城市地下通道交叉中隔墙法超前支护小导管的参数优化分析

Optimization Analysis of Advance Support Small Pipe Parameters for Urban Underground Passage CRD Method Construction

目的:隧道开挖前的超前支护是采用交叉中隔墙法施工的关键一环,研究交叉中隔墙法超前支护的小导管在不同支护参数下施工对围岩产生的变形和应力影响,能根据现场实际更好地调整超前支护的效果。方法:以连接大连恒隆广场与大连地铁2号线人民广场站的地下通道为工程背景,将施工现场数据结合理论分析和MIDAS GTS有限元软件数值模拟试验;将地下通道开挖过程中产生的拱顶下沉、水平收敛、地面沉降作为分析指标,以小导管的外插角、导管长度、环向间距作为研究对象。对比分析多种小导管参数组合对围岩的支护效果,从中选取优化后的小导管参数进行数值模拟分析。结果及结论:现场监测的数据与数值模拟的结果拟合表明,超前支护效果主要与小导管的管长和外插角相关,通过调整小导管的长度和外墙角可以有效增强支护效果;环向间距对超前支护的效果不明显,应根据小导管的注浆半径来确认环形间距。通过对小导管参数的调整可以有效地提高对围岩的支护效力,保障地下人行通道的运营安全和施工效率。

Objective:The AS(advance support)before tunnel excavation is a key link in CRD(center cross diagram)method construction.The deformation and stress of surrounding rock under influence of different supporting parameters of CRD method AS small pipes are studied,to better enhance the AS effect according to the actual site conditions.Method:The underground passage connecting Dalian Henglong Plaza and Dalian Metro Line 2 People′s Square Station is taken as engineering background,and the construction site data is combined with theoretical analysis and MIDAS GTS finite element software numerical simulation test;the vault subsidence,horizontal convergence and land subsidence during underground passage excavation are taken as analysis indexes,and the external insertion angle,pipe length and circumferential distance of small pipes are studied.The support effect of various small pipe parameter combinations on surrounding rock is compared and analyzed.Optimized small pipe parameters are selected for numerical simulation.The fitting of field monitoring data and numerical simulation results show that the advance support effect is mainly related to the pipe length and external insertion angle of the small pipes,adjustment to the above factors can effectively enhance the support effect;as the effect of circumferential spacing on AS is not obvious,the circumferential spacing should be determined according to the grouting radius of small pipes.Result&Conclusion:By adjusting the parameters of the small pipes,the effectiveness of supporting surrounding rock can be evidently improved,ensuring the operation safety and construction efficiency of underground pedestrian passage.