渗流–应力耦合作用下碎屑岩流变特性和渗透演化机制试验研究  

EXPERIMENTAL INVESTIGATION ON RHEOLOGICAL PROPERTIES AND PERMEABILITY OF CLASTIC ROCK UNDER HYDRO-MECHANICAL COUPLING

作　　者：张玉[1,2] 徐卫亚[2] 邵建富[2] 赵海斌 王伟[2] 梅松华 

机构地区：[1]中国石油大学储运与建筑工程学院,山东青岛266580 [2]河海大学岩土工程科学研究所,江苏南京210098 [3]中南勘测设计研究院水能资源利用关键技术湖南省重点实验室,湖南长沙410014

出　　处：《岩石力学与工程学报》2014年第8期1679-1690,共12页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(11172090);中南勘测设计研究院水能资源利用关键技术湖南省重点实验室开放研究基金项目(PKLHD201306);中央高校基本科研业务费专项资金资助项目(13CX02095A)

摘　　要：基于物理和常规变形特性分析,认为某水电站坝基碎屑岩力学特性异常复杂,故采用岩石三轴伺服仪开展渗流–应力耦合作用下的流变和渗透特性试验研究。首先绘制流变全程试验曲线,探讨轴向、侧向及体积流变特性和速率变化规律;其次对流变过程中渗流规律和演化机制进行详细分析;最后,对破坏岩样开展微细观电镜扫描试验,研究宏微观破坏机制。结果表明,碎屑岩表现出显著的流变力学特性,流变曲线主要分为初始衰减和稳态流变两阶段,且最后级应力施加后呈现快速流变现象;应力和渗透压力增加导致流变变形加剧,围压对流变变形存在限制作用;最终破坏表现出轴向压缩变形过大、体积延性扩容明显、稳态流变速率较大等特点,且流变速率与应力符合指数增加关系。鉴于岩样的非均质性,加载作用导致渗透系数变化存在部分波动,但整体呈降低的趋势。稳态流变阶段,渗透系数恢复至平缓线性下降趋势,说明波动对渗透率的整体演化无显著影响,且围压增加导致渗透系数降低。试验结果旨在为渗流–应力耦合作用下岩石工程长期稳定分析及流变模型构建提供可靠的依据。The mechanical properties of clastic rock of dam foundation in a hydropower station in virtue of conventional physical and deformation analysis are very complex. Triaxial rheological tests were therefore conducted using the automatic triaxial servo-instrument to investigate the rheological properties and permeability of such rock under hydro-mechanical coupling. The axial,lateral and volumetric deformation curves versus time were measured and the rheological deformation properties and rheological rate law were discussed accordingly. The evolution process of permeability during rheological period was analyzed in detail. The scanning electron microscope（SEM） experiments were performed for the rock specimens after failure to study the mechanism and mode of macro-micro failure. The results show that the clastic rock has a pronounced rheological behavior. The rheological curves have a transient period initially,a steady period thereafter and an accelerated period finally at＆amp;nbsp;the last loading step. The rheological deformation were increased when the stress and seepage pressure applied were increased and were reduced if the confining pressure was increased. The finally failed specimen have the characteristics of large axial compression deformation,obvious ductile volumetric dilation and large steady rheological rate. The relationship between the rheological rate and the applied stress can be described by an exponential function. The coefficients of permeability fluctuate during the rheological process possibly because of the heterogeneity of specimens,but overall decrease. During the stage of steady period,the coefficients of permeability decrease linearly. It is shown that the fluctuation has no significant effect on the permeability evolution. Furthermore,the permeability coefficients decrease as the confining pressures increase.

关 键 词：岩石力学 碎屑岩 渗流-应力耦合 三轴流变试验 渗透系数 流变速率 细观破坏机制 

分 类 号：TU45[建筑科学—岩土工程]