(中南大學(xué) 資源與安全工程學(xué)院，長沙 410083)
摘 要: 采用試件養(yǎng)護(hù)前期拔出預(yù)埋插片形成預(yù)制裂隙的方法制作多裂隙脆性材料試件，并在伺服控制單軸加載系統(tǒng)上對其進(jìn)行加載試驗(yàn)。基于單壓下脆性材料局部破損的應(yīng)變軟化機(jī)理建立裂隙體數(shù)值模型，對比試驗(yàn)與數(shù)值計(jì)算結(jié)果分析有序多裂隙脆性材料破壞機(jī)制及其影響因素。結(jié)果表明：除裂隙傾角及其幾何排布外，裂隙在試件中的相對分布位置也影響裂隙體的破壞特征，且影響程度與裂隙面上有效剪切力大小有關(guān)，有效剪切力越大，則影響越顯著。試驗(yàn)與數(shù)值計(jì)算結(jié)果顯示：多裂隙試件中存在一組優(yōu)勢破壞面，與和裂隙走向相一致的試件斜對角線重合，裂隙分布在優(yōu)勢破壞面上或附近時，其尖端發(fā)育微裂紋的機(jī)率大于遠(yuǎn)離優(yōu)勢破壞面位置裂隙。結(jié)合有序多裂隙試件破壞特征及數(shù)值模型單元屈服狀態(tài)，提出2種近置裂隙尖端裂紋發(fā)育簡化模型，并結(jié)合本試驗(yàn)結(jié)果驗(yàn)證了簡化模型的可行性。
關(guān)鍵字: 脆性材料；有序多裂隙；破壞機(jī)制；簡化模型；優(yōu)勢破壞面；應(yīng)變軟化
（School of Resource and Safety Engineering, Central South University, Changsha 410083, China）
Abstract:The loading tests were done on the brittle specimens with ordered multi-fissures which were made by pulling out the metallic shims at the early stage in the curing process under a uniaxial loading system with servo control. The numerical models of fissure bodies were established based on the strain-softening mechanism of brittle material with local damage characteristics under uniaxial compression. The failure mechanism and its influencing factors of brittle material with ordered multi-fissures were analyzed by comparing experiment results with numerical calculations. The results show that the failure characteristics of specimens are also influenced by the relative position of fissures besides the fissure inclination angle and its geometrical arrangement, and the influence degree has relationship with the effective shear stress on fissure surface. The larger the effective shear stress is, the more significant the influence is. The experimental results and numerical calculations show that a dominant failure surface exists in the specimen with ordered multi-fissures, which is coincident with the diagonal that has the same strike with fissures. The probability of micro-cracks appearing at the tips of fissures, which distribute in or are close to the dominant failure surface, is larger than the probability of the ones which are far from the dominant failure surface. Combined with the failure characteristics of specimens with ordered multi-fissures and yield situations of grid cells in numerical models, two kinds of simplified models are proposed to describe the spatial morphologies of closely-spaced fissures. Then, combined with this experimental result, the feasibility of simplified models is verified.
Key words: brittle material; ordered multi-fissures; failure mechanism; simplified model; dominant failure surface; strain-softening
