泥水平衡盾构隧道基岩孤石控制爆破预处理技术

Technology of Controlled Blasting Pre-treatment of Bedrock and Boulders in Slurry Shield Tunnel

泥水平衡盾构在软土地层的隧道施工中,隧道开挖范围内遇到基岩突起或者孤石,基岩、孤石对盾构机刀盘刀具的损坏严重,滚刀难以破碎岩体。以台山核电站1~#、2~#海底取水隧道工程为例,对台山核电站1~#、2~#海底取水隧道始发段存在的基岩突起和孤石群,通过海面石块回填将浅海域填为平地,采用地面垂直钻孔对基岩突起、孤石群段进行无自由面爆破预处理。为了保证爆破效果,采用冲孔和爆破相结合的施工方法。爆破后实测芯样最大粒径为43 cm,98%的芯样粒径小于30 cm,消除了基岩突起和孤石群对盾构掘进的威胁,保证了盾构掘进的顺利进行。

The bedrock and boulders in soft soil layer of slurry balance shield tunnel cannot be excavated direct- ly by hob cutters, and shield machine cutter knives was badly damaged. With the 1# ,2# undersea tunnel of Taishan nuclear power plant as an example, the bedrock and boulders period of the 1# ,2# undersea tunnel is pretreated by means of blasting hole drilling from the ground surface and underground blasting by means of backfilling with rocks reclamation to the ground. The construction combined with punching and blasting was used to improve blasting effect. The results show that the maximum particle size of the cores measured is 43 cm and particle size of 98% cores is less than 30 em after blasting,which eeliminated the threat of the bedrock protrusions and boulders in shield tunneling construction.