黄土隧道地基湿陷变形评价方法探讨
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摘要
隧道穿越自重湿陷性黄土地层时,可能遭受浸水作用下地基湿陷变形的附加作用而产生结构破坏。针对隧道衬砌结构的湿陷性黄土地基,结合隧道围岩及地基的自重湿陷变形特征,首先,提出浅埋隧道围岩压力、衬砌结构自重荷载构成基底压力和隧道两侧基底面分布土层自重共同作用下地基土的附加应力计算方法,以及考虑地基土自重应力的湿陷压缩应力计算方法。其次,在基本物性与构度、构度与结构压缩屈服应力、孔隙比和初始孔隙比比值与压缩应力和结构压缩屈服应力比值关系的基础上,建立自重湿陷系数和湿陷系数的计算方法。依据大厚度自重湿陷黄土场地不同埋深范围黄土具有不同自重湿陷系数门槛值的特征,得到了场地的自重湿陷变形和隧道地基的湿陷变形的计算方法。最后,通过数值计算分析,模拟隧道地基湿陷变形不同沉降差作用下衬砌结构应力场和塑性域发展,随着不均匀湿陷变形的增加,隧道衬砌结构塑性区范围不断增大,并结合铁路路基沉降控制标准,建议隧道地基湿陷变形0~5 cm为一级、5~10 cm为二级、大于10 cm为三级。
When tunnel passes through a self-weight collapsible loess stratum,lining structure of loess tunnel may be destructed by the additional collapse deformation of loess upon water immersion. In this paper,the surrounding pressure of loess tunnel,the characteristics of the self-weight collapse deformation of collapsible loess tunnel foundation,and the destruction of lining structure caused by the collapse deformation of foundation are discussed. Firstly,a calculation method for the additional stresses of foundation soil under the surrounding pressure and weight of lining structure and under soil self-weight stress of both sides of tunnel was proposed. The collapsible compression stress is obtained by the additional stresses adding the soil weight under foundation. Secondly,the relationships between the structural index and physical index,between the structural index and structural yield stress,and between the ratio of void ratio to initial void ratio and the ratio of compressive stress to structural yield stress were used to establish a calculation method for the collapsible coefficient and self-weight collapsible coefficient of loess by comparing the confined compression curves of loess in natural moisture content and in saturation. According to the fact that the loess at the different depths has the different threshold values in the region with thick layer of self-weight collapsible loess,the self-weight collapsible deformation of the site and the collapsible deformation of the tunnel foundation are derived. Finally,the different collapsible deformations of tunnel foundation,the stress fields and plastic region of lining structure were analyzed numerically. The larger the settlement difference is,the more extensive the range of plastic region is. Three grades of collapse deformation of tunnel subgrade,0–5,5–10 cm and more than 10 cm are proposed according to the control standard of railway bed.
When tunnel passes through a self-weight collapsible loess stratum,lining structure of loess tunnel may be destructed by the additional collapse deformation of loess upon water immersion. In this paper,the surrounding pressure of loess tunnel,the characteristics of the self-weight collapse deformation of collapsible loess tunnel foundation,and the destruction of lining structure caused by the collapse deformation of foundation are discussed. Firstly,a calculation method for the additional stresses of foundation soil under the surrounding pressure and weight of lining structure and under soil self-weight stress of both sides of tunnel was proposed. The collapsible compression stress is obtained by the additional stresses adding the soil weight under foundation. Secondly,the relationships between the structural index and physical index,between the structural index and structural yield stress,and between the ratio of void ratio to initial void ratio and the ratio of compressive stress to structural yield stress were used to establish a calculation method for the collapsible coefficient and self-weight collapsible coefficient of loess by comparing the confined compression curves of loess in natural moisture content and in saturation. According to the fact that the loess at the different depths has the different threshold values in the region with thick layer of self-weight collapsible loess,the self-weight collapsible deformation of the site and the collapsible deformation of the tunnel foundation are derived. Finally,the different collapsible deformations of tunnel foundation,the stress fields and plastic region of lining structure were analyzed numerically. The larger the settlement difference is,the more extensive the range of plastic region is. Three grades of collapse deformation of tunnel subgrade,0–5,5–10 cm and more than 10 cm are proposed according to the control standard of railway bed.
