中文摘要：

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。

英文摘要：

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.