Screw anchor of overlap blocks with application to sea dike slope

Abstract

     Protected slope by overlap blocks is popular types of revetments in Vietnam. However, instability of overlap blocks still occurs near the point of maximum downrush, where uplift forces are higher or wave impact. Screw anchor of overlap blocks is a new choice of protection, higher resistance against uplift and reducible displacement of revetments. Screw anchor of overlap blocks has three essentially parts: anchor head, tendon and fixed anchor. The anchor head is made from plastic with twisted slot. High tensile plastic cable is used for tendon. Fixed anchor is connected to concrete blocks. The number of anchors depend on weight of concrete blocks, wave forces and dike funtion. The equation (11) is established base on the upper and lower bound theorems of plastic collapse set limits to the collapse load of a soil structure with the principle of virtual work.