The Rock Failure Mechanism of Air-Decked Blasting in Hole Bottom

2012 ◽  
Vol 201-202 ◽  
pp. 375-378 ◽  
Author(s):  
Liang Wu ◽  
Yong Zhou ◽  
Zhi Hua Guo
Keyword(s):  
Failure Mechanism ◽  
Damage Evolution ◽  
Shear Failure ◽  
Dynamic Stress ◽  
Near Field ◽  
Blast Hole ◽  
Tensile Failure ◽  
Charge Structure ◽  
Concrete Damage ◽  
Bottom Rock

The application of air-decked blasting technology has enabled the efficient use of explosion energy, which proves that the air-decked blasting technology can overcome many disadvantages caused by column charge effectively, getting ideal explosion effect. Based on the JHC model of concrete damage evolution, the dynamic stress characteristics and failure mechanism of blast-hole near-field about bottom-air-decked charge structure is studied by numerical simulation. Result shows that the failure mechanism of typical elements changes from compression-shear failure into shear-tensile failure gradually with the increase of their position, for the effecting factors of the freedom and the loading from the hole. Comparing the dynamic stress characteristics of different detonating manners, indirect initiation can improve the static function intensity and delay the time of detonation gas, so it is easier to destroy the bottom rock of hole.

Effect of Air Position to the Mechanism of Air-Decked Blasting

2011 ◽  
Vol 328-330 ◽  
pp. 1167-1171
Author(s):  
Liang Wu
Keyword(s):  
Failure Mechanism ◽  
Shear Failure ◽  
Near Field ◽  
Blast Hole ◽  
Tensile Failure ◽  
Detonation Waves ◽  
Affecting Factors ◽  
Concrete Damage ◽  
Failure Properties ◽  
The Media

Based on the JHC model of concrete damage evolution, the dynamic stress characteristics and failure mechanism of blast-hole near-field about different air-decked charge structures are studied by numerical simulation. Result shows that the failure mechanism of typical elements changes from compression-shear failure into shear-tensile failure gradually with the increase of their position in indirect initiation of both top-air-decked and bottom-air-decked charges, because of the affecting factors of the freedom and the loading from the hole. If middle-air-decked charges detonate from the top and bottom at the same time, loading and unloading waves in blasting hole are more influential to the damage of bottom elements than the surface freedom, because detonation waves of both top and bottom meet at the middle hole, so it is conducive to the media failure at the bottom hole, the elements of freedom surface have the same failure properties to top-air-decked charge.

The Dynamic Stress Characteristics of Air-Decked Bench Blasting under Soft Interlayer

2011 ◽  
Vol 101-102 ◽  
pp. 400-404
Author(s):  
Liang Wu ◽  
Dong Xiao Yu ◽  
Wei Dong Duan
Keyword(s):  
Dynamic Stress ◽  
Near Field ◽  
Blast Hole ◽  
Material Model ◽  
Explosion Energy ◽  
Element Analysis ◽  
Charge Structure ◽  
Soft Interlayer ◽  
Bench Blasting ◽  
Project Construction

In modern mining and project construction, how to make use of the explosion energy effectively is the key technology demanding prompt solution at present. The application of air-decked blasting technology has enabled the efficient use of explosion energy, which proves that the air-decked blasting technology can overcome many disadvantages caused by column charge effectively, getting ideal explosion effect. Based on the dynamic finite element analysis software with the material model of Mat-Plastic-Kinemetic, the dynamic stress characteristics and failure mechanism of blast-hole near-field with level soft interlayer are researched with different air-decked charge structures. There is significant effect on the rock at the middle of blast-hole if top-air-decked charge structure with indirect initiation and middle-air-decked charge structure with two ends initiation at the same time. If bottom-air-decked charge structure with indirect initiation, soft inter-layer don’t change the peek of compression and tensile stress curves of typical elements with distance from the bottom of hole, so there is not effect significantly of level soft interlayer on bottom-air-decked charge structure with indirect initiation.

