Flowslides, as one type of landslides, are becoming a research hotspot due to their high speed and long runout distance, which can cause tremendous damage and economic loss. The scale of damage and deposit morphology of flowslide is closely related to factors like deposit volume, slope height, and slope angle. In order to assess the influence of these factors, a sandbox apparatus is developed, and the Taguchi method is used to design an experimental scheme to analyze the results of factors affecting the deposit morphology of flowslide. The results show that the factor that has the greatest impact on flowslide deposit morphology is slope angle, followed by the influence of volume and slope height. As slope angle increases, the maximum width, maximum length, area, and length-width ratio of the deposit first increase and then decrease. In addition, there should be a critical angle in the changes of deposit morphology that is between 60° and 70° under the experimental conditions. When the volume is 5.4 × 10−3 m3, the slope angle is 70°, the slope height is 0.90 m, and the changes of deposit morphology of the flowslide are the largest. In this study, considering the slope angle as a single variable, there is a single upheaval for a slope angle of 40° and 50° and a double upheaval at 60° and 70°. The formation mechanism of the upheaval is analyzed based on the Mohr-Coulomb criterion and considered properties of the material. The apparent friction coefficient of a flowslide is spatially and lithologically different and increases nonlinearly as the slope angle increases. The initial benchmark of the slope angle and apparent friction coefficient curve are affected by the friction coefficient of the material; the position of the inflection point at which the curve increases rapidly is affected by the coefficient of velocity restitution.

The frequency of catastrophic geological disasters has been increasing significantly, causing tremendous losses of life and property. The study of landslide motion remains incomplete. The variables H/L (ratio of landslide height to length) are often used to describe landslide motion; however, they may also be affected by the height of the landslide itself. To better understand landslide dynamics, this paper aimed to 1) identify the process of landslide motion in relation to height; 2) understand the range of influence of sliding bodies according to height; and 3) construct a formula of landslide disaster range based on the travel distance of the slide center and changes in the center and shape of the sliding body. In this paper, medium-fine quartz sand was used in experiments to observe the movement patterns and sliding body barycenter variations occurring during landslides. We describe the changes that occur during landslides and their deposits’ morphological characteristics and barycenter variations with height. Based on these observations, a landslide model is derived. This paper proposes a new method of estimating the effects of landslides, which can help to mitigate the effects of disasters.

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Abstract. Deposit morphologies and sedimentary characteristics are methods for investigating rock avalanches. The characteristics of structural geology of source volume, namely the in-place rock mass structure, will influence these two deposit characteristics and rock avalanche mobility. In this study, a series of experiments were conducted by setting different initial configurations of blocks to simulate different characteristics of structural geology of source volume, specifically including the long axis of the blocks perpendicular to the strike of the inclined plate (EP), parallel to the strike of the inclined plate (LV), perpendicular to the inclined plate (LP), randomly (R) and without the blocks (NB) as a control experiment. The experimental materials comprised both cuboid blocks and granular materials to simulate large blocks and matrixes, respectively, in natural rock avalanches. The results revealed that the mobility of the mass flows was enhanced in LV, LP and R configurations, whereas it was restricted in the EP configuration. The mobility decreased with the increase in slope angles at LV configurations. Strand protrusion of the blocks made the elevation of the deposits at LV configuration larger than that at EP, LP and R configurations. A zigzag structure is created in the blocks resulting from the lateral spreading of the deposits causing the blocks to rotate. Varying degrees of deflection of the blocks demonstrated different levels of collision and friction in the interior of the mass flows; the most intensive collision was observed at EP. In the mass deposits, the blocks' orientation was affected by their initial configurations and the motion process of the mass flows. This research would support studies relating characteristics of structural geology of source volume to landslide mobility and deposit morphology.