1467 RESEARCH ON TECHNOLOGY AND EQUIPMENT SYSTEM OF LARGE DIAMETER SHAFT DRILLING BASEDON GRAVITY SLAGGING Liu Zhiqiang1,2, *Song Zhaoyang1,2, Cheng Shouye1,2, Jing Guoye1,2, Zhao Junxian3, Chen Yun4 , Zhao Like5 1.Beijing Coal Mine Construction Company Ltd., Beijing 100013, China, (*Presenting author:liuzhiqiang@vip.sohu.com) 2.National Engineering Research Center of Deep Shaft Construction, Beijing 100013, China; 3.Jiangsu Hexin Petroleum machinery Corporation Limited, Yancheng 224200, Chinaa; 4.Ningxia Tiandi Benniu Industrial Group Co., Ltd., China Coal Technology and Engineering Group, Yinchuan 750001, China; 5.Inner Mongolia YitaiGroup Co., Ltd., Ordos 017000, China） ABSTRACT Aiming at the problems of low efficiency and poor collaborative operation performance of the traditional skip slag removal technology, the adoption of the gravity-driven slag discharge process has become an important development direction to improve the drilling efficiency of large-diameter shafts. This process involves the preconstruction of a pilot shaft, allowing the crushed rock slag to fall directly to the lower level under the action of gravity before being mechanically loaded and transported. This paper systematically analyzes the limitations of the positive and negative circulation upward slag removal technologies applied in mechanical rock-breaking drilling, expounds the current development status of gravity-driven slag discharge technologies including raise boring, direct upward drilling, and pilot shaft-based shaft boring machines, summarizes the key technical challenges such as hard rock fragmentation, drilling tool reliability, deviation control, and intelligent drilling, sorts out the processes and equipment such as pilot hole drilling, drill-blasting enlargement, raise boring with forward drilling reaming, and one-pass shaft forming, and constructs an integrated multi-process shaft construction system. This technology can provide important technical support for the mechanized and intelligent construction of large-diameter shafts in fields such as coal mining, metal mining, hydropower, and transportation engineering. KEYWORDS Wellbore; Mechanical Rock Breaking; Gravity Slag removal; Raise Boring machine; Wellhead Machine 1. INTRODUCTION The exploitation of mineral resources by the underground mining method first requires the construction of a mine entry development system in the stratum, including vertical shafts, inclined shafts, roadways, chambers, blind vertical shafts, blind inclined shafts, panel roadways, ore passes and other engineering structures. Among them, shafts and main haulage roadways serve the entire life cycle of mine production, while panel roadways, ore passes and other works are only limited to the ore mining stage of the panel. In recent years, shaft engineering and construction technologies, which have evolved from the field of mineral mining, have now been extended to the construction of vertical or inclined shaft projects in fields such as urban underground space development, hydropower, transportation, large-scale scientific experiments and national defense. In accordance with past conventions, shaft sinking by drilling rigs, shaft sinking by artificial ground freezing, and shaft sinking by surface pre-grouting are defined as special shaft sinking methods. However, due to the limitations of rock-breaking tools and equipment capabilities, shaft sinking by drilling was previously only applicable to water-rich soft alluvial strata. Shaft sinking by freezing reduces the temperature of the stratum around the shaft, converting liquid water into solid ice, temporarily improving the overall strength of the stratum and preventing groundwater from flowing into the shaft during excavation, which can be redefined as a physical stratum modification method. Shaft sinking by grouting mainly refers to the surface pre-grouting process, that is, before shaft excavation, cementitious materials are injected into the unfavorable strata traversed by the shaft through boreholes to fill the
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