地形偏压隧道地表处理措施分析

Analysis of Surface Treatment Measures for Biased Tunnel

以回头沟隧道工程为依托,对削坡法、回填法、地表注浆法等偏压隧道地表处理措施进行数值模拟,从控制围岩变形、减小围岩应力出发,分析不同地表处理措施对隧道偏压产生的影响。结果表明:削坡法将坡比由1∶1.65削至1∶2和1∶2.5后,左右拱肩位移差分别降低了52.7%和75.3%,对围岩竖向位移影响差别较大;回填法将坡比由1∶1.65回填至1∶2和1∶2.5后,左右拱肩位移差分别降低了48.9%和50.0%,对围岩竖向位移影响几乎相同;注浆法注浆后,拱顶及左、右拱肩的竖直位移均比注浆前降低90%以上,地形偏压对隧道的影响基本消失,但注浆区域水泥-水玻璃浆液使围岩密度增大,引发应力场的重新分布,需提高相应位置支护强度。故从围岩变形和应力两方面考虑,采用削坡法将坡比由1∶1.65削至1∶25是处理回头沟隧道偏压段最有效的措施。

Based on the Huitougou tunnel project,numerical simulation was used to analyze tunnel surface treatment measures such as slope cutting method,backfilling method and surface grouting method.The effects of different surface treatment measures on the tunnel bias were analyzed from the perspective of controlling surrounding rock deformation and reducing surrounding rock stress.Results show that the displacement difference between the left and right arch shoulders is reduced by 52.7%and 75.3%respectivelyafter the slope ratio is cut from 1∶1.65 to 1∶2 and 1∶2.5 respectively with the slope cutting method,indicating a quite different influence on the vertical displacement of surrounding rock.The displacement difference between the left and right arch shoulders is reduced by 48.9%and 50.0%respectively after the slope ratio is cut from 1∶1.65 to 1∶2 and 1∶2.5 respectively with the backfilling method,indicating almost the same influence on the vertical displacement of surrounding rock.After grouting,the vertical displacement of the arch roof and the left and right arch shoulders is reduced by more than 90%compared with that before grouting,and the effect of terrain bias on the tunnel almost disappears.However,cement-sodium silicate slurry in the grouting area increases the proportion of surrounding rock and causes the redistribution of stress field,which requires increasing the support strength of the corresponding position.Therefore,from the perspective of surrounding rock deformation and stress,cutting the slope ratio from 1∶1.65 to 1∶2.5 by slope cutting method is the most effective measure to deal with the biasing section of the Huitougou tunnel.