基于差异冻结技术的深厚冲积层三维冻结温度场数值计算分析  

Numerical analysis of three-dimensional freezing temperature field in deep alluvial layer based on differential freezing technique

作　　者：吴冬 荣传新[1] 龙伟 王彬[1,2] WU Dong;RONG Chuanxin;LONG Wei;WANG Bin(School of Civil Engineering and Architecture,Anhui University of Science and Technology,Huainan 232001,Anhui,China;Engineering Research Center of Underground Mine Construction,Ministry of Education,Anhui University of Science and Technology,Huainan 232001,Anhui,China)

机构地区：[1]安徽理工大学土木建筑学院,安徽淮南232001 [2]安徽理工大学矿山地下工程教育部工程研究中心,安徽淮南232001

出　　处：《冰川冻土》2024年第4期1423-1439,共17页Journal of Glaciology and Geocryology

基　　金：国家自然科学基金项目(51878005);矿山地下工程教育部工程研究中心开放基金(JYBGCZX2022103);安徽省科技重大专项(202003c08020007)资助。

摘　　要：为了探究人工地层冻结(artificial ground freezing, AGF)多圈管冻结壁温度场分布与发展规律,以淮北青东煤矿东风井为工程背景,利用现场实测数据和COMSOL Multiphysics软件建立三维冻结温度场数值计算模型,分析了立井井筒所在土层在差异冻结技术下的冻结温度场时空演化规律。研究结果表明:在对比分析中三圈管相较两圈管冻结扩展速度较快,相同的冻结时间下,冻结壁平均温度要低0.73~3.32℃·d^(-1),有效厚度增加0.38 m;砂土层相同冻结时间的条件下冻结壁平均温度要比黏土层低0.94~1.50℃,有效厚度增加0.21 m。冻结井筒计算范围内,径向温度场呈现出圈管之间温度低,圈管两侧温度较高的“马鞍型”分布;在土体深度方向,不同土性的土层温度梯度较为明显,具体表现为三圈管以及细砂层位温度更低,30 d左右Ⅱ层土体(三圈管砂土层)降温速率达到最大,约为1.12℃·d^(-1),首先完成土体降温阶段进入冻结壁交圈和拓展阶段,此时其他土层仍处于土体降温阶段。“长短腿”冻结管布置形式既可以提高井筒开挖的时间,缩短工期;又可以防止深部冻土入荒径过多,降低开挖难度,节约工程成本。采用差异冻结的方式,开机冻结30 d,去路盐水温度降至-30℃后维持该温度循环制冷盐水,使得该冻结工程取得了圆满成功。此研究可以为类似矿井冻结施工提供一定的参考。In order to investigate the distribution and development of temperature field in the artificial ground freezing(AGF)multi-loop pipe frozen wall,taking the Dongfeng Shaft of Qingdong Coal Mine in Huaibei city as the engineering background,a three-dimensional numerical model of the frozen temperature field was established using field measurement data and COMSOL Multiphysics software.The spatiotemporal evolution of the frozen temperature field in the soil layer of the vertical wellbore under different freezing techniques were analyzed.The research results showed that in the comparative analysis,the three-loop pipe had a faster freezing expansion speed compared to the two-loop pipe.Under the same freezing time,the average temperature of the frozen wall was 0.73℃to 3.32℃lower,and the effective thickness increased by 0.38 m.In the sandy soil layer,the average temperature of the frozen wall was 0.94℃to 1.5℃lower than that in the clay soil layer under the same freezing time,and the effective thickness increased by 0.21 m.Within the calculation scope of the frozen wellbore,the radial temperature field showed a“Saddle-shaped”distribution,with lower temperatures between the loop pipes and higher temperatures on both sides of the loop pipes.In the depth direction of the soil,the temperature gradient of different soil layers with different soil properties was more pronounced.Specifically,the three-loop pipe and the fine sand layer had lower temperatures.Around 30 d,the temperature decrease rate in the Layer II soil(sand layer with three-loop pipe)reached its maximum,about 1.12℃·d^(-1),indicating that it had entered the stage of frozen wall intersection and expansion,while other soil layers were still in the stage of temperature decrease.The arrangement of the“Long and Short Leg”frozen pipes can not only increase the excavation time of the well and shorten the construction period,but also prevent excessive freeze-thaw of the deep frozen soil,reduce the difficulty of excavation,and save construction costs.By

关 键 词：人工地层冻结 差异冻结技术 三维冻结温度场 时空演化规律 数值计算 

分 类 号：TD265.34[矿业工程—矿井建设]