基于三维离散-连续耦合方法的NPR锚索-围岩相互作用机理研究

恒阻大变形(NPR)锚索作为一种高效的吸能锚索已广泛应用于边坡和采矿工程的加固和监测预警中。NPR锚索工作时的径向膨胀特性将影响整个锚固系统的性能。因此,基于离散元法(DEM)-有限差分法(FDM)耦合方法对静力拉伸作用下NPR锚索-围岩的相互作用机理进行分析。NPR锚索考虑为连续单元体,围岩和锚固材料由离散球体单元表征,将整个NPR锚固系统实现了离散元法与有限元法耦合模拟。围岩的离散元细观参数得到校准,NPR锚索的有限差分宏观参数由相应的静力拉伸室内试验进行验证。通过分析数值结果,对NPR锚索与NPR锚固系统的恒阻力进行了比较;描述了锚索-围岩界面的正应力与切应力的分布特征;此外,对锚固剂与围岩的破坏模式进行了细观研究。研究结果描述了NPR锚索与围岩的相互作用并揭示了NPR锚索的特殊锚固机理,可用于预测和提高NPR锚索锚固系统的性能。

NUMERICAL STUDY ON NPR CABLE-ROCK INTERACTION USING3D DISCRETE-CONTINUOUS COUPLING METHOD

Due to the characteristics of efficient energy absorption, constant-resistance-large-deformation (NPR) cables have been applied in many rock slopes and mining engineering for monitoring and reinforcement. The NPR cable-rock interaction differs from that of traditional cables owing to the pipe-shaped expansion during the working process, and it affects the performance of a NPR cable reinforcement system. Therefore, a coupled numerical method is used to study the characteristics of the NPR cable-rock interaction under static pull-out loading. The structure of the NPR cable is considered as a continuous zone via the finite-difference method (FDM), and the surrounding rock and grouting material was modelled by the discrete element spherical particles via the discrete-element method (DEM). The micro parameters of the grouting material and surrounding rock were carefully calibrated, and the comparisons of corresponding experimental tests in the laboratory to verified the macro parameters of the NPR cable. The numerical results were carefully discussed and analyzed. The constant-resistance forces between a onefold NPR cable and the NPR cable reinforcement system were compared. The spatial arrangement of the normal and shearing stresses on the cable-rock interface was obtained. Furthermore, the failure mode of grouting material and surrounding rock was researched at the micro scale. The results describe the interaction between the NPR cable and the surrounding rock and reveal its special anchorage mechanism, and help improve and predict the performance of the NPR cable reinforcement system.