千斤顶作用下带榫管片的裂纹扩展规律

Crack Propagation Law of Segment Tendon under Jacking Forces

针对盾构隧道施工过程中带榫管片易出现裂纹及局部破损的现象,运用ABAQUS中的扩展有限单元法,建立了标准带榫管片的数值模型,并针对管片受力不均、千斤顶加压不同步和千斤顶偏心荷载3种不良施工荷载情况下的12个具体工况,对施工过程中带榫管片裂纹初始开裂位置、扩展方向及裂纹空间分布规律等进行了系统分析.研究结果表明:不良施工荷载是带榫管片产生裂纹的主要因素,荷载大的位置易产生裂纹,千斤顶先接触部位易产生裂纹;带榫管片凸榫端中部较两端易产生裂纹,带榫管片内弧面较外弧面更易产生裂纹;3种不良施工荷载对带榫管片的损害程度由强到弱依次为千斤顶偏心荷载、千斤顶加压不同步和管片受力不均.

To explore the cracking and local damage of tenon segment that easily occurs during the construction of shield-driven tunnels, a model of standard tenon segment was built using the extend finite element method （XFEM） with ABAQUS. The initiation location, propagation direction and distribution of segment cracks were analyzed in a dozen of working conditions including non-uniform jacking forces, asynchronous jacking and eccentric jacking loads. Numerical results indicate that bad construction load is the main cause of cracks. Areas burden with large loads and that the jacks first contact are liable to crack. Cracks are easier to initiate and propagate at the central area of the top surface of segment than at both ends, and at the intrados than at outer surface. Three factors, if sorted in a descending order by their damage severity to a tenon segment, are eccentric jacking loads, asynchronous jacking and non-uniform jacking forces.