新建地铁隧道曲线下穿既有地铁施工影响控制研究

RESEARCH ON IMPACT CONTROL OF CURVED CROSSING OF NEW SUBWAY TUNNEL BELOW EXISTING SUBWAY

为保证新建隧道曲线近接既有地铁安全施工,采用工程调研的方法研究了该工程的主要风险,对近接施工风险和既有运营结构现状进行了调查分析;结合工程施工风险调研结构和既有结构现状调查,有针对性地提出了施工加固措施,并结合现场实施结构对提出的风险控制措施进行了验证。结果表明:(1)该工程曲线下穿段包括曲线下穿车站风道和既有运营地铁隧道,其中下穿车站风道施工为一级风险,下穿地铁区间施工为特级风险;(2)曲线下穿段近接施工风险控制措施:上半断面深孔注浆;区间洞内增设临时仰拱;缩小格栅步距,由750mm变为500mm;(3)现场监测所有监测指标均在安全阈值内,新建隧道、既有车站风道和既有地铁区间的变形均在安全阈值内,拟定的风险控制措施保证新建隧道顺利下穿既有地铁风道和既有地铁区间。

In order to ensure the safe construction of the new tunnel curve close to the existing subway,the main risks of the project are studied by the method of engineering investigation,and the construction risks of the close connection and the status quo of the existing operation structure are investigated and analyzed.Combined with the construction risk investigation structure and the existing structure status investigation,the construction reinforcement measures are put forward,and combined with the site implementation structure to verify the proposed risk control measures,the results show that:(1)The under curve section of the project includes the under curve station air duct and the existing operating subway tunnel.the construction of the under curve station air duct is the first-level risk,and the construction of the under subway section is the extra-level risk.(2)The construction risk control measures for close connection in the lower penetration section of the curve are as follows:deep-hole grouting in the upper half section.temporary invert is added in the interval cave,reduce the grille step distance from 750mm to 500mm.(3)All monitoring indicators in the field monitoring are within the safety threshold,and the deformation of the new tunnel,the existing station air duct and the existing subway section are all within the safety threshold.The proposed risk control measures ensure that the new tunnel can smoothly run under the existing subway air duct and the existing subway section.The research results can provide reference for the establishment of similar tunnel construction monitoring and early warning system.