DEEP AND EXTRA DEEP DIAPHRAGM WALLS IN SHANGHAI – INCREASING DEMAND FOR INFRASTRUCTURE IN MEGACITIES DRIVES THE REQUIREMENT OF INCREASING DEPTH FOR DIAPHRAGM WALLS

摘要

Diaphragm walls (D-walls) are known as underground structural elements commonly used for retentionsystems and permanent foundation elements. In addition, they are also quite often used as deepgroundwater barriers, called Cut-Off-Walls (COW).Shanghai ranks third among the most densely populated metropolises in the world. In 1990, only eightmillion people lived there. Today, Shanghai has about25 million inhabitants.The increasing demand to accommodate the infrastructure of growing megacities like Shanghai pushesthe required depth for subway, sewage and foundation projects to the limit.Future projects will demand excavation depths of more than 100 m (328 ft) on a regular basis.Already carried out reference projects will be described and a general outlook for upcoming projects willbe given.The paper also explains the installation process in general focusing on the use of trench cutter technology.