含粗骨料尾砂膏体长距离管输流变特性及阻力预测

Rheological properties and pipe resistance prediction of tailing pastecontaining coarse aggregate in long-distance transportation

为探明质量浓度、粗骨料含量、灰砂质量比和水化时间对膏体长距离管输流变特性的影响,本文基于正交设计开展流变实验,采用回归分析建立流变参数预测模型,在此基础上通过理论推导建立管道阻力预测模型,采用现场实测数据验证阻力预测结果的可靠性。结果表明:含粗骨料尾砂膏体属于宾汉流体,质量浓度和粗骨料含量对膏体流变参数的影响最显著;屈服应力随质量浓度的增大呈指数增长,随粗骨料含量的增加呈指数减小,随水化时间的增加呈线性增长,与灰砂质量比的关系不大;塑性粘度随质量浓度的增大呈指数增长,随粗骨料含量的增加呈线性减小,随灰砂质量比和水化时间的增加呈线性增长;建立的流变参数预测模型平均误差小于4.3%,基于宾汉流变模型建立的管道阻力模型预测值比现场实测值偏大12.5%,满足工程应用的精度要求。

To investigate the effects of mass fraction,coarse aggregate content,cement-sand mass ratio,and hydration time on the rheological properties of paste in long-distance pipeline transportation,a rheological experiment was carried out based on orthogonal design.Furthermore,the prediction models of rheological parameters were established by regression analysis.Subsequently,the pipeline resistance prediction model was constructed through theoretical derivation,and the reliability of the prediction result was verified by field measurement data.The results indicate that the tailings paste containing coarse aggregate is a kind of Bingham fluid and that the mass fraction and the coarse aggregate content are the two most significant factors affecting the rheological parameters of the paste.Furthermore,yield stress increases exponentially with the increase in mass fraction,decreases exponentially with the increase in coarse aggregate content,and increases linearly with the increase in hydration time.Yield stress also has a minimal relationship with the cement-sand mass ratio.In addition,the plastic viscosity increases exponentially with the increase in mass fraction,decreases linearly with the increase in coarse aggregate content,and increases linearly with the increase in cement-sand mass ratio and hydration time.The average error of the established rheological parameters prediction model is within 4.3%,and the predicted value of the pipeline resistance model based on the Bingham rheological model is 12.5%larger than the field measurements,thus meeting the precision requirements of engineering application.