Regulation mechanism of slot length on directional fracturing behavior of specimens under expansive loading

Abstract

Static cracking demolition agent (SCDA) is an environmentally friendly and cost-effective material with broad potential for building demolition and rock fracturing engineering. Under expansive loading induced by SCDA, the directional fracture mechanisms of symmetrically slotted boreholes remain inadequately understood. Acoustic emission (AE) monitoring, digital image correlation (DIC), and numerical simulations were combined to systematically investigate the regulating mechanism of slot length on fracture behavior. The results indicate that as the slot length increases, the fracture modes transition from competitive propagation of multiple cracks to rapid through-going propagation of the main cracks along the slot direction. The competitive propagation of multiple cracks disperses the expansive energy among the propagating cracks, whereas rapid through-going propagation along the slot concentrates energy release in the slot direction. A critical slot length is identified at which energy release is most intense, causing the cumulative AE energy to first increase and then decrease with increasing slot length. The expansive pressure required for through-going of the main crack decreases progressively as the slot length increases. Once the main crack causes pressure release, the propagation of secondary cracks is suppressed due to insufficient driving force. These findings provide a theoretical basis for achieving controllable SCDA-induced directional fracturing.

Keywords

SCDA / Slot length / Directional fracturing / Fracture mode / Regulation mechanism

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