盾构超近距离穿越大型立交桩基群影响研究

针对砂卵石地层中盾构隧道超近距离穿越大型立交桩基群工程特点,为确定设计方案的可行性、保证盾构施工中的桥梁安全,采用FLAC3D三维快速拉格朗日差分方法分析软件对盾构穿越桩基群进行了数值模拟,分别对桩基群加固前后的沉降和应力等进行了分析,并通过理论计算分析了盾构隧道塌落拱高度范围内土体松弛对桩基产生负摩阻力的影响,验算了桩基承载力,为满足桩基沉降变形和承载力要求,提出了注浆加固的处理措施,相应地给出了注浆的加固范围,并制定了施工应急预案。计算结果表明:桩基群经过土体加固后,可有效地减小盾构掘进造成的地层损失,立交桥的沉降、桩基承载力及结构应力均满足安全要求。

Research on the Influences of Shield Closely Passing through the Pile Foundations of Large Interchange

In this paper, numerical simulation of shields stretching into the foundations was conducted by the software FLAC3D, including the analysis of the settlement and stress of the foundations before and after strengthening, for the characteristics of shields closely driving by the foundations of large interchange in sandy cobble stratum, and in order to ensure the feasibility of the design schemes and the security in the process of shield construction. Moreover, through calculation, this thesis analyzes the influence of the negative friction force caused by soil slack within the highest range of ground arch. In order to meet the requirement of settlement and bearing capacity, the thesis validates the pile bearing capacity, poses the measure of grouting reinforcement, presents the scope of grouting consolidation and makes the safety emergency preplan of common accidents. The calculation result indicates that it can effectively lighten the ground loss and setting of overpass bridges, and moreover, the bearing capacity and structure stress all meet the safety requirement.