循环荷载下铁精矿动力特性试验研究

Dynamic behaviors of iron ore concentrate under cyclic loading by hollow cylinder apparatus

利用空心圆柱扭剪仪(HCA)施加竖向—环向耦合循环荷载模拟波浪荷载的作用,对船载散装铁精矿进行了动力特性试验。通过对动应变、动强度和孔隙水压力变化曲线进行分析,探讨了含水率、动应力和振动周数等因素对铁精矿动力特性的影响。试验表明:含水率是影响铁精矿动力特性的关键因素。铁精矿存在临界含水率,如果超过这一临界含水率,铁精矿即使在较小的动应力、足够长的振动周数下,也会缓慢发展达到破坏状态。而高含水率的铁精矿试样即使在较小的动应力作用下也会迅速发生破坏。对比常规动三轴试验,可以发现竖向–扭向循环耦合剪切试验得出的铁精矿动强度随含水率的增加而迅速降低。研究可为实际船载铁精矿提供安全的含水率范围。

Groups of triaxial and torsional coupling cyclic shear tests on onboard iron ore concentrate are carried out by hollow cylinder apparatus to study the deformation and mechanical properties of iron ore concentrate subjected to cyclic loading. By analyzing curves of strain, dynamic strength and pore pressure, the influence factors on fluidization of the iron ore concentrate are explored. The experimental results show that the moisture content is the key factor for the dynamic behaviors of the iron ore concentrate. There is an critical moisture. When it is above the critical moisture content, the sample will be slowly destroyed under a small dynamic stress and long enough vibration times. The sample with high moisture content will be destroyed rapidly even under a small dynamic stress. Compared with that of the dynamic triaxial tests, the dynamic strength by hollow cylinder apparatus decreases rapidly with the increase of the moisture content. It has certain practical significance that the experiments provide safe moisture content range for the onboard iron ore concentrate.