大断面隧道下穿既有客运专线施工安全监控

Safety Monitoring on Construction of Large Profile Tunnel Passing Under Existing Passenger Dedicated Railway

依托北京至石家庄客运专线石家庄隧道下穿既有石(家庄)太(原)直通线暗挖工程,从客运专线运营的安全和舒适性出发,制定了中洞法+CRD法的暗挖施工方案,并进行了现场监测与安全分析。结果表明:采用中洞法+CRD法进行大断面隧道施工时,地表沉降最大值为9.1 mm;初期支护与二次衬砌之间的接触压力增加缓慢,隧道二次衬砌左洞和右洞所承受的围岩压力较小,而中墙部位所承受的围岩压力较大,施工时应加大衬砌厚度;隧道开挖引起的既有线路基沉降最大值为8.6 mm,铁路轨道沉降最大值为5.3 mm,均在可控范围内。

Based on the subsurface excavation engineering of Shijiazhuang tunnel of Beijing-Shijiazhuang passenger dedicated railway passing under existing Shijiazhuang-T aiyuan railway straight line,the subsurface excavation scheme of center drift method ＋ CRD method was made considering the safety and comfort of passenger dedicated railway. Field monitoring and safety analysis results showed that the maximum surface subsidence was 9. 1 mm by using center drift method ＋ CRD method for the large profile tunnel construction,the contact pressure between the primary support and secondary lining increases slowly,the surrounding rock pressure born by the left and right hole of tunnel secondary lining was less and the surrounding rock pressure in the middle wall was larger,which means the lining thickness should be increased during construction,the maximum existing railway subgrade settlement caused by tunnel excavation was 8. 6 mm and the maximum railway track settlement was 5. 3 mm,which were all in the controllable range.