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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。
The dynamical characteristics of bulk iron concentrates on ships were tested by applying vertical cyclic coupling load to simulate the wave loads. Through the analysis of dynamic strain, dynamic strength and pore water pressure curve, the influence of moisture content, dynamic stress and vibration weeks on the dynamic characteristics of iron ore concentrate is discussed. Tests show that: the moisture content is the key factor affecting the dynamic characteristics of iron ore concentrate. The iron ore concentrate has a critical moisture content. If this critical moisture content is exceeded, the iron concentrate will slowly develop to the point of failure even with small dynamic stresses and long enough vibration cycles. The high water content of iron ore samples even under the action of smaller dynamic stress will quickly destroy. Compared with the conventional triaxial test, it can be found that the dynamic strength of iron ore concentrate obtained by the coupled cyclic shear test of the vertical-torsional direction rapidly decreases with the increase of the water content. The study provides a safe water content range for actual on-board iron concentrates.