Discussion on technology and process of mechanical rock breaking and drilling in inclined shaft of high inclined pressure pipeline

With the increase of the installed capacity of pumped storage power stations, the height of the water head for power generation of the water delivery system will increase, which will inevitably require long-distance, large inclination and large-diameter pressure pipeline inclined shaft projects.However, its construction is difficult and risky, and it has become one of the key issues restricting the construction of pumped storage power stations.By sorting out the existing methods of pressure pipeline excavation for pumped storage power stations, the excavation by climbing tank method has disadvantages such as poor ventilation conditions on the surface, large personnel damage and long auxiliary working time.However, when the reverse well method is used for the expansion and drilling construction, the diameter of the pressure pipeline formed is small, and the initial formation of the broken formation cannot be effectively supported during the reverse well drilling process.In view of this, based on the shaft boring machines developed by the national“Twelfth Five-Year Plan”and“863 planning”projects, a series of studies have been carried out through equipment modification, technical research and process demonstration.Based on comprehensive analysis of the existing special directional drilling rigs and reverse drilling rig drilling technologies and equipment,a full-section mechanical drilling process for inclined shafts in the pressure pipelines of pumped storage power stations based on directional drilling rigs, reverse boring rigs, and well-boring machines is proposed.The brief process flow is as follows:① The guide hole is drilled with the technology of fixed guide hole drilling. The deviation rate of the hole can be controlled between 0.3% and 0.5%. ② The first expansion was carried out using a reverse drilling rig, and the pilot hole was used as the lower slag discharge channel to form a 2.0~2.5 m guide shaft. ③ The second expansion is carried out by using a shaft boring machine, and the guide shaft is used as the lower slag discharge channel.This “three-machine step-by-step”construction process can meet the construction requirements of inclined shafts with an inclination angle of 50°～90°, a length of less than 800 m, and the maximum diameter of 5.8 m. The mechanical rock breaking method reduces the disturbance and damage to the surrounding rock of the inclined shaft, which is beneficial to guarantee the stability of the surrounding rock, and can realize the efficient mechanical rock drilling of large inclined, long distance and large diameter inclined shafts.To promote the mechanized, unmanned, and intelligent development of well construction technology and equipment.