真三轴条件下原煤的动态应变率效应和宏观-微观断裂机理

IF 4.8 2区 地球科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY
Li Zhang, Yubing Liu, Enyuan Wang, Dong Chen, Xiaoran Wang
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引用次数: 0

摘要

煤和岩体在复杂应力状态下的应力波传播和能量演化对深部资源的高效开采以及动态灾害的预防和管理具有重要意义。为了研究真三轴条件下原煤中应力波的传播特征和能量耗散,本研究采用了自制的真三轴分体式霍普金森压杆试验系统和扫描电子显微镜。对原煤样品进行了动态和静态组合冲击试验。研究结果表明,真三轴预应力下的σ2和σ3增强了样品的阻力,促进了应力波的传播,但阻碍了能量转换。σ2和σ3都会增强传递应力和应变,从样品 tr#1 中的 11.0 兆帕和 0.53 × 10-4 增加到样品 tr#5 中的 16.3 兆帕和 0.78 × 10-4。在入射能量中,反射能量所占比例最大,其次是耗散能量,传输能量最小。此外,在试样 tr#2(中间主应力的初始增加阶段)和试样 tr#4(最小主应力的初始增加阶段)中观察到了能量比变化率的两个拐点。应力波的频谱表现为先上升后下降,反射波频谱的峰值比透射波的峰值大一个数量级。透射波频谱达到峰值点和静止阶段的频率较低。在 σ2 和 σ3 的影响下,样品的宏观破坏程度呈现逐渐减弱的趋势。微裂纹断裂形态由河流状裂纹转变为阶梯状裂纹,最终形成人字形宏观断裂,表明煤体在应力波作用下的破坏归因于脆性断裂。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Dynamic Strain Rate Effect and Macro–Micro-Fracture Mechanism of Raw Coal Under True Triaxial Conditions

Dynamic Strain Rate Effect and Macro–Micro-Fracture Mechanism of Raw Coal Under True Triaxial Conditions

The stress wave propagation and energy evolution of coal and rock masses under complex stress states hold significant implications for the efficient extraction of deep resources and the prevention and management of dynamic disasters. To investigate the propagation characteristics of stress waves and the energy dissipation in raw coal under true triaxial conditions, this study employed the self-constructed true triaxial split Hopkinson pressure bar test system in conjunction with a scanning electron microscope. Dynamic and static combined impact tests were conducted on raw coal samples. The findings indicate that σ2 and σ3 under true triaxial prestress strengthen the sample's resistance, facilitating stress wave propagation but hampering energy conversion. Both σ2 and σ3 enhance transmission stress and strain, increasing from 11.0 MPa and 0.53 × 10−4 in sample tr#1 to 16.3 MPa and 0.78 × 10−4 in sample tr#5. Reflected energy constitutes the largest proportion of incident energy, followed by dissipation energy, with transmission energy being the smallest. Moreover, two inflection points in the change rate of energy ratio were observed in sample tr#2 (initial increase stage of intermediate principal stress) and sample tr#4 (initial increase stage of minimum principal stress). The spectrum of the stress wave exhibited an initial increase followed by a decrease, and the peak value of the reflected wave spectrum was an order of magnitude greater than that of the transmission wave. The frequency at which the transmission wave spectrum reached the peak point and the stationary phase was lower. The macroscopic failure degree of the sample exhibited a gradual weakening trend under the influence of σ2 and σ3. The micro-crack fracture pattern shifted from river-like cracks to steplike cracks, eventually forming herringbone macroscopic fractures, indicating that the coal body failure under stress waves was attributed to brittle fracture.

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来源期刊
Natural Resources Research
Natural Resources Research Environmental Science-General Environmental Science
CiteScore
11.90
自引率
11.10%
发文量
151
期刊介绍: This journal publishes quantitative studies of natural (mainly but not limited to mineral) resources exploration, evaluation and exploitation, including environmental and risk-related aspects. Typical articles use geoscientific data or analyses to assess, test, or compare resource-related aspects. NRR covers a wide variety of resources including minerals, coal, hydrocarbon, geothermal, water, and vegetation. Case studies are welcome.
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