填料应力控制的预应力筋预拉力的合理取值
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摘要
预应力加筋土挡墙内部的应力分布影响挡墙的力学性能,控制预应力筋的拉力值可以有效控制加筋区的应力分布。首先研究了该类型挡墙的数值模拟方法,将其结果与模型试验结果对比验证了数值模拟方法的可靠性,进而利用有限元方法对单层预应力加筋土挡墙内的应力分布、塑性区大小及筋带预拉力合理取值进行研究。研究结果表明:增大预应力筋的预拉力会引起侧压板附近的填料产生贯通的塑性区,随着预拉力的增加,塑性区向墙面板发展,并使墙面板的位移增加,预拉力的增加应避免塑性区贯通。填料在预应力作用下产生的水平应力沿筋长方向呈中间小两端大的分布形态。引入了破坏比系数表示填料的应力达到抗剪强度的比例,发现增加预拉力系数会使填料的平均破坏比系数先减小后增加,表明填料存在最优的安全状态。预拉力的合理取值由侧压板附近是否出现贯通的塑性区和填料的最优安全状态来控制。增加预应力筋长度与挡墙高度比可以提高填料的抗剪强度,预拉力合理取值的上限和下限相应增加,进而对预拉力合理取值提供了理论依据。
The stress distribution inside prestress reinforced-earth retaining wall influences the mechanical properties of the retaining wall. The stress distribution in the reinforced area could be effectively controlled by controlling the tension value of reinforcement. First, the numerical simulation method of the retaining wall is studied, and its rationality is verified by comparison of simulation result and model test result. Then, the stress distribution, the plastic zone size and the reasonable value of pretension in the single-layer prestressed reinforced-earth retaining wall are studied by using FE method. The research result shows that(1) The increase of pretension of prestressed reinforcement will cause the plastic zone to penetrate around the side plate. As the prestress increases, the plastic zone expand to the wall panel and the displacement of the wall panel increases, the increase of pretension should be controlled to avoid the penetration plastic zone. The horizontal stress of filler induced by the prestress is distributed with the shape of smaller in middle area and larger in both ends along the length of the reinforcements. The failure ratio coefficient is introduced to indicate the ratio of filler stress to its shear strength. It is found that the increase of pretension coefficient will lead to the average failure ratio coefficient of filler decreases at first and then increases. It indicates that the filler has an optimal safety state. The reasonable value of pretension can be controlled both by whether there is a penetrating plastic zone around the side plate and the optimal safety state of filler.(2)Increasing the ratio of prestressed reinforcement length to retaining wall height could improve both the shear strength of the filler and the upper/lower limit of the reasonable pretension range, which provides a theoretical basis for the reasonable value of pretension.
The stress distribution inside prestress reinforced-earth retaining wall influences the mechanical properties of the retaining wall. The stress distribution in the reinforced area could be effectively controlled by controlling the tension value of reinforcement. First, the numerical simulation method of the retaining wall is studied, and its rationality is verified by comparison of simulation result and model test result. Then, the stress distribution, the plastic zone size and the reasonable value of pretension in the single-layer prestressed reinforced-earth retaining wall are studied by using FE method. The research result shows that(1) The increase of pretension of prestressed reinforcement will cause the plastic zone to penetrate around the side plate. As the prestress increases, the plastic zone expand to the wall panel and the displacement of the wall panel increases, the increase of pretension should be controlled to avoid the penetration plastic zone. The horizontal stress of filler induced by the prestress is distributed with the shape of smaller in middle area and larger in both ends along the length of the reinforcements. The failure ratio coefficient is introduced to indicate the ratio of filler stress to its shear strength. It is found that the increase of pretension coefficient will lead to the average failure ratio coefficient of filler decreases at first and then increases. It indicates that the filler has an optimal safety state. The reasonable value of pretension can be controlled both by whether there is a penetrating plastic zone around the side plate and the optimal safety state of filler.(2)Increasing the ratio of prestressed reinforcement length to retaining wall height could improve both the shear strength of the filler and the upper/lower limit of the reasonable pretension range, which provides a theoretical basis for the reasonable value of pretension.
引文
[1]杜运兴,龙述尧,尚守平.预应力加筋中砂路堤模型静力试验研究[J].湖南大学学报:自科版,2008,35(2):27-30.DU Yun-xing,LONG Shu-yao,SHANG Shou-ping.Static Model-test Study on Reinforced Medium-sandy Embankment with Prestress[J].Journal of Hunan University:Natural Science Edition,2008,35(2):27-30.
