循环荷载作用下宕渣颗粒破碎行为及累积变形预测

Crushing behavior and cumulative deformation prediction of slag particles under cyclic loading

动载作用下宕渣低路堤沉降较大,而真实公路荷载下宕渣的累积变形模型匮乏,且宕渣易破碎,颗粒破碎行为与累积变形相关性有待厘清,故建立了可破碎宕渣动三轴离散元模型,基于颗粒破碎率进行细观动态表征,探讨颗粒破碎的时域演化规律.分析围压、荷载频率和循环动偏应力对颗粒破碎及累积变形的影响,研究颗粒破碎与累积变形的相关性,建立累积变形预测公式,并利用SBZ30型振动器开展现场激振试验进行对比,验证模型准确性.结果表明:动载作用下,宕渣颗粒破碎方式以破碎、研磨为主,加载初期破碎率大幅增加,随振次增加破碎率增速减缓;围压、荷载频率和动应力幅值与颗粒破碎率正相关,颗粒破碎对累积应变有双重影响,相同围压下线性相关;累积变形公式能合理预测宕渣填筑路基累积应变的发展趋势.研究结果可为宕渣路基运营期动力沉降计算提供理论参考.

The settlement of low slag embankment under dynamic load is large, while the cumulative deformation model of slag under real road load is lacking;slag is easy to be crushed, and the correlation between particle crushing behavior and cumulative deformation needs to be clarified. Therefore, a dynamic triaxial discrete element model of crushable slag was established to explore the time-domain evolution law of particle crushing based on the mesoscopic dynamic characterization of the particle crushing rate. The effects of surrounding pressure, load frequency, and cyclic dynamic deflection stress on particle crushing and cumulative deformation were analyzed, the correlation between particle crushing and cumulative deformation was studied, and the cumulative deformation prediction formula was established. Then, a field excitation test based on the SBZ30 shaker was used for comparison to verify the accuracy of the model. The results show that under the action of dynamic load, slag particle crushing mode is mainly crushing and grinding, the crushing rate increases significantly at the beginning of loading, and the growth rate of the crushing rate slows down with the increase of vibration;the surrounding pressure, loading frequency and dynamic stress amplitude are positively correlated with the particle crushing rate, and particle crushing has a double effect on the cumulative strain, which is linearly correlated under the same surrounding pressure;the cumulative deformation formula can reasonably predict the development trend of the cumulative strain of slag filled roadbed. The research results can provide a theoretical reference for the calculation of dynamic settlement of slag roadbed during operation.