scholarly journals Ricochet of steel spheres on sand with varying water content

2020 ◽  
Vol 12 (12) ◽  
pp. 168781402097728
Author(s):  
Yoon Keon Kim ◽  
Woo Chun Choi
Keyword(s):  
Kinetic Energy ◽  
Internal Friction ◽  
Energy Loss ◽  
Water Content ◽  
Yield Stress ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Element Analysis ◽  
Lower Yield Stress ◽  
Safety Distance

The explosion of a building generates plenty of debris that flies far away. The flying debris is hazardous because it contains large amounts of kinetic energy. Therefore, determining the safety distance from the debris is essential. However, debris ricochet that collides onto the ground affects the safety distance because the ricochet phenomenon is influenced by the condition of the medium. In this study, experiments and finite element analysis were performed to investigate the ricochet based on the water content of sand. From a direct shear test, the internal friction angle and cohesion of sand were obtained based on the water content. The effects of internal friction angle and adhesion on the yield stress and ricochet were investigated. The results indicated that as the water content increased, the internal friction angle increased and then decreased, and the cohesion continued to decrease. The yield stress was proportional to the internal friction angle and inversely proportional to adhesion. Therefore, lower yield stress resulted in deeper penetration of debris, leading to higher energy loss, which increased the kinetic energy loss factor. Thus, the condition of the medium should be considered for setting a proper safety distance suitable for the surrounding environment of the building.

scholarly journals Ricochet of Spheres on Sand of Various Temperature

2018 ◽  
Vol 68 (2) ◽  
pp. 150 ◽  
Author(s):  
Yoon Keon Kim ◽  
Woo Chun Choi
Keyword(s):  
Shear Stress ◽  
Kinetic Energy ◽  
Internal Friction ◽  
Initial Conditions ◽  
Fem Analysis ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Depth Of Penetration ◽  
Safety Distance ◽  
Sand Temperature

The debris generated by the explosion of a building or ammunition is flown far away through the ricochet phenomenon. The debris contains a very large amount of energy, and a risk factor surrounding it may be applied. The safety distance from debris is set from experiments or FEM analysis. The ricochet of debris is affected not only by the initial conditions of the debris, but also by the conditions of the medium. In this paper, the effect of sand temperature on the ricochet of sphere projectiles was investigated through experiments and FEM, by measuring the shear stress and internal friction angle when the sand temperature increases. As the temperature of the sand increases, the shear stress and the internal friction angle decrease, and the penetration depth of the projectile increases. As the depth of penetration becomes longer, the kinetic energy is lost more by the friction force with the sand and, the sphere projectile speed decreases more. This is mainly caused by the energy loss of the projectile, so the kinetic energy of the ricocheted projectile is reduced. Therefore, when setting the optimized inhabited building distance (IBD), the conditions of the medium should be taken into account.

Characterization of Shear Strength and Interface Friction of Organic Soil

2020 ◽  
Vol 857 ◽  
pp. 203-211
Author(s):  
Majid Hamed ◽  
Waleed S. Sidik ◽  
Hanifi Canakci ◽  
Fatih Celik ◽  
Romel N. Georgees
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Internal Friction ◽  
Moisture Content ◽  
Water Content ◽  
Friction Angle ◽  
Structural Materials ◽  
Organic Soil ◽  
Internal Friction Angle ◽  
Interface Friction

This study was undertaken to investigate some specific problems that limit a safe design and construction of structures on problematic soils. An experimental study was carried out to examine the influence of loading rate and moisture content on shear strength of organic soil. Influece of moisture content on interface friction between organic soil and structural materials was also attempted. A commonly used soil in Iraq was prepared at varying moisture contents of 39%, 57% and 75%. The experimental results showed that the increase in water content will decrease the shear stress and the internal friction angle. An increase of the shearing rate was found to decrease the shear stress and internal friction angle for all percetanges of water contents. Further, direct shear tests were carried out to detect the interface shear stress behavior between organic soil and structural materials. The results revealed that the increase in water content was shown to have significant negetavie effects on the interface internal friction and angle shear strength.

scholarly journals Field Test Research on Red Clay Slope under Atmospheric Action

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Kaisheng Chen
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Red Clay ◽  
Failure Characteristics ◽  
Clay Slopes

By embedding water content sensors and pore water pressure sensors inside the red clay slope on-site in Guiyang, Guizhou, shear tests were performed on soil samples at different depths of the slope under different weather. The changes of water content, pore water pressure, and shear strength index of the slope inside the slope under the influence of the atmosphere were tracked and tested, and the failure characteristics and evolution of the red clay slope were analyzed. It is believed that the depth of influence of the atmosphere on red clay slopes is about 0.7 m, rainfall is the most direct climatic factor leading to the instability of red clay slopes, and the evaporation effect is an important prerequisite for the catastrophe of red clay slopes. The cohesion and internal friction angle of the slope soil have a good binary quadratic function relationship with the water content and density. The water content and density can be used to calculate the cohesion and internal friction angle. Failure characteristics of red clay slopes: the overall instability failure is less, mainly surface failure represented by gullies and weathering and spalling, and then gradually evolved into shallow instability failure represented by collapse and slump. The damage evolution law is as follows: splash corrosion and surface corrosion stage⟶ fracture development stage⟶ gully formation stage⟶ gully development through stage⟶ local collapse stage⟶ slope foot collapse stage.