引文
[1]赵勇,李国良,喻渝.黄土隧道工程[M].北京:中国铁道出版社,2011:239–258.(ZHAO Yong,LI Guoliang,YU Yu.Loess tunnel engineering[M].Beijing:China Railway Publishing House,2011:239–258.(in Chinese))
[2]中华人民共和国国家标准编写组.GB 50025—2004湿陷性黄土地基建筑规范[S].北京:中国建筑工业出版社,2004.(The National Standards Compilation Groups of the People's Republic of China.GB50025—2004 Code for building construction in collapsible loess regions[S].Beijing:China Architecture and Building Press,2004.(in Chinese))
[3]邵生俊,杨春鸣,焦阳阳,等.湿陷性黄土隧道的工程性质分析[J].岩土工程学报,2013,35(9):1 580–1 590.(SHAO Shengjun,YANG Chunming,JIAO Yangyang,et al.Engineering properties of collapsible loess tunnel[J].Chinese Journal of Geotechnical Engineering,2013,35(9):1 580–1 590.(in Chinese))
[4]邵生俊,李骏,李国良,等.大厚度自重湿陷黄土湿陷变形评价方法的研究[J].岩土工程学报,2015,37(6):965–978.(SHAO Shengjun,LI Jun,LI Guoliang,et al.Evaluation method on self weight collapsible deformation of large thickness loess foundation[J].Chinese Journal of Geotechnical Engineering,2015,37(6):965–978.(in Chinese))
[5]李大展,何颐华,隋国秀.Q2黄土大面积浸水试验研究[J].岩土工程学报,1993,15(2):1–11.(LI Dazhan,HE Yihua,SUI Guoxiu.Study and test on immersion of Q2 loess in large area[J].Chinese Journal of Geotechnical Engineering,1993,15(2):1–11.(in Chinese))
[6]黄雪峰,陈正汉,哈双,等.大厚度自重湿陷性黄土场地湿陷变形特征的大型现场浸水试验研究[J].岩土工程学报,2006,28(3):382–389.(HUANG Xuefeng,CHEN Zhenghan,HA Shuang,et al.Large area field immersion tests on characteristics of deformation of self weight collapse loess under overburden pressure[J].Chinese Journal of Geotechnical Engineering,2006,28(3):382–389.(in Chinese))
[7]谢家杰.浅埋隧道的地层压力[J].土木工程学报,1964,10(6):58–70.(XIE Jiajie.Formation pressure of shallow tunnel[J].China Civil Engineering Journal,1964,10(6):58–70.(in Chinese))
[8]邵生俊,郑文,王正泓,等.黄土的构度指标及其试验确定方法[J].岩土力学,2010,31(1):15–19.(SHAO Shengjun,ZHENG Wen,WANG Zhenghong,et al.Structural index of loess and its testing method[J].Rock and Soil Mechanics,2010,31(1):15–19.(in Chinese))
[9]邵生俊,王丽琴,陶虎,等.黄土的构度及其与粒度,密度,湿度之间的关系[J].岩土工程学报,2014,36(8):1 387–1 393.(SHAO Shengjun,WANG Liqin,TAO Hu,et al.Structural index of loess and its relation with granularity,density and humidity[J].Chinese Journal Geotechnical Engineering,2014,36(8):1 387–1 393.(in Chinese))
[10]机械工业勘察设计研究院.西安市地铁五号线月登阁试坑浸水试验报告[R].西安:机械工业勘察设计研究院.2014.(China Jikan Institute of Engineering Investigations and Design.Report on soaking test of Yue Deng Ge site in Xi'an Metro Line 5[R].Xi'an:China Jikan Institute of Engineering Investigations and Design,2014.(in Chinese))
[11]姚志华.大厚度自重湿陷性黄土的水气运移和力学特性及地基湿陷变形规律研究[博士学位论文][D].重庆:后勤工程学院,2012.(YAO Zhihua.Water-air migration,mechanics characteristics and foundation collapse deformation of self-weight collapse loess with large thickness loess strata[Ph.D.Thesis][D].Chongqing:Logistics Engineering College,2012.(in Chinese))
[12]宋玉普.多种混凝土材料的本构关系和破坏准则[M].北京:中国水利水电出版社,2002:140–141.(SONG Yupu.Constitutive relation and failure criterion of multiple concrete material[M].Beijing:China Water Conservancy and Electric Power Press,2002:140–141.(in Chinese))
[13]中华人民共和国行业标准编写组.TB10001—2005铁路路基设计规范[S].北京:中国铁道出版社,2005.(The Professional Standards Compilation Groups of the People's Republic of China.TB10001—2005 Code for design on subgrade of railway[S].Beijing:China Railway Publishing House,2005.(in Chinese))
