近距侧穿高铁桥桩盾构施工影响规律及加固措施

依托西安地铁14号线盾构侧穿大西高速铁路特大桥群桩基础工程，采用三维有限元数值模拟、结合现场监测，对盾构施工近距离穿越超长群桩的影响及加固方案进行了研究。研究结果表明：盾构施工过程引的起前排桩桩体位移变化大于后排桩，竖向位移均为负值，且桩底沉降均大于桩顶，水平位移变化主要在隧道所在深度及以上区域，桩体最大弯矩和轴力均出现在隧道拱顶对应位置；无隔断、加固措施的工况下，桥台沉降最大值为4.19 mm，超过控制指标；提出的三种加固方案效果呈现以下规律：袖阀管注浆加固<钻孔灌注桩隔断<注浆+隔断桩+钢横撑综合加固，采用综合加固方案对桩身位移、内力优化效果最优，水平、竖向位移及轴力、弯矩分别减小65%、20%、80%、50%，并且桥台沉降最大值为1.47 mm，满足控制指标。

Influence of Shield Construction of Pile Foundation for High-speed Railway Bridge in Short

Based on Xi ''an Metro Line 14 Shield Crossroads Daxi High-speed Railway Extraordinary Bridge Pile Group Foundation Project, 3D numerical simulation and field monitoring are adopted. In this paper, the influence of shield tunnel construction through super-long pile group in short distance and the reinforcement scheme are studied. The results show that the displacement change of the front pile is greater than that of the back pile, the vertical displacement is negative, and the settlement of the bottom pile is greater than that of the top pile. The horizontal displacement changes mainly in the tunnel depth and above, and the maximum bending moment and axial force of the pile appear in the corresponding position of the tunnel vault. Under the working condition without partition and reinforcement measures, the maximum abutment settlement is 4.19mm, which exceeds the control index. The effects of the three proposed reinforcement schemes show the following rules: Sleeved valve pipe grouting reinforcement < borehole cast-in-place pile partition < grouting + partition pile + steel transverse support comprehensive reinforcement, the comprehensive reinforcement scheme has the best effect on pile displacement and internal force optimization, horizontal and vertical displacement, axial force and bending moment are reduced by 65%, 20%, 80% and 50% respectively, and the maximum abutment settlement is 1.47mm, meeting the control indicators.