摘要
近年来随着环保理念的贯彻和对城市水资源保护的重视,许多地区对地下水抽排进行限制,导致大量基坑工程必须寻找新的止水方式。对此,“地下连续墙+水平冻结封底”的组合式冻结加固被提出,利用模型试验对其在不同水压地层中可行性和差异性进行了分析,验证了该支护方式的可行性。结果表明:(1)随着水头高度的增大,冻结壁水分补给速率有所提升,冻结壁交圈时间与地层水头高度呈正相关,而冻结壁厚度与地层水头高度呈负相关关系。(2)临时竖井受地层冻结影响,会有明显冻胀压迫作用,伴随冻结壁发育,冻胀力最终降至某一特定值,并趋于平稳,且其峰值与水头高度成正相关关系;(3)模型试验中冻结壁上部土体的最大位移点位于土体35 cm深度位置,其位移数据为2~3 mm;(4)基坑开挖期间,冻土帷幕的温度随着基坑的开挖和积极冻结的双重作用下能够维持相对的平衡,整个冻结壁保持基本稳定状态。研究成果可为该支护方式在基坑工程中的应用提供理论支撑。
In recent years,with the implementation of the concept of environmental protection and the needs of urban water resources protection,many areas have restricted the pumping of groundwater,resulting in a large number of foundation pit projects must find new ways to stop water.In this regard,a new foundation pit supporting method"underground diaphragm wall+horizontal frozen back cover"is proposed.The feasibility and difference of the combined freezing artificial method in different height of water head are analyzed by model test.The experimental results show that:①the connection for construction of frozen wall is positively correlated with formation head height,while the thickness of frozen wall is negatively correlated with formation head height.②Affected by stratum freezing,the temporary shaft will have obvious frost heaving compression.With the development of frozen wall,the frost heaving force will appear two peak values,and finally decrease to a certain value,and then tend to be stable,and the peak value is correlated with head height.③The maximum displacement point in the model test is 35cm layer position,and the displacement data is 2~3 mm.④During excavation unloading,The temperature of frozen soil curtain maintain relative balance with the double action of excavation of foundation pit and active freezing.The relevant research results have certain reference value for the application of combined freezing method in foundation pit engineering.
作者
郭飞
李兆平
韩雪刚
崔向阳
宋健平
Guo Fei;Li Zhaoping;Han Xuegang;Cui Xiangyang;Song Jianping(Beijing Municipal Engineering Group Co.,Ltd.,Beijing,100089,P.R.China;School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,P.R.China)
出处
《地下空间与工程学报》
CSCD
北大核心
2024年第2期535-545,共11页
Chinese Journal of Underground Space and Engineering
基金
国家自然科学基金(52172347)
唐山开滦集团资助项目(TZ2022-15,K2020-03)。
关键词
基坑工程
冻结温度场
模型试验
冻结法
基坑开挖
foundation pit engineering
freezing temperature field
model test
artificial freezing method
excavation of foundation pit
