基于PFC^(2D)的砂岩直剪试验尺寸效应数值模拟研究  

Numerical Simulation of Size Effect in Sandstone Direct Shear Test Based on PFC^(2D)

作　　者：宋岳 柳滔 余俊爽 SONG Yue;LIU Tao;YU Junshuang(Changjiang Water Resources and Hydropower Development Group Co.,Ltd.,Wuhan 430010,Hubei,China;Guangxi Youjiang Water Resources Development Co.,Ltd.,Baise 530029,Guangxi,China)

机构地区：[1]长江水利水电开发集团(湖北)有限公司,湖北武汉430010 [2]广西右江水利开发有限责任公司,广西百色530029

出　　处：《水力发电》2025年第4期18-24,共7页Water Power

基　　金：三峡库区地质灾害教育部重点试验室开放基金项目(2018KDZ09);长江水电集团自主科研项目基金(SDJTKY-2023-01)。

摘　　要：以三峡库区库岸边坡砂岩为例,基于PFC^(2D)颗粒流平行黏结本构模型,采用离散元模拟方法,模拟不同尺寸、不同正应力下的砂岩试件直剪破坏试验过程,分析尺寸效应对砂岩剪应力-位移曲线、抗剪强度以及细观黏结键破坏和裂纹扩展特征的影响。结果表明,弹性变形阶段小尺寸试件更能表现整体性和均一性,而大尺寸试件则表现更强的塑性;随着尺寸的增大,试件的抗剪强度(黏聚力和内摩擦角)产生弱化现象。尺寸效应还表现在裂纹的扩展形式上,小尺寸试件易发生脆性剪切破坏,次生裂纹较少且主裂纹多为直线型;大尺寸试件多产生剪胀性裂纹,次生裂纹较多且主裂纹多为曲线型。Taking the sandstone in the bank slope of Three Gorges reservoir as an example,the direct shear failure test process of specimens with different sizes and normal stresses is simulated by discrete element simulation method based on the PFC^(2D) particle flow parallel bonding constitutive model,and the effects of size effect on the shear stress-displacement curve,the shear strength,and the characteristics of bond failure and crack propagation are analyzed.The results show that,(a)in elastic deformation stage,small-size specimens show more integrity and uniformity,while large-size specimens show stronger plasticity;and(b)with the increase of the size,the shear strength(cohesion and internal friction angle)of the specimen weakens.The size effect is also manifested in the form of crack propagation,that is,the small-size specimens are prone to brittle shear failure,with fewer secondary cracks and mostly linear main cracks,but the large-scale specimens are mostly dilatant cracks,with more secondary cracks and mostly curved main cracks.

关 键 词：砂岩 直剪试验 尺寸效应 数值模拟 宏-细观特征 颗粒流 平行黏结本构模型 

分 类 号：TU458[建筑科学—岩土工程]