露天煤矿矿坑回填对冻土恢复的影响分析

An analysis of the impact of opencast coal-mining pit backfill on permafrost recovery

为分析露天煤矿矿坑回填对冻土恢复的影响,采用数值模拟方法,对一定初始温度条件和不同边界条件下露天开挖回填后的冻土恢复进行预测分析。分析结果表明:填土温度对回填后冻土恢复有很大的影响,当填土温度由+2.0℃降低为-2.0℃时,冻土的恢复速率明显加快,厚度明显增大;当填土表面温度为正温时,坑底内的冻土恢复较难;当填土表面温度为负温时,坑底内的冻土恢复速率以及冻土厚度均比正温时更快更厚;随着天然地表温度的降低,冻土恢复速率与冻土厚度也逐渐加快增厚。因而,应尽量选择冷季,并对回填土体作降温处理后再进行回填,以保证冻土快速恢复并保持稳定,这样更有利于矿区的生态环境恢复。

The status of permafrost recovery after excavation backfill in opencast coal-mine is examined in this article. The permafrost recovery under certain conditions of the initial temperature and different boundary conditions is forecast by using the numerical simulation methods. The results show that the filling temperature significantly influences the permafrost recovery after backfilling. When the filling temperature reduces from＋ 2. 0℃ to- 2. 0℃,the permafrost recovery rate greatly accelerates and the permafrost thickness significantly increases. When the surface temperature of filling is positive,the permafrost recovery at the bottom of the excavation is more difficult than that under the negative temperature. The permafrost recovery rate and the permafrost thickness are slow and thin,respectively. The permafrost recovery also speeds up gradually the thickening with the reduction of natural surface temperature. Therefore,it is suitable to backfill in the cold season and do the cooling treatment to the filling before backfilling. The treatment will ensure that the permafrost recovery is more fast and stable. The measures are also conducive to the recovery of mine ecological environment.