It is common in underground structures, such as tunnels, mines and large buildings with subterranean foundations, to require that the structures be watertight. Thus, it is essential to prevent groundwater from contacting the porous portions of structures or joints, which are typically of concrete. It is also essential to remove water present in the voids of such concrete as such water may swell during low temperatures and fracture the concrete or may contact ferrous portions of the structure, resulting in oxidation and material degradation. Therefore, devices have been developed for removing water from the concrete structure and for preventing water from contacting the concrete structure.
Attempts at removing groundwater from the concrete structure have included a permeable liner and an absorbent sheet. Both absorb adjacent water, carrying it from the concrete structure. This type is system is limited, however, because it cannot introduce a fluid or gaseous substance to the concrete and as the water removed is only that in contact with the system. Additionally, this system does not provide a waterproof barrier.
Among attempts at preventing water from contacting the concrete structure has been the installation of a waterproof liner between a shoring system and the concrete form. This method fails if the waterproof liner is punctured with rebar or other sharp objects, which is common at construction sites. In such an occurrence, it may be necessary for the concrete form to be disassembled so a new waterproof liner may be installed. Such deconstruction is time consuming and expensive. It would therefore be preferable to install a system that provides a secondary waterproof alternative, should the initial waterproof layer fail. Additionally, attempts at preventing water from contacting a concrete structure have included installation of a membrane that swells upon contact with water. While this type of membrane is effective in absorbing the water and expanding to form a water barrier, this type of membrane is limited in its swelling capacity. Therefore, it would be preferable to provide a system that is unlimited in its swelling capacity by allowing a material to be added until the leak is repaired.
Another attempt to resolving this problem was disclosed in “Achieving Dry Stations and Tunnels with Flexible Waterproofing Membranes,” published by Egger, et al. on Mar. 2, 2004, which discloses a flexible membrane for waterproofing tunnels and underground structures. The flexible membrane includes first and second layers, which are installed separately. The first layer is a nonwoven polypropylene geotextile, which serves as a cushion against the pressure applied during the placement of the final lining where the membrane is pushed hard against the sub-strata. The first layer also transports water to the pipes at the membrane toe in an open system. The second layer is commonly a polyvinyl chloride (PVC) membrane or a modified polyethylene (PE) membrane, and is installed on top of the first layer. The waterproof membrane is subdivided into sections by welding water barriers to the membrane at their base. Leakage is detected through pipes running from the waterproof membrane to the face of the concrete lining. The pipes are placed at high and low points of each subdivided section. If leakage is detected, a low viscosity grout can be injected through the lower laying pipes. However the welding and the separate installation of the first and second layers make this waterproof system difficult to install, thus requiring highly skilled laborers.
It would therefore be advantageous to provide an in-situ multi-layered device for post-installation concrete sealing, and more particularly a providing a medium for post-installation injection of waterproofing resin.