Abstract：The characteristics of crack initiation in rock under far-field tension-compression and biaxial compression loading were analyzed by considering both the singular and nonsingular stress(T-stress) terms at the crack tip. The modified maximum tangential and shear stress criterion was developed for evaluating tensile and shear cracking. The condition of tensile and shear fracture was discussed to further clarify the effect of inclination angle，friction angle，tensile strength and cohesion on fracture types in rock. The results indicate that the nonsingular stress terms have important influence on the near-tip stress field and the modified theory agrees well with experiment. Results with the increment of the friction angle，the shear failure is weakened while the tensile failure is strengthened. However，with the increment of the cohesion or decreases of the tensile strength，the shear failure is strengthened and the tensile failure is weakened.
唐世斌，张 恒. 岩石材料裂纹尖端起裂特性研究[J]. 岩石力学与工程学报, 2017, 36(3): 552-561.
TANG Shibin，ZHANG Heng. The characteristics of crack initiation at the crack tip in rock material. , 2017, 36(3): 552-561.
[1] 李世愚，和泰名，尹祥础. 岩石断裂力学导论[M]. 合肥：中国科学技术大学出版社，2010：99–114.(LI Shiyu，HE Taiming，YIN Xiangchu. Introduction to rock fracture mechanics[M]. Hefei：University of Science and Technology of China Press，2010：99–114.(in Chinese))
[2] NEMAT-NASSER S，HORII H. Compression-induced nonplanar crack extension with application to splitting，exfoliation，and rockburst[J]. Journal of Geophysical Research，1982，87：6 805–6 821.
[3] HORII H，NEMAT-NASSER S. Brittle failure in compression：splitting，faulting and brittle-ductile transition[J]. Philosophical Transactions of the Royal Society of London，1986，319：337–374.
[4] HEALY D，JONES R R，HOLDSWORTH R E. Three-dimensional brittle shear fracturing by tensile crack interaction[J]. Nature，2006，439：64–67.
[5] 林拜松. 滑开型断裂的复合型脆断判据[J]. 应用数学与力学， 1985，6(11)：977–983.(LIN Baisong. The mixed mode brittle fracture criteria in sliding mode fracture[J]. Applied Mathematics and Mechanics，1985，6(11)：977–983.(in Chinese))
[6] 杨 慧，曹 平，江学良，等. 闭合裂纹断裂的有效剪应力准则[J]. 岩土力学，2008，29(增1)：470–474.(YANG Hui，CAO Ping，JIANG Xueliang，et al. Effective shear stress criterion for closed-crack fracture[J]. Rock and Soil Mechanics，2008，29(Supp.1)：470–474. (in Chinese))
[7] COTTERELL B. Brittle fracture in compression[J]. International Journal of Fracture Mechanics，1972，8(2)：195–208
[8] WOO C W，CHOW C L. On inclined crack under compressive loading[C]// Proceedings of ICF International Symposium on Fracture Mechanics. Beijing：Science Press，1983：251–257.
[9] CHAKER C，BARQUINS M. Sliding effect on branch crack[J]. Physics and Chemistry of the Earth，1996，21(4)：319–323.
[10] SMITH D J，AYATOLLAHI M R，PAVIER M J. On the consequences of T-stress in elastic brittle fracture[J]. Proceedings of the Royal Society of London：Series A，2006，462：2 415–2 437.
[11] SHLYANNIKOV V N. T-stress for crack paths in test specimens subject to mixed mode loading[J]. Engineering Fracture Mechanics，2013，108：3–18.
[12] LU K，MESHII T. Three-dimensional T-stresses for three-point-bend specimens with large thickness variation[J]. Engineering Fracture Mechanics，2014，116：197–203.
[13] MIRSAYAR M M. On fracture of kinked interface cracks-The role of T-stress[J]. Materials and Design，2014，61：117–123.
[14] BOBET A，EINSTEIN H H. Numerical modeling of fracture coalescence in a model rock material[J]. International Journal of Fracture，1998，92(3)：221–252.
[15] BOBET A，EINSTEIN H H. Fracture coalescence in rock-type materials under uniaxial and biaxial compression[J]. International Journal of Rock Mechanics and Mining Sciences，1998，35(7)：863–888.
[16] WILLIAMS M L. On the stress distribution at the base of a stationary crack[J]. Journal of Applied Mechanics，1957，24(1)：109–114.
[17] WILLIAMS J G，EWING P D. Fracture under complex stress-the angled crack problem[J]. International Journal of Fracture，1972，8(4)：441–444.
[18] YANG S Q，JING H W. Strength failure and crack coalescence behavior of brittle sandstone samples containing a single fissure under uniaxial compression[J]. International Journal of Fracture，2011，168(2)：227–250.
[19] 赵永红，梁晓峰. 灰岩平板试件变形破坏过程的实验观测研究[J]. 岩石力学与工程学报，2004，23(10)：1 608–1 615.(ZHAO Yonghong，LIANG Xiaofeng. Testing study on crack development in limestone plate specimen under uniaxial compression[J]. Chinese Journal of Rock Mechanics and Engineering，2004，23(10)：1 608–1 615. (in Chinese))
[20] 李银平，王元汉，陈龙珠，等. 含预制裂纹大理岩的压剪试验分析[J]. 岩土工程学报，2004，26(1)：120–124.(LIN Yinping，WANG Yuanhan，CHEN Longzhu，et al. Experiment research on pre-existing cracks in marble under compression[J]. Chinese Journal of Geotechnical Engineering，2004，26(1)：120–124.(in Chinese))
[21] AYATOLLAHI M，ALIHA M. On the use of Brazilian disc specimen for calculating mixed mode I-II fracture toughness of rock materials[J]. Engineering Fracture Mechanics，2008，75(16)：4 631–4 641.
[22] ALIHA M R M，AYATOLLAHI M R，SMITH D J，et al. Geometry and size effects on fracture trajectory in a limestone rock under mixed mode loading[J]. Engineering Fracture Mechanics，2010，77(11)：2 200–2 212.
[23] WOO C W，LING L H. On angled crack initiation under biaxial loading[J]. Journal of Strain Analysis for Engineering Design，1984，19(1)：151–159.
[24] UEDA Y，IKEDA K，YAO T，et al. Characteristics of brittle fracture under general combined modes including those under bi-axial tensile loads[J]. Engineering Fracture Mechanics，1983，18(6)：1 131–1 158.
[25] 唐大雄，刘佑荣，张文姝，等. 工程岩土学[M]. 2版. 地质出版社，北京，1998：243–247.(TANG Daxiong，LIU Yourong，ZHANG Wenshu，et al. Engineering soil mechanics[M]. 2nd ed. Beijing：Geological Publishing House，1998：243–247.(in Chinese))
[26] BOBET A. The initiation of secondary cracks in compression[J]. Engineering Fracture Mechanics，2000，66(2)：187–219.
2017, Vol. 36 
