基于冻结壁地层相变环境下大体积混凝土温度场研究

Temperature Field Research of Mass Concrete Based on the Phase Change Condition of Ground Freezing Wall

介绍了中国矿山冻结法凿井井壁混凝土温度问题的现状和发展,研究了井筒冻结相变导热环境下大体积混凝土井壁温度场数学模型;介绍了营盘壕冻结副立井套内壁的工程概况、垂深704m壁座结构和温度监测方案,7个实测点数据,图形展示了混凝土浇筑72h内井壁及围岩的实测温度发展.有限元数值模型计算获得了对应实测点的温度数据,和实测结果相当接近,并预测了在停止冻结后直至全部融化的井壁及围岩温度分布发展情况.数值计算还原了井壁距内缘深682mm测点2的一段丢失数据,弥补了对测温量程考虑不足导致数据丢失的遗憾,并显示出在混凝土搅拌后37.5h时井壁测点最高温度可达到92.3℃,高温发生在内壁中间部位,井壁内外温差最高达到了65℃以上,如此高的内外温差值得设计和施工人员关注.模型还揭示了停冻120d后冻结壁全部融化,即围岩都上升到摄氏正温以上.

This paper reviewed the current state and development of thermal problem of lining concrete numeral freezing of shaft sinking with artificial ground freezing in China, and presented a research of model of temperature field of mass concrete considering phase change in the ground shaft. It also introduced the outline of the auxiliary shaft of Yin-Pan-hao colliery, showing the detail of the lining structure of the shaft lining seat at the depth of 704 m, and monitoring plan of the temperature field. The temperature data were presented for seven points arranged from the lining structure to the surrounding freezing rock in a radial direction in the initial period of 72 hours of concrete pouring. A FEM model was used to simulate the development of the corresponding period at the same monitoring points of concrete lining, and predict the temperature variation from the beginning of termination of freezing to the state of completely thawed of frozen wall, which are well agree with the monitoring data. The FEM also restored the lost data of the point at the depth of 684mm apart from the inner edge of shaft lining, which makes up the regret of data lost because of choice mistake of the limited measurement range of temperature. It was found that the highest temperature was about 92.3℃ occurred at the time of 37. 5 hours of concrete placing of shaft lining, and the maximum temperature difference between inner and outside the lining structure were up to 65℃. The large temperature difference should be mentioned to take consideration seriously to the designer and builder. In addition, the model predicted that the frozen wall would thaw completely in 120 day after freezing is terminated.