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[7]YU Y,BATHURST R J,MIYATA Y.Numerical Analysis of a Mechanically Stabilized Earth Wall Reinforced with Steel Strips[J].Soils and Foundations,2015,55(3):536-547.
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[9]CHEN X B,ZHANG J S,LI Z Y.Shear Behaviour of a Geogrid-reinforced Coarse-grained Soil Based on Largescale Triaxial Tests[J].Geotextiles and Geomembranes,2014,42(4):312-328.
[10]周世良,汪承志,何光春,等.台阶式格栅加筋挡墙潜在破裂面计算模式研究[J].公路交通科技,2007,24(11):15-20.ZHOU Shi-liang,WANG Cheng-zhi,HE Guang-chun,et al.Study on Rational Model of Potential Fractured Surface for Stepped Geogrid Reinforced Soil Retaining Wall[J].Journal of Highway and Transportation Research and Development,2007,24(11):15-20.
[11]YU Y,BATHURST R J,ALLEN T M,et al.Physical and Numerical Modelling of a Geogrid-reinforced Incremental Concrete Panel Retaining Wall[J].Canadian Geotechnical Journal,2016,53(12):1883-1901.
[12]HUANG B Q,BATHURST R J,HATAMI K.Numerical Study of Reinforced Soil Segmental Walls Using Three Different Constitutive Soil Models[J].Journal of Geotechnical and Geoenvironmental Engineering,2009,135(10):1486-1498.
[13]GU M X,COLLIN J G,HAN J,et al.Numerical Analysis of Instrumented Mechanically Stabilized Gabion Walls with Large Vertical Reinforcement Spacing[J].Geotextiles and Geomembranes,2017,45(4):294-306.
[14]张社荣,祝青,李升.大型渡槽数值分析中预应力的模拟方法[J].水力发电学报,2009,28(3):97-100,90.ZHANG She-rong,ZHU Qing,LI Sheng.Simulation Methods of Prestress in Numerical Analysis of Large Aqueduct[J].Journal of Hydroelectric Engineering,2009,28(3):97-100,90.
[15]何琳,王家林.模拟有效预应力的等效荷载-实体力筋降温法[J].公路交通科技,2015,32(11):75-80.HE Lin,WANG Jia-lin.Method of Equivalent Load and Temperature Reduction on Prestressing Tendon for Effective Prestress Simulation[J].Journal of Highway and Transportation Research and Development,2015,32(11):75-80.
[16]熊欢,李鹏辉,李庆斌,等.PCCP受载响应分析中三种预应力施加方法的比较研究[J].水力发电学报,2010,29(6):178-186.XIONG Huan,LI Peng-hui,LI Qing-bin,et al.Comparative Study of Three Methods for the Prestressing Simulation in the Analysis of Load-bearing Response of a PCCP[J].Journal of Hydroelectric Engineering,2010,29(6):178-186.
[17]郁大照,陈跃良.含裂纹螺接件应力强度因子三维有限元分析[J].机械工程学报,2011,47(20):121-126.YU Da-zhao,CHEN Yue-liang.Stress Intensity Factor of Cracks in Bolted Joints Based on Three-dimensional Finite Element Analysis[J].Journal of Mechanical Engineering,2011,47(20):121-126.
[18]杜运兴,周芬,梁强.双根无黏结预应力筋加筋体力学性能研究[J].长江科学院院报,2017,34(2):45-51.DU Yun-xing,ZHOU Fen,LIANG Qiang.Mechanical Properties of Reinforced Body with Double Unbonded Prestressed Reinforcements[J].Journal of Yangtze River Scientific Research Institute,2017,34(2):45-51.
[19]BS 8006-1:2010,Code of Practice for Strengthened/Reinforced Soils and Other Fills[S].
[2]YANG M,TANG X.Rigid Retaining Walls with Narrow Cohesionless Backfills under Various Wall Movement Modes[J].International Journal of Geomechanics,2017,17(11):04017098.
[3]黄向京,许桂林,杨果林,等.加筋格宾新型组合支挡结构试验研究[J].公路交通科技,2011,28(2):7-13.HUANG Xiang-jing,XU Gui-lin,YANG Guo-lin,et al.Experimental Research on a New Kind of Compound Supporting and Retaining Structure with Reinforced Gabion Retaining Wall[J].Journal of Highway and Transportation Research and Development,2011,28(2):7-13.
[4]CLOUGH R W,WOODWARD R J.Analysis of Embankment Stresses and Deformations[J].Journal of Soil Mechanics and Foundations Division,1967,93(4):529-549.
