框架通风锚管多年冻土边坡新型支护结构的提出及通风能力初探

针对寒区冻土边坡失稳普遍采用被动技术治理的缺陷,基于“主动降温保护冻土”的理念,结合通风管和框架锚杆各自的优势,提出一种具有主动降温、减胀、支挡锚固功能一体化的多年冻土边坡新型支护结构,对其构造和工作原理进行了阐述;在考虑风速阻力损失的情况下,根据结构自然通风的驱动力和结构风场压差的等量关系,得出结构内部的风速计算公式,进而评价通风锚管的通风能力。结合算例,采用有限元和理论计算的方法对结构通风能力及影响因素进行分析,结果表明：结构具有较好的通风能力,对保持边坡的稳定有利;风压差为结构自然通风的主要驱动力,沿程阻力损失为结构的主要风速损失;抽风弯管的设置显著提高了通风能力;结构通风的最优管径比为0.4~0.7;结构自由段长度越大,通风能力越弱。

Proposal of the permafrost slope supporting structure with framed ventilation anchor pipe and preliminary study on its ventilation effect

Aimed at the defects of passive method commonly adopted for the treatment of frozen soil slope failure in cold region, a new permafrost slope supporting structure with framed ventilation anchor pipe, which integrates the functions of active cooling, frost expansion reduction, retaining and anchoring, is developed based on the advanced concept of “active cooling to protect the frozen soil” and the advantages of ventilating pipe and framed anchor, and then the structural characteristics and working principle of the new supporting structure are elaborated. In consideration of the resistance loss of wind speed, the calculation formula for the wind speed inside the structure is obtained based on the quantity relationship between the driving force of the natural ventilation and the pressure difference of the wind field, and then, the ventilation capacity of ventilation anchor pipe can be evaluated. Based on the example, the structural ventilation capacity and the influencing factors are analyzed using the finite element method and the theoretical calculation. The results show that the new structure has good ventilation capacity, which shall be beneficial to the stability of the slope. The wind pressure difference is the main driving force of natural ventilation of the structure, and the resistance loss along the structure is the main wind speed loss of the structure. The setting of the induced-draft elbow pipe can improve the ventilation capacity significantly. The optimal diameter ratio of pipe for the structure is about 0.4~0.7. The larger the free segment length of the structure is, the weaker the ventilation capacity of the structure is.