Mechanical properties of ultra-high-strength reinforced reactive powder concrete (UHSRPC) shaft lining structure in western China

To improve the efficiency of deep vertical shaft construction in western China, a pilot-hole drilling and one-step reaming method with prefabricated shaft lining sinking has been developed. However, this method requires shaft linings with ultra-high bearing capacity, adequate ductility, and reduced wall thickness. Hence, an ultra-high-strength reinforced reactive powder concrete (UHSRPC) shaft lining structure was developed in this study to meet these requirements. First, the triaxial loading and testing system of the shaft lining was set up. Then, the structural load-bearing capacity experiment under standard curing and autoclave curing was conducted to investigate the mechanical properties and failure characteristics of the proposed shaft lining structure. The drilling shaft lining of C70 high-strength reinforced concrete was used as the control group for the test. Next, the Bresler octahedral stress theory was used to establish the strength criterion of UHSRPC and the compressive strength improvement coefficient calculation formula. Meanwhile, dimensional and regression analyses were used to establish a formula for the ultimate bearing capacity of the proposed shaft lining. Finally, a numerical model of the UHSRPC shaft lining structure was established, the stress distribution characteristics of the UHSRPC of the drilling shaft lining under uniform horizontal load were obtained, and the results were compared with the experimental results. Furthermore, the limit bearing capacity formula for the proposed shaft lining structure was improved. Overall, this study has a practical engineering value for rapidly constructing deep vertical drilling shafts.