Influence factors on the ground temperature recovery process of an open-pit coal mine backfill in the permafrost area of northeastern China
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摘要: 针对东北多年冻土区古莲河露天煤矿回填的问题，利用数值模拟方法，对露天煤矿回填后地温变化及影响因素进行分析。结果表明：影响地温恢复的主要因素是填土深度，其次是填土温度；气候变暖情景下，填土区地温呈现先降低后升高的趋势，起负影响的控制时间点是填土后50 a左右；填土对下覆及侧向区域的热影响随外界因素变化不大，影响范围在5 m内，影响时间在5 a内。其中，填土温度20 ℃、15 ℃、10 ℃及2℃，回填区地温可在27 a、21 a、16 a和10 a时恢复到0℃以下；回填深度2.6 m、10 m、20 m、30 m及40 m，填坑区域可在回填后1 a、9 a、27 a、65 a及114 a形成冻土；建立的统计回归模型与回填80 m数值分析结果吻合，验证了模型的可靠性；在此基础上，定量给出适宜回填施工作业季节和回填作业方式。Abstract: Open-pit coal mine backfill is an effective method for ecological environment recovery in permafrost areas. Quantitative analyses for ground temperature changes are lack and the main influence factors affecting the ground temperature recovery remains unknown. The numerical simulation method is implied to analyze the open coal mine backfill effects on the thermal status of permafrost in the Gulian area. The results show that the main factors influencing the ground temperature recovery is the depth of the backfilling soil and the filling soil temperature. The backfilling soil tends to decrease and then increase in 50 years under the climate warming background. The underneath and lateral heat effect is about 5 m and it will recover in 5 years in any condition. The backfill area will froze in about 27, 21, 16, and 10 years with different soil temperatures of 20℃, 15℃,10℃ and 2℃, respectively. With the filling back depth of 2.6, 10, 20, 30 and 40 m, the corresponding temperature of the backfill area depress to negative after 1, 9, 27, 65 and 114 years. The reliability of the model is validated through the statistical regression model compared with the numerical analysis results of the backfill depth of 80 m. On the basis of the above study, we give a suitable backfill solution such as the proper construction season and backfill practice ways.
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Key words:
- permafrost /
- open-pit coal mine backfill /
- ground temperature recovery /
- Gulian mine area
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