岩溶塌陷影响下加筋路基承载机理研究
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摘要
在可能发生岩溶塌陷的地区建造路堤,可采用在路堤底部铺设土工合成材料加筋垫层的方法加固路基,防止岩溶突然坍塌造成路堤塌陷。采用PLAXIS3D软件,运用更新网格的大变形有限元分析方法,研究加筋路基在岩溶塌陷影响下路堤和筋材位移、应力场分布规律及加筋路基的承载机理,分析了岩溶塌陷尺寸、路堤填土高度、筋材抗拉刚度和路堤填土性质对地表最大沉降和最大拉力的影响。结果表明,地表最大沉降与路堤中是否形成封闭的应力穹顶密切相关,封闭的应力穹顶高度主要受塌陷尺寸和路堤填土黏聚力影响;筋材抗拉刚度、路堤高度和路堤填土内摩擦角对封闭的应力穹顶高度影响较小;筋材横纵向最大拉力按筋材横纵向抗拉刚度比例分配,单向与双向加筋差别不大。
Geosynthetics could be used for reinforcing embankment subjected to the influence of potential localised karst collapse. In this paper,the displacements and stresses in both embankment and geosynthetics,and the bearing mechanism of geosynthetic-reinforced embankment are analyzed in detail based on the numerical simulation results from PLAXIS3 Dsoftware by using large deformation analysis method with updated mesh function. Moreover,the influences of design parameters( including size of karst collapse,embankment height,geosynthetic's tensile stiffness and properties of embankment soil) on the maximum settlements of embankment and the maximum tensions of geosynthetics are investigated. Results indicate that the maximum settlement of embankment is depended on whether a closed stress dome in embankment is formed,and the height of the stress dome is mainly related to the size of collapse and the cohesion of embankment soil. Geosynthetic's tensile stiffness,embankment height,and internal friction angle of embankment fill have slight influence on the height of stress dome. The maximum longitudinal and transverse tensions of geosynthetics are related to the longitudinal and transverse stiffness of geosynthetics,and the differences of both maximum pavement settlement and strain in geosynthetics caused from uniaxial and biaxial geogrids are small.
Geosynthetics could be used for reinforcing embankment subjected to the influence of potential localised karst collapse. In this paper,the displacements and stresses in both embankment and geosynthetics,and the bearing mechanism of geosynthetic-reinforced embankment are analyzed in detail based on the numerical simulation results from PLAXIS3 Dsoftware by using large deformation analysis method with updated mesh function. Moreover,the influences of design parameters( including size of karst collapse,embankment height,geosynthetic's tensile stiffness and properties of embankment soil) on the maximum settlements of embankment and the maximum tensions of geosynthetics are investigated. Results indicate that the maximum settlement of embankment is depended on whether a closed stress dome in embankment is formed,and the height of the stress dome is mainly related to the size of collapse and the cohesion of embankment soil. Geosynthetic's tensile stiffness,embankment height,and internal friction angle of embankment fill have slight influence on the height of stress dome. The maximum longitudinal and transverse tensions of geosynthetics are related to the longitudinal and transverse stiffness of geosynthetics,and the differences of both maximum pavement settlement and strain in geosynthetics caused from uniaxial and biaxial geogrids are small.
引文
[1]BONAPARTE R,BERG R.The Use of Geosynthetics to Support Roadways over Sinkhole Prone Areas[C]∥Proceedings of 2nd Multidisciplinary Conference on Sinkholes and the Environment Impacts of Karst.Orlando,USA,February 9-11,1987:437-450.
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[8]BRIANCON L,VILLARD P,CHEVALIER B.New Developments in the Modeling and the Design of Geosynthetic Reinforcements of Platforms Subjected to Localized Sinkholes[C]∥Proceedings of the Geo Florida 2010:Advances in Analysis,Modeling&Design,Florida,USA.February 20-24,2010:664-671.
[9]TRAN V,MEGUID M,CHOUINARD L.Three-Dimensional Analysis of Geogrid-Reinforced Soil Using a FiniteDiscrete Element Framework[J].International Journal of Geomechanics,2014,32(2):138-149.
[10]刘嘉平,丁善鸿.三种岩溶塌陷形态的产生条件[J].中国岩溶,1994,13(3):300-305.
[11]GIROUD J,BONAPARTE R,BEECH J,et al.Design of Soil Layer-geosynthetic Systems Overlying Voids[J].Geotextiles and Geomembranes,1990,9(1):11-50.
