Analysis of key technology and research path of full section boring machine for 1 000 m vertical shaft with hard rock strata

At present, the drilling and blasting method in vertical shaft sinking has many problems, such as too many workers required, complicated working procedures, serious occupational injury and environmental pollution. Mechanical rock breaking is non blasting rock breaking, which is an important development direction of shaft sinking technology. Currently, there are vertical drilling rig suitable for soft formation conditions and reverse drilling rig for a passage in the lower part of wellbore. Both technologies have limited applicability, and neither penetrates beyond 1 000 meters. The drilling technology and equipment of a full section boring machine for 1 000 m deep hard rock shaft are still in the initial stage of research and development. The hard rock full section boring machine for kilometer deep vertical shaft is not only the demand of national high end equipment manufacturing, but also an important support of a step change in kilometer deep shaft sinking technology. In this paper, the development course and the present situation of shaft boring machine are described. The paper analyzes four problems of hard rock full section boring machine, such as variable formation stability of kilometer deep shaft and control of high pressure water gushing, efficient crushing of hard rock, overcoming gravity slag discharge, and change of shaft section corresponding to support. The core functional requirements of hard rock full section boring machine are put forward, such as “dry shaft boring” of formation pre modification, “combined rock breaking” of hard rock, “cooperative slag discharge” of overcoming gravity, and “intelligent diameter changing” of excavation support. Three key scientific and eight key technical problems are summarized in view of the high efficiency and reliable service requirements of the shaft boring machine under complex environment and working conditions. Among them, the scientific problems include: ① The theory of surrounding rock classification based on the in situ exploration of kilometer deep strata；② The mechanism of rock fragmentation assisted by multi knife cooperation and jet flow in large section of hard rock；③ The distribution, migration and vertical transport mechanism of rock slag in large diameter rock fragmentation face. Key technical issues include: ① The kilometers formation in situ detection, risk identification and modification technology；② The big cross section hard rock with disc cutter hob combined with water jet assisted rock technology efficiently；③ The combination of big diameter cutter machinery and fluid slag discharge technology；④ The shaft machine attitude regulation and whole machine centralized control technology；⑤ The shaft machine system coupling dynamics analysis and optimization；⑥ The parallel operation of the boring and formation modification of the shaft boring machine based on the coordination of time and space relationship；⑦ The optimal layout of the spatial cross section of the shaft based on the boring of the shaft boring machine；⑧ The temporary support with high toughness and thin injection in front of the shaft boring machine and the collaborative permanent support with excavation support. Finally, according to the scientific and technical problems, five key tasks for engineering demonstration are formulated including：① Machine shaft sinking technology and engineering adaptability；② Kilometers shaft formation in situ detection, formation lithology recognition and modification of key technologies；③ The kilometers large volume of broken rock, vertical shaft discharge with digging the key technology；④ The development of kilometer deep full cross section hard rock shaft boring mathine completely；⑤ The engineering demonstration with shaft boring machine drilling, and clearing the logical relationship among the tasks. Based on the above mentioned, the shaft boring technological system, and research and development path for 1 000 m deep hard rock full section shaft boring machine are preliminarily formulated in order to provide a reference for the safe, efficient, green and intelligent construction of kilometer deep vertical shaft in China in the future.