Flexible pipe, of woven high-strength synthetic fibres - is filled with e.g. concrete, for underground tunnel supports

A flexible pipe permeable to water in formed in order to offer support, when filled with hardening material, to underground tunnels or mine workings. The pipe is formed of high strength synthetic fibres, such as polyester or aromatic polyamide fibres, which are woven, e.g. on circular looms, and treated with a water-resistant and antistatic finish. The pipe is filled with e.g. concrete mixture, and must remain resistant to the pentration of the solid material, but must allow water to pass through as the mixture dries out. Before the concrete sets, the pipe is allows to adopt the shape of the earthworking. The pipe must be constructed to fulfill support requirements even in conditions of unexpected and excessive rockfall.