DOI: 10.5061/dryad.m905qfv9x
title: Data from: The retard-boost effect of fragmentation in rock avalanches

description: This study presents a micro-mechanical numerical investigation into the
 fundamental aspects of progressive fragmentation and its effects on rock
 avalanche dynamics. The simulations involve breakable rock assemblies that
 are released along an inclined plane and subsequently collide onto a
 horizontal surface. A discrete-continuous numerical model is adopted to
 effectively capture progressive particle breakage and complex
 interparticle interactions. By incorporating variations in fracture
 mechanics parameters, the model systematically evaluates the influence of
 progressive grain fragmentation on rock avalanche dynamics. A multi-layer
 analysis method and the interlayer transmitting coefficient is proposed to
 analyze the temporal and spatial kinematics, stress distribution and the
 ongoing particle size reduction process. The results indicate that grain
 fragmentation significantly influences rock avalanche motion, identified
 as the "retard-boost" effect in this study. At low fragmentation
 degree, densely packed rock particles exhibit an interlayer transmitting
 effect, with kinematic energy dissipation primarily resulting from grain
 breakage. Conversely, full mobilization of rock fragmentation from the
 base upwards enhances flow mobility by reducing basal friction through the
 agitation of fragments. The findings indicate a competition between
 positive feedback, which enhances rock avalanche mobility at high
 fragmentation levels, and negative feedback, which results in energy
 dissipation at low fragmentation levels, with the predominance of these
 effects varying according to the degree of fragmentation.
description: This includes results of the numerical investigation into the
 fundamental aspects of progressive fragmentations within rock avalanches.
 This model is developed based on the platform of the commercial software
 ABAQUS. This link includes dataset of figures in this
 manuscript.
description: # Data from: The retard-boost effect of fragmentation in rock avalanches
 [https://doi.org/10.5061/dryad.m905qfv9x](https://doi.org/10.5061/dryad.m905qfv9x) ## Description of the data and file structure This dataset includes the results of a numerical investigation into the fundamental aspects of progressive fragmentation within rock avalanches. This model is developed based on the platform of the commercial software ABAQUS. The data supports the figures in the associated manuscript, providing detailed information on velocity distributions, stress evolution, energy dissipation, and particle dynamics. This link includes dataset of figures in this manuscript. ### Files and variables #### File: Dataset.xlsx **Overview** The dataset is organized into an Excel file, where each sheet corresponds to a specific figure in the manuscript. Each sheet contains the raw or processed data used to generate the respective figure. Below is a detailed description of the data in each sheet. **Sheet of Figure 1** This sheet contains data on the equivalent coefficient and apparent coefficient of rock avalanches, derived from three sources: **(1) Manzella's Study (Columns A-C)**: * **Column B**: Equivalent coefficient from Manzella's study. * **Column C**: Apparent coefficient from Manzella's study. **(2) The Former Study (Columns D-F)**: * **Column E**: Equivalent coefficient from the former study. * **Column F**: Apparent coefficient from the former study. **(3) This Study (Columns H-Q)**: * **Columns P**: Equivalent coefficient from this study. * **Columns Q**: Apparent coefficient from this study. **Sheet of Figure 2** * **Rows 1-10**: Time evolution of the breakage degree *t*10​ for Cases S1-S4, from 0.5s to 5s. * **Rows 13-19**: Average particle size along depth for Cases S1-S4, including refined results. **Sheet of Figure 3** * **Rows 1-13**: Evolution of the overall velocity of the granular mass in the horizontal direction. * **Rows 16-28**: Evolution of the overall velocity of the granular mass in the vertical direction. **Sheet of Figure 4** * **Downslope Velocity Distribution**: Along depth at time of *t*=0.5*s*,0.75*s*,1*s*,2*s*,3*s*,4*s* for Cases S1-S4. Each case includes three random scenarios. **Sheet of Figure 5** * **Plots b-d**: * Average downslope velocity *vs*​ (Plot b) and normal velocity *vn*​ (Plot d) at different layers (Layer 1-3) for Cases S1 and S4 during the inclined-slope stage. * **Plots h-j**: * Evolution of downslope velocity *vs*​ (Plot h), normal velocity *vn*​ (Plot i), and angular velocity *ω* (Plot j) at the horizontal plane for Layers 1-3 in Cases S1 and S4. **Sheet of Figure 5e-5g** * **Columns A-J**: All grains' velocity values. * **Columns L-O**: Grains with positive normal velocity values at *t*=1*s*. * **Columns Q-S**: Velocity values of broken particles at *t*=1*s*. * **Columns U-W**: Particle size distribution of grains with positive normal velocity. **Sheet of Figure 6** * **Rows 1-20**: Multi-layer stress distribution during the inclined-plane stage, including average normal stress (sigma_n​) and shear stress (sigma_s). * **Rows 24-49**: Multi-layer stress distribution during the horizontal-plane stage, including average normal stress (sigma_n​) and shear stress (sigma_s). **Sheet of Figure 7** * **Evolution of Velocities**: Average downslope velocity, normal velocity, and angular velocity for particles of different sizes at times from 0.3s to 0.9s. **Sheet of Figure 8** * **Columns A-D**: Plot of particle angularity and particle size for Case S4 at *t*=1*s*. * **Columns F-K**: Average downslope velocity *vs*​, normal velocity *vn*​, and angular velocity *ω* related to particle angularity for Case S4 at *t*=1*s*. **Sheet of Figure 9** * **Average Translational Velocities**: At measurement lines A (*vx*1​) and B (*vx*2​). * **Momentum Transfer Coefficient**: *η*. **Sheet of Figure 10** * **Rows 1-13**: Evolution of vibrational granular temperature* *in layers L1-L3 for Cases S1 and S4. * **Rows 16-69**: The Savage number along the traveling path at the horizontal-plane stage. **Sheet of Figure 11** * **Interlayer Transmitting Coefficients**: alpha_0​ and alpha_*r*​ for Cases S1 and S4 at the inclined-plane and horizontal-plane stages. * **Columns A-I**: Data for layers 1-2. * **Columns J-R**: Data for layers 2-3. * **Columns S-AA**: Data for layers 3-4. * **Bold Values**: Data points in the figure. **Sheet of Figure 12** * **Ratio of Cumulative Dissipated Energy Components** **to Total Potential Energy** * *Ed*​: Fragmentation dissipation energy. * *Ek*​: Kinetic energy. * *Ef*​: Frictional dissipation energy. * *Ev*​: Viscous damping dissipation energy. * *Es*​: Strain energy. **Sheet of Table2** This sheet contains the raw data for calculating the equivalent coefficient and apparent coefficient of rock avalanches, including the breakage degree (Column B), the distance of the center of mass (Column C), and the height of the center of mass (Column D). The meanings of the other columns are indicated by the respective column headers. ## Code/software The numerical model was developed using ABAQUS, a commercial finite element analysis software. The specific version used was ABAQUS 2021. No additional scripts or code are included in this dataset.