粘性泥石流体阵性流形成机理研究

通过粘性泥石流体阵性流的野外观测 ,和应用最新研制的大型平板旋转式泥石流流变仪测定粘性泥石流体的应力应变特性 ,发现含有砾石的粘性泥石流体启动时具有明显的应力过冲特征。这种应力过冲特征 ,与由粘性介质阻力形变初期的剪切稀化和高浓度粗细颗粒相互挤压的内摩擦力共同组成的泥石流体的应力滞后特性 (抗剪强度 )有关。根据所测定的粘性泥石流体的准静摩擦角、正压力和动摩擦系数 ,通过剪切面上流动坡度的推导与泥石流体启动高度的演算 ,并与粘性泥石流体阵性流观测资料进行对比 ,初步揭示了粘性泥石流体阵性流的形成机理。

Study on forming mechanism of viscous debris flow surges

Based on field observations of surge in viscous debris flow in Jiangjia Ravine, Yunnan, and measurements of stress strain behavior obtained from lately designed and constructed rheogoniometer, an obvious overstress phenomenon at starting stage of viscous debris flow with gravels is found. This overstress phenomenon is related to stress hysteresis of debris flow which consists of shear sparsity at beginning of deformation from viscous drag and internal friction from mutual extrusion of granulae with different sizes. In terms of measurements of quasi static friction angles, normal stresses and friction coefficients, the forming mechanism of surge in viscous debris flows is revealed preliminarily through derivation of flowing slope in shear surface, calculation of starting height of debris flow and comparison with observations of surges in viscous debris flow.