THE EFFECT OF BOTTOM BOUNDARY RIGIDITY OF SAND CUSHION ON ROCK FALL IMPACT FORCE USING DEM

Based on experiments and finite element analysis, the impact resistance of metal flexible net was studied, which can provide reference for the application of metal flexible net in rock fall protection. The oblique (30 degrees) impact experiment of metal flexible net was carried out, the corresponding finite element (FE) to the experiment was established, and the FE model was verified by simulation results to the experimental tests from three aspects: the deformation characteristics of metal flexible net, the time history curves of impact force on supporting ropes, and the maximum instantaneous impact force on supporting ropes. The FE models of metal flexible nets with inclination angles of 0, 15, 30, 45, 60, and 75 degrees were established, and the impact resistance of metal flexible nets with different inclination angles was analyzed. The research shows that the metal flexible net with proper inclination can bounce the impact rock fall out of the safe area and prevent rock fall falling on the metal flexible net, thus realizing the self-cleaning function. When the inclination angle of the metal flexible net is 15, 30, and 45 degrees, respectively, the bounce effect after impact is better, the remaining height is improved, the protection width is improved obviously, and the impact force is reduced. Herein, the impact force of rock fall decreases most obviously at 45 degrees inclination, and the protective performance is relatively good.

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Impact force propagation behaviors of rock fall into horizontal granular mat using 2D-DEM

Journal of Japan Society of Civil Engineers Ser A2 (Applied Mechanics (AM)) ◽

10.2208/jscejam.67.i_355 ◽

2011 ◽

Vol 67 (2) ◽

pp. I_355-I_364

Author(s):

Kenichi Maeda ◽

Hirofumi Hashiba ◽

Keiichi Karita ◽

Yuji Ushiwatari ◽

Ryoji Kawase

Keyword(s):

Impact Force ◽

Rock Fall ◽

Force Propagation

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IMPACT FORCE PROPAGATION BEHAVIORS OF ROCK INTO SAND CUSHION FOCUSED ON STRESS AND STRAIN USING DEM

Journal of Japan Society of Civil Engineers Ser A2 (Applied Mechanics (AM)) ◽

10.2208/jscejam.70.i_495 ◽

2014 ◽

Vol 70 (2) ◽

pp. I_495-I_506

Author(s):

Naoto NAITO ◽

Kenichi MAEDA ◽

Satoru YAMAGUCHI ◽

Yuji USHIWATARI ◽

Kentaro SUZUKI ◽

...

Keyword(s):

Impact Force ◽

Stress And Strain ◽

Force Propagation ◽

Sand Cushion

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Analysis and Numerical Simulation on Dynamic Response of Buried Pipeline Caused by Rock Fall Impaction

Volume 2: Pipeline Integrity Management ◽

10.1115/ipc2012-90053 ◽

2012 ◽

Author(s):

Hongyuan Jing ◽

Qinglu Deng ◽

Jianbin Hao ◽

Bing Han ◽

Liangliang Li

Keyword(s):

Numerical Simulation ◽

Dynamic Response ◽

Cross Section ◽

Impact Force ◽

Equivalent Stress ◽

Rock Fall ◽

Major Influence ◽

Buried Pipeline ◽

Stress Concentration Region ◽

The Impact

Theoretical analysis methods are discussed to estimate additional stresses of shallow buried oil and gas pipeline caused by rock fall impaction. The process of impaction is simulated using finite elements software, in the model a 1 m3 square shape falling hard rock impacts soil ground upright of pipe with a vertical velocity, and dynamic response of pipeline is analyzed. The impact force, soil additional stresses, pipe displacement and additional stresses in the impaction process are studied. The effect of pipeline buried depth and rock velocity to the impaction also discussed. Results show that the impaction process is very short and the duration is about 10−3∼10−2s. The maximum impact force has approximately direct ratio with the velocity of rock. The additional vertical stress in soil caused by impaction load has a stress concentration region near the surface of pipe, and its distribution has the similar pattern with that in static load, but has a faster attenuation from the impaction center to sidewall. The most dangerous pipe cross-section appears in the underside of impaction center, and the maximum additional equivalent stress appears in the top of the cross-section, and has an approximately direct ratio with the velocity of rock if other impaction conditions are confirmed. The buried depth of pipeline has major influence to impaction. Large thickness of soil cover has marked effect on improve the protection of pipeline. According the study, shallow buried pipeline has weak defense to rock fall. The additional internal force and stress of pipeline caused by impaction of rock fall can be approximately estimated using theoretical methods or numerical simulation.

