Abstract: The aim of this study is to analyze the applicability of singlecantilever tunneling machines in shallowcovered tunnels adjacent to existing buildings and largesection railway tunnels. Studies regarding comparison and selection of nonblasting excavation methods are conducted along with investigation of the surrounding environment and lithology of the surrounding rocks, numerical simulation, and field test of New Hongyan tunnel on ChengduChongqing highspeed railway crossing underneath underground shopping mall. Following conclusions are drawn: (1) The singlecantilever tunneling machine can decrease the construction disturbance on surrounding rocks and buildings, considerably affecting the deformation control and construction safety. (2) The excavation efficiency of singlecantilever tunneling machine is high in surrounding rocks with a strength of approximately 30 MPa. (3) The singlecantilever tunneling machine costs much more than the conventional tunneling machine, and it costs almost the same in Grade Ⅳ and Ⅴ surrounding rocks. (4) The excavation of a singlecantilever tunneling machine is subject to restrictions of tunnel crosssection size and safe step pitch control, leading to complex excavation procedures and low tunneling efficiency. The machine is recommended for shortdistance excavation in delicate construction sites of special environments. Longdistance tunneling requires further optimization of the excavation method system of singlecantilever tunneling machine, as well as dust control measures in the environments mixed with sandstone and mudstones.

Key words: railway tunnel, adjacent existing structures, nonblasting excavation, mechanical adaptability, singlecantilever tunneling machine, numerical simulation, field test