Study on the Effect of Water Content on Shearing Strength Parameters of Unsaturated Loess

2014 ◽  
Vol 638-640 ◽  
pp. 585-588 ◽  
Author(s):  
Si Zhong Qian
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Direct Shear ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Micro Particles ◽  
Shearing Strength ◽  
Unsaturated Loess

This paper experiments on typical Malan loess, performs consolidated quick direct shear tests under different water contents by conventional direct shear apparatus, then analyzes the effects of water content on shearing strength parameters, namely cohesion and internal friction angle. The results show that cohesion decreases linearly as the water content increasing, and the relation could be obtained by data fitting. However, internal friction angle keeps basically stable with the increase of water content. Finally, based on the force analysis for micro particles, the changing rules of cohesion and internal friction angle with water content were deeply explained.

Stability Analysis of the Cutting Slope Considering the Influence of Water Content of Soil

2012 ◽  
Vol 204-208 ◽  
pp. 115-118 ◽  
Author(s):  
Qiang Ma ◽  
Heng Lin Xiao ◽  
Qi Zhi Hu ◽  
Li Hua Li
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Safety Factors ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Cutting Slope ◽  
Influence Of Water ◽  
The Stability

Based on the method of strength reduction, numerical simulations were carried out to analyze the stability of the cutting slope. The direct shear tests of slope soil samples with different water content were carried out, and the safety factors of stability of the cutting slope were investigated with different cohesions and internal friction angles. At last, displacements and safety factors of stability of the slope with drains and without drains were calculated, and the observations of displacement of the cutting slope in field were also carried out. The results show that: The water content of the slope soil has great effects on the strength parameters, the cohesion and the internal friction angle decrease with the increase of the water content, and the effect is more significant on the cohesion than that on the internal friction angle. The safety factor of stability for the slope increases with the increase of the strength parameters, hence it increases with the decrease of the water content. The section of the slope without drains in the field is unstable, while the section with drains maintains stable.

scholarly journals Effect of conglomeration gradation on loess shear strength with different water content

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110105
Author(s):  
Dequan Kong ◽  
Rong Wan ◽  
Chenkai Zhao ◽  
Jiumei Dai ◽  
Tijian Dong ◽  
...  
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Empirical Formulas ◽  
Factors Affecting ◽  
Direct Shear Tests ◽  
Loess Particles ◽  
The Difference

Particle gradation and water content are important factors affecting shear strength of soil. However, due to chemical cementation and molecular attraction, loess particles commonly stick together forming conglomerations. Till date, the superposition effect of water content and conglomeration gradation on loess shear strength has rarely been studied and undeniably requires further systematic explorations and development. In this study, loess samples were prepared with three conglomeration gradations and five water contents, and the direct shear tests were systematically performed. The shear strength of sample 1 (continuous conglomeration gradation) was found to be the best, followed by sample 2 (large size conglomerations), and sample 3 (small size conglomerations). The difference of samples’ shear strength decreased with increasing water content, and almost closed to zero when water content was 20%. The cohesion of samples first increased and then decreased with increasing water content, the maximum cohesion occurred at 10% water content. The internal friction angles decreased with increasing water content, and reached similar minimum values when the water content was 15%. The increased percentage values of cohesion and internal friction angle caused by conglomeration gradation are in the range of 33.2%–42.1% and 9.8%–32.5%, respectively. Finally, the empirical formulas for water content-cohesion and water content-internal friction angle of different conglomeration gradations samples were established, and the calculated values are in good agreement with test data. The effect of loess conglomeration gradation on shear strength decreased with increasing water content. When the water content was less than 15%, using a good conglomeration graduation could effectively improve loss shear strength.

scholarly journals Experimental Study on the Impact of Water Content on the Strength Parameters of Coral Gravelly Sand

2020 ◽  
Vol 8 (9) ◽  
pp. 634
Author(s):  
Yang Wu ◽  
Xing Wang ◽  
Jian-Hua Shen ◽  
Jie Cui ◽  
Chang-Qi Zhu ◽  
...  
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Particle Breakage ◽  
Internal Friction Angle ◽  
Capillary Water ◽  
Strength Parameters ◽  
Apparent Cohesion ◽  
The Impact

