Research on the Mechanical Properties and Energy Consumption Transfer Law of Cement Tailings Backfill Under Impact Load

2021 ◽  
Vol 13 (5) ◽  
pp. 889-898
Author(s):  
Yong-Ye Mu ◽  
Xiang-Long Li ◽  
Jian-Guo Wang ◽  
Zhi-Gao Leng
Keyword(s):  
Mechanical Properties ◽  
Energy Transfer ◽  
Impact Load ◽  
Peak Stress ◽  
Peak Strain ◽  
Impact Compression ◽  
Average Strain Rate ◽  
Failure Morphology ◽  
The Stability ◽  
The Impact

The cemented tailings backfill (CTB), which plays a significant role in the stability of mine structure, is made of cement, tailings, and water in a certain proportion. When blasting and excavating an underground mine, the CTB will be disturbed by blasting. The impact load of blasting has an impact on the stability of the CTB, which is directly related to the safety of mine construction. The mechanical behaviour of CTB is generally affected by the cement-tailings ratio (C/T) and average strain rate (ASR). Therefore, a series of impact experiments were carried out on three CTB specimens with different C/T using a SHPB. Combined with the experimental results, this account reports studies on the effects of C/T and ASR on the mechanical properties of CTB, and on the energy transfer laws of CTB during impact compression. The research results show that when the ASR is less than 70 s−1, the peak stress and the peak strain have the same trend, and both of them continue to increase with the increase of ASR.When the ASR exceeds 70 s−1, as the ASR increases, the peak stress continues to increase, but the peak strain decreases gradually. Afterwards, the law of energy transfer of the CTB specimen was analyzed. It was found that as the incident energy increased, the energy reflection ratio of the CTB increased. Both the energy transmitted ratio and the energy dissipation ratio decreased. The volumetric energy showed a sharp increase first and then a trend Because of the slowly increasing trend. Finally, according to the failure morphology of the CTB, it is found that the ASR and the C/T together affect the failure of the CTB. The failure model of the CTB is mainly split failure and crush failure.

scholarly journals Experimental Study of the Influence of Moisture Content on the Mechanical Properties and Energy Storage Characteristics of Coal

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Nan Liu ◽  
Chuanming Li ◽  
Ruimin Feng ◽  
Xin Xia ◽  
Xiang Gao
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Rock Burst ◽  
Elastic Energy ◽  
Coal Sample ◽  
Water Injection ◽  
Peak Stress ◽  
Peak Strain ◽  
Energy Index ◽  
The Impact

Rock burst occurs frequently as coal mining depth goes deeper, which seriously impacts the safety production of underground coal mines. Coal seam water injection is a technique commonly used to prevent and control such accidents. Moisture content is a critical factor tightly related to rock burst; however, an in-depth insight is required to discover their relationship. In this study, the influence of moisture content on the mechanical properties of coal and rock burst tendency is explored via multiple measurement techniques: uniaxial compression test, cyclic loading/unloading test, and acoustic emission (AE) test. These tests were performed on coal samples using the MTS-816 rock mechanics servo testing machine and AE system. The testing results showed that with the increase in moisture content, the peak strength and elastic modulus of each coal sample are reduced while the peak strain increases. The duration of the elastic deformation phase in the complete stress-strain curves of coal samples is shortened. As the moisture content increases, the area of hysteretic loop and elastic energy index W ET of each coal sample are reduced, and the impact energy index K E is negatively correlated with the moisture content, whereas dynamic failure time is positively correlated with the moisture content, but this variation trend is gradually mitigated with the continuous increase of moisture content. The failure of the coal sample is accompanied by the sharp increase in the AE ring-down count, whose peak value lags behind the peak stress, and the ring-down count is still generated after the coal sample reached the peak stress. With the increase in moisture content, the failure mode of the coal sample is gradually inclined to tensile failure. The above test results manifested that the strength of the coal sample is weakened to some extent after holding moisture, the accumulative elastic energy is reduced in case of coal failure, and thus, coal and rock burst tendency can be alleviated. The study results can provide a theoretical reference for studying the fracture instability of moisture-bearing coal and prevention of coal and rock burst by the water injection technique.

scholarly journals Experimental Study on Physical and Dynamic Mechanical Properties of Temperature-Water Coupled Sandstone

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Qi Ping ◽  
Dezhi Qi ◽  
Qi Diao ◽  
Chuanliang Zhang ◽  
Qi Gao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Quadratic Function ◽  
Bath Temperature ◽  
Dynamic Mechanical Properties ◽  
Water Bath ◽  
Peak Strain ◽  
Impact Compression ◽  
Dynamic Mechanical ◽  
The Impact ◽  
Temperature Water

