南京地铁集庆门盾构隧道进洞端头人工冻结加固温度实测

Temperature study on artificial soil freezing reinforcement for shield entry in Ji Tsing-men station of Nanjing metro

在人工冻结法施工过程中,及时掌握冻土温度场的发展情况是控制和指导施工的重要手段。以南京地铁集庆门站左线盾构到达冻结工程为依托,运用数字测温系统对人工冻结法加固盾构进洞端头的地层温度进行了原位监测,获得了在地层初始温度高、土层含水量大的情况下进行人工地层冻结施工的温度实测数据。在后期停止冻结后对人工冻土的自然解冻温度进行了监测分析。监测结果表明:土质对冻结温度场的影响胜于含水率对其的影响;地下水流速过快和土体中的空气能够阻碍冻结壁的有效形成;在洞口加固工程中注浆水化热不会对土体的冻结产生明显影响;冻土壁轴面上的自然解冻速率快于其他位置,但轴面处冻土的解冻周期性相对较长。

During the process of artificial soil freezing, mastering the progress of thermal field in time is an important method for controlling and guiding construction. Relying on the artificial soil freezing construction for the arrival of shield machining in Ji Tsing-men station of Nanjing Metro, digital temperature- monitoring system was applied to monitor the temperature in the artificial frozen soil in-situ for the shield entry reinforcement. Measuring data were obtained in the conditions that the initial ground temperature and the ground water content were high. Thawing temperature was also measured and analysed at the end of the freezing period when freezing ceased. Conclusions were made as follows according to the measuring results that the soil materials make more effects than the moisture percentage on the thermal field, that excessively quick speed of ground water flowing and air in soil will prevent the effective conformation of frozen soil wall, that the frozen soil wall will not be influenced by concrete hydration heat in metro reinforcement construction, and that the thawing periodicity is comparatively longer than the latter,although the nature thawing velocity in the middle frozen soil wall is quicker than that in other parts of frozen soil wall.