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.
WhatsApp: +86 18838072829A scheme of the uniaxial cyclic loading and unloading tests is shown in Fig. 2b. The test process used the displacement control method, and the loading and unloading rate was mm/min, with 6 ...
WhatsApp: +86 18838072829Both coal companies and Railways have envisaged to jointly ensure per day coal loading of 415 rakes of domestic coal and 30 rakes of imported coal to the power sector. 'In the current month ...
WhatsApp: +86 18838072829In this paper, the alternate loading and unloading by stages tests of raw coal samples were carried out by using the "Triaxial seepage test device of thermal fluid solid of coal and rock", the conclusions are as follows: The axial strain change rate ε 1 ′, the radial strain change rate ε 3 ′ and the permeability change rate k′ under unit stress state are used to represent the ...
WhatsApp: +86 18838072829Effect 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
WhatsApp: +86 18838072829The 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.
WhatsApp: +86 18838072829A semicontinuous process system consisting of a singlebucket excavator, truck, crushing station, and belt conveyor is the main coal mining process system of a largescale hard coal openpit mine. Through analyzing the coal mining production process, the key issues of coal mining truck flow optimization are obtained. Statistical method of using triangular fuzzy numbers analyzes the key time ...
WhatsApp: +86 18838072829Coal mining leads to stress loadingunloading variation in front of the working face, which influences the occurrence of disasters. In order to study the influence mechanism of stress loadingunloading to the coal failure, a series of experiments of gasbearing coal deformation and failure under triaxial stress were conducted and acoustic emission (AE) was monitored.
WhatsApp: +86 18838072829During the process of underground mining, roadway excavation and heading face cause the surrounding rock to produce stress disturbance and break the equilibrium state of coal and rock, which is usually manifested as axial loading and confining pressure unloading. This phenomenon is more obvious during the deep mining of coal and rock.
WhatsApp: +86 18838072829A new energydissipation method to identify crack initiation and propagation thresholds is introduced. Conventional and cyclic loadingunloading triaxial compression tests and acoustic emission experiments were performed for coal specimens from a 980m deep mine with different confining pressures of 10, 15, 20, 25, 30, and 35 MPa. Stressstrain relations, acoustic emission patterns, and ...
WhatsApp: +86 18838072829The 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 ...
WhatsApp: +86 18838072829True 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 ...
WhatsApp: +86 18838072829Coal isn't carrying the burden for other commodities anywhere except on the subdivisions that are almost nothing but coal. At present, coal supplies % of electricity, nuclear %, natural gas %, oil %, hydro %, and other sources (mostly biomass, but also wind, geothermal, and solar) about %.
WhatsApp: +86 18838072829The process of rock cycle loading and unloading results in the external force constantly performing work on the specimen. The external force is converted into elastic strain and dissipation energy. Using the principles of thermodynamics, energy transformation is the essential process by which the energy state of the specimen changes, as ...
WhatsApp: +86 18838072829The repeated mining causes the unloading and loading of the caved zone, so that the pore structures of caved zone change accordingly, and thus affect the permeability value, which controls the gas migration in the caved zone. The main factors affecting the permeability of the unloading process are different from those controlling it during loading.
WhatsApp: +86 18838072829Load 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
WhatsApp: +86 18838072829The working process of the underground coal bunker was actually the loading or unloading of coal for the silo wall. And the stress environment of the silo wall and surrounding rock continually changes, resulting in the deformation of the silo wall under the inner lateral pressure. Stress Analysis
WhatsApp: +86 18838072829Given the roadway deformation and surrounding rock control in the process of thin coal seam mining, the coalrock combination with inclination angles for 0°, 15°, 30°, 45°, and 60° was designed. The rock mechanic test machine was used to conduct a uniaxial compression test and a graded loading and unloading test on the coalrock combination; the failure characteristics of the two were ...
WhatsApp: +86 18838072829To 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 ...
WhatsApp: +86 18838072829During the loading/unloading process, the gas pressure in the coal sample is maintained constant through the ingenious structure design of the system. As shown in Fig. 2 b, the constantvolume chamber is connected to the sample by a gas tube, and the constantvolume pistons are connected to the axial indenter.
WhatsApp: +86 18838072829The residual strains has produced by the first loadingunloading of coal are 7 × 10 −5, × 10 −4, and × 10 −4, respectively. ... However, if the loadingunloading process was continued beyond this point, the residual strain reappeared. The occurrence of the nonresidual strain phenomenon was found to be directly related to the ...
WhatsApp: +86 18838072829The D s characterizes the effect of a single loadingunloading cycle on a coal body permeability transformation. During the stress unloading process, the pore spaces in a coal body expand after it is unloaded from the highstress environment. The original fractures in a coal sample reopen during the effective stress reduction.
WhatsApp: +86 18838072829In the process of coal formation, the internal structure is different from the occurrence of primary cracks. As a result, the new crack generation and primary crack development of different samples are affected to different degrees during loading and unloading. Energy characteristics under true triaxial loading and unloading
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