水压环境下砂岩蠕变特性试验研究

发布时间：2018-04-28 20:08

本文选题：岩石力学 + 水围压　；参考：《工程科学与技术》2017年S1期

【摘要】：水利工程中的坝基和库岸岩体长期在高应力和高水压的共同作用下会产生蠕变现象,对工程稳定性影响很大。针对水利工程中岩石在流固耦合作用下的蠕变问题,选取某水电站引水隧道线路上震旦系砂岩为研究对象,利用MTS试验机和扫描电镜(SEM)分别对干燥和饱和状态下砂岩的常规物理力学参数和微观结构进行测试,分析砂岩在不同状态下的主要物理参数和微观结构变化;基于此,利用专用的微机控制轴压水压联合作用岩石流变试验系统,通过对砂岩试样施加不同的水围压,对其蠕变过程进行试验研究,分析水压对蠕变变形量、蠕变速率和长期强度的影响。结果表明:砂岩内部存在大量的微孔隙,砂岩在饱水状态下,呈现出软化特性,饱水砂岩的抗压强度与弹性模量均小于干燥砂岩;砂岩在稳定蠕变阶段的变形量随水压的增大而增加,水压的增加降低了砂岩的强度和抵抗变形的能力,导致岩石初期和稳定蠕变阶段蠕变量的增大;水压越高岩石蠕变的初始应变率越大,衰减至稳定蠕变阶段所需时间越长;水压能通过岩石表面的孔隙渗入到岩石内部,在裂纹发展的过程中,孔隙水压力能及时到达裂纹尖端,形成"锲入"作用,促使裂隙的扩展和贯通,加速岩石破坏变形,从而降低岩石的承载能力和长期强度。
[Abstract]:Under the action of high stress and high water pressure, the dam foundation and reservoir bank rock mass in water conservancy project will produce creep phenomenon for a long time, which has great influence on the engineering stability. Aiming at the creep problem of rock under fluid-solid coupling in hydraulic engineering, the Sinian sandstone on the diversion tunnel of a hydropower station is selected as the research object. The conventional physical and mechanical parameters and microstructure of sandstone under dry and saturated conditions were tested by MTS and SEM, respectively, and the main physical parameters and microstructure changes of sandstone in different states were analyzed. The creep process of sandstone specimen is studied by applying different water confining pressure to the rock rheological test system controlled by special microcomputer, and the amount of creep deformation caused by water pressure is analyzed. The influence of creep rate and long term strength. The results show that there are a large number of micropores in sandstone. The sandstone shows softening characteristics under saturated state. The compressive strength and elastic modulus of saturated sandstone are lower than that of dry sandstone. The deformation of sandstone in the stable creep stage increases with the increase of water pressure, and the increase of water pressure decreases the strength of sandstone and the ability to resist deformation, which leads to the increase of creep amount in the initial and stable creep stages of rock. The higher the water pressure, the greater the initial strain rate of rock creep, the longer the time needed to attenuate to the stable creep stage, and the longer the water pressure can penetrate into the rock through the pores of the rock surface, and in the process of crack development, Pore water pressure can reach the crack tip in time and form the role of "wedge in", which can promote the expansion and penetration of cracks, accelerate rock failure and deformation, and thus reduce the bearing capacity and long-term strength of rock.
【作者单位】：四川大学水力学与山区河流开发保护国家重点实验室;四川大学水利水电学院;四川电力设计咨询有限责任公司;四川大学-香港理工大学灾后重建与管理学院;
【基金】：国家自然科学基金煤炭联合基金重点资助项目(51134018);国家自然科学基金资助项目(51369001)
【分类号】：TV223

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