Superelevation analysis of the debris flow curve in Xiedi gully, China
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ORIGINAL PAPER
Superelevation analysis of the debris flow curve in Xiedi gully, China Zhuang Wang 1,2
&
Yong You 1 & Guangze Zhang 3 & Tao Feng 3 & Jinfeng Liu 1 & Xiaobo Lv 1,2 & Dongwei Wang 1,2
Received: 30 May 2020 / Accepted: 30 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The superelevation phenomenon is common in the movement of debris flows around curves. This paper presents a new method to calculate the superelevation of debris flow when it encounters obstacles in the flow process. The calculation method is based on the Bingham Model for debris flow determination. In this paper, physically significant internal and external roughness coefficients are determined by analysing the internal characteristics and external channel boundary conditions of viscous debris flows in Xiedi gully, China. According to the situation of debris flow passing through the bend, when the debris flow moves to the sidewall of the gully with velocity, the movement state is divided into two parts: radial and normal. One part of the mud rock fluid continues to move in the tangential direction and generates superelevation, and the other part moves in the radial direction and generates upward climbing along the sidewall. Thus, the formula for calculating the superelevation of debris flow bend is derived. Based on the debris flow physical and dynamic parameters, such as density and weight of the debris flow, cohesion, internal friction angle, yield stress and dynamic viscosity of liquid-phase slurry, the reliability of the formula is verified, which provides a theoretical basis for future studies of debris flow disaster prevention and control in similar areas. Keywords Debris flow . Velocity . Superelevation . Particle size distribution . Calculation formula
Introduction In the process of debris flow disaster control, the effective determination of the superelevation value around curves in the debris flow area plays an important role in disaster control. The calculation of debris flow superelevation has a long history in debris flow analysis, especially in the study of debris flow disaster reduction countermeasures. Early research in this particular field was carried out by Japanese researchers in the early 1980s (Ikeya and Uehara 1982; Ikeya 1989). The existing superelevation models can be divided into two kinds: free vortex theory models and forced vortex
theory models. Within the framework of free vortex theory, the velocity of the fluid is inversely proportional to the radius of curvature, the fluid rotates freely around the curvature centre on the basis of constant angular momentum and the friction within the fluid is assumed to be negligible (Iverson et al. 1994; McClung 2001; Khadem et al. 2018; Torabizadeh et al. 2018). The rotational motion associated with the free vortex theory is thought to be the rotation of a rigid body, i.e., the fluid particles rotate at a constant angular velocity, and the total energy of the unit mass increases with the radius (Bambrey et al. 2007; He et al.
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