铁路大临线地下水热活动特征及其工程影响

Characteristics of hydrothermal activities and their engineering impacts on the Dali-Lincang railway

铁路大临线穿越云南多个地热异常带,强烈的地下水热活动对铁路隧道工程影响较大。根据区域地质构造特征和50多处温泉的水热特征,该铁路工程区可分为凤仪-弥渡等5个水热活动带,对铁路工程有潜在影响的地热异常区主要包括西洱河、巍山、澜沧江、茂兰和云县等5个地热异常区。地热异常带的地下水经深循环加热形成带状分布的低温和中温地热系统,地热水的循环深度2. 0~5. 3km,温泉水化学类型及其组分呈现多样性。澜沧江以北和以南地区,平均地温梯度分别为3. 07℃/100m和2. 54℃/100m。为避免热害,线路应尽量从地热水的补给区和径流区通过,绕避地热水的排泄区。其中,大麦地隧道、巍宝山隧道、新华隧道、红豆山隧道存在中等热害,林保山等12个隧道热害轻微,可针对不同情况采取降温和加固结构等措施。

Dali-Lincang railway passes through many geothermal abnormal zones in Yunnan,and the strong groundwater thermal activity has great influence on railway tunnel engineering.According to the regional geological structure characteristics and the hydrothermal characteristics of more than 50 hot springs,the railway engineering area can be divided into five hydrothermal active zones such as Fengyi-Midu active zone.The geothermal abnormal zones that have potential impact on railway engineering mainly include five geothermal abnormal zones,such as Xier River,Weishan,Lancang River,Maolan and Yunxian geothermal abnormal zones.Groundwater in geothermal anomaly zones is heated by deep circulation to form zonal distribution of low and medium temperature geothermal system.The circulation depth of geothermal water is 2.0~5.3km,and the chemical types and components of the hot spring water show diversity.In the north and south of Lancang River,the average geothermal gradients are 3.07℃/100m and 2.54℃/100m respectively.In order to avoid the heat damage,the railway line should pass through the recharge area and runoff area of geothermal water as far as possible to avoid the drainage area of geothermal water.Among the railway tunnel engineering,there are moderate heat hazards in Damaidi tunnel,Weibaoshan tunnel,Xinhua tunnel and Hongdoushan tunnel,and there are slight heat hazards in 12 tunnels such as Linbaoshan tunnel etc.Measures such as cooling and strengthening structure can be taken according to different conditions.