Ductile support mechanism and application of high pre-stressed long and short NPR anchor cable in deep-buried soft rock roadway

Abstract

Significant deformation and failure pose severe challenges to the stability of deeply buried soft rock roadways. Focusing on the soft rock roadways in the Wanfu Mine, this study elucidates the stress accumulation and release mechanisms of the surrounding rock through a combined approach of laboratory experiments, theoretical analysis, and numerical simulations. A resilience-oriented support strategy utilizing micro-NPR steel anchor cables is proposed and validated. Based on the zone failure range theory, the dimensions of the flow layer, plastic softening layer, and plastic hardening layer were calculated to optimize the lengths of long and short anchor cables. Static tensile tests and elastoplastic theoretical analysis were conducted to quantify and compare the energy absorption capacities of conventional and micro-NPR cables. Findings indicate that while conventional cables succumb to failure after energy absorption, micro-NPR cables effectively accommodate energy release without fracturing. Numerical results demonstrate that using PR and micro-NPR cables reduced roadway displacement by 13.8% and 36.9%, and decreased plastic zone radii by 14.2% and 37.6%, respectively, while surface pressures increased by 0.26 MPa and 1.53 MPa. Furthermore, the high strength and toughness of NPR cables facilitate stress compensation and restoration post-excavation. Field monitoring confirms that the toughness-based support strategy significantly controls large deformations, providing a novel material and methodology for ensuring the stability of deep-buried soft rock roadways.

Keywords

deep mining / soft rock roadway / npr cable / ductile support system / control mechanism

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Central South University