[12]BS8006-1,Code of Practice for Strengthened/Reinforced Soils and Other Fills(STANDARD B)[S].UK:The British Standards Institution,2010.
[13]BLIVET J,GOURC J,VILLARD P,et al.Design Method for Geosynthetic as Reinforcement for Embankment Subjected to Localized Subsidence[C]∥Proceedings of the Seventh International Conference on Geosynthetics,Delams,France,September 22-27,2002:341-344.
[14]SIEIRA A C C,GERSCOVICH D,SAY O A S.Displacement and Load Transfer Mechanisms of Geogrids under Pullout Condition[J].Geotextiles and Geomembranes,2009,27(4):241-253.
[15]SLOAN J A.Column-supported Embankments:Fullscale Tests and Design Recommendations[D].Virginia:Virginia Polytechnic Institute and State University,2011.
[16]VAN EEKELEN S J,BEZUIJEN A,LODDER H,et al.Model Experiments on Piled Embankments.Part I[J].Geotextiles and Geomembranes,2012,32:69-81.
[17]陈福全,吕艳平,侯永峰.桩承加筋式路堤的承载机理研究[J].铁道学报,2007,29(4):74-79.
[2]KINNEY T C,CONNOR B.Geosynthetics Supporting Embankments over Voids[J].Journal of Cold Regions Engineering,1987,1(4):158-70.
[3]BRIANCON L,NANCEY A,ROBINET A,et al.Set up of a Warning System Integrated inside a Reinforced Geotextile for the Survey of Railway[C]∥Proceedings of the8th International Conference on Geosynthetics.Yokohama,Japan.September 18-22,2006:857-860.
[4]VILLARD P,BRIANCON L.Design of Geosynthetic Reinforcements for Platforms Subjected to Localized Sinkholes[J].Canadian Geotechnical Journal,2008,45(2):196-209.
[5]GOURC J,VILLARD P.Reinforcement by Membrane Effect:Application to Embankments on Soil Liable to Subsidence[C]∥Proceedings of the 2nd Asian Geosynthetics Conference.Seoul,Korea,2000:57-74.
[6]LAWSON C,YEE T.Serviceability Limits for Basal Reinforced Embankments Spanning Voids[C]∥Proceedings of the Geo-Frontiers 2011:Advances in Geotechnical Engineering.California,USA,March 13-16,2011:3276-3285.
[7]殷苗苗.岩溶区加筋路堤处治技术的设计理论与数值模拟研究[D].长沙:长沙理工大学,2011.
[8]BRIANCON L,VILLARD P,CHEVALIER B.New Developments in the Modeling and the Design of Geosynthetic Reinforcements of Platforms Subjected to Localized Sinkholes[C]∥Proceedings of the Geo Florida 2010:Advances in Analysis,Modeling&Design,Florida,USA.February 20-24,2010:664-671.
[9]TRAN V,MEGUID M,CHOUINARD L.Three-Dimensional Analysis of Geogrid-Reinforced Soil Using a FiniteDiscrete Element Framework[J].International Journal of Geomechanics,2014,32(2):138-149.
[10]刘嘉平,丁善鸿.三种岩溶塌陷形态的产生条件[J].中国岩溶,1994,13(3):300-305.
[11]GIROUD J,BONAPARTE R,BEECH J,et al.Design of Soil Layer-geosynthetic Systems Overlying Voids[J].Geotextiles and Geomembranes,1990,9(1):11-50.
[12]BS8006-1,Code of Practice for Strengthened/Reinforced Soils and Other Fills(STANDARD B)[S].UK:The British Standards Institution,2010.
[13]BLIVET J,GOURC J,VILLARD P,et al.Design Method for Geosynthetic as Reinforcement for Embankment Subjected to Localized Subsidence[C]∥Proceedings of the Seventh International Conference on Geosynthetics,Delams,France,September 22-27,2002:341-344.
[14]SIEIRA A C C,GERSCOVICH D,SAY O A S.Displacement and Load Transfer Mechanisms of Geogrids under Pullout Condition[J].Geotextiles and Geomembranes,2009,27(4):241-253.
[15]SLOAN J A.Column-supported Embankments:Fullscale Tests and Design Recommendations[D].Virginia:Virginia Polytechnic Institute and State University,2011.
[16]VAN EEKELEN S J,BEZUIJEN A,LODDER H,et al.Model Experiments on Piled Embankments.Part I[J].Geotextiles and Geomembranes,2012,32:69-81.
[17]陈福全,吕艳平,侯永峰.桩承加筋式路堤的承载机理研究[J].铁道学报,2007,29(4):74-79.