混凝土/花岗岩界面动态断裂性能的轴拉试验研究

Axial tensile tests for dynamic fracture characteristics of concrete-granite interface

为研究混凝土和花岗岩界面断裂的加载应变率效应,利用MTS试验机对带有双边预制裂缝的花岗岩试件、混凝土试件和混凝土/花岗岩复合试件等三种试件进行了轴向拉伸试验。通过裂缝张开口位移进行控制,获得了不同应变率(10'6~10-3 s")下的荷载-裂缝张开口位移曲线,据此计算了荷载上升段的吸能能力,并基于结构动力分析和断裂力学、界面力学理论获得了试件的断裂韧度;结果表明,三类试件的断裂面形态随着应变率的变化呈现不同的特征,三者的峰值荷载、吸能能力和断裂韧度均随应变率的提高而增加。对三类试件断裂特性在中低应变率范围内的率效应机理进行了分析,对比了准脆性材料界面断裂与母材断裂率效应的异同。

In order to study the loading strain rate effect of interfacial fracture of concrete-granite, axial tensile tests were performed on granite specimens, concrete ones and concrete-granite composite ones with bilateral precast cracks using a MTS testing machine under different loading rates. Through controlling crack opening displacement, load-crack opening displacement curves under strain rates of 10~6 10 ~3s_1 were obtained, and then the energy absorption capacity during loading rising was calculated. Based on theories of structural dynamic analysis, fracture mechanics and interfacial mechanics, the specimens * fracture toughness were calculated. The results showed that with the variation of strain rate, fracture surface morphologies of the three kinds of specimens exhibit different features;their peak load, energy absorption capacity and fracture toughness increase with increase in strain rate. The rate effect mechanisms of the three kinds of specimens' fracture characteristics were analyzed, respectively within the range of middle-low strain rates;quasi-brittle materials' interfacial fracture and base material' s fracture rate effect are compared.