负温对基坑悬臂桩水平冻胀力影响的模拟研究
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摘要
寒冷地区基坑悬臂桩支护工程,在桩后土体水平冻胀力作用下,易出现桩体倾斜、水平裂缝、剪断等问题.负温是水平冻胀力产生的关键因素,采用数值模拟方法,分别模拟粉质黏土、黏土在一定的负温变化下,桩体水平冻胀力的大小和分布模式,结果表明:负温越低,土体冻结速率越大,水平冻胀力越大;桩身范围内,水平冻胀力大致呈上下小、中间大的抛物线型分布,最大值出现在基坑的中下部,为开挖深度的0.5~0.8倍,力值约为冻胀前土压力的2~15倍,同时拟合出最大水平冻胀力与温度、桩顶位移之间的关系公式;此外,桩体水平位移随负温增加而增加,桩顶位置处,冻胀引起的水平位移为开挖引起位移量的0.88~11.38倍.
Supporting project of foundation pit cantilever pile in cold area,under the horizontal frost heaving force of soil,the pile may be appear these problems,such as tilt,horizontal crack or cut. Negative temperature is key factor of horizontal frost heaving force,with numerical simulation method,simulated silt clay,clay under certain negative temperature change,the size and distribution of pile horizontal frost heaving force,results showthat negative temperature is lower,the greater soil freezing rate,the larger horizontal frost heaving force; In the length of pile,horizontal frost heaving force is roughly fluctuation and large middle parabolic distribution,maximum value appeared in the foundation pit of the part,is 0. 5- 0. 8 times depth of excavation,frost heaving force value is 2- 15 times to the initial soil pressure. And fitting out formula of maximum horizontal frost heaving force with temperature or displacement of pile top in respectively. In addition,the horizontal displacements of pile increases with decrease of temperature,horizontal displacement caused by frost heave is 0. 88 to 11. 38 times of excavation displacement in pile top.
Supporting project of foundation pit cantilever pile in cold area,under the horizontal frost heaving force of soil,the pile may be appear these problems,such as tilt,horizontal crack or cut. Negative temperature is key factor of horizontal frost heaving force,with numerical simulation method,simulated silt clay,clay under certain negative temperature change,the size and distribution of pile horizontal frost heaving force,results showthat negative temperature is lower,the greater soil freezing rate,the larger horizontal frost heaving force; In the length of pile,horizontal frost heaving force is roughly fluctuation and large middle parabolic distribution,maximum value appeared in the foundation pit of the part,is 0. 5- 0. 8 times depth of excavation,frost heaving force value is 2- 15 times to the initial soil pressure. And fitting out formula of maximum horizontal frost heaving force with temperature or displacement of pile top in respectively. In addition,the horizontal displacements of pile increases with decrease of temperature,horizontal displacement caused by frost heave is 0. 88 to 11. 38 times of excavation displacement in pile top.
引文
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[2]Ding Jingkang,Lou Anjin.A field method of horizontal frost heaving force[J].Journal of Glaciology and Geocryology,1980(1):33-36.[丁靖康,娄安金.水平冻胀力的现场测定方法[J].冰川冻土,1980(1):33-36.]
[3]Guan Fengnian,Zhou Changqing,Ji Yongwei.Horizontal frost heaving force on the retaining structure[J].Water Resources and Hydropow er Engineering,1981(11):37-43.[管枫年,周长庆,赍永为.作用于支挡建筑物上的水平冻胀力[J].水利水电技术,1981(11):37-43.]
[4]Sui Tieling,Li Dazhuo,Na Wenjie,et al.Design method of horizontal frost heaving force on the retaining structure in seasonal frozen area[J].Journal of Hydraulic Engineering,1992(1):67-72.[隋铁龄,李大倬,那文杰,等.季节冻土区挡土墙水平冻胀力的设计取值方法[J].水利学报,1992(1):67-72.]
[5]Geng Ke.Impacts of freeze-thaw cycle on frost heaving forces on tunnel structures in cold regions[J].Journal of Glaciology and Geocryology,2013,35(4):913-919.[耿珂.冻融循环对寒区隧道结构冻胀力的影响[J].冰川冻土,2013,35(4):913-919.]
[6]Zhou Xiaohan,Zeng Yanhua,Yang Zongxian,et al.Discussion of anti-freeze and frost resistance of shallow buried tunnels in high latitude cold region[J].Journal of Glaciology and Geocryology,2016,38(1):121-128.[周小涵,曾艳华,杨宗贤,等.高纬度寒区浅埋隧道的温度场及防寒抗冻探讨[J].冰川冻土,2016,38(1):121-128.]
[7]Zhou Shengquan,Chen Haiming.Wall temperature field of a deep frozen shaft in Cretaceous strata[J].Journal of Glaciology and Geocryology,2013,35(5):1232-1236.[周盛全,陈海明.白垩系地层深井冻结温度场分布规律[J].冰川冻土,2013,35(5):1232-1236.]
[8]Zhao Lianping.Prevention and treatment of deep foundation pits in w inter cold injury[J].China Science and Technology Information,2015(5):130-131.[赵连平.深基坑越冬冻害的预防及处理[J].中国科技信息,2015(5):130-131.]
[9]Chen Yumin,Xu Dingping.FLAC/FLAC3D foundation and engineering examples[M].Beijing:China Water&Pow er Press,2013:53-56.[陈育民,徐鼎平.FLAC/FLAC3D基础与工程实例[M].北京:中国水利水电出版社,2013:53-56.]
[10]Engineering Geology Manual Editorial Board.Engineering geology manual[M].Beijing:China Architecture&Building Press,2007:160-161.[工程地质手册编委会.工程地质手册[M].北京:中国建筑工业出版社,2007:160-161.]
[11]Ministry of Housing and Urban-Rural Development of the People's Republic of China.GB 50324-2001,Code for engineering geological investigation of frozen ground[S].Beijing:China Architecture&Building Press,2001:23-26.[中华人民共和国住房和城乡建设部.GB 50324-2001,冻土工程地质勘察规范[S].北京:中国建筑工业出版社,2001:23-26.]