Rock Failure Mechanism of Air-Decked Smooth Blasting under Soft Interlayer

2011 ◽  
Vol 402 ◽  
pp. 617-621 ◽  
Author(s):  
Liang Wu ◽  
Dong Xiao Yu ◽  
Wei Dong Duan ◽  
Dong Wang Zhong
Keyword(s):  
Tensile Strength ◽  
Failure Mechanism ◽  
Near Field ◽  
Blast Hole ◽  
Material Model ◽  
Element Analysis ◽  
Charge Structure ◽  
Soft Interlayer ◽  
Main Effect ◽  
Smooth Blasting

In order to enhance smooth blasting adaptability and its effect in mining for rock mass complex characteristics, and based on the dynamic finite element analysis software with the material model of Mat-Plastic-Kinemetic, the dynamic stress characteristics and failure mechanism of blast-hole near-field with level soft interlayer are researched on different air-decked charge structures. The main effect of soft interlayer on top-air-decked charge structure is the tensile strength and range at the top of blasting hole, but the main effect of soft interlayer on middle-air-decked charge structure is the tensile strength and range at the middle of blasting hole, and some effect of soft interlayer on bottom-air-decked charge structure is the extension of rock crack at the bottom of blast- hole.

scholarly journals Failure Characteristics and Mechanism of Multiface Slopes under Earthquake Load Based on PFC Method

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Tao Yang ◽  
Yunkang Rao ◽  
Huailin Chen ◽  
Bing Yang ◽  
Jiangrong Hou ◽  
...  
Keyword(s):  
Moisture Content ◽  
Failure Mechanism ◽  
Failure Modes ◽  
Shear Failure ◽  
Shaking Table ◽  
Tensile Failure ◽  
Particle Flow Code ◽  
Shear Cracks ◽  
Local Shear ◽  
Shear Slip

Understanding the failure mechanism and failure modes of multiface slopes in the Wenchuan earthquake can provide a scientific guideline for the slope seismic design. In this paper, the two-dimensional particle flow code (PFC2D) and shaking table tests are used to study the failure mechanism of multiface slopes. The results show that the failure modes of slopes with different moisture content are different under seismic loads. The failure modes of slopes with the moisture content of 5%, 8%, and 12% are shattering-shallow slip, tension-shear slip, and shattering-collapse slip, respectively. The failure mechanism of slopes with different water content is different. In the initial stage of vibration, the slope with 5% moisture content produces tensile cracks on the upper surface of the slope; local shear slip occurs at the foot of the slope and develops rapidly; however, a tensile failure finally occurs. In the slope with 8% moisture content, local shear cracks first develop and then are connected into the slip plane, leading to the formation of the unstable slope. A fracture network first forms in the slope with 12% moisture content under the shear action; uneven dislocation then occurs in the slope during vibration; the whole instability failure finally occurs. In the case of low moisture content, the tensile crack plays a leading role in the failure of the slope. But the influence of shear failure becomes greater with the increase of the moisture content.

Study on Mechanism of Slope Instability with Weak Interlayer

2011 ◽  
Vol 71-78 ◽  
pp. 3615-3618 ◽  
Author(s):  
Yun Fei Wang ◽  
Fu Ping Zhong ◽  
Huai Bao Chu ◽  
Li Ping Wang
Keyword(s):  
Stress Field ◽  
Failure Mechanism ◽  
Shear Failure ◽  
Slope Instability ◽  
Tensile Failure ◽  
Cyclic Process ◽  
Research Subject ◽  
Geological Conditions ◽  
Weak Interlayer ◽  
Mass Rock

In the process of the highway building, especially in mountain region the some complex geological conditions often appears. In this paper, using the slope of highway with weak interlayer as the research subject, systematically analyzing the stress field and plastic field during the excavation of the slope, obtained the failure mechanism of the slope with weak interlayer, which is a cyclic process that weak interlayer shear failure led to the tensile failure of its upper mass rock. It has extraordinarily important guiding significance for the protection and reinforcement of similar slope.

