基于扩展有限元的重力坝尺寸效应  

Size effects of concrete gravity dams based on XFEM analyses

作　　者：石杰[1] 李庆斌[1] 

机构地区：[1]清华大学水沙科学与水利水电工程国家重点实验室,北京100084

出　　处：《清华大学学报（自然科学版）》2017年第4期345-350,共6页Journal of Tsinghua University(Science and Technology)

基　　金：国家"九七三"重点基础研究项目(2013CB035902);国家自然科学基金重点资助项目(51339003)

摘　　要：准脆性材料的结构破坏试验会引起尺寸效应现象,相似模型的结果不能简单地由相似关系换算至原型。该文利用扩展有限元方法,研究了预制缝重力坝的破坏过程和极限承载力。同时,为揭示结构承载力的尺寸效应,建立了一系列几何相似的离心模型和重力加速度模型(不考虑自重相似),并进行了超载破坏评价。结果表明:随着结构尺寸的增加,离心模型的极限承载力大致呈指数衰减趋势下降,并逐渐趋于稳定值;重力加速度模型的极限承载力首先呈指数衰减趋势下降,当超过一定尺寸范围后,又大致呈线性增长;断裂过程区相对长度和自重应力效应分别是结构强度尺寸效应的内在因素和外部荷载因素。Similarity model test results cannot be simply converted to the prototype without consideration of the size effect.The extended finite element method（XFEM）was used to analyze the failure mechanism and overall structure strength of a type of prenotched gravity dam.The size effect was investigated by analyzing the nominal strength of geometrically similar prenotched gravity dams with various sizes.The nominal strength and failure mechanism were analyzed for two sets of models with an extra centrifugal force and a self-weight force.The results show that the structural strength in the centrifugal models decreases exponentially and tends to be stable for larger sizes,while in gravitational models the strength decreases exponentially up to a critical height and then increases gradually due the self-weight contribution.The relative length of the fracture process zone is an intrinsic factor while the self-weight stress is an external loading factor for the effect of size on the structural strength.

关 键 词：水工结构 重力坝 尺寸效应 离心模型 重力加速度模型 

分 类 号：TV313[水利工程—水工结构工程]