卸荷速率和孔隙水压力对砂岩卸荷特性影响研究

发布时间：2018-01-13 02:25

本文关键词：卸荷速率和孔隙水压力对砂岩卸荷特性影响研究　出处：《岩土工程学报》2017年11期 　论文类型：期刊论文

【摘要】：为了研究卸荷速率和孔隙水压力对砂岩卸荷力学特性的影响,设计进行了不同卸荷速率(0.005,0.02,0.05,0.1 MPa/s)和不同孔隙水压力(0,0.3,0.6,0.9,1.2 MPa)下的三轴卸荷试验。研究结果表明:(1)在加载阶段,随着孔隙水压力的增大,岩样的应力应变曲线斜率逐渐降低;(2)在围压卸载阶段,卸荷速率越大,卸载阶段的应变围压柔量越小,岩样破坏时的围压越小,岩样强度相对较高,但破碎程度更严重,而且,在相同的卸荷速率情况下,孔隙水压力越大,岩样侧向扩容现象越明显,岩样越容易破坏;(3)在围压卸载阶段,岩样的变形模量出现了先缓后陡的劣化趋势,而且,卸荷速率越小、孔隙水压力越大,变形模量劣化幅度越大;(4)卸载过程中,卸荷速率越大,岩样脆性破坏特征越明显;孔隙水压力越大,岩样破坏时的近轴向的张性裂纹越多和追踪次生裂纹越多,孔隙水压力在岩样内部裂纹、裂隙尖端的应力集中是导致岩石变形破坏的主要原因。
[Abstract]:In order to study the effect of unloading rate and pore water pressure on the unloading mechanical properties of sandstone, different unloading rates (0.005 / 0.02 / 0.05) were designed. The triaxial unloading tests were carried out at 0.1 MPA / s and 0. 3 / 0. 6 ~ 0. 9 ~ 1. 2 MPa under different pore water pressures. The results show that 1 / 1) is at the loading stage. With the increase of pore water pressure, the slope of stress-strain curve decreases gradually. 2) at the stage of confining pressure unloading, the larger the unloading rate is, the smaller the strain confining pressure is, the smaller the confining pressure of rock sample is, the higher the strength of rock sample is, but the more serious the fracture degree is. At the same unloading rate, the bigger the pore water pressure is, the more obvious the lateral expansion of rock sample is, and the easier it is to destroy rock sample. (3) at the stage of confining pressure unloading, the deformation modulus of rock samples shows a tendency of decreasing first and then steep, and the smaller the unloading rate is, the greater the pore water pressure is, and the larger the degradation range of deformation modulus is. (4) in the unloading process, the higher the unloading rate, the more obvious the brittle failure characteristics of rock samples; The larger the pore water pressure, the more the near axial tensile cracks and the tracing secondary cracks, and the more the pore water pressure cracks in the rock samples. Stress concentration at the crack tip is the main cause of rock deformation and failure.
【作者单位】：三峡库区地质灾害教育部重点实验室(三峡大学);
【基金】：国家自然科学基金项目(51679127);国家自然科学基金重点项目(51439003) 水利部公益基金项目(201401029)
【分类号】：TU45
【正文快照】： Yichang 443002,China)20世纪90年代,针对工程岩体中出现的较多常规岩石力学理论无法较好解释的工程问题,如金川边坡、链子崖边坡的大变形等,哈秋聆等[1]以三峡永久船闸高边坡为研究对象,创新性地提出了卸荷岩体力学的概念,在至今30余年的研究过程中,岩体卸荷力学特性越来越被

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