Abstract: A parallel adit is installed for Sanlian tunnel so as to speed up the construction of the main tunnel. The construction of the parallel adit in soft surrounding rocks with trackless transportation system is slow. The influencing factors and causes for the slow construction of the trackless parallel adit in soft surrounding rocks are analyzed. The working platform, the tunneling design, the construction technology, the detail management and the encouraging methods are optimized. In the end, rapid construction of the trackless parallel adit in soft surrounding rocks is realized. The paper can provide reference for the construction of other small crosssection parallel adit with trackless transportation system in the future.

Key words: Sanlian tunnel, soft surrounding rock, parallel adit, trackless transportation system, rapid construction