The effect of capillary water caused by heavy rainfall and groundwater level fluctuations can induce the erosion and collapse of island reef coral sand foundations. Here, the effects of water content (ω) on the shear strength parameters of coral gravelly sand are analyzed at the macro and micro scales by laboratory consolidated-drained triaxial compression and nuclear magnetic resonance tests. Furthermore, particle breakage characteristics of coral gravelly sand under the static load are discussed. With increasing ω, (1) the internal friction angle increases slightly (<1°) then decreases; (2) the apparent cohesion is more sensitive to the change in the ω; (3) with an increase from 5.4% to 21.3%, the bound water content remains almost unchanged; (4) the capillary water content is the main factor impacting the apparent cohesion; (5) the increase in free water content is the internal cause of the decreasing internal friction angle of coral gravelly sand with ω > 11.1%; and (6) the particle breakage increases, and there is an approximately linear relationship between the median particle diameter (d50) and relative breakage index (Br). The established physical model can reflect the influence of water content and plastic work and describe the evolution law of particle breakage.

Experimental Study on Shear Strength of West Sichuan Unsaturated Mixed-Soil

2013 ◽  
Vol 353-356 ◽  
pp. 772-778 ◽  
Author(s):  
Kai Cui ◽  
Bang Wen Huang
Keyword(s):  
Internal Friction ◽  
Moisture Content ◽  
Water Content ◽  
Mineral Water ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Cohesive Force ◽  
Dry Density ◽  
Control Matrix ◽  
Matrix Suction

By controlling moisture content to control matrix suction indirectly, three typical unsaturated remolded mixed-soil from west Sichuan are studied by the consolidated untrained triaxial shear test .The test data show that for different kinds of soil samples, the sample with less amount of clay and high content of quartz has bigger internal friction angle relatively, and the sample with hydrophilic mineral and high content of clay has bigger cohesive force. Meanwhile, for the sample without or less hydrophilic mineral, cohesive force is affected mainly by water content, and for the sample with large content of hydrophilic mineral, water content and dry density affect cohesive force together. For a certain sample, the variation of moisture content and dry density affects internal friction angle less, while affects cohesive force more. In addition, the change of internal friction angle resulting from the variation of matrix suction is less, and cohesive force increases as matrix suction increases.

scholarly journals Strength of Vegetated Coal-Bearing Soil under Dry-Wet Cycles: An Experimental Study

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Gang Huang ◽  
Mingxin Zheng
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Southern China ◽  
Orthogonal Design ◽  
Friction Angle ◽  
Chain Structure ◽  
Internal Friction Angle ◽  
Soil Reinforcement ◽  
Dry Density ◽  
Mineral Particles

Strength of vegetated coal-bearing soil is of great significance to evaluate the shallow stability of vegetated slopes in coal-bearing soil regions. This paper takes D-W cycles, dry density, water content, and vegetation root (VR) content as four factors and carries out the triaxial test for the orthogonal design of vegetated coal-bearing soil in southern China. The strength curves of vegetated coal-bearing soil under four factors were obtained. The Taguchi method was used to quantitatively analyse the effects of four factors. The microstructure of coal-bearing soil under D-W cycles and the theory of soil reinforcement by VR were discussed. The results indicated that D-W cycles had a significant effect on the cohesion and internal friction angle ( P < 0.05 ). The internal friction angle was little affected by the water content and VR content, which had considerable influence on the cohesion. The cohesion could be improved with less than 2% VR content. The cohesion was the largest for no D-W cycles, 10% water content, and 2% VR content. The links between mineral particles go from a stable layered structure to unsteadiness chain structure with the increase in the number of D-W cycles.

Research on Shear Strength of Compacted Loess

2013 ◽  
Vol 448-453 ◽  
pp. 1284-1288 ◽  
Author(s):  
Juan Juan Wang ◽  
Jun Tao Deng ◽  
Song Lin Wu
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Dry Density ◽  
Dam Foundation ◽  
Direct Shear Tests ◽  
Strength Formula ◽  
Compacted Loess

Compacted loss widely used in the construction, such as embankment, dam, foundation backfill and other projects. Influenced by rainfall factors, the moisture content of compacted loess often vary so the shear strength will also changed. This paper studies the shear strength parameters of compacted loess through direct shear tests. In the dry density under the same conditions, the cohesion, internal friction angle of compacted loess decreases with the increase of water content. Summed cohesion and water content showed a quadratic parabola and internal friction angle and water content was also found quadratic parabola; further considering the effects of water content and dry density of compacted loess got shear strength formula. Shear strength formula.

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