大断面通道“冻结壁+水泥加固体”联合围护体系与开挖方法

Excavation method and"freezing wall+cement reinforcement"joint support system of large cross section channel

通过分析富水软弱地层浅埋大断面隧道工程的特点,以人工冻结法与注浆法为基础,提出“冻结壁+水泥加固体”联合围护体系与开挖方法,该方法在广州地铁11号线云大区间2号横通道冻结工程得以应用。2号横通道采用外圈筒形冻结壁形式,横通道外围冻结壁范围内土体形成高强度的冻土帷幕,开挖区域形成弱冻结区,采用矿山法进行横通道开挖支护施工。2号横通道分成3个开挖区域,依次自上而下水平开挖,每台阶采用超前注浆加固封水,每台阶开挖完成后,在端头对下一台阶进行垂直注浆加固。现场应用结果表明:“冻结壁+水泥加固体”联合围护体系既有效增强了围岩自身的承载能力,又隔绝了地下水的联系。该工程现已安全顺利完工。

With the analysis on the features of the shallow depth large cross-section tunnel project in the watery soft and weak strata,based on the artificial ground freezing method and grouting method,a"freezing wall+cement reinforcement"joint support system and excavation method was provided.The method was applied to the freezing engineering of the No.2 transverse passage way between YunDa Section of No.11 Line in Guangzhou Metro.The outer ring freezing wall shape was applied to No.2transverse passage way.Within the outer freezing wall of the transverse passage way,the soil mass formed a high strength freezing soil curtain.The excavated area became a weak freezing area and the excavation and support construction of the transverse passage way was operated with the mine tunneling method.No.2 transverse passage way was divided to three excavation areas and was excavated from top to low level.Each bench was reinforced and water sealed with the advanced grouting.After each bench was excavated,a vertical grouting and reinforcement was conducted on the end of the next bench.The site application results showed that the"freezing wall+cement reinforcement"joint support system could effectively improve the loading capacity of the surrounding rock self and could isolate the connection of the underground water.The project was safety and successfully completed.