碾压混凝土断裂试验分析与静动态断裂韧度关系研究

碾压混凝土开裂破坏是一个＂损伤——开裂——裂缝扩展——断裂失稳＂动态演变过程,为摸清其损伤断裂理与规,本文完成了12根实际坝体材料碾压混凝土三点弯曲梁试验,分析了强度等级、缝高比对碾压混凝土断裂特性影响.以材料静态断裂试验为础,通过研究声发射信号参量与动态荷载下裂缝扩展关系,到了动静态断裂韧度转化关系.最后利用有限元对武都重力坝裂缝在地震作用下开裂破坏进行分析,为实际坝体混凝土裂缝安全评价提供科学依据.

Fracture experiment of roller compacted concrete and the relation of static and dynamic fracture toughness

Crack destruction of Roller compacted concrete in dams belongs to the process of ＂damage--cracking--crack propagating--failure＂. In order to study the basis of reliable theories and technical supports for analysis of structural failure, 12 RCC speciments were finished using materials from the actual dam in three-point bending beam testing. The fracture influence of RCC were analyzed in factors of seam high and strength grade. The factors of concrete fracture parameters systematically were discussed through using material properties and size effect as the main lines. Under static fracture experiments of concrete, the parameters of acoustic emission signals were studied on dynamic loading rate of crack propagation. Then the formulae of transformation relationship were gotten between dynamic and static stress intensity factors. Based on the tests and analyzed results in this paper, the crack destruction of Wudu gravity dam was analyzed under earthquake using the finite method so that it provided the scientific basis for safety assessment of this dam.