Effect of Cyclic Loading and Unloading on the Deformation and Damage Properties of Sandstone from Beizao, a Coal Mine underneath the Bohai Sea in China September 2022 Geofluids 2022(3):111
Permeability changes with confining stress loadingunloading: (a) is the PUC; (b) is the cataclastic coal; (c) is the mylonitic coal; (d) is the loadingunloading process of confining stress. The increase in confining pressure compressed the coal matrix and internal fissures of the coal cores, and their permeability rapidly and then slowly ...
The coils are then loaded either on a reel style or cradle style uncoiling system. Cradle style uncoilers are relatively easy to load, you basically lower your coil onto the cradle, position the sides guides to center the coil and your coil is ready to be released. On a reel type the process is not as easy. You have a large heavy object either ...
Cyclic Loading and Unloading Process. Based on the results of AE filtering experimental results, the loading process for the ultrasonic test experiments carried out in this study is as follows: measure the ultrasonic wave parameters before the process of loading, load up to kN and maintain the force for 34 minutes; load up to kN and maintain the force for 34 minutes; unload up ...
As the coal body has a hysteresis effect during the unloading process, it cannot be unloaded to 0 when unloading, and the minimum unloading level was set for the four kinds of samples; that is, after unloading to 2% σ c, the loading was performed until the sample was destabilized.
The rock mass in fault zones is frequently subjected to cyclic loading and unloading during deep resource exploitation and tunnel excavation. Research on the mechanical and hydraulic characteristics of fault rock during the cyclic loading and unloading is of great significance for revealing the formation mechanism of waterconducting pathways in fault and preventing water inrush disasters. In ...
Coal is an important, widelyused source of energy and a chemical raw material, which is transported globally in large quantities; more than a billion tonnes of coal per year are transported by sea (IEA International Energy Agency, 2020). However, its carriage as a cargo is associated with a number of hazards and coal must be carried in ...
Conventional and cyclic unloading tests with different unloading rates were conducted to study the influences of unloading patterns and rates on the deformation characteristics and mechanical properties of tectonic coal. The results demonstrate that, under continuous unloading, a lower unloading rate promotes an increase in the circumferential strain but inhibits increases in axial strain.
The size effect of coalgangue mass after loading and unloading test is the reflection of its inherent structural complexity, which is due to the existence of fracture network system in rock mass and the joint influence of loading and unloading process. Coalgangue physical and mechanical properties and particle distribution, as well as defects ...
Observing the whole unloading process, the unloading time is 133 s when the density of coal bulk is 1600 kg/m 3, the unloading time is s when the density is 1350 kg/m 3 and the unloading time is s when the density is 1100 kg/m 3, so the higher the particle density in the silo, the faster is the unloading speed.
The mining of coal resources causes the stress on the front and both sides of the working face to be in a complex loading and unloading process, and the gas contained in the coal body migrates, which can cause gasdynamic disasters in severe cases.
The effects of repeated loading and unloading paths on the raw coal samples were studied by analyzing the samples' permeability, energy dissipation and AE characteristics. ... During the loading and unloading process, the work done by the effective confining pressure on coal mass is far smaller than that of the axial effective stress ...
The process of loading and unloading can involve heavy equipment, moving machinery, and manual labor, which increases the risk of accidents and injuries. It is crucial to provide comprehensive training, enforce safety protocols, and use proper personal protective equipment to minimize these risks. 2. Damage to cargo and vessel.
The loading and unloading rate for uniaxial and cyclic fatigue load were mm/min. The Express8 AE monitoring system was adopted to continuously log the acoustic events/micro failure inside the coal samples during the whole loading process.
Load restraint: Load restraint includes lashing/unlashing, tie down, twistlock locking/unlocking for the purposes of ensuring a load is secured to the truck to meet the performance standards in the load restraint guide or unsecured in preparation for removal. Safe zone: is an area free of interaction between equipment/machinery and people. The safe
To investigate the influence of loadingunloading paths as well as loading and unloading rates on the deformation and failure behavior of coal, laboratory experiments and numerical simulations of unloading under axial pressure and confinement were carried out. The effect of different axial loading rates and unloading rates on the deformation and failure behavior of coal under the unloading ...
In this process, the coal in a protected seam is subjected to cyclic loadingunloading effects, which significantly change the mechanical properties and seepage characteristics of the coal. Related research results show that gas has a significant influence on the mechanical properties and energy dissipation characteristics of coal [ 17, 18 ...
In the unloading process, the fracture space in coal sample extends and expands passively, instead of the compression of fracture under stress loading. The microcracks and beddings in the coal sample gradually connect, the number of gas permeation channels increases, and the rate of gas transport within coal becomes faster.
The loadingunloading process is represented as follows: 0 ... In cyclic loading process, the coal samples first exhibit the appearance of microcracks at the beginning stage. With the increase in the axial stress, the damage gradually accumulates and produces irreversible plastic deformation. When the peak load is reached, partial area of ...
Thus, the axial stress in the experiment is equal to the confining stress. In this study, three loading and unloading seepage tests have been carried out to simulate the effect of three coal seams mining on the caving zone and the second and third loading and unloading stress paths are the same as the first loading and unloading stress path.
This is the technology that used in power plant, while the coal is unload to the convayer belt
True triaxial loadingunloading tests of coal samples were performed using a multifunctional true triaxial fluidsolid coupling experimental system. The deformation, seepage, damage, strength, and failure characteristics of the coal samples were analyzed. Based on this, the variation mechanism of the permeability and yield conditions under different gas pressures was investigated, and the ...
To further validate and promote the proposed damage constitutive model, the loadingunloading process of coal material is also simulated. Because energy is continuously transformed during loading, in the loadingunloading process, the damage variable is also defined by energy dissipation.
In this study, coal fly ash was functionalized, using a simple onestep process (loading with Al3+ and sulfonation), to yield a solid acid catalyst (S/AlCFA) with strong acid sites. The catalyst was then used to produce furfural from xylose in a biphasic system (H2O(NaCl)/tetrahydrofuran). The furfural yield reached 82% at 180 °C60 min with catalyst/xylose ratio of : (w/w). With the ...
In the cyclic loading and unloading process, the load ing and unloading elastic modulus of coal samples experi ences a rapid increase at the beginning stage of the cyclic
During the cyclic loading and unloading process, assuming that there was no energy exchange between the machine and the external environment, the test equipment transferred energy to the sample through mechanical work, part of which was converted into elastic energy stored inside the coal body, and could be completely released during unloading ...
and the Permeability of Coal under Cyclic Loading and Unloading Tianyu Xin, Bing Liang,* Junguang Wang, Weiji Sun, and Yashengnan Sun ... ABSTRACT: In the deep mining process of coal seams, the mechanical environment of the coal body is complex and in the state of cyclic loading and unloading. The change in the stress state leads to the change ...
To study the weakening process, deformation, and failure characteristics of rock masses surrounding deep chambers under complex stress environments, triaxial loading tests along with triaxial loading/unloading followed by uniaxial loading tests were conducted on sandstone specimens. The internal microcracks of the specimens under the loading and unloading of triaxial confining pressure were ...
Both coal mining and tunnel excavation exhibit significant unloading effects, with the process of confining pressure unloading causing damage to coal, thereby affecting coal impact characteristics and gas outburst characteristics. 1820 Based on their investigation, Ding et al. 21 performed a stability assessment study of deep mine dynamic ...
Unloading PRB coal cars with a Dravo rotary dumper
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