不同荷载条件下冻土融化沉降过程试验研究  

Experimental study of thaw-settlement process of frozen soil under different load conditions

作　　者：黄永庭 马巍 何鹏飞 栗晓林[1,2,4] HUANG Yongting;MA Wei;HE Pengfei;LI Xiaolin(State Key Laboratory of Frozen Soil Engineering,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China;School of Science,Lanzhou University of Technology,Lanzhou 730050,China;College of Civil Engineering and Architecture,Jiaxing University,Jiaxing 314001,Zhejiang,China)

机构地区：[1]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,甘肃兰州730000 [2]中国科学院大学,北京100049 [3]兰州理工大学理学院,甘肃兰州730050 [4]嘉兴学院建筑工程学院,浙江嘉兴314001

出　　处：《冰川冻土》2021年第1期184-194,共11页Journal of Glaciology and Geocryology

基　　金：中国科学院科研仪器设备研制项目(28Y928581);国家自然科学基金重点项目(41630636)资助。

摘　　要：融沉是困扰多年冻土区工程建设与安全运营的关键因素之一。通过室内试验,针对两种初始干密度不同的青藏粉质黏土,在-8~24℃之间正弦波动的周期温度边界条件下,分别开展了无荷载、静荷载及动荷载作用下冻结饱和试样的融沉试验(试样的初始温度为-1℃),研究了试样内部温度、变形、孔隙水压力的时间变化过程。结果表明:温度边界相同时,在不同荷载作用下试样内部温度响应过程差异显著,反映了荷载对冻土融化速率的影响。在无荷载作用下,试样的竖向变形呈线性发展趋势,每次冻融过程中的融沉变形变化不大。在静荷载和动荷载作用下,试样的竖向变形呈先快速增加后逐渐稳定的趋势,且融化沉降变形主要发生在前3~4个冻融循环过程。试验结束时,在静、动荷载作用下试样最终变形量大于无荷载作用下,且干密度较小时竖向变形较大。在动荷载作用下,试样内部孔隙水压力变化幅度大于静荷载,且在前3次冻融循环过程中,动荷载作用下试样内部孔隙水压力消散数值大于静荷载,之后随着冻融循环次数的增加两者差异逐渐减小。试样融沉变形过程与温度变化、孔隙水压力的积累和消散过程密切相关。试验结果可为复杂边界条件下融化固结理论研究和工程中地基土体的融沉变形预测提供依据。Thaw settlement is one of the key factors those could affect the construction and safety of projects in permafrost areas.Through experimental tests,thawing settlement tests of the frozen saturated soil samples with the initial temperature of-1℃under unload,static and dynamic loads are carried out for two soil samples of Qinghai-Tibet silty clay with different initial dry densities at periodical temperature boundary conditions with sinusoidal fluctuations between-8℃and 24℃.and the variation of temperature,vertical deformation and pore water pressure in soil samples under different loads are investigated.The results show that the temperature response processes in the soil samples vary significantly under different loads when the temperature boundary conditions are same,reflecting the effect of load on the thawing rate of frozen soil.The vertical deformation of the soil samples under unload shows a linear development trend,and the thaw settlement changes little during each freezing-thawing process.However,the vertical deformation of the soil samples tends to increase rapidly and then stabilize gradually under the static and dynamic loads,and the thaw settlement deformation mainly occurs in the first 3~4 freeze-thaw cycle process.At the end of the test,the final vertical deformation of the soil samples under the static and dynamic loads is greatly larger than that under the unload,and the final vertical deformation is larger when the initial dry density is smaller.The changing amplitude of pore water pressure in the soil samples under the dynamic load is significantly larger than that under the static load,and during the first three freeze-thaw cycles,the pore water pressure dissipation value under the dynamic load is larger than that under the static load,and then the difference in pore water pressure gradually decreases with increasing freeze-thaw cycles.The thaw settlement deformation of the soil samples is closely related to the temperature change,pore water pressure accumulation and dissipation process.The

关 键 词：融化速率 变形 孔隙水压力 冻融循环 不同荷载 

分 类 号：P642.14[天文地球—工程地质学]