砂岩层理构造对力学特性影响分析

层理构造是影响岩石力学特性的重要因素,通过开展不同层理构造砂岩的三轴蠕变试验,分析层理构造对砂岩力学特性的影响。试验结果表明:砂岩具有蠕变特性,并且层理构造不同,蠕变特性具有明显的各向异性特性。分析表明,在三轴应力状态下砂岩表现出瞬时变形、衰减蠕变、稳定蠕变和加速蠕变特征;在低应力水平条件下,砂岩变形以瞬时变形为主,随着应力水平增加,蠕变变形不断增大,最终导致试样破坏;随着层理角度增大,砂岩试件的长期强度、峰值强度、弹性模量先减小后增大,稳定蠕变速率呈"M"形变化;应力与层理夹角不同导致砂岩的破裂模式不同,层理角度30°时,主要发生沿着层理面的剪切破坏,其他层理角度时,主要发生斜交层理面的剪切破坏。

Analysis of the Influence of Sandstone Bedding Structure on Its Mechanical Properties

Bedding structure is an important factor affecting the mechanical properties of rocks. Triaxial creep tests of sandstone with different bedding structures are carried out to analyze the influence of bedding structures on the mechanical properties of sandstone. The test results show that sandstone has creep characteristics, and the creep characteristics have obvious anisotropic characteristics because of different bedding structures. The analysis shows that sandstone under triaxial stress has the characteristics of instantaneous deformation, attenuation creep, steady creep and accelerated creep. Under the condition of low stress level, the main deformation of sandstone is instantaneous deformation. With the increase of stress, creep deformation increases continuously, which eventually leads to sample failure. With the increase of bedding angle, the long-term strength, peak strength and modulus of elasticity of sandstone specimens decrease first and then increase, and the steady creep rate changes in the form of "M". The different stress and bedding angle result in different fracture modes of sandstone. When the bedding angle is 30 degrees, the shear failure surface of the specimens is mainly parallel to the bedding surface, and the shear failure surface of other bedding angle specimens intersects with the bedding surface.