A seal for leaking fissures or faults of a tunnel which has a first, deformable layer with two surfaces, one of which is scalloped in vertical cross-sectional dimension and the other of which abuts a second flexible layer of more dense material such as neoprene. The surface of the second layer remote from the first layer is overlain about its periphery by strapping preferably made from steel. The seals are generally rectangular in horizontal plan and if the seal is sufficiently elongated intermediate strappings are provided between the width end straps as required. A plurality of registering apertures are provided in the first and second layers and the strapping material to receive therethrough elongated self-threading concrete screws for securing the seal into pilot holes in the tunnel surface around a leaking fissure or fault.
