冷媒温度和渗流速度对富水砂层冻结温度场的影响规律研究OA

In response to the frozen issues in subway tunnel constuction in Tianjin area where complex hydrogeological conditions exist such as water-rich sand strata,the laboratory model experiments and numerical simulations was combined to investigate the effects of cold media tempreture and seepage velocity on the frozen temperature field,closure time,and growth of frozen walls in sandy soil.The research findings indicate that as the cold media tempreture decreases,the temperature gradient near the frozen pipe becomes steeper,and the frozen wall becomes thicker.In the presence of seepage,the seepage water transports cold energy from the upstream to the downstream,which impedes the development of the frozen wall to the upstream direction while promotes it to some extent to the downstream direction,which leads to the uneven thickness of the frozen wall.Ultimately,the shape of the frozen wall changes from circular in still water to heart-shape.In practical engineering,measures such as grouting to reduce the seepage velocity and lower cold media temperature can be used to cut the clolure time and finally ensure a smooth frozen process.