In order to study the influence characteristics of water bath at different temperatures on rock physical and dynamic mechanical properties, a total of 15 groups of temperature-water bath treatment were carried out on coal mine roadway sandstone at 25°C∼95°C, and the basic physical parameters were tested. The impact compression test was carried out using the split Hopkinson pressure bar (SHPB) device. The results show that, with the increase of water bath temperature, the particle gap on the specimen surface increases. The volume, mass, and density of the specimens all increased with the increase of water bath temperature, and the increase was closely related to the water bath temperature. The dynamic compressive strength increases as a quadratic function of the water bath temperature, and the rate of increase is different before and after 45°C. The dynamic peak strain and average strain rate showed a quadratic function with the water bath temperature. The dynamic peak strain before 45°C decreased with the temperature increasing, and the dynamic peak strain after 45°C increased with the temperature increasing. The dynamic elastic modulus increased first and then decreased with the increase of water bath temperature and reached the maximum at 45°C. The failure pattern of sandstone is spalling. With the increase of water bath temperature, the fracture degree of the specimen gradually decreases.

scholarly journals Experimental Investigation of Dynamic Compression Mechanical Properties of Frozen Fine Sandstone

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jiehao Wu ◽  
Haibo Wang ◽  
Qi Zong ◽  
Ying Xu
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Failure Modes ◽  
Peak Stress ◽  
Freezing Temperature ◽  
Fracture Morphology ◽  
Tensile Failure ◽  
Average Strain ◽  
Average Strain Rate ◽  
The Impact

Aiming at the dynamic mechanical properties of weakly cemented fine sandstone in the rich water-bearing strata in western China under dynamic loading, a 50 mm rod diameter separation Hopkinson pressure bar (SHPB) test was used to study the Paleogene fine sandstone in a coal mine in Ningxia. The system carried out the impact compression tests of −15°C, −20°C, and −30°C and the average strain rate of 28 s−1–83 s−1 and obtained the dynamic compressive strength of the frozen fine sandstone specimens under different test conditions. The strain curve and the fracture morphology were analyzed for the relationship between dynamic peak stress, peak strain, dynamic strength growth coefficient (DIF), and fracture morphology and strain rate. The results show that the peak stress of frozen fine sandstone increases from the decrease of freezing temperature under the same average strain rate. The peak stress of the specimen increases from the increase in the average strain rate of the same freezing temperature. The failure modes of specimen are mainly divided into axial splitting tensile failure and compression crushing failure. To the splitting tensile failure and the compression crushing failure, the main factors determining the two failure modes are the strain rate, while the temperature affects the severity of the impact damage. In the load strain rate and temperature range, the DIF of the frozen fine sandstone is linearly correlated with the strain rate, and the lower the temperature, the slower the growth rate of the DIF.

scholarly journals Failure Properties and Stability Monitoring of Strip and Column Cemented Gangue Backfill Bodies Under Uniaxial Compression In Constructional Backfill Mining

2022 ◽  
Author(s):  
Hongyu Ran ◽  
Yuxia Guo ◽  
Guorui Feng ◽  
Chunqing Li
Keyword(s):  
Mechanical Properties ◽  
Uniaxial Compression ◽  
Constitutive Models ◽  
Peak Stress ◽  
Peak Strain ◽  
Height Ratio ◽  
Stability Monitoring ◽  
Backfill Mining ◽  
Failure Properties ◽  
The Stability

Abstract The strip and column cemented gangue backfill bodies (CGBBs) are the main supporting components in the design of constructional backfill mining for coal mining, which determines the stability of goaf. Previous researches have mostly focused on the mechanical properties of column CGBB, but the mechanical properties of strip CGBB are still unclear. Herein, the uniaxial compression experiments for strip and column CGBBs were conducted to compare the failure properties. The acoustic emission (AE) and two types of resistivity monitoring were used to monitor the damage evolution. The effect of the length-height ratio on the mechanical characteristic of strip CGBB was analyzed by discrete element simulation. The results show that: the strength and peak strain of strip CGBB under uniaxial compression is higher than those of column CGBB, and the strip CGBB shows better ductility. The stress of column CGBB decreases significantly faster than that of strip CGBB at the post-peak stage. The strength and ductility of strip CGBB increase with the increase of length-height ratio. The strip CGBB is destroyed from both ends to the middle under uniaxial compression, and the core bearing area is reduced correspondingly. The AE signal evolution of CGBBs under uniaxial compression before the peak stress contains three stages, and the AE signals of strip CGBB at the peak stress will not rise sharply compared with column CGBB. The resistivity monitoring effect of the horizontally symmetrical conductive mesh is better than that of the axial. The horizontal resistivity increases gradually with the increase of stress under uniaxial compression, and increases sharply at the peak stress, and then drops after the peak stress. The damage constitutive models and the stability monitoring models of the CGBBs are established based on the experimental results. This work would be instructive for the design and stability monitoring of CGBB.

