单轴压缩下层理砂岩力学响应与能量耗散规律研究

Mechanical response and energy dissipation characteristics of bedded sandstone under uniaxial compression

  • 摘要: 在单轴压缩条件下,层理砂岩的强度、变形及能量演化规律不仅取决于砂岩基质的固有属性,更受层理倾角、层理面胶结强度及分布密度等因素的控制,呈现出强烈的各向异性特征。目前对于层理砂岩在单轴压缩过程中的力学性能及能量耗散规律的系统研究仅关注单一角度或单一能量参数,缺乏对不同层理倾角下能量参数与力学参数、破坏类型与特征的协同分析。针对上述问题,以层理砂岩为研究对象,通过单轴压缩试验,系统测试 0,30,45,60,90° 5种层理倾角下层理砂岩的应力−应变曲线,分析其力学性能(峰值强度、弹性模量、泊松比等),观察主导破坏类型与特征,并结合能量守恒原理计算输入能、弹性能及耗散能的演化规律。研究结果表明:① 层理倾角显著影响砂岩力学性能,峰值强度和弹性模量随层理倾角呈“U 型”变化,45° 时最低,90° 时最高。泊松比呈单峰规律,45° 时达最大值,为0.32。峰值应变则表现为 45° 时最大,90° 时最小。② 破坏类型与特征随层理倾角呈现“穿层破坏→沿层剪切+局部穿层→沿层剪切滑移”的转变,0° 和 90° 以穿层脆性破坏为主,45° 和 60° 以沿层剪切塑性破坏为主。③ 输入能、弹性能及耗散能均受层理倾角调控,0° 和 90° 试件弹性能占比高,破坏时集中释放。30~60°试件耗散能占比更高,呈持续增长趋势。

     

    Abstract: Under uniaxial compression, the strength, deformation, and energy evolution characteristics of bedded sandstone depend not only on the inherent properties of the sandstone matrix but are also strongly controlled by factors such as bedding dip angles, bonding strength of bedding planes, and bedding density, exhibiting pronounced anisotropic behavior. At present, systematic studies on the mechanical properties and energy dissipation characteristics of bedded sandstone during uniaxial compression have mainly focused on a single bedding angle or a single energy parameter, lacking a synergistic analysis of energy parameters and mechanical parameters, as well as failure types and characteristics, under different bedding dip angles. To address this issue, bedded sandstone was taken as the research object, and uniaxial compression tests were conducted to systematically obtain stress-strain curves of bedded sandstone with five bedding dip angles of 0, 30, 45, 60, and 90°. The mechanical properties, including uniaxial compressive strength, elastic modulus, and Poisson's ratio, were analyzed, the dominant failure types and characteristics were observed, and the evolution laws of input energy, elastic energy, and dissipated energy were calculated based on the principle of energy conservation. The results showed that the bedding dip angle significantly influenced the mechanical properties of sandstone. The peak strength and elastic modulus exhibited a U-shaped variation with bedding dip angle, reaching the minimum at 45° and the maximum at 90°. Poisson's ratio showed a single-peak pattern, attaining the maximum value of 0.32 at 45°. The peak strain reached the maximum at 45° and the minimum at 90°. The failure types and characteristics evolved with bedding dip angle from through-bedding failure to along-bedding shear combined with local through-bedding failure, and finally to along-bedding shear slip. Specimens with bedding dip angles of 0° and 90° were dominated by through-bedding brittle failure, whereas those with 45° and 60° were dominated by along-bedding shear plastic failure. The input energy, elastic energy, and dissipated energy were all regulated by bedding dip angle. Specimens with bedding dip angles of 0° and 90° showed a higher proportion of elastic energy, which was released intensively at failure, while specimens with bedding dip angles of 30-60° exhibited a higher proportion of dissipated energy with a continuously increasing trend.

     

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