深厚砂黏分界处不同工况下多圈管冻结温度场特性

多圈管冻结壁设计方案是解决深冻结问题的有效方法，为研究深厚砂黏层分界处不同工况下多圈管冻结温度场特性，采取分界处原黏性土XRD试验结果，利用ANSYS数值模拟冻结三圈管，对比分析了细砂土与膨胀性黏土在冻结管偏斜与不偏斜工况下温度场冻结壁形成与发展特性。研究表明：多圈管不偏斜冻结，细砂层与膨胀性黏土层冻结壁温度场均呈规则、对称、有序发展，主冻结中圈管间、内圈管间、中-内圈管间、中-外圈管间、外圈管依次形成交圈过程，随着冻结时间增加，中-内圈、中-外圈管间冻结温度由抛物线型发展为梯形降温形状，且温差减少，内、外圈管外侧呈倒八字型发展形态，内圈管内侧降温效果明显好于外圈管外侧。偏斜时，冻结壁温度场交圈降温不规则，冻结冷锋交圈叠加具有随机性和离散性。膨胀性黏土冻结壁形成时间严重滞后，偏斜、土性差异对冻结壁温度影响均较大，偏斜对膨胀性黏土影响尤其明显，与某矿冻结法凿井在地层-400 m以上砂黏分界处发生的多根冻结管断管事件较为吻合，研究成果可以为类似深层矿井冻结施工提供参考。

Freezing temperature field characteristics of multi-loop pipers under different working conditions at the interface of deep thick sand and clay

The design scheme of multiple-loop pipe freezing wall is an effective method to solve the problem of deep freezing, In order to study the freezing temperature field characteristics of multiple-loop pipes under different working conditions at the boundary of deep thick sand and expansive clay, the XRD test results of the original cohesive soil at the boundary were taken. ANSYS numerical simulation was used to compare under the skewed and non-skewed conditions of fine sand and expansive clay. Studies have shown that:multiple-loop pipes are frozen without non-skewed, and the temperature field of the frozen wall of the fine sand layer and the expansive clay layer develops in a regular, symmetrical and orderly manner. The main freezing center ring tube, inner ring tube, middle-inner tube, middle-outer tube, the outer ring tube form an intersection process in turn. As the freezing time increases, the freezing temperature between the middle-inner ring and the middle-outer ring tube develops from a parabolic shape to a trapezoidal cooling shape, and the temperature difference decreases. The outer side of the inner and outer ring tubes is inverted. The cooling effect on the inside of the inner tube is obviously better than that on the outside of the outer tube. When skewed, the temperature field of the freezing wall is ir-regular in the temperature field, and the superposition of the freezing cold front is random and discrete. The formation time of the frozen wall of expansive clay is seriously lagging behind deviation and soil properties have a greater influence on the temperature of the frozen wall. The deviation has a particularly obvious effect on the expansive clay. It is more consistent with the multiple freezing pipe broken events that occurred in a mine's freezing shaft sinking at the sand-clay boundary of the formation above -400 m. The research results can provide a reference for similar deep mine frozen construction.