[2]中华人民共和国国家标准编写组.GB 50025—2004湿陷性黄土地基建筑规范[S].北京:中国建筑工业出版社,2004.(The National Standards Compilation Groups of the People's Republic of China.GB50025—2004 Code for building construction in collapsible loess regions[S].Beijing:China Architecture and Building Press,2004.(in Chinese))
[3]邵生俊,杨春鸣,焦阳阳,等.湿陷性黄土隧道的工程性质分析[J].岩土工程学报,2013,35(9):1 580–1 590.(SHAO Shengjun,YANG Chunming,JIAO Yangyang,et al.Engineering properties of collapsible loess tunnel[J].Chinese Journal of Geotechnical Engineering,2013,35(9):1 580–1 590.(in Chinese))
[4]邵生俊,李骏,李国良,等.大厚度自重湿陷黄土湿陷变形评价方法的研究[J].岩土工程学报,2015,37(6):965–978.(SHAO Shengjun,LI Jun,LI Guoliang,et al.Evaluation method on self weight collapsible deformation of large thickness loess foundation[J].Chinese Journal of Geotechnical Engineering,2015,37(6):965–978.(in Chinese))
[5]李大展,何颐华,隋国秀.Q2黄土大面积浸水试验研究[J].岩土工程学报,1993,15(2):1–11.(LI Dazhan,HE Yihua,SUI Guoxiu.Study and test on immersion of Q2 loess in large area[J].Chinese Journal of Geotechnical Engineering,1993,15(2):1–11.(in Chinese))
[6]黄雪峰,陈正汉,哈双,等.大厚度自重湿陷性黄土场地湿陷变形特征的大型现场浸水试验研究[J].岩土工程学报,2006,28(3):382–389.(HUANG Xuefeng,CHEN Zhenghan,HA Shuang,et al.Large area field immersion tests on characteristics of deformation of self weight collapse loess under overburden pressure[J].Chinese Journal of Geotechnical Engineering,2006,28(3):382–389.(in Chinese))
[7]谢家杰.浅埋隧道的地层压力[J].土木工程学报,1964,10(6):58–70.(XIE Jiajie.Formation pressure of shallow tunnel[J].China Civil Engineering Journal,1964,10(6):58–70.(in Chinese))
[8]邵生俊,郑文,王正泓,等.黄土的构度指标及其试验确定方法[J].岩土力学,2010,31(1):15–19.(SHAO Shengjun,ZHENG Wen,WANG Zhenghong,et al.Structural index of loess and its testing method[J].Rock and Soil Mechanics,2010,31(1):15–19.(in Chinese))
[9]邵生俊,王丽琴,陶虎,等.黄土的构度及其与粒度,密度,湿度之间的关系[J].岩土工程学报,2014,36(8):1 387–1 393.(SHAO Shengjun,WANG Liqin,TAO Hu,et al.Structural index of loess and its relation with granularity,density and humidity[J].Chinese Journal Geotechnical Engineering,2014,36(8):1 387–1 393.(in Chinese))
[10]机械工业勘察设计研究院.西安市地铁五号线月登阁试坑浸水试验报告[R].西安:机械工业勘察设计研究院.2014.(China Jikan Institute of Engineering Investigations and Design.Report on soaking test of Yue Deng Ge site in Xi'an Metro Line 5[R].Xi'an:China Jikan Institute of Engineering Investigations and Design,2014.(in Chinese))
[11]姚志华.大厚度自重湿陷性黄土的水气运移和力学特性及地基湿陷变形规律研究[博士学位论文][D].重庆:后勤工程学院,2012.(YAO Zhihua.Water-air migration,mechanics characteristics and foundation collapse deformation of self-weight collapse loess with large thickness loess strata[Ph.D.Thesis][D].Chongqing:Logistics Engineering College,2012.(in Chinese))
[12]宋玉普.多种混凝土材料的本构关系和破坏准则[M].北京:中国水利水电出版社,2002:140–141.(SONG Yupu.Constitutive relation and failure criterion of multiple concrete material[M].Beijing:China Water Conservancy and Electric Power Press,2002:140–141.(in Chinese))
[13]中华人民共和国行业标准编写组.TB10001—2005铁路路基设计规范[S].北京:中国铁道出版社,2005.(The Professional Standards Compilation Groups of the People's Republic of China.TB10001—2005 Code for design on subgrade of railway[S].Beijing:China Railway Publishing House,2005.(in Chinese))