Also in gravity retaining walls fairly heavy section of stem is required .By providing some reinforcement in toe and stem ,the section of the retaining wall can be reduced.(3) CANTILEVER WALLS :-- This type of retaining wall consists of three cantilever beams --- vertical stem , toe projection and heel projection .Fillets are sometimes provided at the junction of steam with heel and toe slabs for higher walls.The resistant to sliding of a cantilever type of a retaining wall is sometimes increased by providing vertical projection known as key at the base .The key may be provided near the toe , near heel or at the middle of base ,as the case may be .(4) COUNTERFORT RETAINING WALLS :- The cantilever types of retaining walls are economical only up to height of about 6to 8 mt .However for higher walls the design of cantilever slabs ,stem and heel will prove uneconomical. Greater economy can be achieved by providing Counterforts ,as the stem and heels are not designed as cantilevers but as the continuous slabs over Counterforts and thus bending moments are reduced .However in this type of retaining walls additional concrete, Reinforcement and the form work is required for the Counterforts. Some times retaining walls with Counterforts on the side of toe , in addition to Counterforts on the side of the heel , are constructed, but these types of walls are not commonly used. (5) BUTTRESSED WALLS:--  It is similar to a Counterfort type of the wall but in this case Counterforts are placed on the front of the wall and are known as buttresses rather than Counterforts.In this type of wall heel projection is small and hence the backfill contributes less to the stability of the wall .Also buttress reduce clearance in front of the wall .These types of walls are rarely used.