Durability analysis and damage constitutive modeling of fiber-reinforced reactive powder concrete of drilling shaft in porous water-bearing rock stratum

Abstract

The drilling activities at the mining sites in western China generally involve an extremely high drilling depth and complex formation environment, and the external load borne by the drilling shaft lining is also very high. Hence, in this study, fiber-reinforced reactive powder concrete (FRRPC) is proposed as the construction material to enhance the durability of deep drilling shaft structures. Firstly, the main physical and mechanical properties of FRRPC are examined by an orthogonal test method. Then, range analysis and comprehensive balance method are used to determine the optimal mix ratio of FRRPC as cement: silica fume: quartz sand: quartz powder: water: water reducer = 1: 0.25: 1.1: 0.40: 0.0237: 0.031. Next, taking C70 concrete commonly used in drilling engineering of deep loose layers in central and eastern China as a control, the permeability resistance and sulfate resistance of drilling shaft FRRPC in porous water-bearing rock stratum are investigated. The results show that compared with the C70 control group, the relative permeability and corrosion resistance coefficient of FRRPC are increased by 87.7% and 9.9%, respectively. Besides, the FRRPC specimen exhibits significantly better impermeability and sulfate resistance than the C70 control group. Finally, a damage constitutive model of FRRPC under sulfate attack is deduced based on the sulfate resistance test. Overall, this study provides useful insights to boost the application of FRRPC in drilling shafts in northwest China.