Research on the Mechanical Properties and Energy Evolution of Coal Rock under Triaxial Cyclic Gradient Loading

IF 0.8 4区 工程技术 Q4 CHEMISTRY, MULTIDISCIPLINARY
Minbo Zhang, Shilong Zhang, Chunxin Li, Dangyu Zhang, Cuiling Wang, Yan Jin
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引用次数: 0

Abstract

With the depletion of shallow coal seam resources, deep mining has become a trend, and deep stress makes coal mining in the process of repeated cyclic loading and unloading. In order to study the energy evolution law of mechanical properties of coal and rock under the action of cyclic gradient loading, the RTX-1000 high temperature and high pressure dynamic rock triaxial loading experiment is carried out on coal samples. The changes of residual strain, elastic modulus, input energy density and dissipated energy density of coal and rock under different cyclic gradient loading are compared and analyzed. The results show that with the increase of confining pressure, the number of cyclic gradients of coal and rock samples increases, and the peak strength increases, which are 16.04, 32.04, and 43.92 MPa, respectively, and the axial, radial and volumetric strains have obvious memorability. In the cyclic gradient loading, the residual variable of the coal sample under the same confining pressure decreases sharply and then slowly, and the graph is concave with the number of cycles. Under the same confining pressure and the cyclic loading gradient, the loading elastic modulus is always higher than the unloading elastic modulus, and the elastic mod-ulus of the coal sample gradually decreases under the same cyclic gradient. In the process of cyclic gradient loading, most of the input energy density is stored in the rock sample in the form of elastic strain energy, and the dissipated energy increases between 0.05 and 0.29% of the total input energy in a single cycle, which provides theoretical guidance for deep coal seam mining and roadway support.

Highlights

• The variation law of residual strain and elastic modulus of coal samples under cyclic gradient loading were investigated.

• The stress peaks of coal samples under different confining pressures were 16.04, 32.04, and 43.92 MPa at 5, 8, and 12 MPa, respectively.

• The calculation formulas of input energy density, elastic energy density, plastic energy density and dissipated energy density of coal samples were presented.

• The energy of each part of coal sample under the last cycle gradient was studied with the increase of cycle times, which provides theoretical guidance for deep coal mining and roadway support in reality.

Abstract Image

三轴循环梯度加载下煤岩力学特性及能量演化研究
随着浅层煤层资源的枯竭,深部开采已成为一种趋势,深部应力使煤炭开采处于反复的循环加载和卸载过程中。为了研究循环梯度加载作用下煤岩力学性能的能量演化规律,对煤样进行了RTX-1000型高温高压岩石动态三轴加载试验。对比分析了不同循环梯度荷载作用下煤岩的残余应变、弹性模量、输入能密度和耗散能密度的变化。结果表明:随着围压的增大,煤岩试样的循环梯度次数增多,峰值强度增大,分别为16.04、32.04和43.92 MPa,轴向、径向和体积应变具有明显的记忆性;在循环梯度加载下,相同围压下煤样的残余变量先急剧减小后缓慢减小,且随循环次数的增加呈凹形。在相同围压和循环加载梯度下,煤样加载弹性模量始终高于卸载弹性模量,且在相同循环梯度下,煤样的弹性模量逐渐减小。在循环梯度加载过程中,大部分输入能量密度以弹性应变能的形式存储在岩样中,单次循环耗散能量增加在总输入能量的0.05 ~ 0.29%之间,为深部煤层开采和巷道支护提供理论指导。•研究了循环梯度加载下煤样残余应变和弹性模量的变化规律。•不同围压下煤样在5、8、12 MPa时的应力峰值分别为16.04、32.04、43.92 MPa。•给出了煤样输入能量密度、弹性能量密度、塑性能量密度和耗散能量密度的计算公式。•随着循环次数的增加,研究了最后一个循环梯度下煤样各部分能量的变化规律,为现实中深部煤矿开采和巷道支护提供理论指导。
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来源期刊
Solid Fuel Chemistry
Solid Fuel Chemistry CHEMISTRY, MULTIDISCIPLINARY-ENERGY & FUELS
CiteScore
1.10
自引率
28.60%
发文量
52
审稿时长
6-12 weeks
期刊介绍: The journal publishes theoretical and applied articles on the chemistry and physics of solid fuels and carbonaceous materials. It addresses the composition, structure, and properties of solid fuels. The aim of the published articles is to demonstrate how novel discoveries, developments, and theories may be used in improved analysis and design of new types of fuels, chemicals, and by-products. The journal is particularly concerned with technological aspects of various chemical conversion processes and includes papers related to geochemistry, petrology and systematization of fossil fuels, their beneficiation and preparation for processing, the processes themselves, and the ultimate recovery of the liquid or gaseous end products.
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