Abstract: To ensure rapid and safe railway tunnel crossing coalrich stratum without gas outburst, the outburst prevention specification of 〖WT５《TNR#I》〗Technical Code for Railway Tunnel with Gas〖WT５《TNR》〗 (2019) and the technological characteristics of rotary jet grouting pile are investigated. In addition, a new construction method for rapid outburst prevention of rotary jet grouting pile is proposed based on the blocking and releasing method. First, the proposed method is studied with respect to the advance comprehensive gas outburst prevention and tunnel face gas outburst prevention. Second, a case study is performed on the gas outburst prevention of Oujiawan highgas tunnel on XuyongBijie railway, and a multischeme design of the pile diameter and the number of gas release holes is developed for the proposed method. Finally, the proposed method is compared with the traditional gas drainage method from the perspectives of construction cost and time. The results reveal the following: (1) The highstrength jet grouting pile reinforces the geological structure of the coal seam on the contour lines of the gas outburst prevention area, isolates the coal outside the enclosure pile, and cuts off the way of coal and gas outburst extending the pile. (2) The gas outburst prevention range can be significantly reduced by releasing gas through geological drilling holes inside the enclosure pile. (3) Compared with the traditional gas outburst prevention methods, the number of releasing holes inside the enclosure pile and the total length of geological drilling holes of the recommended method are reduced by 4/5~ 2/3 and 13%~22%, respectively, and the construction cost is increased by only 1.7% ~10.5%, which is safe and efficient.

Key words: coal and gas outburst, railway tunnel, coal stratum, rotary jet grouting enclosure pile, comprehensive outburst prevention