Dynamic fragmentation in rock avalanches: A numerical model of micromechanical behaviour

2010 ◽  
pp. 451-456 ◽  
Keyword(s):  
Numerical Model ◽  
Dynamic Fragmentation ◽  
Rock Avalanches

Physical models of rock avalanche spreading behaviour with dynamic fragmentation

2012 ◽  
Vol 49 (4) ◽  
pp. 460-476 ◽  
Author(s):  
E.T. Bowman ◽  
W.A. Take ◽  
K.L. Rait ◽  
C. Hann
Keyword(s):  
High Speed ◽  
Rock Avalanche ◽  
Physical Models ◽  
Cube Root ◽  
Long Runout ◽  
Dynamic Fragmentation ◽  
Solid Coal ◽  
Rock Avalanches ◽  
Average Position ◽  
Degree Of Fragmentation

The dynamic fragmentation of rock during avalanche motion has been postulated as a mechanism explaining the long runout of large rock avalanches or Sturzströme. This paper investigates whether test conditions that produce dynamic fragmentation can lead to greater runout or spreading of physical model rock avalanches. Model avalanche experiments were carried out under enhanced acceleration to generate breakage in coal, a fragmentable, brittle solid. Coal blocks were released from a stationary position on a slope to run out on a plane. The motion of the ensuing fragmenting debris was captured using a high-speed camera placed above the horizontal plane. The average position of the front was tracked and the degree of fragmentation of the model avalanches was quantified. The paper presents results of the frontal velocity of the avalanches, corrected for centrifuge Coriolis effects. Comparison is made between the peak and impulsive front velocities, the final runout, and the degree of fragmentation of the model avalanches. Strong relationships are found between runout normalized by the cube root of volume, impulse velocity, and Hardin’s relative breakage parameter, BR. Results are discussed in light of the mechanics involved and are compared with field-scale events.

Surface microscopic examination of quartz grains from rock avalanche basal facies

2015 ◽  
Vol 52 (2) ◽  
pp. 167-181 ◽  
Author(s):  
Yu-feng Wang ◽  
Qian-gong Cheng ◽  
Qi Zhu
Keyword(s):  
High Stress ◽  
Rock Avalanche ◽  
Particle Dynamic ◽  
Overburden Pressure ◽  
Surface Textures ◽  
Dynamic Fragmentation ◽  
Rock Avalanches ◽  
Excited Vibration ◽  
Fracturing Process ◽  
Quartz Grains

The Wenchuan earthquake, which occurred on 12 May 2008, triggered many rock avalanches that presented abundant fractured surface textures. The surface textures of the rock avalanche clasts bear abundant characteristic signatures that are significant for understanding the mechanical behavior of rock avalanche dynamic fragmentation. To study this mechanism of rock avalanche basal facies further, two large rock avalanches were investigated using microscopic surface texture examination of quartz grains sampled from their basal facies with a scanning electron microscope. After the morphological and statistical analyses of the surface textures on the quartz grains, the following features are noted: (i) surface textures on the quartz grains are all fresh, with obvious irregular shapes and very sharp edges; (ii) the display of brittle fractures, including conchoidal fractures, step fractures, concavities, and V depressions or marks, is very common; (iii) cracks or fissures are also visible on the quartz grains. The display of these features reveals that a brittle fracturing process occurred during the formation of these surface textures on the quartz grains, indicating the existence of a high-stress history suffered by the particles in the basal facies. Hence, by the mechanical analysis of the formation of these surface textures, the authors propose that both the overburden pressure and the self-excited vibration energized by the undulated slip surface may play dominant roles in the occurrence of the particle dynamic fragmentation in the basal facies.

scholarly journals Transferability of a calibrated numerical model of rock avalanche run-out: Application to 20 rock avalanches on the Nuussuaq Peninsula, West Greenland

2018 ◽  
Vol 43 (15) ◽  
pp. 3057-3073 ◽  
Author(s):  
J. Benjamin ◽  
N.J. Rosser ◽  
S.A. Dunning ◽  
R.J. Hardy ◽  
K. Kelfoun ◽  
...  
Keyword(s):  
Numerical Model ◽  
Rock Avalanche ◽  
West Greenland ◽  
Rock Avalanches

NUMERICAL MODEL TO SIMULATE THE EROSION ON THE SLOPE DUE TO OVERTOPPING

2010 ◽  
Vol 13 (3) ◽  
pp. 78-87
Author(s):  
Hoai Cong Huynh
Keyword(s):  
Numerical Model ◽  
Flow Model ◽  
Bed Load ◽  
Experiment Data ◽  
Step Method ◽  
Morphological Model ◽  
Load Transport ◽  
Bed Load Transport ◽  
The Finite Difference Method ◽  
Good Agreement

The numerical model is developed consisting of a 1D flow model and the morphological model to simulate the erosion due to the water overtopping. The step method is applied to solve the water surface on the slope and the finite difference method of the modified Lax Scheme is applied for bed change equation. The Meyer-Peter and Muller formulae is used to determine the bed load transport rate. The model is calibrated and verified based on the data in experiment. It is found that the computed results and experiment data are good agreement.

A numerical model to verify the communication between Gari and Peccia springs (Cassino, Central Italy)

2015 ◽  
Vol 35 ◽  
pp. 268-271
Author(s):  
Michele Saroli ◽  
Michele Lancia ◽  
Marco Petitta ◽  
Gabriele Scarascia Mugnozza
Keyword(s):  
Numerical Model ◽  
Central Italy
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