盾构隧道60°斜穿地裂缝的变形破坏机制试验研究

 从西安地铁盾构隧道工程背景和西安地裂缝地质环境出发，根据相似理论设计盾构隧道管片衬砌结构60°斜穿地裂缝的物理模型试验。管片混凝土应变、纵向和环向螺栓应变、结构接触土压力和结构外围土压力、结构内部收敛位移、模型顶表面土体变形以及宏观变形破坏现象表明，盾构隧道管片衬砌结构60°斜穿地裂缝的变形破坏模式以剪切变形为主，局部有扭转和弯曲变形；结构破坏范围为上盘0.75D(D为管片环外径1.20 m)，下盘0.50D；管片混凝土破坏主要发生在螺栓孔附近，地裂缝处纵向螺栓发生较强的剪切、扭转和拉伸变形破坏；管片衬砌结构变形破坏不对称，管片环向处于偏压状态；环缝拱顶错位量大于拱底和拱腰，拱顶最大错位量达30 mm(0.025D)，模型难以适用地裂缝错动变形20 cm(0.166 7D)，盾构管片衬砌结构不适用于地裂缝活动强烈的地质环境。

MODELING TEST RESEARCH ON FAILURE MECHANISM OF SHIELD TUNNEL CROSSING GROUND FISSURE WITH 60°

Based on the background of Xi'an metro shield tunnel engineering and the geological environment of Xi'anan ground fissure,the physical modeling of segment lining structure experiment of shield tunnel crossing the ground fissure with 60° is designed according to similarity theory. The strains of segment concrete of longitudinal bolt and circumferential bolt,the contact soil pressure and peripheral soil pressure,the convergence displacement of segment lining,the soil settlement on the top of model and other macrophenomena all show that the main deformation and damage of segment lining structures of shield tunnel crossing the ground fissure with 60° are of shearing with local distortion and bending. The deformation and damage range are from 0.75D(D is the external diameter of segment ring) in the hanging side to 0.50D in the lying side. The distribution of concrete crack is near the bolt hole;and the deformation of longitudinal bolt near ground fissure is of shearing first with distortion and tension. The deformation and damage of segment ring are asymmetric and partial compression;and the dislocation of circumferential seam on the crown which is up to 30 mm(0.025D) is bigger than those of soffit and arch waist. It is difficult for the segment lining to undergo the deformation 20 cm(0.166 7D) of ground fissure;and the segment lining structure of shield tunnel is unsuitable for the geological environment with violent activity of ground fissure.