摘要
两河口水电站是雅砻江干流规划开发中的中游控制性龙头电站,大坝为300米级砾石土心墙堆石坝。由于地处川西高原气候区,冬季气候寒冷干燥,大坝心墙土料填筑过程中面临着冻融问题的困扰。基于一个完整冬季的现场监测,系统分析了这一寒区大坝心墙建筑过程中砾石土、接触黏土土料温度变化规律、冻融特征与影响因素以及现有保温措施防冻效果。结果表明,无保温措施条件下,砾石土、接触黏土均出现了负温冻结现象,其中砾石土最大冻结深度达20 cm,接触黏土达14 cm,土料冻结持续时间不超过1个昼夜,为短时冻土。土料降温冻结过程以与外界大气对流换热过程为主,受气温、风速条件影响显著,波动范围较大,而升温融化过程以太阳辐射增温过程为主,与有效辐射起始时间密切相关,因此波动范围较小。监测期内,采用三布两膜保温材料覆盖可有效防止心墙土料冻结的发生,有、无保温材料覆盖条件下浅层土料最低温度可相差约5℃。结合监测结果和现场实际,建议将现有心墙防渗土料半幅填筑方式转换为全幅填筑,并研发轻质、憎水保温材料及其快速收放机械设备,以提高填筑作业进度、强化防冻效果。系统完整的现场实测结果,可为未来寒区水电大坝建设提供基础数据和参考。
Lianghekou Hydropow er Station is a control leading station in the middle reaches of the Yalong River.The dam of the station is a 300-m-high rock-fill dam constructed with gravel soil core w all. Because of the dry and cold climate in w inter,filling of anti-seepage soil material is alw ays affected by freezing-thaw ing. In this paper,based on monitored temperature of one w inter in 2016/2017,the freezing-thaw ing characteristics and influence factors of gravel soil and clay soil and the effect of thermal insulation method were analyzed. The results show ed that shallow gravel soil and clay soil without thermal insulation all experienced freezing during the monitored w inter,but the freezing duration was less than 24 hours. The maximum freezing depth of gravel soil and clay soil could reach 20 and 14 cm,respectively. The freezing process of the soil was controlled by heat convection with ambient air,thus was heavily influenced by w ind speed. The thaw ing process was controlled by heat radiation,thus the beginning of the thaw ing was closely related to the time of sun rise. During the monitoring period,coverage of thermal insulation material w ould effectively prevent freezing of the soil; the difference of the minimum temperature of soil was as much as 5 ℃ betw een the soils with and without thermal insulations. From the monitoring results and field conditions,one can see that light and hydrophobic thermal insulation materials are needed,as w ell as quick package machine for thermal insulation materials. Also,it is considered that w hole surface filling of the dam core w ill be better than half surface filling. The monitored data in this paper w ill be useful for dam construction in cold regions in the future.
作者
穆彦虎
朱忻怡
岳攀
王新斌
任秀玲
张振宇
俞祁浩
MU Yanhu;ZHU Xinyi;YUE Pan;WANG Xinbin;REN Xiuling;ZHANG Zhenyu;YU Qihao(State Key Laboratory of Frozen Soil Engineering,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences Lanzhou 730000,China;School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;Lianghekou Construction Administration,Yalong River Hydropower Development Company,Ltd.,Chengdu 610051,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《冰川冻土》
CSCD
北大核心
2018年第4期756-763,共8页
Journal of Glaciology and Geocryology
基金
雅砻江流域水电开发有限公司科研试验项目(LHKA-G20160*)
国家自然科学基金项目(41690144)资助
关键词
冻融特征
保温材料
防渗土料
心墙
寒区大坝
freezing-thawing characteristics
thermal insulation
anti-seepage soils
core wall
cold region dam
