Field mechanical tests and analyses of partition walls in unequal-span four-arch tunnels

Based on the Guanyinyan unequal-span four-arch highway tunnel project in Changsha, a typical section is selected to test and analyze the internal forces of the partition walls during the whole construction process of two main caverns and two auxiliary caverns so as to obtain their mechanical characteristics under frequent disturbances caused by excavation of multiple caverns. The results show that the stresses of the partition walls of the four-arch tunnel are most affected by the excavation of adjacent firstly-excavated caverns, and less influences on them are caused by the excavation of non-adjacent caverns. The partition wall in the middle is subjected to greater loads than those at both sides, and it is more obviously affected by the construction disturbances. The safety of each partition wall structure during the whole construction process meets the specification requirements, indicating that its structural design and construction measures are reasonable. The research results provide reference for the design and construction of multi-arch tunnels under complex conditions.