Surface control techniques for tunnels in karst areas under airport taxiways

Under the conditions of karst development and soft upper and hard lower strata, ground-settlement control for tunnels under airport taxiways is stricter than for ordinary tunnels. Tunnel construction methods and karst disposal measures are also important. These are engineering problems that need to be solved urgently to ensure the safe passage of tunnels under airport taxiways. Taking the intercity railway tunnel under taxiways T3 and T4 of Guangzhou Baiyun international airport as a case study, theoretical analysis and field tests on karst treatment measures and ground-settlement control measures were conducted. Karst treatment measures and a pile support plate (PSP) structure have been proposed to support the taxiways. The effect of the system was analysed numerically method and on-site surface settlement was monitored. The maximum monitored settlement of T3 and T4 taxiway surfaces was 5.90 mm and the differential settlement was 0.12‰. The numerical results provided a similar value and did not exceed the settlement control standard for airport taxiways. The key technologies for the construction of tunnels under airport taxiways in karst areas and upper soft and lower hard strata are presented, karst disposal measures are summarised and the PSP protection system is described. The results provide reference information for similar projects.