新近系红层软岩流变特性试验研究

Experimental Study on Rheological Properties of Neogene Red-bed Soft Rock

流变是控制岩体稳定的主要因素之一。流变试验结果显示,新近系红层软岩蠕变和松弛曲线具有明显的三阶段变化特征。对比研究新近系粉砂质泥岩和泥质粉砂岩的流变结果,得出粉砂质泥岩较泥质粉砂岩强度低,蠕变量大,达到稳定需要的时间长。经过模型辨识,认为红层软岩流变符合伯格斯模型(Burgers model)。利用改进后的麦夸托(Marquardt)算法求取了红层软岩的流变参数。结果显示,反映岩石流变特性的两个主要指标弹性模量和黏滞系数远低于硬岩的同类指标,充分说明新近系红层软岩具有显著的流变性。获取的流变参数可用于伯格斯模型计算。

Rheological property is a major controlling factor for rock mass stability. By a set of rheological experiments, the creep and relaxation curves of Neogene red-bed soft rock are obtained, whose variation process can be classified as three change stages. Compared with argillaceous siltstone, Neogene silty mud- stone has lower strength, larger creep and longer time to stabilization. Based on scientific analysis and com- parative study, rheological curves of red-bed soft rock are in accord with Burgers rheological model. Using Marquardt algorithm, the rheological parameters of red-bed soft rock under different test conditions were obtained. The rheological parameters of red-bed soft rock are far lower than those of the hard rock, which indicates that Neogene argillaceous siltstone and silty mudstone have remarkable rheological property. All these parameters can be applied to characterize the rheological properties of red-bed soft rock.