Wang Yan, Liu Haoran, Feng Shuo
School of Civil Engineering, Qingdao University of Technology, Qingdao, 266520, Shandong, China.
Sci Rep. 2024 Oct 23;14(1):25050. doi: 10.1038/s41598-024-77197-w.
To understand the mechanical properties and deformation failure patterns of coal pillar dams in gently inclined coal seam mine underground reservoirs, compression-shear coupling tests with variable angles were conducted on coal pillar dam samples under different saturation states. The digital image correlation (DIC) technique was utilized to obtain the deformation patterns of the displacement field throughout the compression-shear failure process of the samples. Numerical simulations were used to perform a comparative analysis and validation of the experimental results. The results indicated that the load-bearing capacity of the coal pillar dam samples decreased by 12.8-17.4% under water-saturated conditions. For every 5° increase in the inclination angle, the load-bearing capacity of the coal pillar dam samples decreased by an average of 3.53%. The normal stress and shear stress on the shear surface of the saturated samples were both lower than those of the natural samples, and both exhibited a linear variation with increasing inclination angle. The deformation evolution of the coal pillar dam samples under different test conditions exhibited similarity. The initial positive and negative displacement extremities in the horizontal direction were located at the lower right and upper left corners of the samples, respectively. Ultimately, the displacement field of the samples showed a pattern of smaller displacements at the top and larger displacements at the bottom, with negative values at the top and positive values at the bottom, distributed along the direction of the sample's bedding. The saturated state and the increase in inclination both had a weakening effect on the load-bearing performance of the samples but had a relatively small impact on the differences in the displacement field deformation patterns. The research results can provide a reference for the study of the stability of coal pillar dams under similar conditions.
为了解缓倾斜煤层矿井地下水库煤柱坝体的力学特性及变形破坏模式，对不同饱和状态下的煤柱坝体试样进行了变角度压剪耦合试验。利用数字图像相关（DIC）技术获取试样在压剪破坏全过程中的位移场变形模式。采用数值模拟对试验结果进行对比分析与验证。结果表明，在饱水条件下，煤柱坝体试样的承载能力下降了12.8% - 17.4%。倾斜角度每增加5°，煤柱坝体试样的承载能力平均下降3.53%。饱和试样剪切面上的正应力和剪应力均低于天然试样，且均随倾斜角度的增加呈线性变化。不同试验条件下煤柱坝体试样的变形演化具有相似性。水平方向上初始的正负位移极值分别位于试样的右下角和左上角。最终，试样的位移场呈现出顶部位移小、底部位移大的模式，顶部为负值，底部为正值，沿试样层面方向分布。饱和状态和倾斜角度的增加均对试样的承载性能有削弱作用，但对位移场变形模式的差异影响相对较小。研究结果可为类似条件下煤柱坝体稳定性研究提供参考。
