层状围岩中管片衬砌受力特征的模型试验研究
Experimental study on behaviors of segment linings in an anisotropically jointed rock mass
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摘要: 深部层状围岩结构强度具有各向异性特点,此类地层中修建盾构隧道,管片衬砌易受偏压作用,对结构安全构成挑战。开展层状围岩与盾构管片衬砌相互作用关系的相似模型试验研究,研究不同层理倾角下管片衬砌壁后围岩压力、管片衬砌内力和变形分布规律。研究结构表明:管片衬砌受力和变形特征受层理面控制明显,管片衬砌受力极不均匀,弯矩、轴力和变形呈现非对称分布;管片衬砌壁后围岩压力最大值集中在强度最弱的层理面法线方向,该方向上管片衬砌的弯矩最大,轴力最小,变形最大;层理倾角对管片衬砌的受力和变形影响显著,层理倾角不仅影响管片衬砌壁后围岩压力分布形状还影响其量值大小;均质地层中,管片衬砌裂缝主要出在封顶块接头处和其他环向接头处,层状地层中管片衬砌裂缝出现位置受接头位置影响减弱,而受层理倾角影响明显,管片衬砌裂缝出现位置主要集中在层理面法向。研究结果对层状围岩中修建盾构隧道的支护结构型式设计具有一定参考价值。Abstract: As the structural strength in the deep layered rock is of anisotropic characteristics, the segment lining is susceptible to unsymmetrical pressure when the shield tunnel is constructed in such formations. Similar model tests are carried out to study the interaction between layered surrounding rock and shield segment lining, and the pressures on the surrounding rock behind the segment lining, internal forces and deformations of the segment lining are investigated. The research results indicate that the stress and deformation characteristics of the segment lining are obviously controlled by bedding plane, the segment lining is pressed very unevenly, and the axial forces, bending moments and deformations exhibit asymmetrical distribution. The maximum pressures on the surrounding rock behind the segment lining are concentrated in the normal direction of the weakest plane, and in this direction, the bending moments of the segment lining are the largest, the axial forces are the smallest and the deformations are the largest. The bedding angle has significant influence on the stress and deformation of the segment lining as well as the distribution and size of pressures on the surrounding rock. In the homogeneous surrounding rock, the fractures of the segment lining are mainly located at the joints of the key segment and other annular joints, while in the layered surrounding rock, the location of fractures of the segment lining is weakened by the influence of the position of joints, and the influence of the bedding dip is obvious. The location of fractures of the segment lining is mainly concentrated in the normal direction of the weakest plane. The results of this study have certain reference value for the design of the supporting structure type of shield tunnels in layered surrounding rock.