| With the rapid urbanization in China, urban NATM tunnels become the main development tendency of urban transportation. Due to influence on environment, ground water cannot be discharged unrestrainedly in urban tunnels. The key issue of urban NATM tunnels is to find a waterproof and drainage mode that can satisfy the requirement of safety and environment both..A will-be-built highway tunnel in the downstream of Shenzhen reservoir was used as background support. Based on relevant literature and fluid-solid coupling mechanism, Seepage and mechanical characteristics of the urban NATM tunnel with different waterproof and drainage mode were analyzed through finite difference software (FLAC3D). Theoretical derivation was conducted to study the influence upon environment by tunnel drainage. The main contents and results are listed as follows:(1)Data on domestic and foreign urban NATM tunnels’ waterproof and drainage mode was collected and studied. The waterproof and drainage modes suitable for urban NATM tunnels, along with their characteristics, were summarized.(2)There representative sections of the will-be-built highway tunnel with different waterproof and drainage mode were modeled. The seepage field of surrounding rock mass, the pore water pressure behind the second lining, the stress of the second lining, the displacement of second lining and water discharge were obtained(3)The environment effect of tunnel were analyzed and concluded into three aspects: vegetative cover, water quality and ground settlement. Water table was chosen as the index to evaluate tunnels’ influence on environment. According to Dupuit Hypothesis, the relationship between water table and water discharge was deducted.(4)The structural force of the tunnel and the water table caused by the tunnel with different waterproof and drainage mode were compared. The appropriate waterproof and drainage mode was proposed based on different sections. |
