偏压顶推工况下管片开裂成因分析及改善措施研究

Study on the Segment Cracking and Its Counter-measure Under Eccentric Jacking Condition

根据福州地铁某区间隧道衬砌管片开裂的现场调研,在MIDAS数值平台上对均压/偏压顶推工况下,衬砌管片的受力状态展开精细化数值模拟,重点关注其第一主应力及轴向变形的分布规律。偏压工况下,偏压区及其对侧区域的轴向位移较均匀,而在偏压区两侧其轴向位移急剧变化;较大的位移差使得偏压两侧区域的管片出现显著的弯曲变形,因此第一主应力在此区域较集中,其峰值已超出混凝土抗拉强度标准值,是裂缝发展的危险区域。

Based on the in-site investigation for the segment cracking in Fuzhou Subway interval tunnel,the numerical simulations for shield uniform/bias jacking conditions are carried out on the MIDAS platform,where the distributions of major principle stress and axial deformation are carefully focused.Under bias jacking conditions,the axial deformations on the bias jacking area and its opposite area are relatively even,whereas the axial deformations on its two lateral areas change sharply. Therefore,the two lateral areas near the bias jacking area are subjected to bending significantly,and the major principle stress is concentrated here and then exceeds the tensile strength of concrete.