## 1 Introduction  
The shaft drilling method, a modern mechanical shaft sinking method, is one of the most effective methods for sinking shafts through deep alluvium in coal mines. In this method, a drill bit is used to crush the rock, and rock fragments are removed under the protection of a slurry wall. After drilling to the designated location, a shaft lining prefabricated on the ground is sunk by flotation. Finally, the gap between the lining and the surrounding rock is filled with cement to constrain the shaft. This method, characterized primarily by excellent safety (all the construction personnel are on the ground) and reliable quality of the poured concrete shaft lining, allows for the mechanized construction of vertical shafts in coal mines [1; 2; 3] and is particularly suitable for use in the construction of new air shafts in operating coal mines. In recent years, to ensure the safety of ventilation, some operating coal mines constructed air shafts of large diameter using the drill method. Zhangji coal mine is a large modern mine. According to safety reconstruction requirements, an intake shaft and a return air shaft were to be constructed in the west zone of this coal mine. They were designed to have net diameters of 8.3 and 7.2 m, drilling diameters of 10.8 and 9.6 m, and depths of 458.0 and 440.0 m, respectively. Each of the two shafts needed to pass through 401.2 m thick alluvial strata. The intake shaft had a net diameter of 8.3 m and a drilling diameter of 10.8 m, making it the largest vertical shaft ever constructed using the mine shaft drilling method in China and elsewhere. According to shaft lining structure design theory [4; 5], as the shaft diameter increases, a shaft lining structure with higher strength is required to withstand the high pressure from water and soil in the deep alluvium. Generally, the bearing capacity of a shaft lining could be improved by increasing its thickness, increasing the compressive strength of the concrete [6; 7], and using a steel-plate-confined concrete structure. However, due to the limited hoisting capacity of construction equipment, the deadweight of each section of a shaft lining cannot exceed 2000 kN [8], which limits the extent to which the shaft lining thickness could be increased. Meanwhile, for technical reasons relating to site construction, the concrete strength should not be too high. The bearing capacity of the composite structure of steel plate and concrete could be improved when the high tensile strength of steel plate and high compressive strength of concrete are utilized effectively. To improve the composite effect of steel and concrete, anchor clamps are added in the inner steel cylinder and concrete [9; 10; 11]. Consequently, a dual-steel-plate-confined high-performance composite concrete shaft lining is needed to improve the bearing capacity of the shaft lining [12; 13; 14]. In other words, a thin and high-strength shaft lining structure should be used to address the challenge of providing support for large-diameter drill shafts. Regarding research on high-strength lining structures for drill shafts, [PERSON] et al. studied an inner-steel-plate-confined concrete shaft lining structure [15; 16; 17]. [PERSON] et al. studied the mechanical characteristics of high-strength steel-fiber-reinforced concrete shaft lining with inner steel plate [18]. In addition, [PERSON] et al. and [PERSON] et al. examined the mechanical properties of dual-steel-plate-confined high-strength concrete shaft linings [19; 20]. [PERSON] et al. studied the mechanical characteristics of a two-layer steel plate concrete shaft lining under nonuniform pressure [21]. However, the aforementioned two types of steel-plate-confined concrete shaft lining structures were relatively thick. Consequently, the results could not be directly applied to the construction of the intake shaft, namely, a large-diameter drill shaft.