武汉一级阶地基坑降水引起土层水位变化及压缩变形研究
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摘要
武汉一级阶地地层具有典型的二元结构特征,从浅层至深层土体渗透性逐渐增加,在基坑工程开挖降水过程中,随着疏干含水层水位的下降,各层土体水位变化特点各不相同,水位的变化影响着土体固结的压缩变形。采用现场群井抽水试验的方法,通过在抽水试验期间对不同深度含水层水位的观测及不同深度土体沉降的监测,结合各层土体性质及相关理论对武汉一级阶地基坑降水引起的土层水位变化及压缩变形规律进行研究。结果表明,武汉一级阶地基坑降水水位变化存在着明显的时空效应,沉降与水位变化密切相关,且沉降过程中土层中出现架空效应。
Layers in the Wuhan first terrace have the typical characteristics of the binary structural stratum,whose permeabilities increase gradually from the superficial layer to the deep layer. In the foundation pit dewatering engineering, with the fall of groundwater level in the objective aquifer, the laws of each groundwater level variation are different. What 's more, the variation in groundwater level affects the consolidation settlement of soil deformation. In this paper,the field group pumping test is used,and during the pumping test,groundwater levels at different depths of the aquifers are observed. In the same time,the ground subsidence at different depths is monitored. Combining with the properties of soil and the correlation theory,the groundwater level variation and ground subsidence caused by foundation pit dewatering at the Wuhan first terrace are examined. The results show that in the Wuhan first terrace,there is significant "timespace effect"on groundwater level variation,and ground subsidence is closely related to groundwater level variation,and there is "aerial effect"in ground subsidence.
Layers in the Wuhan first terrace have the typical characteristics of the binary structural stratum,whose permeabilities increase gradually from the superficial layer to the deep layer. In the foundation pit dewatering engineering, with the fall of groundwater level in the objective aquifer, the laws of each groundwater level variation are different. What 's more, the variation in groundwater level affects the consolidation settlement of soil deformation. In this paper,the field group pumping test is used,and during the pumping test,groundwater levels at different depths of the aquifers are observed. In the same time,the ground subsidence at different depths is monitored. Combining with the properties of soil and the correlation theory,the groundwater level variation and ground subsidence caused by foundation pit dewatering at the Wuhan first terrace are examined. The results show that in the Wuhan first terrace,there is significant "timespace effect"on groundwater level variation,and ground subsidence is closely related to groundwater level variation,and there is "aerial effect"in ground subsidence.
引文
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[2]马郧,徐光黎,刘佑祥.长江Ⅰ级阶地某深基坑地下水控制分析[J].安全与环境工程,2012(5):144-149.[MA Y,XU G L,LIU Y X.Ground water controlling of a deep foundation pit on the first terrace of Yangtze River[J].Safety and EnvironmentalEngineering,2012(5):144-149.(in Chinese)]
[3]宁国民,陈国金,徐绍宇,等.武汉城市地下空间工程地质研究[J].水文地质工程地质,2006,33(6):29-35.[NING G M,CHEN G J,XU S Y,et al.Engineering geological research on the underground space of Wuhan City[J].Hydrogeology&Engineering Geology,2006,33(6):29-35.(in Chinese)]
[4]张建山.基坑抽水地面沉降理论与工程应用[D].西安:西安理工大学,2005.[ZHANG J S.The Fundamental of Land Subsidence and Case Studies Due to Groundwater Withdrawal[D].Xi'an:Xi'an University of Technology,2005.(in Chinese)]
[5]叶为民,万敏,陈宝,等.深基坑承压含水层降水对地面沉降的影响[J].地下空间与工程学报,2009,5(增刊2):1799-1805.[YE W M,WAN M,CHEN B,et al.Influence of dewatering of confined aquifers on land subsidence during deep excavation[J].Chinese Journal of Underground Space and Engineering,2009,5(Sup2):1799-1805.(in Chinese)]
[6]张勇,赵云云.基坑降水引起地面沉降的实时预测[J].岩土力学,2008,29(6):1593-1596.[ZHNAG Y,ZHAO Y Y.Real time prediction of land subsidence caused by foundation pit dewatering[J].Rock and Soil Mechanics,2008,29(6):1593-1596.(in Chinese)]
[7]冯晓腊,张睿敏,熊宗海,等.武汉某工程超深基坑降水设计与技术应用[J].施工技术,2015(增刊2):11-14.[FENG X L,ZHANG R M,XIONG Z H,et al.Dewatering design and technology application of super deep foundation excavation in a project in Wuhan[J].Construction Technology,2015(Sup2):11-14.(in Chinese)]
[8]徐杨青,朱小敏.长江中下游一级阶地地层结构特征及深基坑变形破坏模式分析[J].岩土工程学报,2006,28(增刊1):1794-1798.[XU Y Q,ZHU X M.Studies on strata characteristics and model of deformation and collapse of deep excavation in the first terrace of Yangtze River[J].Chinese Journal of Geotechnical Engineering,2006,28(Sup1):1794-1798.(in Chinese)]
[9]冯晓腊,蔡娇娇,熊宗海,等.落底式止水帷幕条件下深基坑群井试验研究[J].水文地质工程地质,2016,43(6):107-112.[FENG X L,CAI J J,XIOMG Z H,et al.Research on well group pumping test for foundation pit with drop waterproof curtain[J].Hydrogeology&Engineering Geology,2016,43(6):107-112.(in Chinese)]
[10]张弘怀,郑铣鑫,唐仲华,等.宁波平原地面沉降全耦合数值模拟研究[J].水文地质工程地质,2013,40(4):77-82.[ZHANG H H,ZHENG X X,TANG Z H,et al.A study of full coupling numerical simulation of land subsidence in the Ningbo plain[J].Hydrogeology&Engineering Geology,2013,40(4):77-82.(in Chinese)]
[11]李英,何忠泽,严桂华,等.武汉二元结构地层基坑降水及其地面沉降研究[J].岩土工程学报,2012,34(增刊1):767-772.[LI Y,HE Z Z,YAN G H,et al.Excavation dewatering and ground subsidence in dual structural stratum of Wuhan[J].Chinese Journal of Geotechnical Engineering,2012,34(Sup1):767-772.(in Chinese)]
[12]熊小锋,施小清,吴剑锋,等.弹塑性变形条件下抽水引起的地面沉降三维数值模拟[J].水文地质工程地质,2017,44(2):151-159.[XIONG X F,SHI X Q,WU J F,et al.3D numerical simulation of elasto-plastic land subsidence induced by groundwater pumping[J].Hydrogeology&Engineering Geology,2017,44(2):151-159.(in Chinese)]
[13]马郧.武汉长江Ⅰ级阶地超深基坑支护结构设计参数选取与变形关系研究[D].武汉:中国地质大学(武汉),2014.[MA Y.Research on the relationship between deformation and design parameters for ultra deep foundation pit retaining structure in Wuhan Yangtze river first terrace[D].Wuhan:China University of Geosciences,2014.(in Chinese)]