通过脆性岩石试样巴西圆盘试验研究了疲劳效应对脆性岩石断裂韧度KIC的影响,阐释了脆性岩石的疲劳损伤机制,首次展示了脆性岩石破坏前宏观裂纹的张开和闭合行为。巴西圆盘试验结果表明,循环荷载作用下,脆性岩样的KIC降低了35%,巴西劈裂...通过脆性岩石试样巴西圆盘试验研究了疲劳效应对脆性岩石断裂韧度KIC的影响,阐释了脆性岩石的疲劳损伤机制,首次展示了脆性岩石破坏前宏观裂纹的张开和闭合行为。巴西圆盘试验结果表明,循环荷载作用下,脆性岩样的KIC降低了35%,巴西劈裂拉伸强度降低了30%。通过高速相机数小时的观测并记录到了岩石力学领域从未观测到的过程,即脆性岩样破坏前,疲劳裂纹在正弦荷载作用下弹性张合。扫描电镜和计算机断层扫描结果显示,巴西圆盘和V形切槽巴西圆盘试样的破坏是由断裂过程区(fracture process zone,简称FPZ)引起的,FPZ中包含许多异于循环荷载作用下单条宏观裂纹的微裂纹,切槽裂纹尖端FPZ的形成导致未破坏脆性岩样中可视疲劳裂纹弹性张合。室内试验和数值计算结果表明,切槽裂纹倾角为60°时获得最大FPZ(即FPZmax),这表明最大FPZ的形成可能与Ⅰ-Ⅱ型(拉伸和剪切)组合加载模式有关。展开更多
An analytical expression for the prediction of shear-compressive fracture process zone(SCFPZ) is derived by using a proposed local strain energy density criterion, in which the strain energy density is separated into ...An analytical expression for the prediction of shear-compressive fracture process zone(SCFPZ) is derived by using a proposed local strain energy density criterion, in which the strain energy density is separated into the dilatational and distortional strain energy density, only the former is considered to contribute to the brittle fracture of rock in different loading cases. The theoretical prediction by this criterion shows that the SCFPZ is of asymmetric mulberry leaf in shape, which forms a shear-compression fracture kern. Dilatational strain energy density along the boundary of SCFPZ reaches its maximum value. The dimension of SCFPZ is governed by the ratio of K_Ⅱ to (K_Ⅰ.) The analytical results are then compared with those from literatures and the tests conducted on double edge cracked Brazilian disk subjected to diametrical compression. The obtained results are useful to the prediction of crack extension and to nonlinear analysis of shear-compressive fracture of brittle rock.展开更多
文摘通过脆性岩石试样巴西圆盘试验研究了疲劳效应对脆性岩石断裂韧度KIC的影响,阐释了脆性岩石的疲劳损伤机制,首次展示了脆性岩石破坏前宏观裂纹的张开和闭合行为。巴西圆盘试验结果表明,循环荷载作用下,脆性岩样的KIC降低了35%,巴西劈裂拉伸强度降低了30%。通过高速相机数小时的观测并记录到了岩石力学领域从未观测到的过程,即脆性岩样破坏前,疲劳裂纹在正弦荷载作用下弹性张合。扫描电镜和计算机断层扫描结果显示,巴西圆盘和V形切槽巴西圆盘试样的破坏是由断裂过程区(fracture process zone,简称FPZ)引起的,FPZ中包含许多异于循环荷载作用下单条宏观裂纹的微裂纹,切槽裂纹尖端FPZ的形成导致未破坏脆性岩样中可视疲劳裂纹弹性张合。室内试验和数值计算结果表明,切槽裂纹倾角为60°时获得最大FPZ(即FPZmax),这表明最大FPZ的形成可能与Ⅰ-Ⅱ型(拉伸和剪切)组合加载模式有关。
基金Project(50274074) supported by the National Natural Science Foundation of China project(04JJ6030) supported by theNatural Science Foundation of Hunan Province
文摘An analytical expression for the prediction of shear-compressive fracture process zone(SCFPZ) is derived by using a proposed local strain energy density criterion, in which the strain energy density is separated into the dilatational and distortional strain energy density, only the former is considered to contribute to the brittle fracture of rock in different loading cases. The theoretical prediction by this criterion shows that the SCFPZ is of asymmetric mulberry leaf in shape, which forms a shear-compression fracture kern. Dilatational strain energy density along the boundary of SCFPZ reaches its maximum value. The dimension of SCFPZ is governed by the ratio of K_Ⅱ to (K_Ⅰ.) The analytical results are then compared with those from literatures and the tests conducted on double edge cracked Brazilian disk subjected to diametrical compression. The obtained results are useful to the prediction of crack extension and to nonlinear analysis of shear-compressive fracture of brittle rock.
