Design methods for pile supported basal reinforced embankments over soft clay

The piled embankment technique allows the time bound construction of high embankments with subsequent control of post construction settlements. A polymer based basal reinforcement is often used to span across the pile tops to distribute the load and maximize the economic benefits of piles installed in soft foundations. There are different methods for the design of piled embankments viz. BS 8006 Method, Russell Design Method, Empfehlung 6.9(Kempfert et al.) Method. BS 8006 assumes that all of the embankment loading will be transferred to the piles down to a firm stratum through the basal reinforcements. In the Russell design method a parameter called stress reduction ratio is defined as the average stress at the base of the embankment between the pile caps relative to the stress at the base of the embankment with no piles present. The Russell design method allows for both primary and secondary reinforcement to be installed. The third method is the German recommended procedure for designing embankments over piles. This design method calculates the tension in the reinforcement using the theory of elastically embedded tension membranes. The support from the subsoil is also considered in terms of the modulus of subgrade reaction. The present paper is an attempt to make a comparison between the three methods and to suggest the adaptability of each method in specific situations.