灰岩试样三点弯曲断裂特性试验研究
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摘要
为掌握灰岩的断裂特性,进行了灰岩预制切缝试样三点弯曲试验,通过声发射监测及粗糙度测定,分析得出灰岩断裂韧度以及断裂面粗糙度。试验结果表明:灰岩的断裂韧度比较低,仅为20～30 N/mm3/2,致使其断裂破坏的最大载荷很低,仅为1 100 N左右,表明灰岩本身抵抗裂纹失稳扩展的能力较差。试样的断裂面为平断口,粗糙度系数不超过6,断裂后迅速垮塌,说明碎裂灰岩体的整体力学性能取决于断裂面粗糙度的大小,即在常温常压下,断裂面的粗糙度越小,剪切强度也越小,碎裂岩体也就越容易沿断裂面滑动失稳。因此,灰岩的低断裂韧度和小断裂面粗糙度系数等断裂特性,决定了灰岩及以灰岩为主的岩层容易断裂、断裂后容易滑动失稳。
In order to master the broken features of limestone,a three point bending experiment with pre-slitting limestone samples was conducted.With the acoustic emission monitoring and measuring and the roughness measurement,the fracturing toughness of the limestone and the fracturing surface roughness were obtained analyzed.The experiment results showed that the fracturing toughness of the limestone was low and only about 20~30 N/mm3/2.Thus the max load of the fracturing failure was low and only about 1 100 N.Therefore,the capacity of the anti fracturing and stability lost expansion of the limestone was poor.The fracturing surface of the sample was flat and the roughness coefficient was not over six.When the limestone fractured,the limestone would be quickly failed and the completed mechanics performances of the fractured limestone would be depended on the roughness size of the fractured surface.Under the normal temperature and normal pressure,the smaller roughness of the fractured surface was,the smaller of the shearing strength would be and the fractured rock mass would be easy lost the stability sliding along the fractured surface.The low fracturing toughness of the limestone,the small roughness coefficient of the fracturing surface and other fracturing features set that the limestone and the rock strata mainly as the limestone would be easy fractured and would lost the stability when the rock was fractured.
In order to master the broken features of limestone,a three point bending experiment with pre-slitting limestone samples was conducted.With the acoustic emission monitoring and measuring and the roughness measurement,the fracturing toughness of the limestone and the fracturing surface roughness were obtained analyzed.The experiment results showed that the fracturing toughness of the limestone was low and only about 20~30 N/mm3/2.Thus the max load of the fracturing failure was low and only about 1 100 N.Therefore,the capacity of the anti fracturing and stability lost expansion of the limestone was poor.The fracturing surface of the sample was flat and the roughness coefficient was not over six.When the limestone fractured,the limestone would be quickly failed and the completed mechanics performances of the fractured limestone would be depended on the roughness size of the fractured surface.Under the normal temperature and normal pressure,the smaller roughness of the fractured surface was,the smaller of the shearing strength would be and the fractured rock mass would be easy lost the stability sliding along the fractured surface.The low fracturing toughness of the limestone,the small roughness coefficient of the fracturing surface and other fracturing features set that the limestone and the rock strata mainly as the limestone would be easy fractured and would lost the stability when the rock was fractured.
引文
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[3]何平笙.高聚物的力学性能[M].2版.合肥:中国科学技术大学出版社,2008:12-16.
[4]国际岩石力学学会实验室和现场试验标准化委员会.岩石力学试验建议方法[M].郑雨天,傅冰骏,卢世宗,等译.北京:煤炭工业出版社,1982:191-205.
[5]陈颙,黄庭芳,刘恩儒.岩石物理学[M].合肥:中国科学技术大学出版社,2009:10-12.
[6]陈颙.地壳岩石的力学性能:理论基础与实验方法[M].北京:地震出版社,1988:50-58.
[7]Barton N,Choubey V.The Shear Strength of Rock Joints inTheory and Practice[J].Rock Mechanics,1977(10):1-65.
[8]李庆芬,胡胜海,朱世范.断裂力学及其工程应用[M].哈尔滨:哈尔滨工程大学出版社,1998:102-105.
[9]黄志鹏,朱可善,郭映忠.重庆砂岩三点弯曲断裂及声发射试验研究[J].地下空间与工程学报,1998,18(1):23-25.
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[11]维诺格拉多夫.石灰岩[M].北京:地质出版社,1954:1-19.
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