真三轴应力状态下含预制裂隙煤系泥岩强度与破坏特征
Strength and failure characteristics of coal measures mudstone specimens containing a prefabricated flaw under true triaxial tests
李文帅 1蒋邦友 2李兆霖 3王连国 4杨旭旭1
作者信息
- 1. Shandong Key Laboratory of Civil Engineering Disaster Prevention and Mitigation,Shandong University of Science and Technology,Qingdao 266590,China
- 2. College of Energy and Mining Engineering,Shandong University of Science and Technology,Qingdao 266590,China
- 3. State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines,Anhui University of Science and Technology,Huainan 232001,China
- 4. State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou 221116,China
- 折叠
摘要
对一系列含有预制缺陷的煤系泥岩试样进行了真三轴试验(TTT),即中间主应力(σ2)平行于预制缺陷的试样(TTT-Flaw-2)和最小主应力平行于预制缺陷的试样(σ3)(TTT-Flaw-3),研究σ2加载方向和预制缺陷的位置对试样强度和破坏模式的影响.结果表明,完整试样和含预制缺陷试样的峰值强度随σ2的增加先增大后减小,符合Mogi-Coulomb准则.在相同的应力条件下,完整试样的强度明显大于含预制缺陷试样的强度,且TTT-Flaw-2试样的强度最低.CT扫描结果显示,在常规三轴试验条件下,含预制缺陷试样中的裂纹并不总是沿着预制缺陷尖端形成,而是随机分布在试样内部;在TTT-Flaw-2试样中,反翼型裂纹从预制缺陷尖端附近开始形成,最终主要分布在σ2加载方向上;而在TTT-Flaw-3试样中,在σ2加载方向上出现剪切裂纹,而在σ3加载方向上几乎没有观察到反翼型裂纹.
Abstract
In this study,a series of coal measures mudstone specimens containing a prefabricated flaw were subjected to true triaxial test(TTT),namely,specimens of the intermediate principal stress(σ2)parallel to prefabricated flaw(TTT-Flaw-2)and specimens of the minimum principal stress(σ3)parallel to prefabricated flaw(TTT-Flaw-3).The main objective of this study was to investigate the effects of the loading direction of σ2 and the position of prefabricated flaw on the strength and failure modes of specimens.The results showed that the peak strength of intact and flawed specimens first increased and then decreased with increasing σ2,which could be fitted by the Mogi-Coulomb criterion.Under the same loading stresses,the strength of intact specimen was larger than that of flawed specimens,and specimens TTT-Flaw-2 had the lowest strength.The X-ray computerized tomography scanning results revealed that fractures were not always observed to form along the prefabricated flaw tips but were distributed randomly inside the specimen under conventional triaxial test conditions.Under TTT conditions,anti-wing cracks initiated from the vicinity of the prefabricated flaw tip and were observed in σ2-direction for specimens TTT-Flaw-2.While for specimens TTT-Flaw-3,shear cracks appeared in σ2-direction,and few anti-wing cracks were observed in σ3-direction.
关键词
真三轴试验/煤系泥岩/预制缺陷/强度/破裂模式Key words
true triaxial test/coal measures mudstone/prefabricated flaw/strength/fracture pattern引用本文复制引用
基金项目
Natural Science Foundation of China(52204144)
Natural Science Foundation of China(52004144)
Natural Science Foundation of Shandong Province,China(ZR2022QE232)
出版年
2024
NETL
NSTL
万方数据