Permissible Water Leakage in Road and Railway Tunnel

Given that water infiltration into tunnel resulted in damage of tunnel construction equipment¡ personnel and tunnel construction process¡ tunnel designer must determine the amount of water infiltration volume into tunnel before the construction of tunnel began. Knowing the water infiltration volume could be effective in choosing appropriate tunnel boring technic and designing tunnel support and drainage method. According to various studies¡ water has the main source of tunnel detoriation in serviceability stage while the water proofing method used in these tunnels. Experience shows that construction tunnel lining with complete waterproofing are expensive and sometimes it is not practical. So¡ depending upon the use of subsurface facility¡ the permissible leakage defined and this permissible amount of water collected by the drainage systems and conduct to out of tunnel. There are many factors that affect the permissible water leakage. Also in the most of tunnel standards and guidelines¡ the permissible water leakage suggested. If we use standards with high safety factors¡ then we must use expensive material¡ needs more time and high experienced supervisor. In this paper¡ the permissible water leakage based on different standards in road and railway tunnel presented. In our country¡ there is no standard that proposed permissible water leakage. So the permissible water leakage determined based on personal experience and this caused conflict between contractor¡ supervisor and employer.