单裂隙砂岩破坏特征和破裂演化规律试验
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摘要
针对含不同倾角裂隙的板状砂岩试样开展单轴加载试验,从宏细观角度深入探索裂隙倾角对脆性岩石变形破坏特征、声发射及破裂演化规律的影响效应,揭示其破坏机制。结果表明:裂隙倾角α较小时(0°≤α≤30°),应力-应变曲线呈锯齿状;翼裂纹首先在初始裂隙中部萌生,次生拉伸裂纹扩展贯通导致试样破坏,声发射较为分散,以劈裂破坏为主;随裂隙倾角增加(30°<α<90°),应力跌落次数减少,峰值强度和弹性模量不断升高;翼裂纹起裂位置向初始裂隙尖端转移,起裂强度和起裂强度比逐渐增加,次生裂纹转为剪切裂纹,声发射趋于集中,破坏模式向剪切破坏过渡;裂隙倾角为90°时,应力-应变曲线光滑,初始裂隙起裂前试样瞬间破坏,声发射异常集中,以劈裂破坏为主,与完整试样基本一致。
By the uniaxial compression test of slab sandstone specimen containing pre-existing single crack of different dip angles,the influence effect of crack dip angle on the deformation and failure characteristic, AE evolution law and crack propagation evolution law of brittle rock were deeply analyzed from macroscopic and mesoscopic perspectives, meanwhile, the failure mechanism was revealed. The results show that: when the crack angle was small(0°≤α≤30°), the stress-strain curve exhibited a "saw tooth"shape and failure mode was primarily splitting failure; the wing crack firstly sprouted in the middle of the initial crack, then the propagation and coalescence of secondary tensile crack caused the ultimate fail of the specimens, therefore, AE signal during the whole compression process was more dispersed; with the increasing of flaw angle(30°<α<90°), the number of stress dropping decreased, the peak strength and elastic modulus increased continuously, and the failure mode was primarily shear failure; the initiation position of wing crack firstly appeared in the initial crack tip, and the crack initiation strength and crack initiation strength ratio increased gradually, then, the secondary crack transferred to shear crack, which made the AE signal tended to concentrate; for the crack angle of 90°, the stress-strain curve was very smooth, the specimen failed instantaneously and caused AE signal concentrated abnormally before the crack initiation of the initial crack, and the fail mode was splitting damage, which was basically consistent with the complete sample.
By the uniaxial compression test of slab sandstone specimen containing pre-existing single crack of different dip angles,the influence effect of crack dip angle on the deformation and failure characteristic, AE evolution law and crack propagation evolution law of brittle rock were deeply analyzed from macroscopic and mesoscopic perspectives, meanwhile, the failure mechanism was revealed. The results show that: when the crack angle was small(0°≤α≤30°), the stress-strain curve exhibited a "saw tooth"shape and failure mode was primarily splitting failure; the wing crack firstly sprouted in the middle of the initial crack, then the propagation and coalescence of secondary tensile crack caused the ultimate fail of the specimens, therefore, AE signal during the whole compression process was more dispersed; with the increasing of flaw angle(30°<α<90°), the number of stress dropping decreased, the peak strength and elastic modulus increased continuously, and the failure mode was primarily shear failure; the initiation position of wing crack firstly appeared in the initial crack tip, and the crack initiation strength and crack initiation strength ratio increased gradually, then, the secondary crack transferred to shear crack, which made the AE signal tended to concentrate; for the crack angle of 90°, the stress-strain curve was very smooth, the specimen failed instantaneously and caused AE signal concentrated abnormally before the crack initiation of the initial crack, and the fail mode was splitting damage, which was basically consistent with the complete sample.
引文
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[10]杜明瑞,靖洪文,苏海健.椭圆形孔洞对砂岩试样强度及变形特征影响研究[J].采矿与安全工程学报,2017,34(1):141-147.
[11]王国艳,于广明,高丽燕,等.初始裂隙倾角对岩石损伤断裂特征的影响研究[J].煤炭科学技术,2017,45(6):100-104.
[12]朱谭谭,靖洪文,苏海健,等.孔洞-裂隙组合型缺陷砂岩力学特性试验研究[J].煤炭学报,2015,40(7):1518-1525.
[2]王宏伟,姜耀东,邓代新,等.义马煤田复杂地质赋存条件下冲击地压诱因研究[J].岩石力学与工程学报,2017,36(S2):4085-4092.
[3]李志远,宫海灵,张永辉,等.某电站地下厂房裂隙发育规律及其对围岩稳定性的影响[J].水电能源科学,2018,48(5):1574-1580.
[4]李树忱,马腾飞,蒋宇静,等.深部多裂隙岩体开挖变形破坏规律模型试验研究[J].岩土工程学报,2016,38(6):987-995.
[5]MARTIN C D,CHANDLER N A.The progressive fracture of Lac du Bonnet granite[J].International Journal of Rock Mechanics and Mining Sciences,1994,31(6):643-659.
[6]M Cai,P K Kaiser,Y Tasaka,et al.Generalized crack initiation and crack damage stress thresholds of brittle rock masses near underground excavations[J].International Journal of Rock Mechanics and Mining Sciences,2004,41(5):833-847.
[7]杨圣奇,戴永浩,韩立军,等.断续预制裂隙脆性大理岩变形破坏特性单轴压缩试验研究[J].岩石力学与工程学报,2009,28(12):2391-2404.
[8]刘学伟,刘泉声,陈元,等.裂隙形式对岩体强度特征及破坏模式影响的试验研究[J].岩土力学,2015,36(S2):208-214.
[9]周辉,孟凡震,张传庆,等.不同位置和尺寸的裂隙对岩体破坏影响的试验研究[J].岩石力学与工程学报,2015,34(S1):3018-3028.
[10]杜明瑞,靖洪文,苏海健.椭圆形孔洞对砂岩试样强度及变形特征影响研究[J].采矿与安全工程学报,2017,34(1):141-147.
[11]王国艳,于广明,高丽燕,等.初始裂隙倾角对岩石损伤断裂特征的影响研究[J].煤炭科学技术,2017,45(6):100-104.
[12]朱谭谭,靖洪文,苏海健,等.孔洞-裂隙组合型缺陷砂岩力学特性试验研究[J].煤炭学报,2015,40(7):1518-1525.