天津滨海地区深部黏土层弹塑性变形特征与地面沉降关系研究
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摘要
利用在滨海新区施工的2眼全取芯钻孔(G2和G3),通过原状土样工程特性指标测试、固结压力试验、0-P_0反复加、卸荷试验及地面沉降分层标监测数据分析等,系统阐述了滨海地区深部黏性土层弹塑性变形特征与地面沉降的关系。结果表明:天津滨海地区100 m以浅主要为欠固结土层;100～400 m土层处于超固结和微超固结状态,主要是由过去地下水超量开采造成的;400 m以下土层以正常固结为主。G2和G3孔不同层位黏性土层在反复加、卸荷试验过程中表现出塑性变形量逐渐减小,而弹性变形量几乎不变,与反复加、卸荷次数无关,表明黏性土层在水位反复升降条件下,逐渐变为以弹性变形为主。黏性土层这种特性显示,在地下水位反复升降多次后,黏性土层将会逐渐变成弹性体,在水位恢复时,将产生同步回弹,对防治地面沉降具有重要意义。分析弹塑性变形与黏性土层深度、天然含水率和黏粒含量的相关性发现:弹性变形量与黏性土层深度、天然含水率及黏粒含量呈正相关性;塑性变形量与深度相关性不明显,与天然含水率和黏粒含量呈负相关性。
Two boreholes of G2 and G3 were drilled at Tanggu and Dagang in Tianjin, and undisturbed samples were extracted at various depths. Through laboratory test of all soil samples, this study measured the physical and mechanical properties and conducted consolidation test and repeated loading and unloading tests for clayey soils. By analyzing the test results, this study delineated the characteristics and influence factors of elastic-plastic deformation. Study results indicate that clayey soils in depth less than 100 m are under-consolidated soft soil. Clayey soils in depth from 100 m to 400 m are in the states of over-consolidated or slightly over-consolidated, which causes by long-term over-exploitation of groundwater in the past. Deep clayey soils in depth more than 400 m show the state of normal consolidated. Based on the repeated loading and unloading tests of clayey soils in boreholes G2 and G3, it is found that plastic deformation decreases gradually and elastic deformation remains unchanged, independent on repeating times. The test results also suggest that clayey soils will gradually become an elastic body in the process of groundwater fluctuation, and deformation will rebound when groundwater recovers. By analyzing correlation between elastic-plastic deformation and depth, natural moisture content and clay content of clayey soil, it is found that elastic deformation shows positive correlation with depth, natural moisture content and clay content, and plastic deformation shows negative correlation with natural moisture content and clay content and no obvious correlation with depth.
Two boreholes of G2 and G3 were drilled at Tanggu and Dagang in Tianjin, and undisturbed samples were extracted at various depths. Through laboratory test of all soil samples, this study measured the physical and mechanical properties and conducted consolidation test and repeated loading and unloading tests for clayey soils. By analyzing the test results, this study delineated the characteristics and influence factors of elastic-plastic deformation. Study results indicate that clayey soils in depth less than 100 m are under-consolidated soft soil. Clayey soils in depth from 100 m to 400 m are in the states of over-consolidated or slightly over-consolidated, which causes by long-term over-exploitation of groundwater in the past. Deep clayey soils in depth more than 400 m show the state of normal consolidated. Based on the repeated loading and unloading tests of clayey soils in boreholes G2 and G3, it is found that plastic deformation decreases gradually and elastic deformation remains unchanged, independent on repeating times. The test results also suggest that clayey soils will gradually become an elastic body in the process of groundwater fluctuation, and deformation will rebound when groundwater recovers. By analyzing correlation between elastic-plastic deformation and depth, natural moisture content and clay content of clayey soil, it is found that elastic deformation shows positive correlation with depth, natural moisture content and clay content, and plastic deformation shows negative correlation with natural moisture content and clay content and no obvious correlation with depth.
引文
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[14]白晋斌,牛修俊.天津新生界固结特征与地面沉降[J].中国地质灾害与防治学报,2010,21(1):42-46.BAI Jin-bin,NIU Xiu-jun.Cenozoic consolidation characteristics and land subsidence in Tianjin[J].The Chinese Journal of Geological Hazard and Control,2010,21(1):42-46.
[15]李桂玲.天津海岸带松散岩类地下水地球化学特征调查与评价[D].北京:中国地质大学(北京),2007.LI Gui-ling.Investigation and evaluation of geochemical characteristics of unconsolidated rock groundwater in Tianjin coastal zone[D].Beijing:China University of Geosciences(Beijing),2007.
[16]师旭超,韩阳.卸荷作用下软黏土回弹吸水试验研究[J].岩土力学,2010,31(3):732-742.SHI Xu-chao,HAN Yang.Water absorption test of soft clay after rebound under unloading[J].Rock and Soil Mechanics,2010,31(3):732-742.
