王卫军,马谕杰,范磊,等. 双向极不等压软岩巷道围岩裂隙分布及变形机制[J]. 煤炭学报,2024,49(7):1−13. doi: 10.13225/j.cnki.jccs.2023.0913
引用本文: 王卫军,马谕杰,范磊,等. 双向极不等压软岩巷道围岩裂隙分布及变形机制[J]. 煤炭学报,2024,49(7):1−13. doi: 10.13225/j.cnki.jccs.2023.0913
WANG Weijun,MA Yujie,FAN Lei,et al. Fracture distribution and deformation mechanism of surrounding rock in two-way extremely unequal pressure soft rock roadway[J]. Journal of China Coal Society,2024,49(7):1−13. doi: 10.13225/j.cnki.jccs.2023.0913
Citation: WANG Weijun,MA Yujie,FAN Lei,et al. Fracture distribution and deformation mechanism of surrounding rock in two-way extremely unequal pressure soft rock roadway[J]. Journal of China Coal Society,2024,49(7):1−13. doi: 10.13225/j.cnki.jccs.2023.0913

双向极不等压软岩巷道围岩裂隙分布及变形机制

Fracture distribution and deformation mechanism of surrounding rock in two-way extremely unequal pressure soft rock roadway

  • 摘要: 巷道围岩蝶形塑性区破坏是引起巷道围岩大变形的重要原因,近年来引起了巷道支护工作者的高度重视。掌握蝶形塑性区内围岩变形机制是实现软岩巷道围岩控制的基础。然而,有关于蝶形破坏理论中围岩变形机制的研究却鲜有报道。针对上述问题,以南方某矿一采区南运巷产生的大变形特征为研究对象,在分析巷道所处应力环境及地质条件的基础上,对围岩裂隙分布、巷道变形机制及控制方法进行了系统研究。结果表明:南运巷是典型的极不等压软岩巷道,巷道开挖后,围岩裂隙呈“蝶形”分布;“蝶形裂隙区”集中出现在“蝶形塑性区”范围内,蝶叶部位围岩裂隙以剪切裂隙为主,且蝶叶部位剪切裂隙大多围绕巷道呈“环形”分布,而张拉裂隙则集中出现在巷道围岩自由面附近。蝶形塑性区内围岩应力特征主要有2方面:一为围岩的主应力方向发生了偏转,具体表现为最大主应力围绕巷道呈环形分布,巷道上部最小主应力方向指向巷道中心,巷道下部最小主应力方向背离巷道中心;二为围岩最大/最小主应力比值较大,且主应力比值等值线呈“蝶形”分布。根据塑性区内围岩裂隙分布特点及应力特征,建立了含软弱面围岩力学剪胀模型,认为处于此应力特征下的围岩剪胀作用较强,剪胀作用使围岩向巷道空间内挤压,进而使巷道产生大变形。围岩裂隙分布不规则及原支护方案不合理是导致巷道产生大变形的主要原因。基于上述研究,提出了以“全断面预应力短锚索+关键部位长锚索加强支护+注浆”为核心的差异化支护方案,现场监测表明,新支护方案可有效控制围岩变形,保证巷道在使用期间的稳定性。

     

    Abstract: The failure of butterfly plastic zone in roadway surrounding rock is an important reason for the large deformation of roadway surrounding rock.In recent years, it has attracted the attention of roadway support workers.Mastering the deformation mechanism of surrounding rock in butterfly plastic zone is the basis for realizing the control of surrounding rock in soft rock roadway. However, there are few reports on the deformation mechanism of surrounding rock in butterfly failure theory. In view of the above problems, the large deformation characteristics of the south transport roadway in a mining area of a mine in the south are taken as the research object. Based on the analysis of the stress environment and geological conditions of the roadway, the distribution of surrounding rock cracks, the deformation mechanism and control methods of the roadway are systematically studied.The results show that the Nanyun roadway is a typical extremely unequal pressure soft rock roadway. After the excavation of the roadway, the surrounding rock cracks are distributed in a ‘butterfly’ shape. The ‘butterfly fracture zone’ is concentrated in the ‘butterfly plastic zone’. The fractures of the surrounding rock at the butterfly leaf are mainly shear fractures, and the shear fractures at the butterfly leaf are mostly distributed around the roadway in a ‘ring’ distribution, while the tensile fractures are concentrated near the free surface of the surrounding rock of the roadway. There are two main aspects of the stress characteristics of the surrounding rock in the butterfly plastic zone. One is the deflection of the principal stress direction of the surrounding rock, which is manifested in the annular distribution of the maximum principal stress around the roadway. The direction of the minimum principal stress in the upper part of the roadway points to the center of the roadway, and the direction of the minimum principal stress in the lower part of the roadway deviates from the center of the roadway. The second is that the maximum / minimum principal stress ratio of the surrounding rock is large, and the principal stress ratio contour is ‘butterfly’ distributed. According to the distribution characteristics and stress characteristics of surrounding rock cracks in plastic zone, the mechanical dilatancy model of surrounding rock with weak surface is established. It is considered that the dilatancy effect of surrounding rock under this stress characteristic is strong, and the dilatancy effect makes the surrounding rock squeeze into the roadway space, which makes the roadway produce large deformation. The irregular distribution of surrounding rock fissures and the unreasonable original support scheme are the main reasons for the large deformation of the roadway. The study mentioned above is used to suggest a differentiated support system, the heart of which is ‘full-section prestressed short anchor cable + key part long anchor cable strengthening support + grouting’. Field observation demonstrates that the revised support plan can successfully manage the surrounding rock’s deformation and guarantee the stability of the road while it is in operation.

     

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