地下水渗流作用下多圈管冻结温度场形成规律与机制

    Formation laws and mechanism of freezing temperature fields of multiple coil tubes under groundwater seepage conditions

    • 摘要: 为了研究地下水渗流作用下的深厚冲积层人工地层冻结温度场的形成规律与冻结壁形成机制,以临涣矿中央风井冻结法施工为工程背景,利用现场实测数据,分析了现场的不同层位、土性下冻结温度场的时空演化规律;并用该数据验证了基于现场冻结孔实际成孔位置构建的埋深228 m砂层在地下水渗流作用下水热耦合数值计算模型的合理性;基于此模型,探究了地下水渗流对冻结温度场形成规律与发展机制的影响。结果显示:在多圈管冻结进程中,圈径内部土体受冷量叠加影响,降温快于外部土体,冻结相变阶段表现更明显;双圈管冻结土体主面温度呈“马鞍形”、界面温度呈“抛物线形”分布,主面温度下降速度比界面更快;不同的地下水渗流速度对冻结壁交圈时间与交圈模式有着较大影响,交圈时间可用“双阶段反应函数”进行拟合,区分双阶段的地下水界限流速为21 m/d;地下水渗流速度由0 m/d增加至40 m/d时,上游和侧翼冻结壁厚度分别减小25.06%和16.41%,下游冻结壁厚度增大59.29%;地下水流速加大会加剧冻结壁温度场的非对称性发展与分布,诱导冻结壁产生非对称性的“不良发育”。

       

      Abstract: In order to study the formation law of artificial frozen temperature field and the formation mechanism of frozen wall in deep alluvial layer under the action of groundwater seepage, the paper analyzes the spatiotemporal evolution law of frozen temperature field under different layers and soil properties based on the construction background of central wind shaft freezing method in Linhuan Mine. The data are used to verify the rationality of the groundwater thermal coupling numerical calculation model based on the actual location of frozen hole in the field and the buried depth of 228 m sand layer. Based on this model, the influence of groundwater seepage on the formation rule and development mechanism of freezing temperature field is explored. The results show that the soil inside the ring diameter is affected by the superposition of cooling capacity, and the cooling is faster than that outside, and the freezing phase is more obvious in the freezing process of the multiple coil tubes. The temperature on the main surface of the frozen soil in the double coil tube is “saddle shape” and the temperature on the interface is “parabolic shape”, and the temperature on the main surface drops faster than that on the interface. The different seepage velocity of groundwater has a great influence on the circulation time and circulation pattern of frozen wall. The circulation time can be fitted with the “two-stage response function”, and the groundwater limit flow rate of the two stages is 21 m/d. When the seepage velocity increases from 0 m/d to 40 m/d, the thickness of the frozen wall in the upper reaches and flanks decreases by 25.06% and 16.41%, respectively, while the thickness of the frozen wall in the lower reaches increases by 59.29%. The increase of groundwater flow rate increases the asymmetric development and distribution of the temperature field of the freezing wall, and induces the asymmetric “bad development” of the freezing wall.

       

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