基于断裂力学理论的诱导缝开裂相似试验模拟

为了研究诱导缝在结构模型破坏试验中的开裂相似条件和试验模拟方法,进行了材料的断裂特性实验和力学理论推导。根据结构模型试验的相似性要求和诱导缝的工作原理,原型、模型材料须满足开裂特性和抗剪断强度相似的要求。通过材料的断裂特性试验,获得了考虑尺寸效应的碾压混凝土的断裂韧度值和石膏的断裂韧度与水膏比的关系曲线。在此基础上运用断裂力学理论,分析应力强度因子与断裂韧度之间的关系,推导出诱导缝的开裂特性相似条件和满足开裂条件的诱导缝模型尺寸。试验中选用包裹聚脂薄膜的铜片来模拟诱导缝,按f、c综合效应满足了抗剪断强度相似条件。从而在结构模型试验中实现了诱导缝的开裂相似模拟,并为研究含诱导缝拱坝的开裂和破坏机理提供了依据。

Test Study on Cracking Similarity Simulation of Induced Joint Based on Theory of Fracture Mechanics

In order to study on the problems of cracking similarity conditions and test simulating method of induced joint in structural model test,fracture property tests of material and mechanics theory deducing are presented in this paper.According to the similarity criterion of structural model test,prototype material and model material need to conform to the similarity conditions of fracture property and shear-friction strength.The fracture toughness of RCC,considering the size effect,and the curve of water-gypsum ratio vs.fracture toughness of gypsum are obtained by material fracture tests.Furthermore,theory of fracture mechanics is used to analyze the relation between fracture toughness and stress intensity factor,the similarity conditions of cracking property is deduced,and the model sizes of induced joint,conformed to the cracking conditions,is calculated.In the test,a copper sheet cover with mylar is used as the joint material and the shear-friction strength similarity condition is satisfied by considering the comprehensive effects of f and c.Consequently,cracking similarity simulation of induced joint is realized in structural model test.The results provide the basis for researching cracking and failure mechanism of RCC arch dam with induced joints.