耦合效应下联络通道解冻规律研究

Investigation on Thawing of Cross Passage Based on Coupling Effect

摘要:

人工冻结法施工隧道联络通道施工过程中及施工完成后，冻土帷幕的解冻规律研究的较少。本文结合上海长江隧道一号联络通道工程，在温度-应力耦合控制方程的基础上，分别考虑自然解冻和人工强制解冻条件下对流散热、混凝土初衬、二衬水化热等影响因素，分析了土体内部温度场、冻土厚度的发展变化及由于冻土的解冻产生的融沉效应。通过分析发现自然解冻条件下经过大约44天冻土完全融化，衬砌混凝土的水化热对冻土的解冻影响较大；不考虑混凝土水化热的作用, 至50天冻土仅能解冻23%；由于冻土的融沉效应，联络通道区域整体沉降，通道中心竖向位移为-2cm；采用强制解冻冻土解冻较快，仅需4.3天就可完全解冻, 与冻结过程相反，双排管之间最先解冻，然后是内侧冻土，最后是外侧冻土。

Abstract:

Thawing of artificially frozen soil during and after the excavation of cross passage constructed by artificial ground freezing method isn’t well studied. Coupling the governing equations of temperature and stress, this paper investigates the issues of temperature field, development of frozen wall thickness, and thaw settlement considering the effects of convection and hydration heat from preliminary/secondary concrete lining. Cases of both naturally and artificially thawing are studied for the scenario of cross passage #1 in Shanghai Yangtze River Tunnel. In naturally thawing condition, it takes 44 days for all frozen soil to melt and this process is significantly influenced by the hydration heat from preliminary concrete lining while that only 23% of the frozen soil melt without regard to the hydration heat in 50 days. Soil mass in the cross passage area shows a downward displacement of 2cm due to the thawing effect. As for the case of artificial thawing, all frozen soil melts after 4.3 days. Contrary to the process of freezing, thawing of soil first occurs within the area between the two rings of freezing pipes, then that between the preliminary lining and the inner freezing pipe ring, and last that out of the outer ring.