Cavidrain: An efficient combined drainage and waterproofing liner for tunnels.

It was Karl Terzaghi’s view that the worst problems of tunnelling could be traced to the presence of water. The need to control water via suitable drainage is a fundamental in tunnel engineering. Solutions utilising crushed stone and pipes or by completely sealing a tunnel against external water pressure.

Tunnels by their nature are linear and relatively inaccessible to construction traffic requiring careful and often costly phasing to allow optimum transport of construction materials along their length. Engineers are looking for innovative ways to reduce excavation and importing of raw materials for environmental and cost reasons. Geocomposite drainage systems can save space and time resulting in lower cost and less environmental impact and even address challenges such as calcification which clogs both stone and pipe systems.

This webinar will illustrate methods of construction including case studies of successful installations. These specially developed geocomposites have been tested to withstand installation and in service static and dynamic loadings. Each project has a series of detailing challenges and illustrations of how some of these were solved in partnership with the manufacturer will be described.

Key learnings:

• Learn new methods of shallow dig drainage systems within tunnels

• Understand the cost and environmental savings over and above traditional methods used

• Show installation and some detailing via use of high profile case studies

• Understand the superior performance criteria for in service and maintenance