铁路桥梁桩基补桩后受力性能研究

Research on the Mechanical Performance of Railway Bridge Pile Foundation After Adding Piles

旧桥改造在桥梁工程中应用越来越广泛,当新建线路与既有线路在平台上有较小移动时,将既有线路上的梁体移至新建线路上是我国既有铁路桥梁改扩建工程中常见的施工方法之一。为满足支撑梁体的要求,工程中常采用桩基补桩和承台帮宽的措施。补桩引发新老桩基及土体间相互作用,需对补桩后桩基的受力性能进行研究。故通过理论计算和数值模拟分析了补桩前后桩基的受力性能。结果表明:补桩后单桩极限承载力有所下降,约为补桩前的90%;增补2根桩后,桩基承载力约提高20%;在同等侧向荷载下,补桩后边桩和中桩的最大弯矩较补桩前分别减小了13.23%和12.50%,补桩后边桩和中桩的最大侧向变形较补桩前分别下降了6.30%和7.19%。

Renovation of old bridges has been becoming more and more common in bridge engineering.When there is smaller movement between the new lines and the existing lines on the platform,moving the beams on the existing line to the new line is one of the most important tasks in the reconstruction and expansion projects of existing railway bridges in China.In order to meet the requirements of supporting the beam,the common construction methods is adding piles and widening piles.Adding pile causes the problem of interaction between old and new piles and soil so that it is necessary to study the mechanical properties of pile after adding pile.The mechanical performance of piles foundations was analyzed before and after pile adding through theoretical calculations and numerical simulations.The results show that,the bearing capacity of a single pile has decreased,which is about 90%of the one before adding pilesafter adding piles;After adding two pile foundations,the bearing capacity of the pile group has increased by about 20%;Under the same lateral load,the maximum bending moment of the side pile and the middle pile has reduced by13.23%and 12.50%respectively after adding pile;And the maximum lateral displacement of the side pile and the middle pile has reduced by 6.30%and 7.19%respectively.