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为探明下伏薄煤层采空区地层中隧道施工对地层的扰动以及衬砌结构受荷特性,采用离散元颗粒流软件,从细观角度对隧道开挖引起的地层应力变化特性进行了模拟分析,同时在室内开展模型试验量测了下伏煤层采空区地层隧道衬砌背后土压力以及二次衬砌结构内力(轴力、弯矩),分析了特定围压下间距对土压力和二次衬砌受力的影响。结果表明,下伏煤层采空区地层因隧道开挖引起的围岩松动区呈“O”形分布,隧道下伏围岩颗粒接触力反而小于隧道上覆围岩;洞周允许位移越大,颗粒接触力链间断区域越大;间距越小,颗粒接触力链间断区域越大,当间距大于2.0D(D为隧道跨度)时,下伏采空区对隧道围岩颗粒接触力影响逐渐消失,降低了地基反力,间距越小,降低程度越高;二次衬砌内力分布有一定的离散性,二次衬砌裂缝最先出现在拱底,是隧道主体结构的薄弱环节。
In order to find out the disturbance to the stratum of the tunnel construction and the load characteristics of the lining structure in the stratum of the next thin seam, the discrete element particle flow software was used to simulate the strata stress change characteristics induced by tunnel excavation At the same time, a model test was conducted indoors to measure the earth pressure behind the tunnel lining and the internal force (axial force and bending moment) of the secondary lining in the coal seam mined-out area. The effects of specific confining pressure on the earth pressure and the secondary lining Affected by the force. The results show that the loose zone of surrounding rock due to tunnel excavation in the coal seam gob area is “O” -shaped and the contact force of the surrounding rock under the tunnel is less than the surrounding rock of the tunnel; The larger the contact area is, the larger the contact area is. The smaller the distance is, the larger the discontinuity area is. When the distance is more than 2.0D (D is the span of the tunnel), the influence of the next gob on the contact force of the surrounding rock of the tunnel Gradually disappears, and the foundation reaction force is reduced. The smaller the distance is, the lower the degree is. The internal lining of the secondary lining has a certain degree of dispersion. The secondary lining cracks first appear at the bottom of the arch, which is the weak link in the main structure of the tunnel.