中文摘要：

利用单圆大直径盾构隧道扩建地铁车站时，采用了预先分为3块的分块型K管片。为了研究分块型K管片接触面的力学性能，按照接触面保留原型、边界由弧形简化为矩形的原则制作试件，在实验室进行加载试验。试验结果表明：当组合荷载达到一定值时，分块间接触面达到滑移临界点，此时接触面问的摩擦由静摩擦变为滑动摩擦，接触面间产生相对位移，混凝土和螺栓的应变陡增，螺栓被卡住。结合试验建立试件的三维几何非线性接触数值模型，对接触面达到滑移临界点时的组合荷载进行模拟分析，得到分块型K管片不同材料接触面的临界轴力弯矩组合包络线，用以判断不同轴力弯矩组合对分块型K管片结构稳定性的影响，为扩挖车站结构的设计与施工提供理论指导和参考。

英文摘要：

The partitioned key segment, which is divided into 3 blocks in advance, is applied to the con- struction for enlarging subway station with single circle large-diameter shield tunnel. For studying the me- chanical properties about the interface on partitioned key segment, the specimens are made following the principles that the interface retains prototype and the boundary is simplified from arc to rectangle. The loading test is carried through in laboratory. According to test results, when the combined load reaches a certain value, the interface between blocks will reach the sliding critical point. By this time, the frictions between interfaces change from static friction into sliding friction. The relative displacement between inter- faces occurs. The strain of concrete and bolts are increased sharply, and at the same time the bolts are stuck. Combined with tests, 3D geometrical nonlinear contact numerical model of specimen is built for the simulation analysis of the combined loads when the interface reaches the sliding critical point. The critical axial force and moment envelope curves of the interfaces with different materials for partitioned key seg- ment can be obtained, which can be used to determine the effect of different combined axial force and mo- ment on the structural stability of partitioned key segment. It provides the theoretical guidance and refer- ence for the design and construction of enlarging subway structure.