冲刷作用下砂岩宏观力学特性及微观结构  

Macromechanical properties and microstructure of sandstone under scouring effect

作　　者：张科 关世豪 齐飞飞 徐奕 金克盛[2] ZHANG Ke;GUAN Shi-hao;QI Fei-fei;XU Yi;JIN Ke-sheng(Faculty of Civil and Architectural Engineering,Kunming University of Science and Technology,Kunming,Yunnan 650500,China;Faculty of Electric Power Engineering,Kunming University of Science and Technology,Kunming,Yunnan 650500,China;Water Resources Bureau of Chuxiong Yi Autonomous Prefecture,Chuxiong,Yunnan 675000,China)

机构地区：[1]昆明理工大学建筑工程学院,云南昆明650500 [2]昆明理工大学电力工程学院,云南昆明650500 [3]楚雄彝族自治州水务局,云南楚雄675000

出　　处：《岩土力学》2024年第7期1929-1938,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.42362034,No.11902128);云南基础研究计划项目(No.202401AS070068)。

摘　　要：水流环境下库岸边坡岩石劣化会严重危害坡体稳定性,如何精细化揭示动水冲刷作用下岩石宏观力学特性及微观结构对库区灾害防治具有重要意义。为模拟库岸边坡所处的水流环境,设计了一套岩石抗冲刷试验装置。以砂岩为研究对象,考虑自然、静水浸泡和动水冲刷3种工况。结合室内试验、数字图像相关方法、扫描电镜和分形理论,从宏观力学参数、应变场分布特征、微观结构等角度系统探讨了不同水环境对岩石力学特性的影响。研究结果表明:(1)动水冲刷后的岩石抗压强度和弹性模量软化系数比饱水试件分别降低了0.07和0.06;(2)应变场分异速率-轴向应变曲线在峰值应力前出现拐点P,与断裂过程区的集聚相关,可作为岩石破裂的前兆信号;相较于饱水作用,冲刷作用使得破裂前兆点出现变早,这是因为冲刷作用加剧了岩石内部缺陷的发育,更易形成裂纹;(3)相较于饱水试件,动水冲刷后砂岩内部矿物颗粒和胶结物流失程度加大,微观结构劣化更为显著,这种变化在扫描电镜图像的分形维数计算结果中得到了印证,冲刷试件的分形维数最大。The deterioration of rocks on reservoir bank slopes under flowing water conditions can seriously compromise slope stability.Meticulously exploring the macro-mechanical properties and microstructures of rocks under dynamic water scouring conditions is of great significance for disaster prevention and control in reservoir areas.To simulate the water flow environment of reservoir bank slopes,a rock scour resistance test device was designed.Taking sandstone as the research object,three conditions namely,natural drying,hydrostatic immersion,and hydrodynamic scouring,,were considered.Combining with laboratory test results,digital image correlation techniques,scanning electron microscopy,and fractal theory,the influences of different water environments on the mechanical properties of rocks were systematically explored in terms of macro-mechanical parameters,distribution characteristics of strain fields,and microstructure.The results indicate that the softening coefficients of compressive strength and elastic modulus of hydrodynamically scoured specimens decrease by 0.07 and 0.06 units,respectively,compared to those of water-saturated specimens.The inflection point of the strain field differentiation rate-axial strain curve appears before the peak stress,associated with the localization of the fracture process zone,serving as a precursor signal for rock fracture.Compared to the effect of hydrostatic immersion,the precursor point P of hydrodynamically scoured specimens appears earlier,as hydrodynamic scouring aggravates the development of internal defects,thereby facilitating the earlier appearance of the precursor point.Furthermore,the loss of mineral particles and cementing materials within the sandstone increases significantly after hydrodynamically scouring,leading to a more pronounced degradation of its microstructure than that of water-saturated specimens.This change is confirmed by the fractal dimension calculations of scanning electron microscope images,indicating that the hydrodynamically scoured specimens exhibi

关 键 词：冲刷 岩石 数字图像相关方法 力学特性 微观结构 分形维数 

分 类 号：TU451[建筑科学—岩土工程]