scholarly journals Buckling Failure Mechanism of a Rock Dam Foundation Fractured by Gentle Through-Going and Steep Structural Discontinuities

2020 ◽  
Vol 12 (13) ◽  
pp. 5426
Author(s):  
Donghui Chen ◽  
Huie Chen ◽  
Wen Zhang ◽  
Chun Tan ◽  
Zhifa Ma ◽  
...  
Keyword(s):  
Numerical Method ◽  
Failure Mechanism ◽  
Shear Failure ◽  
Distinct Element ◽  
Mechanism Analysis ◽  
Rock Masses ◽  
Dam Foundation ◽  
Deformation Features ◽  
Universal Distinct Element Code ◽  
Distinct Element Code

The failure mechanism analysis of dam foundations is key for designing hydropower stations. This study analyses the rock masses in a sluice section, which is an important part of the main dam of the Datengxia Hydropower Station currently built in China. The stability of the sluice rock masses is predominantly affected by gentle through-going soft interlayers and steep structural fractures. Its foundation failure mechanism is investigated by means of a numerical method, i.e., Universal Distinct Element Code (UDEC) and the geomechanical model method. The modeling principle and process, and results for the rock dam foundation are introduced and generated by using the abovementioned two methods. The results indicate that the failure mechanism of the foundation rock masses, as characterized by gentle through-going and steep structural discontinuities, is not a conventional type of shear failure mechanism but a buckling one. This type of failure mechanism is verified by analyzing the deformation features resulting from the overloading of both methods and strength reduction of the numerical method.

scholarly journals Strength and Failure Mechanism of Composite-Steel Adhesive Bond Single Lap Joints

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Kai Wei ◽  
Yiwei Chen ◽  
Maojun Li ◽  
Xujing Yang
Keyword(s):  
Failure Mechanism ◽  
Shear Failure ◽  
Failure Load ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Adhesive Failure ◽  
Interface Failure ◽  
Element Analysis ◽  
Single Lap Joints ◽  
Structural Adhesive

Carbon fiber-reinforced plastics- (CFRP-) steel single lap joints with regard to tensile loading with two levels of adhesives and four levels of overlap lengths were experimentally analyzed and numerically simulated. Both joint strength and failure mechanism were found to be highly dependent on adhesive type and overlap length. Joints with 7779 structural adhesive were more ductile and produced about 2-3 kN higher failure load than MA830 structural adhesive. Failure load with the two adhesives increased about 147 N and 176 N, respectively, with increasing 1 mm of the overlap length. Cohesion failure was observed in both types of adhesive joints. As the overlap length increased, interface failure appeared solely on the edge of the overlap in 7779 adhesive joints. Finite element analysis (FEA) results revealed that peel and shear stress distributions were nonuniform, which were less severe as overlap length increased. Severe stress concentration was observed on the overlap edge, and shear failure of the adhesive was the main reason for the adhesive failure.

Numerical modelling of the crack-pore interaction and damage evolution behaviour of rocklike materials with pre-existing cracks and pores

2020 ◽  
pp. 105678952098387
Author(s):  
PLP Wasantha ◽  
D Bing ◽  
SQ Yang ◽  
T Xu
Keyword(s):  
Principal Stress ◽  
Damage Evolution ◽  
Shear Failure ◽  
Mechanical Response ◽  
Distribution Patterns ◽  
Stress Distributions ◽  
Compressive Stresses ◽  
Major Principal Stress ◽  
The Right ◽  
Macroscopic Failure

