考虑雨水感热的降雨对多年冻土水热变化影响模型研究  

Model study on rainfall effect on hydrothermal dynamics of permafrost considering rainwater sensible heat

作　　者：张明礼[1,2,3] 雷兵兵 周志雄 周凤玺 侯彦东[1] ZHANG Ming-li;LEI Bing-bing;ZHOU Zhi-xiong;ZHOU Feng-xi;HOU Yan-dong(School of Civil Engineering,Lanzhou University of Technology,Lanzhou,Gansu 730050,China;Western Engineering Research Center of Disaster Mitigation in Civil Engineering of Ministry of Education,Lanzhou University of Technology,Lanzhou,Gansu 730050,China;School of Earth Science and Engineering,Nanjing University,Nanjing,Jiangsu 210023,China)

机构地区：[1]兰州理工大学土木工程学院,甘肃兰州730050 [2]兰州理工大学西部土木工程防灾减灾教育部工程研究中心,甘肃兰州730050 [3]南京大学地球科学与工程学院,江苏南京210023

出　　处：《岩土力学》2023年第5期1530-1544,共15页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.42261028,No.41961010);中组部等“西部之光”访问学者项目(张明礼);中科院西部之光“西部青年学者”项目;陇原青年创新创业人才(个人)项目(张明礼);甘肃省基础研究创新群体项目资助(No.20JR5RA478)。

摘　　要：青藏高原暖湿化诱发的多年冻土和寒区工程水热变化是第三极冻土生态与地质演化问题的关注焦点。目前降雨影响下的多年冻土地表能量收支建模未考虑雨水温度的影响,忽略了降雨能量脉冲作用。在已有的冻土水热耦合理论的基础上,通过引入考虑雨水感热的地表能量平衡理论,完善了考虑降雨能量的冻土水热耦合模型,基于青藏高原北麓河现场监测验证了模型的有效性,并分析了夏季降雨对地表能量平衡和活动层水热的影响机制。结果表明:考虑雨水感热的修正模型模拟土壤体积含水率、温度和热通量的平均偏差误差分别在±1.198%、±0.704℃和±1.66 W/m^(2)之内,一致性指数分别大于0.877、0.929和0.937;优化后的模型提升了对地表吸放热状态的评估,能够较好地预测了雨后活动层水热的变化;夏季降雨增加地表蒸发潜热和雨水感热,降低地表净辐射、感热和土壤地表热通量使地面降温,降温效果与降雨强度正相关;同时受降雨时段影响,白天降雨事件的降温效果显著,雨水感热促进地表冷却,而夜间雨水短暂加热地表,蒸发潜热的显著作用使地表依旧持续降温。在地表温度梯度降低和雨水入渗的作用下,温度梯度水汽通量减少,液态水通量增加,在强降雨和连续降雨下出现液态水的向下输送和累积。但相比增加的液态水对流传热,活动层热传导、水汽扩散潜热和水汽对流传热的降低更显著,使土壤总热通量减少而导致土壤降温,延缓活动层温度的升高。The thermal-moisture dynamics of permafrost and cold region engineering caused by the trend of warming and humidification of the Qinghai-Tibet Plateau (QTP) are the focus of research on permafrost ecological and geological evolution in the third pole.Currently,the model of permafrost ground surface energy budget under the influence of rainfall does not consider the influence of rainwater temperature and neglects the effect of rainfall energy pulse.On the basis of the previous frozen soil hydro-thermal coupling theory,a permafrost hydrothermal coupling model considering the rainfall energy was constructed by introducing the surface energy equilibrium theory considering the rainwater sensible heat.Based on the on-site monitoring data of the Beiluhe in the QTP,the validity of the model was verified,and the influence mechanism of the summertime rainfall on the ground surface energy equilibrium and the thermal-moisture dynamics of the active layer was analyzed.The results show that the average deviation errors of soil volumetric water content,temperature,and heat flux simulated by the modified model considering rainwater sensible heat are within±1.198%,±0.704℃,and±1.66 W/m^(2),respectively,and the consistency indexes are greater than 0.877,0.929,and 0.937,respectively.The optimized model improves the assessment of the surface heat absorption or heat release state and can better predict the thermal-moisture dynamics of the active layer after rainfall.Summertime rainfall increases the surface evaporation latent heat and rainwater sensible heat but reduces the surface net radiation,sensible heat,and soil surface heat flux to cool the surface.The cooling efficiency is positively correlated with rainfall intensity.In addition,it is affected by the time of occurrence of the rainfall.The daytime rainfall has a significant cooling effect,and the rainwater sensible heat promotes the cooling of the surface.The rainwater at night temporarily heats the surface,but the significant effect of evaporation latent heat makes the g

关 键 词：多年冻土 雨水感热 耦合模型 地表能量平衡 水热变化 夏季降雨 

分 类 号：TU445[建筑科学—岩土工程]