关键词: 近距离煤层, 区段煤柱, 应力传递特征, 相似材料模型试验, DIC技术

Abstract: Exploring the characteristics of concentrated stress transfer from coal pillars to the floor in the close distance coal seams plays an important guiding role in determining the control method of roadway surrounding rock. Selecting a typical close range coal seam in Duerping Mine, in Shanxi Province as a prototype, building a 100:1 similar material test model, and conducting excavation simulation tests on both sides of the coal pillar in the upper coal seam section. Using DIC technology to collect vertical, horizontal, and shear strains at different levels of the upper coal seam floor depth, and analyzing the distribution characteristics of the three strains and the variation pattern of the horizontal distance between the strain peak and the coal pillar boundary, Exploring the transmission characteristics of concentrated stress in the coal pillar of the upper coal seam to the floor after mining.The results show that: (1) In the coal pillar floor area, the three strains with the coal pillar center as the axis are all asymmetric Multimodal distribution distribution characteristics, and the strain peak values are different. The vertical and shear strain peak values are that the coal pillar side of the first excavation face is smaller than the coal pillar side of the later excavation face, while the horizontal strain peak values are that the coal pillar side of the first excavation face is larger than the coal pillar side of the later excavation face, and the three strain peak values decrease with the increase of the floor depth; The vertical and shear strains of the goaf floor, far from the boundary of the coal pillar in the section, gradually tend to zero, while the horizontal strain shows a constantly changing feature of increasing and decreasing. (2) The horizontal distance between the three types of strain peaks and the boundary of the coal pillar: the vertical strain is greater on the coal pillar side of the excavation face first than on the coal pillar side of the excavation face later, while the shear strain is exactly the opposite. The horizontal strain is equal on the coal pillar side of the excavation face successively, and the horizontal distance between the three types of strains and the boundary of the coal pillar increases as the depth of the bottom plate increases. (3) In the bottom plate area of the coal pillar, the vertical stress is compressive stress, while the horizontal stress is tensile stress, while the shear stress is tensile stress on the first mining face side and compressive stress on the second mining face side. Both vertical and shear stresses show high stress levels, but the horizontal stress is very small. The peak values of vertical and horizontal stress are located in the coal pillar floor area, while the peak values of shear stress are located in the goaf floor area. The vertical and shear stresses on the bottom of the goaf tend to be zero far from the boundary of the coal pillar, while the horizontal stress shows a characteristic of repeated transformation and increase and decrease. (4) The determination of the stability control method for the surrounding rock of close distance coal seam roadways should not only pay attention to the role of vertical stress, but also pay attention to the influence of shear stress on its instability and failure.