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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。
Structural damage test of quasi-brittle materials will cause the phenomenon of size effect. The results of similar models can not be simply converted from the similarity relation to the prototype. In this paper, by using the extended finite element method, the failure process and ultimate bearing capacity of prestressed gravity dam are studied. At the same time, to reveal the size effect of the bearing capacity of the structure, a series of centrifugal model of similar geometry and model of gravity acceleration (similar weight without considering gravity) were established, and the assessment of overload destruction was carried out. The results show that the ultimate bearing capacity of centrifugal model declines exponentially with the increase of structural size and gradually becomes stable. The ultimate bearing capacity of gravitational acceleration model firstly decreases exponentially, and when it exceeds a certain size range , And roughly linearly increased. The relative length of the fracture zone and the self-weighting stress effect are the intrinsic factor and the external load factor of the structural strength dimensional effect, respectively.