Understanding the failure behaviour of rocks is very important for many engineering applications. While conceptual models to predict failure behaviour of rocks have been proposed, very few models exist to quantitatively predict the brittle–ductile characteristics of mudstones at high confining pressures. In this study, we performed triaxial compression tests at confining pressures up to 130 MPa on dry indurated mudstones from the Naparima Hill Formation, Trinidad. Experimental results including stress–strain curves, failure modes, and strength parameters of the mudstones were obtained. Analysing the stress–strain curves, shows that the mudstones experienced brittle, brittle–ductile transition, and ductile failure behaviours as the confining pressure increases. The failure behaviour at confining pressures less than 50 MPa is accompanied by axial splitting fractures and shear fractures. At confining pressures greater than 50 MPa, shear band and ductile flow fractures are observed in the mudstones. A failure behaviour model was developed using the failure behaviour and failure strength of the mudstones. This model predicts the brittle, brittle–transition and ductile zones for mudstones at high confining pressures. The brittle to ductile transition is not sudden, but a gradual process that is controlled by the confining pressure and failure strength. The model indicates a narrow brittle-ductile transition zone for weak mudstones as compared to strong mudstones.

对于许多工程应用而言，了解岩石的破坏行为非常重要。虽然已经提出了预测岩石破坏行为的概念模型，但很少有模型可以定量地预测高围压下泥岩的脆性-延性特征。在这项研究中，我们对来自特立尼达的纳帕里玛山地层的干燥硬质泥岩在最高130 MPa的围压下进行了三轴压缩试验。获得了包括应力-应变曲线，破坏模式和泥岩强度参数在内的实验结果。分析应力-应变曲线表明，随着围压的增加，泥岩经历了脆性，脆性-延性转变和延性破坏行为。围压低于50 MPa时的破坏行为会伴随有轴向劈裂和剪切断裂。在围压大于50 MPa的情况下，在泥岩中观察到剪切带和延性流裂缝。利用泥岩的破坏行为和破坏强度建立了破坏行为模型。该模型预测了在高围压下泥岩的脆性，脆性转变和延性区域。脆性到延性的转变不是突然的，而是由围压和破坏强度控制的渐进过程。该模型表明，与强泥岩相比，弱泥岩的脆性-韧性过渡带较窄。在泥岩中观察到剪切带和韧性流动裂缝。利用泥岩的破坏行为和破坏强度建立了破坏行为模型。该模型预测了在高围压下泥岩的脆性，脆性转变和延性区域。脆性到延性的转变不是突然的，而是由围压和破坏强度控制的渐进过程。该模型表明，与强泥岩相比，弱泥岩的脆性-韧性过渡带较窄。在泥岩中观察到剪切带和韧性流动裂缝。利用泥岩的破坏行为和破坏强度建立了破坏行为模型。该模型预测了在高围压下泥岩的脆性，脆性转变和延性区域。脆性到延性的转变不是突然的，而是由围压和破坏强度控制的渐进过程。该模型表明，与强泥岩相比，弱泥岩的脆性-韧性过渡带较窄。而是由围压和破坏强度控制的渐进过程。该模型表明，与强泥岩相比，弱泥岩的脆性-韧性过渡带较窄。而是由围压和破坏强度控制的渐进过程。该模型表明，与强泥岩相比，弱泥岩的脆性-韧性过渡带较窄。