砂质地层盾构下穿建筑注浆加固体参数优化

Optimization of Grouting Reinforcement Mass Parameters for Shield Under-passing Buildings in Sandy Stratum

[目的]注浆加固是降低隧道施工对既有建筑物扰动的常用处置措施,工程中应重点关注注浆加固体的参数设计。合理的注浆加固体参数是保障加固效果、降低工程造价的前提,为此有必要结合工程实际对其进行优化分析。[方法]以南宁轨道交通5号线五一立交站—新秀公园站区间隧道工程为例,根据既有建筑与隧道的位置关系对下穿施工进行分类,采用数值计算对注浆加固体横断面参数进行分类优化,并对加固体受力机理进行分析。在施工现场,根据参数优化结果进行注浆加固,以验证加固体参数优化的有效性。[结果及结论]下穿施工可分为3类:隧道正穿建筑;隧道侧穿I型建筑;隧道侧穿II型建筑。隧道正穿建筑时,加固体宜伸入微扰动区约1 m,加固厚度宜为6 m。隧道侧穿建筑时,加固体近隧道侧宜超出建筑4 m,远隧道侧宜伸入微扰动区4 m,加固厚度宜为6 m。加固体受力机理在隧道正穿建筑时可简化为两端锚固梁,侧穿建筑时可简化为悬臂梁。监测结果表明,优化加固体参数能够有效控制建筑变形。

[Objective]Grouting reinforcement is a common measure to reduce disturbance on existing buildings during tunnel construction.It is essential to focus on the design of GRM(grouting reinforcement mass)parameters in the engineering.Appropriate GRM parameters are crucial to ensure reinforcement effectiveness and reduce project costs.Therefore,it is necessary to optimize and analyze these parameters based on practical engineering conditions.[Method]Taking the tunneling project of Wuyi Overpass Station to Xinxiu Park Station interval on Nanning Rail Transit Line 5 as example,the under-passing construction is classified by the position relation between existing buildings and tunnel.Numerical calculations are used to optimize the GRM cross-sectional parameters,and the stress mechanism of the GRM is analyzed.On-site grouting reinforcement is carried out according to the parameter optimization results to validate the effectiveness of GRM parameter optimization.[Result&Conclusion]Under-passing construction is divided into three categories:under-passing directly beneath buildings,side-passing Type I buildings,and side-passing Type II buildings.For the first one,the GRM should extend into the micro-disturbance area by approximately 1 m,with a grouting thickness of 6 m.For the second and third,the GRM should extend approximately 4 m beyond the close tunnel side and penetrate 4 m into the micro-disturbance area on the far tunnel side,with a thickness of 6 m.The stress mechanism of the GRM can be simplified to anchor beams at both ends when under-passing directly beneath buildings and to cantilever beams when side-passing buildings.Monitoring results demonstrate that optimizing the GRM parameters can effectively control building deformation.