常州砂性地层联络通道解冻规律研究

人工冻结联络通道施工常采用跟踪注浆解决软弱地层工后融沉问题,为此必须掌握解冻温度场的变化规律。以常州市轨道交通1号线某隧道联络通道冻结法施工为背景,将冻结阶段现场实测与温度场数值模拟进行对比,验证数值模拟方法正确性,并通过数值模拟对自然解冻与强制解冻规律进行分析。结果表明,60 ℃~90 ℃循环热水强制解冻周期为33.5~22 d,较自然解冻周期的160 d缩短了5~7倍,不同温度的强制解冻解冻周期大致呈线性变化。强制解冻完成次序依次为上部结构、冻结管内侧土体、冻结管外侧土体、集水井底部。冻结壁厚度不同工程可采用不同温度热水循环进行强制解冻,冻结壁厚度较薄时可适当降低热水温度;强制解冻融沉注浆前期应将重点放在联络通道上部结构侧边及顶部,后期应将重点放在底部。

Study on Thawing Law of the Connecting Passage in Changzhou Sandy Formation

In the construction of artificial freezing contact channel, track grouting is often used to solve the problem of thaw settlement in soft stratum. Therefore, it is necessary to grasp the law of thawing temperature field. With the background of freezing method construction in the connecting passage of a tunnel on Changzhou City Metro Line 1, the measurement with temperature field numerical simulation in the freezing stage was compared to verify the correctness of the numerical simulation method. Then the law of the natural thawing and freezing of forced by numerical simulation was studied. The results showed that the forced thawing cycle of circulating hot water 60℃~90℃were 33.5~22 days, about 5~7 times was shortened comparing with the160 days of natural thawing cycle. The time of forced thawing at different temperatures is approximately linear. The order of forced thawing is the upper structure, the inner of the freezing pipe, the outer of the freezing pipe, and the bottom of the collecting well is thawed finally. For different thickness of frozen wall, hot water with different temperature can be used for forced thawing. For the thinner thickness of freezing wall, the hot water temperature can be reduced properly. In the early stage of forced thaw grouting, the emphasis shall be placed on the upper structure’s side and top, and the latter shall be placed at the bottom.