含天然微裂隙岩石的力学特性试验研究

Experimental Study on Mechanical Properties of Rock Containing Natural Micro-fractures

为研究含天然微裂隙岩石的劈裂力学特性及微观结构,对含天然微裂隙岩石进行单轴压缩试验、劈裂试验与SEM扫描试验。分析了微裂隙岩石单轴压缩试验及劈裂试验的破坏形式、抗拉强度的变化规律,并对劈裂破坏形式中岩石较为破碎部分进行微观结构分析。研究结果表明:在单轴压缩试验中,天然微裂隙岩石破坏形式主要表现为张拉破坏、沿天然裂隙面剪切破坏以及拉剪复合破坏;天然微裂隙倾角对岩石抗拉强度影响较大,其抗拉强度随微裂隙倾角增大而增大;岩样发生劈裂破坏后较为破碎的部分,其劈裂力学特性主要受天然微裂隙岩石的微观结构决定,其微观结构主要分为根状结构、雾区结构、台阶结构3种形式,根状结构微裂隙岩石的力学性质最差,台阶结构微裂隙岩石的力学性质最好。研究成果可为天然微裂隙岩石的力学特性理论研究及其工程应用提供参考依据。

Uniaxial compression test,splitting test and SEM scanning test were performed to investigate the splitting mechanical properties and microstructure of rock containing natural microfractures.The failure modes and tensile strength of rock containing natural microfractures undergone uniaxial compression test and splitting test were analysed;the microstructure of the broken part of rock specimens of splitting failure mode was examined as well.In uniaxial compression test,the failure modes of rock specimens containing natural microfractures were mainly tension failure,shear failure along natural fracture surface,and tension-shear composite failure;the dip angle of natural microfracture had a remarkable influence on the tensile strength of rock which increased with the increase of dip angle.On the other hand,after splitting failure,the splitting mechanical properties were largely determined by the microstructure of natural microfractures which can be classified as three types,namely,root structure,fog area structure,and step structure,among which root structure had the most inferior mechanical properties whereas step structure was of good mechanical properties.