(中南大學(xué) 土木建筑學(xué)院，長沙 410083)
摘 要:
采用剪切盒和掃描電鏡實驗研究脆性巖石的高溫剪切(Ⅱ型)斷裂特征及微觀機(jī)理,并通過密度、單軸壓縮實驗研究巖石高溫的物性和力學(xué)性能。實驗表明：在高溫加載下，膠結(jié)物材料的干脫和巖石內(nèi)部微裂紋的形成、發(fā)育，這兩種因素共同影響著巖石的彈性模量、抗壓強(qiáng)度、斷裂峰值荷載，前者占主導(dǎo)地位起強(qiáng)化作用，后者占主導(dǎo)地位起弱化作用，臨界溫度為
關(guān)鍵字: 脆性巖石；剪切斷裂；高溫；斷裂機(jī)理
（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
