Analysis of mud rheological characteristics based on debris flow migration process

Abstract The rheological characteristics of debris flow are the basis of the analysis of debris flow initiation, migration and deposition process. In order to explore the rheological characteristics of debris flow mud, according to the shear characteristics of debris flow fluid in different stages, taking Nanyang expansive soil mud as experimental material and using mcr702 rheometer blade rotor system, rheological experiments (twice increasing shear and once decreasing shear) were carried out on mud with different solid volume concentrations. According to the experimental results, the effects of different experimental processes and solid volume concentration on mud rheological parameters are analyzed, and the following conclusions are obtained: In the process of increasing shear rate, when the shear rate is less than 0.002s-1, the first shear stress is lower than the second shear stress; However, the first shear stress is higher than the second shear stress if the shear rate exceeds 0.002s-1. When the shear rate is greater than 1.83s-1, the mud is in the stable flow stage, the shear stress has a power-law relationship with the shear rate, and its rheological parameters increase exponentially with the volume concentration of mud. In the process of decelerating shear, the shear stress decreases in power law with the decrease of shear rate, which is a group of parallel lines in the double logarithmic coordinate system. Its flow index is less affected by solid volume concentration. The static yield stress of mud (the peak shear stress of the first increasing speed) is much larger than the stable flow yield stress (the shear stress value corresponding to the critical shear rate of 1.83s-1), and the difference decreases with the decrease of the volume concentration of mud solids. The static yield stress and steady flow yield stress of mud increase exponentially with the volume concentration of solid.