Effect of confining pressure on rock breaking by high-pressure waterjet-assisted TBM  

作　　者：Chen Xu Yujie Zhu Xiaoli Liu Fei Chen Min Zhu Enzhi Wang Sijing Wang 

机构地区：[1]School of Resource and Environment Engineering,Wuhan University of Technology,Wuhan 430070,China [2]Changjiang Institute of Survey,Planning,Design and Research,Wuhan 430010,China [3]State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084,China [4]Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources,Wuhan 430010,China

出　　处：《Underground Space》2024年第5期151-161,共11页地下空间（英文）

基　　金：supported by Hubei Provincial Natural Science Foundation of China(Grant No.2022CFB673);the Open Research Fund Program of the State Key Laboratory of Hydroscience and Engineering,China(Grant Nos.sklhse-2022-C-04 and sklhse-2022-D-01).

摘　　要：High-pressure waterjet-assisted tunnel boring machine(WTBM)is an efficient method for improving the tunneling performance of a tunnel boring machine(TBM)and reducing the wear of its disc cutters in hard rock with high geostresses.Confining pressure directly affects the efficiency of rock breaking and the configuration of the disc cutters.In this study,we evaluated the effect of confining pressure on WTBM rock breaking by developing a self-designed and manufactured experimental system,including confining pressure loading,TBM disc-cutter penetration,and high-pressure waterjet.The macro fracture,acoustic emission(AE),peak normal force drop,and specific energy(SE)were analyzed for four different confining pressures(10,20,30,and 35 MPa).The results showed that the cutting depth of the waterjet increased linearly as the waterjet pressure increased and decreased with the gradual increase in the nozzle moving speed.The expansion and development of cracks formed rock debris,and the size of the rock fragments decreased with an increase in confining pressure.When the waterjet pressure was 280 MPa,the nozzle moving velocity was 800 mm/min and the kerf space was 75 mm,which indicated that the confining pressure,which was 23.16 MPa,minimized the cutting SE under this condition.However,regardless of the confining pressure,the maximum normal force of WTBM was less than that of a TBM,whereas the SE of WTBM was less than that of complete TBM cutting mode(CTCM).The average force drop and average drop rate of SE were approximately 25%,and 80%,respectively.The results of this study can inspire the design and mechanism of a TBM assisted by a high-pressure waterjet.

关 键 词：Waterjet Tunnel boring machine(TBM) Confining pressure Specific energy Force drop 

分 类 号：U45[建筑科学—桥梁与隧道工程]