Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第18卷    第8期    总第113期    2008年8月

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文章编号:1004-0609(2008)08-1534-07
脆性岩石高温剪切(Ⅱ型)断裂的微观机理
谢海峰,饶秋华,谢 强,黎纵宇,王 志

(中南大学 土木建筑学院,长沙 410083)

摘 要:  

采用剪切盒和扫描电镜实验研究脆性岩石的高温剪切()断裂特征及微观机理,并通过密度、单轴压缩实验研究岩石高温的物性和力学性能。实验表明:在高温加载下,胶结物材料的干脱和岩石内部微裂纹的形成、发育,这两种因素共同影响着岩石的弹性模量、抗压强度、断裂峰值荷载,前者占主导地位起强化作用,后者占主导地位起弱化作用,临界温度为250 。在高温剪切盒加载下,岩石发生沿原裂纹面断裂破坏,裂纹核随着温度增加而增大,断口多为穿晶断裂晶面上具有多而密的平行线条纹和较多的岩屑等典型的剪切破坏特征,表明岩石破坏为剪切断裂(Ⅱ型)

 

关键词: 脆性岩石;剪切断裂;高温;断裂机理

Plane shear (ModeⅡ) fracture experiment analysis of brittle rock at high temperature
XIE Hai-feng, RAO Qiu-hua, XIE Qiang, LI Zong-yu, WANG Zhi

School of Civil Engineering and Architecture, Central South University, Changsha 410083, China

Abstract:Compression-shear box and scanning electron microscope(SEM) tests were used to study the shear fracture characteristics and mechanism of brittle rock at high temperature. The physical and mechanical properties of brittle rock at high temperature were investigated by density test and uniaxial compressive test. The test results show that, under compression-shear loading and at increasing temperature, both the dry-baking of clay material and the micro-cracks initiation and development have effects on elastic modulus, axial compressive strength and fracture peak load. The former is dominant before a certain critical temperature such as 250 ℃ and can increase the mechanical properties of rock, while the latter is dominant after the critical temperature and can decrease the mechanical properties of rock. The new crack is initiated and propagated almost along its original plane of specimen at high temperature. The radius of crack nucleation zone is increased with the increase of temperature and the fracture morphologies are of trans-granular fracture. The crystal surfaces have many dense parallel patterns and rock fragments, which represents the shear fracture (Mode Ⅱ).

 

Key words: brittle rock; shear fracture; high temperature; fracture mechanism

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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