用离散单元法研究混凝土、岩石类材料的拉剪混合型断裂

Tensile-shear mixed mode fracture analysis of concrete-rock material by distinct element method

基于变形体离散单元法,采用固定和旋转的弥散裂缝模型,分析了混凝土、岩石等准脆性材料的拉剪混合型开裂行为,给出了开裂准则以及裂缝扩展机制,初步探讨了从连续介质到非连续介质转化的数值模拟。通过Willam数值试验表明旋转裂缝模型在模拟拉剪混合型开裂问题时更符合客观实际;通过单边切口非对称三点弯梁试验分析,说明在混合形式的荷载条件下,裂缝通常以拉剪Ⅰ/Ⅱ型混合模式起裂,而后以Ⅰ型为控制方式稳定扩展。

The tensile-shear mixed mode fracture of quasi-brittle materials such as concrete and rock is analyzed by fixed and rotating smeared-crack models based on the deformable distinct element method. Herein, The fracture criteria and propagation mechanisms of crack are considered and the numerical simulation of transition from continua to discontinua is performed tentatively. The models are then applied to exam Willam numerical experiment and results show that the rotating crack model compared with fixed crack model is more favorable in simulating the tensile-shear mixed mode fracture. By comparison between numerical and ex edge notch, it ily propagated can be conc perimental luded that in predominant mode results of non-symmetric three-point bending beam test with single the crack is initiated with tensile-shear Ⅰ / Ⅱ mixed mode but stead- Ⅰ when structure is subjected to mixed load.