[17]张云,薛禹群,叶淑君,等.地下水位变化模式下含水砂层变形特征及上海地面沉降特征分析[J].中国地质灾害与防治学报,2006,17(3):103-108.ZHANG Yun,XUE Yu-qun,YE Shu-jun,et al.Analysis of deformation of sand strata and land subsidence based on modes of groundwater level changes in Shanghai city[J].The Chinese Journal of Geological Hazard and Control,2006,17(3):103-108.
[18]田芳,郭萌,罗勇,等.北京地面沉降区土体变形特征[J].中国地质,2012,39(1):236-242.TIAN Fang,GUO Meng,LUO Yong,et al.The deformation behavior of soil mass in the subsidence area of Beijing[J].Geology in China,2012,39(1):236-242.
[19]翟子梅,沈键,孙振营,等.天津城市地质调查成果报告[R].天津:天津市地质调查研究院,2009.ZHAI Zi-mei,SHEN Jian,SUN Zhen-ying,et al.Urban geological survey report of Tianjin[R].Tianjin:Tianjin Institute of Geological Survey,2009.
[20]黄晓明,丁尚起,王润华.浅析塘沽区地面沉降原因与控制[J].地下水,2009,31(1):135-137.HUANG Xiao-ming,DING Shang-qi,WANG Run-hua.Analysis of controlling factors for land subsidence in Tanggu of Tianjin[J].Groundwater,2009,31(1):135-137.
[21]王淼,陆阳,郑玉萍,等.基于线性回归分析的地下水开采与地面沉降相关关系研究[J].中国水运,2006,15(7):108-110.WANG Miao,LU Yang,ZHENG Yu-ping,et al.A study of the relationship between exploitation of groundwater and land subsidence based on linear regression analysis[J].China Water Transport,2006,15(7):108-110.
[22]牛修俊.地层的固结特征与地面沉降临界水位控沉[J].中国地质灾害与防治学报,1998,9(2):68-74.NIU Xiu-jun.Characteristics of strata consolidation and land subsidence controlling by critical water level[J].The Chinese Journal of Geological Hazard and Control,1998,9(2):68-74.
[23]王秀艳,刘长礼,张云.超固结黏性土变形特征及可持续开采水位降的室内试验确定方法[J].岩土力学,2006,27(6):875-879.WANG Xiu-yan,LIU Chang-li,ZHANG Yun.Laboratory tests for determination of deformation characteristics of overconsolidated clayey soils and sustainable exploitation groundwater level[J].Rock and Soil Mechanics,2006,27(6):875-879.
[2]LOFGREN B E.Changes in aquifer-system properties with ground water depletion[C]//Proceedings of the International Conference on Evaluation and Prediction of Land Subsidence.Pensacola:American Society of Civil Engineers,1979:26-46.
[3]ZUO H,LIU T Z,LIN X H.Economic benefit risk assessment of controlling land subsidence in Shanhai[J].Environmental Geology,1993,21(4):208-211.
[4]董克刚,周俊,于强,等.天津市地面沉降的特征及其危害[J].地质灾害与环境保护,2007,18(1):67-70.DONG Ke-gang,ZHOU Jun,YU Qiang,et al.Feature of the land subsidence and its damage in Tianjin city[J].Journal of Geological Hazards and Environment Preservation,2007,18(1):67-70.
[5]刘欢欢,张有全,王荣,等.京津高铁北京段地面沉降监测及结果分析[J].地球物理学报,2016,59(7):2424-2432.LIU Huan-huan,ZHANG You-quan,WANG Rong,et al.Monitoring and analysis of land subsidence along the Beijing-Tianjin high-speed railway[J].Chinese Journal of Geophysics,2016,59(7):2424-2432.
[6]潘云,潘建刚,宫辉力,等.天津市区地下水开采与地面沉降关系研究[J].地球与环境,2004,32(2):36-39.PAN Yun,PAN Jian-gang,GONG Hui-li,et al.Research on the relation between groundwater exploitation and subsidence in Tianjin proper[J].Earth and Environment,2014,32(2):36-39.
[7]董克刚,王伟,于强,等.天津市地面沉降防治历史的调查研究及启示[J].中国地质灾害与防治学报,2008,19(3):54-59.DONG Ke-gang,WANG Wei,YU Qiang,et al.History and enlightenment of land subsidence controlling in Tianjin city[J].The Chinese Journal of Geological Hazard and Control,2008,19(3):54-59.
[8]杨吉龙,曹国亮,李红,等.天津滨海地区晚新生代地层自然固结与地面沉降研究[J].岩土力学,2014,35(9):2579-2586.YANG Ji-long,CAO Guo-liang,LI Hong,et al.Natural consolidation of late cenozoic era clay and land subsidence in the Tianjin coastal area[J].Rock and Soil Mechanics,2014,35(9):2579-2586.
[9]张百鸣,金爱善.天津市滨海地区地热资源开发对地面沉降的影响[J].中国地质灾害与防治学报,1998,9(2):112-117.ZHANG Bai-ming,JIN Ai-shan.Effect of extracting geothermal resources on land subsidence in Binhai area of Tianjin city[J].The Chinese Journal of Geological Hazard and Control,1998,9(2):112-117.