[5]LIU H B.Long-term Lateral Displacement of Geosyntheticreinforced Soil Segmental Retaining Walls[J].Geotextiles and Geomembranes,2012,32(2):18-27.
[6]CHEN R H,WU C P,HUANG F C,et al.Numerical Analysis of Geocell-reinforced Retaining Structures[J].Geotextiles and Geomembranes,2013,39(8):51-62.
[7]YU Y,BATHURST R J,MIYATA Y.Numerical Analysis of a Mechanically Stabilized Earth Wall Reinforced with Steel Strips[J].Soils and Foundations,2015,55(3):536-547.
[8]曹喜仁,赵振勇,赵明华.高填石路堤地基沉降计算方法研究[J].公路交通科技,2005,22(6):38-41.CAO Xi-ren,ZHAO Zhen-yong,ZHAO Ming-hua.Study on Settlement Calculation Method for Subgrade of High Rockfill Embankment[J].Journal of Highway and Transportation Research and Development,2005,22(6):38-41.
[9]CHEN X B,ZHANG J S,LI Z Y.Shear Behaviour of a Geogrid-reinforced Coarse-grained Soil Based on Largescale Triaxial Tests[J].Geotextiles and Geomembranes,2014,42(4):312-328.
[10]周世良,汪承志,何光春,等.台阶式格栅加筋挡墙潜在破裂面计算模式研究[J].公路交通科技,2007,24(11):15-20.ZHOU Shi-liang,WANG Cheng-zhi,HE Guang-chun,et al.Study on Rational Model of Potential Fractured Surface for Stepped Geogrid Reinforced Soil Retaining Wall[J].Journal of Highway and Transportation Research and Development,2007,24(11):15-20.
[11]YU Y,BATHURST R J,ALLEN T M,et al.Physical and Numerical Modelling of a Geogrid-reinforced Incremental Concrete Panel Retaining Wall[J].Canadian Geotechnical Journal,2016,53(12):1883-1901.
[12]HUANG B Q,BATHURST R J,HATAMI K.Numerical Study of Reinforced Soil Segmental Walls Using Three Different Constitutive Soil Models[J].Journal of Geotechnical and Geoenvironmental Engineering,2009,135(10):1486-1498.
[13]GU M X,COLLIN J G,HAN J,et al.Numerical Analysis of Instrumented Mechanically Stabilized Gabion Walls with Large Vertical Reinforcement Spacing[J].Geotextiles and Geomembranes,2017,45(4):294-306.
[14]张社荣,祝青,李升.大型渡槽数值分析中预应力的模拟方法[J].水力发电学报,2009,28(3):97-100,90.ZHANG She-rong,ZHU Qing,LI Sheng.Simulation Methods of Prestress in Numerical Analysis of Large Aqueduct[J].Journal of Hydroelectric Engineering,2009,28(3):97-100,90.
[15]何琳,王家林.模拟有效预应力的等效荷载-实体力筋降温法[J].公路交通科技,2015,32(11):75-80.HE Lin,WANG Jia-lin.Method of Equivalent Load and Temperature Reduction on Prestressing Tendon for Effective Prestress Simulation[J].Journal of Highway and Transportation Research and Development,2015,32(11):75-80.
[16]熊欢,李鹏辉,李庆斌,等.PCCP受载响应分析中三种预应力施加方法的比较研究[J].水力发电学报,2010,29(6):178-186.XIONG Huan,LI Peng-hui,LI Qing-bin,et al.Comparative Study of Three Methods for the Prestressing Simulation in the Analysis of Load-bearing Response of a PCCP[J].Journal of Hydroelectric Engineering,2010,29(6):178-186.
[17]郁大照,陈跃良.含裂纹螺接件应力强度因子三维有限元分析[J].机械工程学报,2011,47(20):121-126.YU Da-zhao,CHEN Yue-liang.Stress Intensity Factor of Cracks in Bolted Joints Based on Three-dimensional Finite Element Analysis[J].Journal of Mechanical Engineering,2011,47(20):121-126.
[18]杜运兴,周芬,梁强.双根无黏结预应力筋加筋体力学性能研究[J].长江科学院院报,2017,34(2):45-51.DU Yun-xing,ZHOU Fen,LIANG Qiang.Mechanical Properties of Reinforced Body with Double Unbonded Prestressed Reinforcements[J].Journal of Yangtze River Scientific Research Institute,2017,34(2):45-51.
[19]BS 8006-1:2010,Code of Practice for Strengthened/Reinforced Soils and Other Fills[S].