Comparison Analysis on the Mechanical Properties of HSC and NSC after the Action of High Temperatures

2014 ◽  
Vol 1014 ◽  
pp. 49-52
Author(s):  
Xiao Ping Su
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Temperatures ◽  
High Strength Concrete ◽  
Elasticity Modulus ◽  
Strain Curve ◽  
Peak Stress ◽  
High Strength ◽  
Peak Strain ◽  
Strength Concrete

With the wide application of high strength concrete in the building construction,the risk making concrete subject to high temperatures during a fire is increasing. Comparison tests on the mechanical properties of high strength concrete (HSC) and normal strength concrete (NSC) after the action of high temperature were made in this article, which were compared from the following aspects: the peak stress, the peak strain, elasticity modulus, and stress-strain curve after high temperature. Results show that the laws of the mechanical properties of HSC and NSC changing with the temperature are the same. With the increase of heating temperature, the peak stress and elasticity modulus decreases, while the peak strain grows rapidly. HSC shows greater brittleness and worse fire-resistant performance than NSC, and destroys suddenly. The research and evaluation on the fire-resistant performance of HSC should be strengthened during the structural design and construction on the HSC buildings.

Effect of Notch Depth on the Butt-Joint under Izod Impact Test with Material Properties and Mechanics Analysis

2013 ◽  
Vol 644 ◽  
pp. 197-200 ◽  
Author(s):  
Xiao Ling Zheng ◽  
Mei Li ◽  
Min You ◽  
Wen Jun Liu ◽  
Kai Liu
Keyword(s):  
Impact Test ◽  
Impact Load ◽  
Peak Stress ◽  
Butt Joint ◽  
Notch Depth ◽  
The Finite Element Method ◽  
Adhesively Bonded ◽  
Izod Impact ◽  
Depth Increase ◽  
The Impact

The effect of the notch depth on the impact toughness of the adhesively bonded steel butt joint under Izod impact test is studied using both the finite element method and experimental method. The results obtained from numerical simulation showed that the response time with the peak stress Seqv occurred becomes little longer when the notch depth increased from 2 mm to 8 mm. And a negative longitudinal stress occurred when there is an 8 mm depth notch which might be beneficial to subject impact load. The results from the experiments showed that the effect of notch depth is evidently on the Izod impact properties. The impact energy absorbed by unit area of joint is increased as the notch depth increase

Relationships Between Wheel/Rail Surface Impact Loadings and Correspondingly Transmitted Tie/Ballast Impact Pressures for Revenue Train Operations

2018 ◽  
Author(s):  
Travis J. Watts ◽  
Jerry G. Rose ◽  
Ethan J. Russell
Keyword(s):  
Test Section ◽  
Impact Load ◽  
Peak Force ◽  
Pressure Measurements ◽  
Track Geometry ◽  
Impact Forces ◽  
Interfacial Pressure ◽  
Degradation Rates ◽  
The Stability ◽  
The Impact

A series of specially designed granular material pressure cells were precisely positioned directly below the rail at the tie/ballast interface to measure typical interfacial pressures exerted by revenue freight trains. These vertical pressures were compared to the recorded wheel/rail nominal and peak forces for the same trains traversing nearby mainline wheel impact load detectors (WILDs). The cells were imbedded within the bottom of new wood ties so that the surfaces of the pressure cells were even with the bottoms of the ties and the underlying ballast. The cells were inserted below consecutive rail seats of one rail to record pressures for a complete wheel rotation. The stability and tightness of the ballast support influenced the magnitudes and consistencies of the recorded ballast pressures. Considerable effort was required to provide consistent ballast conditions for the instrumented ties and adjacent undisturbed transition ties. Norfolk Southern (NS) crews surfaced and tamped through the test section and adjacent approach ties. This effort along with normal accruing train traffic subsequently resulted in reasonably consistent pressure measurements throughout the test section. The impact ratio (impact factor) and peak force values recorded by the WILDs compared favorably with the resulting magnitudes of the transferred pressures at the tie/ballast interface. High peak force and high impact ratio WILD readings indicate the presence of wheel imperfections that increase nominal forces at the rail/wheel interface. The resulting increased dynamic impact forces can contribute to higher degradation rates for the track component materials and more rapid degradation rates of the track geometry. The paper contains comparative WILD force measurements and tie/ballast interfacial pressure measurements for loaded and empty trains. Typical tie/ballast pressures for locomotives and loaded freight cars ranges from 20 to 30 psi (140 to 210 kPa) for smooth wheels producing negligible impacts. The effect of increased wheel/rail impacts and peak force values on the correspondingly transmitted pressures at the tie/ballast interface is significant, with increased pressures of several orders of magnitude compared to nominal impact forces from wheels.

