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基于室内模型试验,对深圳市南坪快速II期双洞8车道小净距隧道施工中隧道变形分布规律、二衬开裂破坏规律、裂缝集中部位及不同净距条件下二衬的极限承载力变化规律进行了研究。研究结果表明:在不同净距条件下,洞周各部位变形大小的分布情况基本相同,拱顶>右拱肩>左拱肩>仰拱>拱脚;起拱线以上各部位,包括拱顶、左拱肩、右拱肩的变形量,位移随双洞净距的增大而减小;可将12 m(约0.5B)作为IV级围岩下的最小合理净距,净距对起拱线以下各部位变形的影响不明显;最终裂缝集中出现在两洞仰拱和拱脚处,仰拱处裂缝全部贯通,拱脚处裂缝较小,一般不继续发展;远离中柱侧的拱肩也有可能出现贯通裂缝。
Based on the indoor model test, the tunnel deformation, the cracking of the second lining and the change of the ultimate bearing capacity of the two linings under the condition of the concentrated crack site and different clearance are studied. The law was studied. The results show that the distribution of the deformation of the various parts of the cave is basically the same under different clearance conditions, with the arch> the right shoulder> the left shoulder> the arch> the arch; the arch above the arch line, , The deformation and displacement of the left spandrel and right spandrel decreases with the increase of the clearance of the two holes; 12 m (about 0.5B) can be used as the minimum reasonable clearance under the IV grade of surrounding rock, The deformation of the arch below the line is not obvious; the final cracks concentrated in the two holes on the arch and arches at the foot, Yang arch cracks all through the cracks at the arch foot smaller, generally do not continue to develop; away from the arch on the side of the column Shoulder may also appear through the cracks.