大型地下洞室初支完成洞段塌方处理施工技术研究

Research on Construction Technology of Cave-in Treatment of Large Underground Cavern after Initial Support

大型地下洞室中下层开挖时其上半洞已初支完成,与上半洞开挖过程中的塌方相比此时的洞室塌方规模更大,上部空腔会更高,且其塌方体系由大量的块石堆积而成,块石之间的空腔大、上部钢支撑亦混杂在塌方体中,不适用常规的小导管注浆、管棚等支护手段。以西藏旁多水利枢纽泄洪洞中层开挖时其已开挖支护完成的上半洞发生塌方的处理为例,介绍了按照分段处置、加强支护、先清后填、确保安全施工的原则顺利完成塌方段处理施工、确保施工安全的过程。

When the middle and lower layers of a large underground cavern are excavated,the upper half of the cavern has been initially completed.Compared with the cave-in during the excavation of the upper half of the cavern,the cave-in at this time is larger in scale and the upper cavity will be higher and the cave-in system is formed by the accumulation of a large number of blocks of stones.The cavities between the blocks are large,and the upper steel supports are also mixed in the cave-in,conventional supporting means such as small conduit grouting and pipe shed are not applicable.Taking the treatment of cave-in in the upper half of the cave-in hole which has been excavated and supported during the middle level excavation of the spillway tunnel in Pangduo Water Conservancy Project in Xizang Province as an example,the treatment and construction of the cave-in section are successfully completed according to the principles of section disposal,strengthening support,clearing first and filling later,ensuring safe construction.