基于大直径盾构隧道扩挖地铁车站的结构方案及其关键节点受力和变形

针对北京地铁14号线将台车站结构方案存在的不足,提出1种基于大直径盾构隧道扩挖地铁车站的塔柱式结构方案,并建立三维非连续接触模型,研究塔柱式结构关键节点的受力和变形。结果表明:盾构隧道和车站2边主体结构的施工,对管片纵缝的张开和错台影响显著,但对管片环间错台影响不明显;横通道施工对管片纵缝的张开和错台影响较小,开口环管片的环间错台不明显,但塔柱环和开口环管片的环间错台急剧增加,最大错台量为2.73 mm;管片接头压应力在扩挖施工阶段均明显增大,尤其在横通道施工阶段,由于部分管片的拆除,塔柱环管片的拱腰处节点压应力剧增,最大值为19.31 MPa;管片和现浇混凝土连接节点的张开和错台均不明显,此类节点压应力小于塔柱环管片相同位置节点的压应力;管片接缝面的剪轴比均大于摩擦系数0.5,但管片接头斜直螺栓的轴向拉力均小于其所能承受的最大抗拉荷载,满足抗拉强度要求。

Structural Scheme of Metro Station Constructed by Enlarging Large Diameter Shield Tunnel and Stress and Deformation of Its Key Joints

The shortcomings of the structural scheme of Jiangtai Station of Beijing Metro Line 14 were analyzed.A tower-column structural scheme of a metro station constructed by enlarging large diameter shield tunnel was proposed.A three-dimensional discontinuous contact model was established to study the stress and deformation of the key joints of tower-column structure.Results show that the construction of the main structures on both sides of shield tunnel and station has significant influence on the opening and dislocation of segment longitudinal joints,but has no obvious influence on the dislocation between the joints of segment rings.The construction of cross passages has little influence on the opening and dislocation of segment longitudinal joints,and the dislocation of ring joints between split ring segments is not obvious.But the dislocation of ring joints between tower-column ring segments and split ring segments increases sharply,and the maximum dislocation value is 2.73 mm.The compressive stress of segment joints increases obviously in the construction stage of expanding excavation,especially in the construction stage of cross passage.Due to the removal of some segments,the compressive stress of joints at the arch waist of tower-column ring segments increases sharply,and the maximum value is 19.31 MPa.The opening and dislocation of the joints between segments and cast-insitu concrete are not obvious,and the compressive stresses of such joints are also smaller than those of the joints at the same position of tower-column ring segments.Although the shear-axial ratio of the segment joint surface is greater than the friction coefficient of 0.5,the axial tensions of inclined/straight bolts of segment joints are less than the maximum tensile load they can bear,which meets the tensile strength requirements.