损伤和破坏岩石的强度研究
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摘要
根据单轴卸载试验,获得岩样相应的应力应变曲线和轴向应变-径向应变曲线,并得到不同程度的损伤岩样。与完整的峰前曲线相比较,推断不同损伤程度岩样的卸载点所处于的应力应变曲线的阶段。将损伤岩样和破坏形成的岩块浇注在混凝土中,通过剪切试验获得岩石的抗剪强度。剪切试验结果显示,在裂纹稳定发展阶段卸载,岩样的抗剪强度下降很小,可能强度的变化掩藏在个体差异中;在裂纹不稳定发展阶段卸载,岩样的抗剪强度明显下降,特别是卸载点靠近强度峰值时;单轴压缩破坏形成的岩块仍具有相当可观的材料强度。
Based on uniaxial unloading tests,stress-strain curves of rock specimens were acquired as well as their axial strain-lateral strain curves.Meanwhile,the rock specimens damaged in different degrees were obtained.By comparing with the complete curves before the strength peak,the segments of the stress-strain curves that correspond to unloading points of the rock specimens damaged in different degrees were determined.The damaged rock specimens and the broken rock were poured in concrete,and shear test on the concreted rock samples was made to acquire their shear strength.The results of test showed that if rock was unloaded in the stage of fracture stably propagating the shear strength of damaged rock slightly decreased,the change of strength might be concealed by individual difference of rock,but if rock was unloaded in the stage of fracture unstably propagating,especially was unloaded when the strength was close to the peak,the shear strength obviously decreased.The bocks formed in uniaxial compression failure still had considerable strength.
Based on uniaxial unloading tests,stress-strain curves of rock specimens were acquired as well as their axial strain-lateral strain curves.Meanwhile,the rock specimens damaged in different degrees were obtained.By comparing with the complete curves before the strength peak,the segments of the stress-strain curves that correspond to unloading points of the rock specimens damaged in different degrees were determined.The damaged rock specimens and the broken rock were poured in concrete,and shear test on the concreted rock samples was made to acquire their shear strength.The results of test showed that if rock was unloaded in the stage of fracture stably propagating the shear strength of damaged rock slightly decreased,the change of strength might be concealed by individual difference of rock,but if rock was unloaded in the stage of fracture unstably propagating,especially was unloaded when the strength was close to the peak,the shear strength obviously decreased.The bocks formed in uniaxial compression failure still had considerable strength.
引文
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[13]吴刚,赵震洋.不同应力状态下岩石类材料破坏的声发射特性[J].岩土工程学报,1998,20(2):82~85.
[14]Tiwari R P,Rao K S.Post failure behaviour of a rock mass underthe influence of triaxial and true triaxial confinement[J].Engi-neering Geology,2006,84:112~129.
[2]尤明庆.岩石的力学性质[M].北京:地震出版社,2007:26~30.
[3]吴永胜,余贤斌.单轴压缩条件下岩石声发射特性的实验研究[J].金属矿山,2008,388:25~28.
[4]Chang C,Haimson B.Non-dilatant deformation and failuremechanism in two Long Valley Caldera rocks under true triaxialcompression[J].Int J Rock Mech Min Sci.2005,42:402~414.
[5]葛修润,任建喜,蒲毅彬,等.岩石细观损伤扩展规律的CT实时试验[J].中国科学(E辑),2000,30(2):104~111.
[6]Chen S,Yue Z Q,Tham L G.Digital image-base numericalmodeling method for prediction of inhomogeneous rock failure[J].Int J Rock Mech Min Sci.2004,41:939~957.
[7]Kozu n姫kov偄A,Mareckov偄K.Analysis of rock failure after triax-ial testing.Int.J.Rock Mech Min Sci[J].1999,36:243~251.
[8]苏承东,杨圣奇.循环加卸载下岩样变形与强度特征试验[J].河海大学学报(自然科学版),2006,34(6):667~671.
[9]尤明庆,华安增.卸围压法测量岩石材料的泊松比[J].实验力学,1997,12(2):274~279.
[10]周纪军.岩石破坏的演变过程及强度衰减研究[D].徐州:中国矿业大学建筑工程学院,2006.
[11]韩立军.岩石破坏后的结构效应及锚注加固特性研究[D].徐州:中国矿业大学建筑工程学院,2004.
[12]任建喜,葛修润,蒲毅彬,等.岩石破坏全过程的CT细观损伤演化机理动态分析[J].西安公路交通大学学报,2000,30(2):12~16.
[13]吴刚,赵震洋.不同应力状态下岩石类材料破坏的声发射特性[J].岩土工程学报,1998,20(2):82~85.
[14]Tiwari R P,Rao K S.Post failure behaviour of a rock mass underthe influence of triaxial and true triaxial confinement[J].Engi-neering Geology,2006,84:112~129.
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