多因素耦合作用下岩石冻融损伤机理试验研究

发布时间：2018-03-19 01:19

本文选题：岩石力学　切入点：冻融循环　出处：《中南大学》2014年硕士论文　论文类型：学位论文

【摘要】：摘要：岩石冻融损伤研究因其极强的寒区工程应用背景,已经成为岩石力学学科的研究热点。开展多因素耦合作用下岩石冻融损伤机理试验研究,对高海拔寒区矿业开发等岩体工程中冻融灾害的分析和防治,具有重要的理论价值和现实意义。论文以砂岩为研究对象,通过开展加卸载作用后岩石的冻融损伤试验和复杂环境下岩石冻融损伤试验,综合运用力学分析和核磁共振测试技术等手段,对多因素耦合作用下冻融岩石的物理力学性质变化和内部细观结构变化进行了观测和分析,并基于试验结果对岩石冻融损伤机理进行了研究。取得的主要成果如下： (1)加卸载作用后岩石在冻融0-135次时,试件质量无显著变化,整体形状完好,单轴抗压强度随冻融次数增加略微下降,试件泊松比变化规律不显著。弹性模量随着加卸载中卸荷点的增大而有所降低,冻融作用使试件脆性有所增强。 (2)化学环境对岩石试件损伤影响非常大,溶液内试件随冻融次数的增加,质量和抗拉强度显著减小,试件表面出现不同程度的剥落和掉块。 (3)黄砂岩试件的孔隙度随冻融次数增加总体呈缓慢上升态势,内部损伤模式为：初始阶段微小尺寸的新孔隙产生较快,后续小孔隙的扩展缓慢。加卸载操作未对试件内冻融损伤模式和孔隙结构演变造成显著影响。(4)红砂岩试件孔隙度随冻融次数增加基本呈线性增加态势,化学溶液显著加速了岩石试件的孔隙扩展。内部损伤模式为：岩石在冻融初期原生小孔隙扩展为大尺寸孔隙,随后岩石内部又产生新的次生小孔隙,小孔隙会迅速扩展为大孔隙直至坍塌破坏。结果表明,均匀大孔径的多孔岩石冻融损伤机理基本符合静水压冻融破坏理论,而非均匀小孔径的多孔岩石冻融损伤机理基本符合渗透压冻融破坏理论。岩石材料孔隙结构不同是冻融损伤作用机理差异的重要原因。
[Abstract]:Abstract: the research of rock freeze-thaw damage has become a hot topic in rock mechanics because of its strong engineering application background in cold region. It is of great theoretical value and practical significance to analyze and prevent freeze-thaw disasters in rock mass engineering such as mining development in high altitude cold region. In this paper, sandstone is taken as the research object, through the freezing and thawing damage test of rock after loading and unloading and the freezing and thawing damage test of rock under complex environment, the comprehensive use of mechanical analysis and nuclear magnetic resonance testing technology is used. The physical and mechanical properties of freeze-thawed rock and the variation of internal meso-structure were observed and analyzed. The mechanism of freeze-thaw damage of rock was studied based on the experimental results. The main results achieved are as follows:. 1) when the rock is frozen and thawed 0-135 times after loading and unloading, the mass of the specimen has no significant change, the whole shape is intact, and the uniaxial compressive strength decreases slightly with the increase of freezing and thawing times. The change of Poisson's ratio is not obvious. The elastic modulus decreases with the increase of unloading point, and the brittleness of the specimen is enhanced by freezing and thawing. (2) the chemical environment has a great influence on the damage of rock specimen. With the increase of freeze-thaw times, the mass and tensile strength of the specimen decrease significantly, and the surface of the specimen appears different degree of spalling and falling. (3) the porosity of yellow sandstone specimen increases slowly with the increase of freeze-thaw times. The porosity of the red sandstone specimen increases linearly with the increase of freezing and thawing times, and the loading and unloading operation has no significant effect on the damage mode and the evolution of pore structure of the specimen, and the porosity of the red sandstone specimen increases linearly with the increase of freezing and thawing times. The chemical solution significantly accelerates the pore expansion of rock specimens. The internal damage pattern is that the primary small pores in the early stage of freezing and thawing become large pores, and then new secondary small pores occur in the rock interior. Small pores can rapidly expand into macropores until they collapse. The results show that the mechanism of freezing and thawing damage of porous rock with uniform and large pore size basically accords with the theory of hydrostatic freezing and thawing failure. However, the mechanism of freezing and thawing damage of porous rock with non-uniform small pore size basically accords with the theory of osmotic freezing and thawing failure, and the difference of pore structure of rock material is the important reason for the difference of mechanism of freezing and thawing damage.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU452

【共引文献】