高海拔冻土区通风管路基管内风速及影响因素研究

在多年冻土地区,路基工程的修筑将对下伏多年冻土的热力稳定性产生显著的影响.为保护多年冻土,保证路基的长期稳定性,通风管作为一种对流换热类主动冷却降温措施被广泛应用.通风管内的对流换热强度与管内风速密切相关,针对这一问题,采用现场监测与数值模拟相结合的方式开展了通风管内风速特征及影响因素的研究.结果表明:随通风管管径的增...

Characteristics and influence factors of wind speed in ventilation duct of ventilation duct embankment in high altitude permafrost regions

In high altitude permafrost regions， roadway embankment construction will exert significant impacts on underlying permafrost thermal regime. In order to protect the long-term stability of permafrost subgrad， ventilation duct embankment is an effective cooling measure used in roadway construction. For ventilation duct embankment， wind speed in ventilation duct is an important factor determining the intensity of convection heat transfer between environment and embankment filling. In this paper， characteristics and influence factors of wind speed in ventilation duct of ventilation duct embankment are studied by field measurement and numerical simulation. The results shows that wind speed in ventilation duct increase exponentially with increasing diameter of the duct. But when the diameter of the duct is greater than 0.6 m， the wind speed does not increase further. The influence of extended length of the ventilation duct on the wind speed is slight， but with increasing environmental wind speed the influence becomes considerable. The wind speed in the ventilation duct add with increase in ventilation duct buried depth. When the buried depth is greater than 2 m， the wind speed does not change considerable. When roadway is constructed with two separated embankments， the wind speed in ventilation duct of the leeward embankment will be influenced by the windward embankment. Taking the discrepancy of wind speeds in the ventilation ducts of the two embankments not exceeding 0.4 m·s^-1 as a standard， the minimum spacing between the two separated embankments is about 50 m with their thickness being 3 m.