随着计算机技术的发展,可以采用仿真的方法来研究新拌混凝土的流变性能.离散元方法适合于新拌混凝土的大变形流动.颗粒的物性参数和接触参数的设定是模拟结果真实可靠的关键.在本研究中,将混凝土分为机制石和砂浆两相.首先测量了物性参数,包含密度、恢复系数、静摩擦系数和滚动摩擦系数.使用Hertz-Mindlin(no slip)接触模型表示粗骨料-边界和粗骨料-粗骨料之间的相互作用,并通过休止角的实验进行了验证;采用Hertz-Mindlin with JKR接触模型来描述粗骨料-砂浆、砂浆-砂浆、砂浆-边界之间的相互作用,用坍落度实验对JKR参数进行了标定,并采用响应曲面法确定了最佳的参数组合值.最后通过L型箱试验对新拌混凝土的离散元仿真方法进行了验证.
Measurement and calibration of discrete element parameters of fresh concrete
With development of computer technology,the numerical method is used to investigate the rheo-logical behavior of fresh concrete.Discrete Element Method is suitable for the larger deformation of fresh concrete.The accuracy of the physical and contact parameters of the particles is key to the reliability of the simulation results.In this study,the concrete was divided into two phases:Mechanism stone and mor-tar.The physical parameters such as density,recovery coefficient,coefficient of static friction and coefficient of rolling friction were firstly measured.Hertz-Mindlin(no slip)model was used to represent in-teractions of the coarse aggregate-boundary or coarse aggregate-coarse aggregate,and was verified by exper-iment with angle of repose.Hertz-Mindlin with JKR contact model was used to describe interactions of coarse aggregate-mortar,mortar-mortar or mortar-boundary,the JKR parameters were calibrated using slump experiment and the optimal parameter combination were determined using the response surface meth-od.Finally the discrete element simulation method of fresh concrete was validated by L-box test.
fresh concretecontact modelangle of reposesecond order regression model
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