谢桥三个冻结井施工的经验教训

Experience with and Lessons from Sinking Three Freezing Shafts in Xieqiao

一、两种方法两样结果淮南谢桥主井、副井和矸石井,都采用冻结法施工(表1)。由于冻结设计和施工不同,其效果也不同。最早施工的矸石井,掘砌至垂深218m,开始发生断管,全井共37根冻结管,除1根偏入井内截去外,先后断管33根,占89％。冻结被迫停止,还有28m未到达基岩,不得不采取快速施工穿过。

the main, auxiliary and muck shafts have been sunk in same geological conditions, with identical freezing station and freeze tubes, however, different design and technology have been introduced with different results. This is worthy of dmaking a summary. When the auxiliary and muck shafts were sunk, emphasis was laid on excavation of soft core. And rapid excavation started as soon as the low strength ice wall was just formed. As a result, 34 out of 37 freeze tubes around the muck shaft were ruptured. Five freeze tubes around the auxiliary shaft were also ruptured which caused a loss of 40 m' of brine and the shaft was flooded because of unclosed ice wall. Freezing was improved in the main shaft, freezing period increased by 83 days. The unstable water-tearing alluvium was passed successfully without rupturing any freeze tubes. From these experience we learnt that materials and verticality of freeze-tubes and Theological properties of the ice wall was one of the reasons for the rupture of freeze tubes and were not the main reasons. The main reasons were low strength of ice wall, inadequate freezing period and the temperature was not low enough. The temperature of the brine in the main shaft decreased from-33℃ to -35℃. The temperature of the shaft wall varied from -12℃ to -14℃. The unfrozen core was 2 m in diameter, the rest was fully frozen. As a result,the srength of the ice wall was high,less Theological deformation and outer wall pressure was observed. Therefore, the author considered that the idea that rupture of freeze tubes was due to ice pressure was inaccurate.