铁路黄土隧道变形规律及建设管理要点研究

Study on Deformation Law and Key Points of Construction Management of Loess Tunnels

黄土隧道施工过程中,常出现支护破坏和隧道塌方等事故。文章基于黄土隧道工程的监控量测数据,采用统计分析方法对不同围岩级别、埋深和含水率下的黄土隧道变形规律进行了研究。结果表明:(1)Ⅳ级围岩黄土隧道拱顶下沉、周边收敛的量值分别集中在50 mm和35 mm以内,Ⅴ级围岩黄土隧道拱顶下沉、周边收敛则集中在60 mm和40 mm以内;(2)Ⅳ级、Ⅴ级围岩双线黄土隧道拱顶下沉和周边收敛变形值与含水率呈正相关关系,变形速率则先增大后减小,在含水量超过16%时变形增大明显;(3)基于拱顶沉降统计,提出Ⅳ级、Ⅴ级围岩黄土隧道设计预留变形量值范围可分别取7～9 cm和12～15 cm;(4)黄土隧道工程建设管理要点是提前梳理重难点工程,施工前严格方案审核,加强地表处理,施工时强化地质预报和监控量测,严格变更设计管理,重点做好工艺管理和施工质量控制。

Support failure and tunnel collapse often occur during construction of loess tunnels.Based on the monitoring and measurement data of railway loess tunnels,a statistical analysis on the deformation laws of loess tunnels with different surrounding rock grades,buried depths and moisture contents were studied,with the results showing that:(1)the values of crown settlements and peripheral convergence of the loess tunnel in surrounding rock of gradeⅣare almost with in 50 mm and 35 mm respectively,while the values of crown settlements and peripheral convergence of the loess tunnel in surrounding rock of gradeⅣare almost within 60 mm and 40 mm respectively;(2)the crown settlement and convergence of double-track loess tunnels in surrounding rock of gradeⅣandⅤhave a positive relationship with moisture content,deformation rate increases at first and then decreases,and deformation increases obviously when water content exceeds 16%;(3)based on the statistics of crown settlements,it proposed that the range of reserved deformation of loess tunnels in surrounding rock of gradeⅣandⅤshould be 7-9 cm and 12-15 cm respectively;(4)the key points of construction management of loess tunnels include identification of key and difficult works,strict construction scheme review before commencement,paying attention to ground surface treatment,enhancing geological forecast,monitoring and measurement during tunnel construction,strict management of the design alteration,construction process and quality.