Experimental validation of a new semi-empirical impact force model of the dry granular flow impact against a rigid barri
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Yuan-Jun Jiang I Xiao-Yi Fan I Li-Jun Su I Si-you Xiao I Jing Sui I Rui-Xiao Zhang I Yue Song I Zhi-Wen Shen
Experimental validation of a new semi-empirical impact force model of the dry granular flow impact against a rigid barrier
Abstract The maximum impact force of granular flow and its action point on a rigid barrier are the key indices of the anti-slip and the anti-overturning calculation, respectively. On the basis of the present impact force models and the observation in model experiments, this paper proposes a new semi-empirical impact force model focusing on the normal impact force and its point of action. By comparing the analytical solution and the experimental results, the new semi-empirical analytical model can estimate the normal impact force composed of both dynamic and static components with an error margin within ± 20% compared with the experimental results and so is for the corresponding point of action and tangential force. To calculate the residual force generated only by the static dead zone, the static friction angle between the dead zone and the chute base should be less than what was measured under kinetic conditions. Based on a large number of tests, it was found that assuming that the reaction force generated by the chute base operates at 2/3 of the deposition length makes the estimated normal impact force best suited to the experimental results. Keywords Dry granular flow . Impact force model . Normal impact force . Point of action . Tangential force . Semi-empirical
Introduction Dry granular flow often occurs in mountainous areas, consisting mainly of rock debris formed by avalanches or avalanches of rocks, the volume of which varies from several tens to thousands of cubic meters. Because of the high degree of fragmentation, high dispersion, and high velocity, a tremendous impact force can be exerted to an obstacle on its flow path (Tai et al. 2001; Sovilla et al. 2008; Faug et al. 2011). In a dry granular flow, the pores between rocky fragments are almost full of air. Such kind of dry granular flow is obviously different from a mud or a debris flow consisting of fine particles and fully or partially saturated with water. In order to protect any facilities threatened by dry granular flows, structures such as a rigid barrier (Fig. 1a) are usually used along mountain roads. Due to the wide variations of the flow type of geological hazards (Cui et al. 2018), the complex composition of sliding material (Iverson 2015), and the fluctuation of the field test data (Bugnion et al. 2012), it is difficult to completely repeat what was monitored in the field. Therefore, many researchers choose indoor experiment as a feasible and stable research tool to investigate the mechanism of geological hazards. In addition, the outdoor experiments are expensive, which is also the reason why the indoor experiments have become the main research method.
The impact mechanism of a dry granular flow against a rigid barrier has been intensively studied in the course of indoor experiments (Jiang and Towhata 2013; F
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