Disc Cutter Application in Beishan Project

Project Name: Beishan Underground Laboratory Tunnel Project

Cooperating Unit: China Railway 18th Bureau Tunnel Engineering Co., Ltd.

Application Period: January 2023 to May 2024

Project Description: The key main project of China's Beishan Underground Laboratory—the spiral inclined shaft project, with a total length of about 7.2 kilometers, a tunnel diameter of 7.03 meters, and passes through intact extremely hard granite. The tunnel is spirally excavated down to a depth of 560 meters underground through an "eight-segment straight line + seven-segment curve" linear structure, with a maximum slope of 10%. The saturated uniaxial compressive strength of the rock is 108MPa-217MPa. Based on the exposed geological conditions, the current uniaxial saturated compressive strength of the surrounding rock is around 150MPa-200MPa.

The TBM cutterhead is designed with 55 disc cutters, including 8pcs of 18-inch center twin disc cutters and 47pcs of 20-inch single disc cutters. The positions S9—S15 are equipped with 15mm-blade-wide disc cutters, totaling 7pcs. The positions S16—S25 are equipped with 17mm-blade-wide disc cutters, totaling 10pcs. The positions S26—S55 are equipped with 19mm-blade-wide disc cutters, totaling 30pcs. The spacing between the face cutters is 60mm. The disc cutters used is a new type of extremely hard rock cutter developed by Litian Heavy Industry Machinery Co., Ltd. 

The project applied the "new extreme hard rock cutter" developed by Litian, achieving good results. A kind of disc cutter suitable for excavation under extremely hard rock geological conditions was designed based on the geological characteristics of this project. The new cutter's rock-breaking ability reaches 200MPa. Under extremely hard rock conditions of 180MPa, the cutter's lifespan reaches 390 meters, with an average bearing operation time of 550 hours. The stability of the cutter is quite good, and the selected domestic bearings can completely replace Timken bearings. The successful application of related technologies has saved equipment, materials, and labor costs for this project, with good prospects for promotion and application under similar geological conditions.