Abstract: To realize safe, rapid, and highlyefficient mechanized construction of long mountainous railway tunnels using drilling and blasting methods, a case study is conducted on a tunnel project of the Hubei section of the ZhengzhouWanzhou railway. A working method of "scientific research, test verification, popularization, and application," the exploration research, and field tests of largescale mechanized construction technology of tunnels are performed. According to investigations and engineering practice, some conclusions are drawn as follows: (1) The mechanized construction method of tunnels is a systematic change based on the traditional method. (2) The traditional multibench method, passive support, and surrounding rock pressure sharing in Grades Ⅳ and Ⅴ surrounding rocks are unsuitable for the large crosssection mechanized method. (3) The key points of large crosssection mechanized construction are fast excavation, fast support, active support, and fast closure. (4) The tunnel structure design adopts the surrounding rock pressure calculation method based on the standard loose pressure, which differs from the actual situation, and can be designed according to the deformation pressure calculation method. (5) For the tunnel constructed by the large crosssection mechanized method, the advance active support system of the tunnel face and tunnel body are the keys to the surrounding rock stability near the tunnel face.

Key words: tunnel, large cross-section mechanized method, tunnel face stability factor, deformation load, active support