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断续三裂隙砂岩强度破坏和裂纹扩展特征研究
引用本文:杨圣奇.断续三裂隙砂岩强度破坏和裂纹扩展特征研究[J].岩土力学,2013,34(1):31-39.
作者姓名:杨圣奇
作者单位:中国矿业大学 深部岩土力学与地下工程国家重点实验室,江苏 徐州 221008
基金项目:国家自然科学基金资助项目(No. 51179189);中国博士后科学基金特别资助项目(No. 201104585)。
摘    要:利用岩石力学伺服试验机,对尺寸为80 mm×160 mm×30 mm的断续三裂隙砂岩试样进行了单轴压缩试验,研究了岩桥倾角? 2对断续三裂隙砂岩(? = 30°和? 1 = 60°)强度破坏和裂纹扩展特征的影响规律。与完整砂岩试样相比,断续三裂隙砂岩试样应力-应变曲线显示了较多的应力跌落,其峰值强度也呈显著降低趋势,但降低程度与? 2密切相关,随着? 2从75°增加到90°,峰值强度从82.04 MPa 降低到77.82 MPa,而当? 2从90°增加到120°,其峰值强度无明显变化。完整砂岩试样呈现轴向劈裂脆性破坏,而断续三裂隙砂岩试样是由许多从裂隙尖端产生的裂纹扩展与汇合,导致了其失稳破坏。通过照相量测技术,探讨了? 2对断续三裂隙砂岩试样裂纹扩展特征的影响:? 2为75°、90°和105°的断续三裂隙试样中裂隙①、③和②、③之间均出现了贯通,而裂隙①、②之间无任何贯通;? 2为120°的断续三裂隙试样中裂隙①、③和①、②之间均出现了贯通,而②、③之间无任何贯通。最后给出了断续三裂隙砂岩试样宏观变形特性与裂纹扩展过程之间的关系。

关 键 词:岩石力学  三裂隙  脆性砂岩  强度特性  裂纹扩展  
收稿时间:2011-10-08

Study of strength failure and crack coalescence behavior of sandstone containing three pre-existing fissures
YANG Sheng-qi.Study of strength failure and crack coalescence behavior of sandstone containing three pre-existing fissures[J].Rock and Soil Mechanics,2013,34(1):31-39.
Authors:YANG Sheng-qi
Institution:State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou, Jiangsu 221008, China
Abstract:The uniaxial compression experiments on the sandstone samples containing three pre-existing fissures (the sample scale of 80 mm×160 mm×30 mm, and fissures angles of ? = 30°, ? 1 =60°) and carried out by using rock mechanics servo-controlled testing system, to investigate the effect of ligament angle ? 2 on strength failure and crack coalescence behavior. Compared with intact sandstone sample, the stress-strain curves of sandstone sample containing three fissures show more stress drops, and their peak strengths also take on a reducing tendency, but the reducing extent is closely related to ligament angle ? 2. When ? 2 increases from 75° to 90°, the peak strength reduces to 77.82 MPa from 82.04 MPa; whereas when ? 2 increases from 90° to 120°, the peak strength does not have a distinct variance. The failure mode of intact sandstone sample is a typical axial splitting fracture; but the sandstone sample containing three fissures results from a lot of crack initiation and coalescence at the tips of pre-existing fissures, so as to lead to the ultimate unstable failure. By using photographic measuring technique, the effect of ? 2 on the crack coalescence behavior of sandstone sample containing three fissures is discussed. The results show that the coalescence in the specimen containing three fissures (? 2 =75°, 90° and 105°) occurs between fissure ① and ③, fissure ② and ③, but no coalescence is observed between fissure ① and ②; but in the specimen containing three fissures (? 2 =120°), the coalescence occurs between fissure ① and ③, fissure ① and ②, but no coalescence is observed between fissure ② and ③. Finally, the relationship between microscopic deformation behavior of sandstone samples containing three fissures and crack coalescence process is constructed.
Keywords:rock mechanics  three fissures  brittle sandstone  strength behavior  crack coalescence
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