The combined effect of pre-existing cracks and pores on the damage evolution behaviour and mechanical properties of rocklike materials under uniaxial compression was numerically studied. Simulations of cracks and pores alone showed that increasing crack length and pore diameter decrease uniaxial compressive strength (UCS) and elastic modulus. Subsequent simulations considered two types of combinations of pre-existing cracks and pores – two cracks either side of a centric pore, and two pores either side of a centric crack – and the distance between cracks and pores was changed. In the case of two cracks at either side of the pore, UCS increased only slightly when the distance between the cracks and pore was increased. This was attributed to the more profound effect of the presence of the pore on UCS, and was confirmed by the progressive crack development characteristics and the major principal stress distribution patterns, which showed that the cracks initiated from the tips of the two pre-existing cracks made little or no contribution to the ultimate macroscopic failure. In contrast, models with two pores at either side of a centric crack showed a marked dependency of UCS on the distance between the pores and the crack. Cracks propagating from pre-existing pores made a greater contribution to the ultimate macroscopic failure when the pores were close to the centric crack and the effect gradually diminished with increasing space between pre-existing pores and the centric crack. Major principal stress distributions showed an asymmetric mobilisation of compressive stresses at the right and left sides of the two pores, favouring macroscopic shear failure when they were close to the centric crack which had led to a lower UCS. Overall, this study presents some critical insights into crack-pore interaction behaviour and the resulting mechanical response of rocklike materials to assist with the design of rock structures.

On the Direction of Fatigue Cracks in Polycrystalline Ingot Iron

1952 ◽  
Vol 19 (1) ◽  
pp. 54-56
Author(s):  
F. A. McClintock
Keyword(s):  
Statistical Analysis ◽  
Shear Failure ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Tensile Failure ◽  
Bending Fatigue ◽  
Polycrystalline Iron

Abstract A statistical analysis is developed to show how a microscopic shear failure can result in the apparent tensile failure of polycrystalline iron in rotary bending fatigue tests.

Investigation of the tensile performance and failure mechanism of carbon–aramid hybrid fibers/epoxy sandwich structure laminates using the UV-thermal synergetic curing mechanism: Experimentation and simulation

2018 ◽  
Vol 22 (8) ◽  
pp. 2582-2603
Author(s):  
Jiaojiao Xi ◽  
Xiaoyan Liu ◽  
Zhiqiang Yu
Keyword(s):  
Finite Element ◽  
Failure Mechanism ◽  
Sandwich Structure ◽  
Experimental Results ◽  
Tensile Failure ◽  
Hybrid Fibers ◽  
Pull Out ◽  
Tensile Performance ◽  
Hybrid Laminates ◽  
Curing Agents

The tensile failure mechanism of carbon–aramid hybrid fibers/epoxy sandwich structure laminates was investigated by using experimental and finite element methods. Double curing agents, triarylsulfonium hexafluoroantimonates and triethylene tetramine with a mass ratio of 4:15 were introduced into the laminates. Sandwich structure laminates, with different proportions of hybrid fibers, were cured by UV-initiated anion/cationic dual curing technique. The results showed that the synergetic curing effects of two curing agents were observed under UV irradiation, leading to the better curing of the system, which further plays a positive influence on the mechanical performance. The tensile properties and failure mechanism of the laminates depended on the stacking sequence and fiber volume fractions of the layer structures. The interplay hybrid laminates, containing three alternate plies with fiber contents of 67.7 vol%, presented the optimal tensile performance, and its tensile strength and modulus were 0.82 GPa and 22.09 GPa, respectively. The fracture morphologies revealed that pull-out and debonding of fibers were the main failure mechanism of hybrid laminates. The performance of sandwich structure laminates was determined by the load-carrying capacity of carbon fiber and load-transferring capacity of the aramid fiber and adhesive. The finite element model based on experiments was established to simulate the stress state and failure mechanism of sandwich laminates. The results demonstrated that the stress was better transferred into carbon fibers from the aramid fibers and adhesive, and the relative error rate of maximum stress from finite element analysis and experimental results was less than 5%, which were in reasonable agreement with the experimental results.

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