[10]林黎,赵苏民,李丹,等.深层地热水开采与地面沉降的关系研究[J].水文地质工程地质,2006,(3):34-36.LIN Li,ZHAO Su-min,LI Dan,et al.A study of the relationship between exploitation of geothermal water in deep-seated aquifers and land subsidence[J].Hydrogeology&Engineering Geology,2006,(3):34-36.
[11]夏大平,王心义,林健旺,等.天津地热开发对环境地质条件的影响[J].山东科技大学学报,2008,27(5):14-18.XIA Da-ping,WANG Xin-yi,LIN Jian-wang,et al.The impact of geothermal development on environmental geology in Tianjin[J].Journal of Shandong University of Science and Technology,2008,27(5):14-18.
[12]SUDDEEPONG A,CHAI Jin-chun,SHEN Shui-long,et al.Deformation behaviour of clay under repeated one-dimensional unloading-reloading[J].Canadian Geotechnical Journal,2014,52:1-10.
[13]王若柏,孙东平,耿世昌,等.天津地区地面沉降及其对地理环境的影响[J].地理学报,1994,49(4):317-323.WANG Ruo-bai,SUN Dong-ping,GENG Shi-chang,et al.Dynamics of ground subsidence and its effects on geogeaphical environment in Tianjin area[J].Acta Geographica Sinica,1994,49(4):317-323.
[14]白晋斌,牛修俊.天津新生界固结特征与地面沉降[J].中国地质灾害与防治学报,2010,21(1):42-46.BAI Jin-bin,NIU Xiu-jun.Cenozoic consolidation characteristics and land subsidence in Tianjin[J].The Chinese Journal of Geological Hazard and Control,2010,21(1):42-46.
[15]李桂玲.天津海岸带松散岩类地下水地球化学特征调查与评价[D].北京:中国地质大学(北京),2007.LI Gui-ling.Investigation and evaluation of geochemical characteristics of unconsolidated rock groundwater in Tianjin coastal zone[D].Beijing:China University of Geosciences(Beijing),2007.
[16]师旭超,韩阳.卸荷作用下软黏土回弹吸水试验研究[J].岩土力学,2010,31(3):732-742.SHI Xu-chao,HAN Yang.Water absorption test of soft clay after rebound under unloading[J].Rock and Soil Mechanics,2010,31(3):732-742.
[17]张云,薛禹群,叶淑君,等.地下水位变化模式下含水砂层变形特征及上海地面沉降特征分析[J].中国地质灾害与防治学报,2006,17(3):103-108.ZHANG Yun,XUE Yu-qun,YE Shu-jun,et al.Analysis of deformation of sand strata and land subsidence based on modes of groundwater level changes in Shanghai city[J].The Chinese Journal of Geological Hazard and Control,2006,17(3):103-108.
[18]田芳,郭萌,罗勇,等.北京地面沉降区土体变形特征[J].中国地质,2012,39(1):236-242.TIAN Fang,GUO Meng,LUO Yong,et al.The deformation behavior of soil mass in the subsidence area of Beijing[J].Geology in China,2012,39(1):236-242.
[19]翟子梅,沈键,孙振营,等.天津城市地质调查成果报告[R].天津:天津市地质调查研究院,2009.ZHAI Zi-mei,SHEN Jian,SUN Zhen-ying,et al.Urban geological survey report of Tianjin[R].Tianjin:Tianjin Institute of Geological Survey,2009.
[20]黄晓明,丁尚起,王润华.浅析塘沽区地面沉降原因与控制[J].地下水,2009,31(1):135-137.HUANG Xiao-ming,DING Shang-qi,WANG Run-hua.Analysis of controlling factors for land subsidence in Tanggu of Tianjin[J].Groundwater,2009,31(1):135-137.
[21]王淼,陆阳,郑玉萍,等.基于线性回归分析的地下水开采与地面沉降相关关系研究[J].中国水运,2006,15(7):108-110.WANG Miao,LU Yang,ZHENG Yu-ping,et al.A study of the relationship between exploitation of groundwater and land subsidence based on linear regression analysis[J].China Water Transport,2006,15(7):108-110.
[22]牛修俊.地层的固结特征与地面沉降临界水位控沉[J].中国地质灾害与防治学报,1998,9(2):68-74.NIU Xiu-jun.Characteristics of strata consolidation and land subsidence controlling by critical water level[J].The Chinese Journal of Geological Hazard and Control,1998,9(2):68-74.
[23]王秀艳,刘长礼,张云.超固结黏性土变形特征及可持续开采水位降的室内试验确定方法[J].岩土力学,2006,27(6):875-879.WANG Xiu-yan,LIU Chang-li,ZHANG Yun.Laboratory tests for determination of deformation characteristics of overconsolidated clayey soils and sustainable exploitation groundwater level[J].Rock and Soil Mechanics,2006,27(6):875-879.