降雨对封闭块石层对流特征与水热状态的影响试验  

Experimental Study on Influence of Rainfall on Convective Properties and Hydrothermal State of Closed Block Stone Layer

作　　者：韩风雷[1,2] 邱凯驰 喻文兵 耿永奇 秦臻 陆妍 HAN Feng-lei;QIU Kai-chi;YU Wen-bing;GENG Yong-qi;QIN Zhen;LU Yan(State Key Laboratory of Mountain Bridge and Tunnel Engineering,Chongqing Jiaotong University,Chongqing 400074,China;School of Civil Engineering,Chongqing Jiaotong University,Chongqing 40o074,China;State Key Laboratory of Frozen Soil Engineering,Northwest Institute of Eco-environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,Gansu,China)

机构地区：[1]重庆交通大学山区桥梁及隧道工程国家重点实验室,重庆400074 [2]重庆交通大学土木工程学院,重庆400074 [3]中国科学院西北生态环境资源研究院冻土工程国家重点实验室,甘肃肃兰州730000

出　　处：《中国公路学报》2023年第3期156-164,共9页China Journal of Highway and Transport

基　　金：国家自然科学基金青年项目(41801053);重庆市自然科学基金项目(cstc2019jcyj-msxmX0835);中国博士后科学基金项目(2020M683710XB);冻土工程国家重点实验室开放基金项目(SKLFSE201903);山区桥梁及隧道工程国家重点实验室开放基金项目(SKLBT-19-003)。

摘　　要：块石路基作为解决青藏高原多年冻土冻胀融沉病害的关键技术而得到广泛应用。近年来青藏高原呈现湿化显著的趋势,夏季降雨携带的部分热量会快速入渗到块石层,从而影响块石路基的传热特性和水热状态,有必要开展降雨条件下块石路基热力学特性研究。基于室内试验,开展了不同降雨量、不同厚度下封闭块石层水热响应规律研究。结果表明:(1)在降雨条件下封闭块石层自然对流的发生与降雨量大小和块石层厚度有关。随降雨量增加,1.4 m厚度的块石层自然对流瑞利数最大值逐渐降低。当降雨量达到23 mm时,块石层不发生自然对流;而0.6 m厚度的块石层自然对流瑞利数最大值则随降雨量增加而逐渐增大,自然对流增强。(2)在降雨入渗作用下,1.4 m厚度的块石层内部与基底土层有升温效应,而0.6 m厚度的块石层基底土层有降温效应。与未来50年青藏高原预测升温速率每年0.052℃相比,降雨入渗对前者下伏土层的升温效应更为显著。(3)暖季的降雨入渗在短时间内会显著影响基底浅层土的体积含水量。随着降雨量的增加,体积含水量峰值有一定抬升,但每循环周期的峰值大小差异不大。主要是因为在经过冷季低温冻结后,块石体与土层之间的部分空隙被凝结冰填充,降雨难以入渗从而会产生基底水分累积。因此,在多雨地区应加强块石层与土层界面间的防排水措施。研究结果对于评价和预测降雨环境下封闭块石路基的热稳定性具有重要工程意义,并可为新建多年冻土区路基工程结构设计与病害防治提供参考。To solve the problem of the frost heaving and thaw settlement of permafrost embankment,the block-stone embankment was widely used in cold regions.The trend of humidification on the Qinghai-Tibet Plateau was greatly significant for the past few years.Part of the heat carried by the rainfall infiltration could affect the heat transfer property and hydrothermal regime on the block stone layer(BSL)in summer.It is necessary to investigate the cooling performance of the block-stone embankment under the condition of rainfall.The hydrothermal response was analyzed for the closed BSL in different depths under rainfall conditions based on laboratory tests.The results show that:(1)The natural convection of the closed BSLis related to the amount of precipitation and layer thickness under rainfall.As rainfall increases,the maximum Rayleigh number gradually decreases for the 1.4 m-thick of the BSL.When the rainfall is set to 23 mm,the natural convection does not occur for the BSL.For the 0.6 m-thick of the BSL,the maximum Rayleigh number was increased and natural convection is gradually enhanced.(2)The rainfall infiltration induces the warming phenomenon for the interior of the 1.4 m-thick of the BSL and the shallow base soil layer.Compared with the warming rate of 0.052℃·a-1on the Qinghai-Tibet Plateau in the next 50 years,that of the shallow base soil layers more greatly influenced by rainfall infiltration.However,it has a cooling effect on the soil layer of the 0.6 m-thick of the BSL.(3)Rainfall in the warm season has a marked impact on the volumetric water content of the shallow soil layer in a short time.However,the peak of the volumetric water content is a certain raised and not large with the increase of rainfall with the freeze-thaw cycle.The part of voids between the rock body and the soil layer could be filled with the frozenice after freezing at low temperatures in the cold season,which is difficult for rainfall infiltration,leading to water accumulation.Therefore,waterproof and drainage measures should be streng

关 键 词：道路工程 水热响应 室内试验 封闭块石层 降雨 对流特征 

分 类 号：U419.92[交通运输工程—道路与铁道工程]