Numerical Analysis on the Butt-Joint under Izod Impact Test

2012 ◽  
Vol 602-604 ◽  
pp. 2279-2282 ◽  
Author(s):  
Xiao Ling Zheng ◽  
Ling Wu ◽  
Min You ◽  
Kai Liu ◽  
Mei Li
Keyword(s):  
Impact Test ◽  
Failure Time ◽  
Impact Load ◽  
Adhesive Layer ◽  
Peak Stress ◽  
Butt Joint ◽  
Adhesively Bonded ◽  
Adhesive Thickness ◽  
Izod Impact ◽  
The Impact

The effect of the adhesive thickness on the impact toughness of the adhesively bonded steel butt joint during Izod impact test and the failure procedure is studied using the finite element method software ABAQUS. The results obtained show that the time with the peak stress Seqv occurred is corresponding to the element failure. And much higher peak stress might be subjected by the element near the bottom of the joint under impact load. The failure time of the element becomes little longer when the adhesive layer thickness increased from 0.1 mm to 0.4 mm. But the peak value of the Seqv decreases and the damage limit of the strain increased evidently as the adhesive thickness increased from 0.2 mm to 0.4 mm.

Fabrication and Preliminary Study of a Prototype Bi-Layered Small Diameter Vascular Prosthesis Composed of Nano-Fiber and Silk Fiber

2013 ◽  
Vol 843 ◽  
pp. 66-69 ◽  
Author(s):  
Hui Jing Zhao ◽  
Guo Li Zhou ◽  
Zhi Qing Yuan
Keyword(s):  
Mechanical Properties ◽  
Blood Vessels ◽  
Outer Layer ◽  
Small Diameter ◽  
Peak Stress ◽  
Silk Fiber ◽  
Content Increase ◽  
Peak Strain ◽  
Tissue Engineering Scaffolds ◽  
Vascular Prostheses

Biomaterials used for vascular prostheses should possess certain strength that can keep the normal blood fluidity, as well as certain flexibility and elasticity that can resist blood pulsation pressure. In order to fabricate small diameter vascular prostheses (SDVP) that possess matchable mechanical properties with natural blood vessels, a bi-layered tubular structure composed of electrospinning blended nanofiber and silk fiber was designed and prepared in this study. The inner layer of the structure, prepared through electrospinning, was composed of Poly (L-lactide-co-ε-caprolactone) (PLCL) and silk fibroin (SF) blended nanofibers. Braided silk tube was used as the outer layer of the structure. Morphological, structural and mechanical properties including peak stress, peak strain, and Youngs modulus of the prototype bi-layered SDVP were characterized initially. Results showed that the diameter range of the blended nanofiber was between 100 and 900 nm, and the fiber diameter increased with the content increase of PLCL. Through blending PLCL together with SF, peak stress and peak strain of the electrospun inner layer were improved, and that of the Youngs modulus decreased. Meanwhile, the outer layer of SDVP was stronger and had higher Youngs modulus. Those mechanical performances of the prototype bi-layered SDVP fabricated in this study are similar to natural blood vessels, which provide a promising biomaterial that could be applied on tubular tissue engineering scaffolds.

Numerical Simulation of the Effect of Temperature on the Failure Strength of Rock

2013 ◽  
Vol 690-693 ◽  
pp. 1737-1740
Author(s):  
Lin Bu ◽  
Tao Xu ◽  
Yun Jie Zhang
Keyword(s):  
Mechanical Properties ◽  
Rock Fracture ◽  
Strain Curve ◽  
Peak Stress ◽  
Effect Of Temperature ◽  
Peak Strain ◽  
Failure Strength ◽  
Stress Strain Curve ◽  
Physical Tests ◽  
Compression Condition

The mechanical properties of granite experiencing high temperatures under uniaxial compression condition were simulated in this paper. Numerically simulated stress-strain curve, peak stress, peak strain and the tangent elastic modulus were compared with the corresponding physical tests. Simulated results agree well with physical tests results, it is shown that Abaqus is suitable for the analysis of the temperature effect on rock fracture.

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