Mechanical responses of anchoring structure under triaxial cyclic loading

Dynamic load on anchoring structures(AS)within deep roadways can result in cumulative damage and failure.This study develops an experimental device designed to test AS under triaxial loads.The device enables the investigation of the mechanical response,failure mode,instability assessment criteria,and anchorage effect of AS subjected to combined cyclic dynamic-static triaxial stress paths.The results show that the peak bearing strength is positively correlated with the anchoring matrix strength,anchorage length,and edgewise compressive strength.The bearing capacity decreases significantly when the anchorage direction is severely inclined.The free face failure modes are typically transverse cracking,concave fracturing,V-shaped slipping and detachment,and spallation detachment.Besides,when the anchoring matrix strength and the anchorage length decrease while the edgewise compressive strength,loading rate,and anchorage inclination angle increase,the failure intensity rises.Instability is determined by a negative tangent modulus of the displacement-strength curve or the continued deformation increase against the general downward trend.Under cyclic loads,the driving force that breaks the rock mass along the normal vector and the rigidity of the AS are the two factors that determine roadway stability.Finally,a control measure for surrounding rock stability is proposed to reduce the internal driving force via a pressure relief method and improve the rigidity of the AS by full-length anchorage and grouting modification.

Study of hydraulic transport characteristics and erosion wear of twisted four-lobed pipe based on CFD-DEM

Pipeline hydraulic transportation is extensively utilized across diverse sectors,with enhancing the performance of pipeline hydrodynamic transport and minimizing erosion wear on the pipeline walls being essential for ensuring the stability of pipeline operations.This paper introduces a methodology for the hydraulic transport of a twisted four-lobed pipe,employing a numerical and erosion model developed through the CFD-DEM(computational fluid dynamics and discrete element method)coupling approach.An experimental circulating flow platform is constructed for validation purposes.The performance of the pipe is assessed by analyzing key indices including fluid velocity,pressure drop,particle trajectory,and erosion wear.The results indicate that twisted four-lobed pipe enhances fluid flow rates,facilitating particle discharge and mitigating accumulation,with reduced wear compared to the twin twist triangle spiral pipe.The analysis of structural parameters’impact on hydraulic conveyance is also presented.These findings offer theoretical insights for optimizing pipeline performance in hydraulic conveyance while minimizing wear.