超浅埋盾构隧道下穿供澳水管施工技术研究

Construction Technology for a Super-Shallow Shield Tunnel underneath the Macao Water Supply Pipe

新建珠海市区至珠海机场城际轨道交通拱北至横琴盾构隧道段下穿供澳水管生命线工程,隧道开挖断面范围为粗砂层和粉质粘土层,且供澳水管底部距刀盘顶部高度仅为4.8 m,管身存在较多裂痕、损坏及修补痕迹,故对沉降控制要求很高。为了确保盾构下穿过程中水管完好无损,文章针对性地编制了盾构下穿施工方案,并进行了预穿管线施工试验。试验过程中采用化学改良剂对土体进行了加固,并根据实时监测情况及时修正注浆和掘进参数。后期盾构下穿施工监测结果表明,预穿试验确定的参数合理,可以有效控制地面沉降,确保盾构隧道安全、顺利地下穿供澳水管。

The shield tunnel section from Gongbei to Hengqin of the new intercity rail transit project from downtown Zhuhai to the Zhuhai airport is constructed underneath the water supply pipe for Macao, with the tunnel excavation section consisting of a coarse sand layer and a silty clay layer. The distance from the bottom of the water supply pipe to the top of the cutterhead is only 4.8 m, and there are many cracks and lots of damage and patch marks, so settlement control requirements are very strict. To guarantee that the water pipe remains intaet during shield construction, a construction scheme was prepared and a preeonstruetion test was conducted to assess passage through the water pipe. Chemical conditioner was used during the test to improve the soil mass, and the grouting and driving parameters were modified based on real-time monitoring. The monitoring results of the shield construction show that the parameters for the preconstruction passage through the water supply pipe are reasonable and effective for controlling ground settlement and guaranteeing safe and smooth construction of the shield tunnel underneath the water supply pipe for Macao.