摘要
以呼和浩特地铁1号线为依托,基于自主研发的冻融循环试验装置,针对基坑土体的温度分布、表面土体冻胀量、地下连续墙受力与变形特性进行室内试验,采用数值仿真分析了不同风速、含水率及温度下基坑的受力与变形特性。研究结果表明:基坑周围土体在从5℃到-30℃的降温过程中呈现双向冻结特征,靠近地下连续墙一定范围内土体最大冻结深度可达18.2 m(即基坑底面向下1.09 m);基坑土体及地下连续墙的最大变形随着冻融循环次数的增加而增大,并在6个冻融循环周期内趋于稳定,末次冻融周期地表隆起量最大可达首次冻结时的3.85倍;水平冻胀力沿地下连续墙大致呈抛物线型分布,最大冻胀力出现在地下连续墙的中部,在-30℃时可达775.8 kPa;风速对基坑土体热交换有显著影响,在风速为0~0.4 m·s^(-1)时风速和基坑水平土压力线性相关,风速为0.4~2.5 m·s^(-1)时土压力波动增长,风速大于2.5 m·s^(-1)后土压力基本稳定;在风速为0~0.4 m·s^(-1)时风速和地表变形线性相关,风速为0.4~2.5 m·s^(-1)时变形阶梯式增长,风速大于2.5 m·s^(-1)后变形基本稳定;当含水率从13.3%提升至33.3%时最大水平土压力增加44.2%;在不同的恒定负温下,环境温度越低最大水平冻胀力的位置越靠近基坑底部,-30℃时最大水平冻胀力可达0.95 MPa,地表最大变形可达56.6 mm。
Based on Hohhot Metro Line 1,a self-developed freeze-thaw cycle test device was used to conduct the laboratory test on the temperature distribution of foundation pit soil,the frost heaving amount of surface soil,and the stress and deformation characteristics of underground continuous wall,and the stress and deformation characteristics of the foundation pit under different wind speeds,water contents,and temperatures were analyzed by the numerical simulation.Analysis results show that the soil around the foundation pit exhibits bidirectional freezing characteristic during the cooling process from 5℃to-30℃,and the maximum freezing depth near the underground continuous wall can reach 18.2 m(the bottom of the foundation pit downward 1.09 m).The maximum deformations of foundation pit soil and underground continuous wall increase with the increase in the freeze-thaw cycles and tends to be stable in six freeze-thaw cycles.The maximum surface uplift during the last freeze-thaw cycle can reach 3.85 times that during the first freeze-thaw cycle.The horizontal frost heaving force is approximately parabolic in distribution along the underground continuous wall.The maximum frost heaving force appears in the middle of the underground continuous wall and can reach 775.8 kPa at-30℃.Wind speed has a significant effect on the heat exchange of foundation pit soil.The horizontal earth pressure of the foundation pit is linearly correlated with the wind speed of 0-0.4 m·s^(-1).The earth pressure fluctuates and increases with the wind speed of 0.4-2.5 m·s^(-1).When the wind speed is greater than 2.5 m·s^(-1),the earth pressure is basically stable.When the wind speed is 0-0.4 m·s^(-1),the surface deformation is linearly correlated with the wind speed.When the wind speed is 0.4-2.5 m·s^(-1),the deformation increases step by step.When the wind speed is greater than 2.5 m·s^(-1),the deformation is basically stable.When the water content increases from 13.3%to 33.3%,the maximum horizontal earth pressure increases by 44.2%.Under different constant negative temperatures,lower ambient temperature indicates that the maximum horizontal frost heaving force is closer to the bottom of the foundation pit.At-30℃,the maximum horizontal frost heaving force can reach 0.95 MPa,and the maximum surface deformation can reach 56.6 mm.
作者
杨晓华
蔡世春
何少华
邵莹
晏长根
YANG Xiao-hua;CAI Shi-chun;HE Shao-hua;SHAO Ying;YAN Chang-gen(School of Highway,Chang'an University,Xi'an 710064,Shaanxi,China;Shaanxi Transportation Holding Group Co.,Ltd.,Xi'an 710065,Shaanxi,China;China Railway First Survey and Design Institute Group Co.,Ltd.,Xi'an 710043,Shaanxi,China)
出处
《交通运输工程学报》
EI
CSCD
北大核心
2023年第4期233-247,共15页
Journal of Traffic and Transportation Engineering
基金
国家自然科学基金项目(42077265)
关键词
岩土工程
地铁车站基坑
冻土
模型试验
冻融循环
水热力耦合
水平土压力
geotechnical engineering
subway station foundation pit
frozen soil
model test
freeze-thaw cycle
hydrothermal coupling
horizontal earth pressure
作者简介
杨晓华(1961-),男,河北唐山人,长安大学教授,工学博士,从事岩土与隧道工程研究。