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Analysis of Impact Response of Sand Cushion for Rockfall by Distinct Element Method

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.82.92 ◽

2011 ◽

Vol 82 ◽

pp. 92-99 ◽

Cited By ~ 3

Author(s):

Takashi Watanabe ◽

Hiroshi Masuya ◽

Akita Satoh ◽

Sachio Nakamura

Keyword(s):

Distinct Element ◽

Distinct Element Method ◽

Point Of View ◽

The Body ◽

Rock Fall ◽

Impact Behavior ◽

The Impact ◽

Impact Experiments ◽

Sand Cushion ◽

Element Method

In order to know efficiently the impact behavior of the actual size sand cushion under rock fall, to achieve a lot of impact experiments under various conditions or to analyze those phenomena by use of reliable accurate methods is generally required. However, there is difficulty in many cases to achieve experiments because of financial reason. Therefore, the analysis method to reproduce full-scale impact behavior is indispensable. From this point of view, we have developed Distinct Element Method. The method to model the body to collide like a rock fall by an assembly of many small elements and the method to present a sand cushion as an assembly of many elements which have different size with randomness were shown. The validity of this method was shown by the comparison with experimental results.

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Analysis of Load Transfer and Penetration Mechanisms of Rock Fall Sand Cushion using 2D Discrete Element Method

Journal of Japan Society of Civil Engineers Ser A2 (Applied Mechanics (AM)) ◽

10.2208/jscejam.69.i_361 ◽

2013 ◽

Vol 69 (2) ◽

pp. I_361-I_370

Author(s):

Naoto Naito ◽

Kenichi Maeda ◽

Satoru Yamaguchi ◽

Yuji Ushiwatari ◽

Kentarou Suzuki ◽

...

Keyword(s):

Discrete Element Method ◽

Load Transfer ◽

Discrete Element ◽

Rock Fall ◽

Sand Cushion ◽

Element Method

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Experimental study on the maximum impact force by rock fall

Landslides ◽

10.1007/s10346-017-0876-x ◽

2017 ◽

Vol 15 (2) ◽

pp. 233-242 ◽

Cited By ~ 7

Author(s):

Bin Yu ◽

Wei Yi ◽

Huaibao Zhao

Keyword(s):

Experimental Study ◽

Impact Force ◽

Rock Fall ◽

Maximum Impact Force

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Experiment of the Rockfall Impact Characteristic onto Gravel Cushion

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.430-432.1729 ◽

2012 ◽

Vol 430-432 ◽

pp. 1729-1732 ◽

Cited By ~ 1

Author(s):

Hong Mei Tang ◽

Lin Feng Wang ◽

Hong Kai Chen ◽

Ren Jie Wu

Keyword(s):

Moisture Content ◽

Impact Force ◽

Soil Mass ◽

Rock Fall ◽

Mountainous Area ◽

Wavelet Theory ◽

Geological Disasters ◽

Prevention And Cure ◽

The Impact ◽

Force Data

Rockfall is one of common geological disasters in the mountainous area. The experiment gained the impact waves for cushion soil mass contained 12density, 4 soil-rock ratio, 4 cushion obliquity, 3 moisture content, 3 rockfall quality, 5 height of rock fall. Used the wavelet theory to deal with the experiment waves, analyzed the experiment results: with rock’s mass, the height and density increased, the impact force is increasing, or the impact force is decreasing with the moisture content and cushion inclination increasing. The impact force spreads from the point of rockfall to all directions. The impact force data of the experiment is a little large than others, so this method provides a gist for choosing the prevention and cure measure for rockfall.

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