紧邻地铁的深厚回填区深基坑支护方案对轨道的影响研究

Research on Influence of Support Scheme for Deep Foundation Pit on Metro Track in Deep Backfill Area Adjacent to Metro

重庆地区以山地、丘陵地形地貌为主,城市建设过程中市区内形成了很多深厚回填区。回填土性质差异大,抗剪和承载力指标低,在邻近地铁结构的深厚回填区进行深基坑开挖,将大大增加工程难度。该文以重庆轨道十号线某段明挖区间邻近的基坑工程为案例,针对该工程提出了改善回填土力学指标的注浆加固方案以及多种基坑支护方案,运用现场试验验证注浆加固效果,采用二维三维数值模拟方法结合现场监测成果,分析研究该支护方案下某基坑开挖项目对轨道结构的影响,证实了该支护方案的有效性,确保了轨道结构的安全,减小了工程风险。

Dominated by mountainous and hilly landforms,Chongqing has numerous deep backfill areas in the urban area during the urban construction process.The backfill soil shows remarkable differences in properties,with low shear and bearing capacity indicators,posing great difficulties to dip foundation pit excavation in the deep backfill area adjacent to a metro track.Based on the foundation pit project adjacent to an open cut section of Chongqing Rail Line 10,this paper presented a grouting reinforcement scheme for the improvement of the backfill soil’s mechanics index and a variety of foundation pit support schemes,verified the grouting reinforcement effect through field experiments,and employed 2D and 3D numerical simulation methods,along with field monitoring results,to analyze and study the impact of the foundation pit excavation on the track structure under this support scheme,which confirmed the effectiveness of the support scheme,ensured the safety of the track structure,and reduced engineering risks.