土工格栅加筋挡土墙的有限元数值分析与性能研究
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摘要
土工格栅加筋挡土墙的工作性能研究是岩土工程实践中一个十分重要而具有现实意义的课题，其中所涉及到的强度(格栅的加筋机理)、稳定性(考虑挡土墙内外稳定性的极限平衡分析)、变形(主要指墙面板的侧向变形分析)以及加筋效果评价等问题，在实际工程中尚未得到合理解决。土工格栅加筋挡土墙的有限元数值分析方法是模拟加筋挡土墙工作机理的一种数值计算方法，该方法要依据土工格栅的加筋机理，能够弥补极限平衡设计方法的不足，得到与实际较为符合的应力、应变以及变形情况等，可以说有限元数值分析方法与加筋挡土墙应用研究的上述问题紧密相关。
本文首先在前人研究的基础上对土工格栅加筋挡土墙结构的应用研究进行了较为全面的总结与分析：深入探讨了加筋土的强度问题—土工格栅的加筋机理；在加筋挡土墙墙面板侧向变形模型分析所得到的变形参数的基础上，结合加筋挡土墙的工作机理分析选择了可能会影响挡土墙工作性能的敏感性参数。上述工作为后面的有限元数值分析及参数的敏感性数值计算提供了依据。
随后对于填土和填土—格栅接触面分别基于双曲线非线性弹性模型E-B模式和无厚度接触面单元模式，建立了能够模拟逐层填筑和分级加载过程的工程实用非线性有限元数值计算模型。以一座土工格栅加筋试验墙和一个坝上填筑的双面板土工格栅加筋挡土墙实际工程为数值分析的研究对象，进行了有限元数值计算，将计算结果与实测结果进行对比分析，验证了加筋挡二墙结构应力与变形有限元分析的合理性与可靠性，同时为后面的参数敏感性数值计算提供了实例验证。
进一步的，以加筋试验墙为数值计算对象，变动其填土的强度和刚度参数，加筋的刚度、长度和间距以及面板的弹性模量一系列参数，进行了参数的敏感性数值计算。通过对比分析探讨了填土、加筋和面板的性质对土工格栅加筋挡土墙工作性能的影响程度，总结得出了对工程实际有参考价值的规律性结论，从而深化了有限单元法对土工格栅加筋挡土墙结构的分析。
上述工作完成后，论文在最后对土工格栅加筋土结构有限元数值分析还有待于进一步研究的问题以及今后的发展方向进行了讨论与展望。
总之，本文所做的很多工作都是有实际意义的，有限元分析及加筋性能的参数敏感性分析结论为土工格栅加筋挡土墙的设计提供了有价值的参考依据。
The study of performance behavior of geogrids-reinforced earth retaining walls is an important and practical problem In practice of geotechnical engineering. At the present time, the application and study of ge ogrids-reinforced earth retaining walls mainly deals with several problems, such as strength(the mechanism of reinforcement), stability(the analysis based on limited-balance methods), deformation(the analysis of lateral deformation of wall face), the effect of reinforcing and so on. These problems are not well settled in practice.
Numerical analysis of FEM which is used to simulate the mechanism of geogrids-reinforced earth retaining walls is based on the mechanism of reinforcement, and makes up the deficiency of limited-balance methods to get the actual strain and stress of geogrids and deformation of construction. So it is closely related to the above several problems.
Based on the studies of predecessors, the author makes a comparatively general study about geogrids-reinforced retaining walls. The reinforcing mechanism of geogrids which belongs to the problem of strength is discussed particularly. Base on the parameters obtained by model analysis of lateral dsformation of wall faces, the author combines with the performance and mechanism of reinforced earth retaining walls to select a series of relevant parameters which are likely to affect the performance behavior of geogrids-reinforced earth retaining walls. The two studies provide some gist for the numerical analysis and the analysis of sensitivity of parameters.
Then a numerical nonlinear analysis model based on finite element method considering the filling of layers by layers and loading step by step is developed for the geogrids-reinforced earth retaining walls, which is based on the E-B mode of Duncan-Chang model of soils and the Goodman model of interfaces. Two cases studies for a large-scale test wall reinforced by geogrids and an actual geogrids-reinforced earth retaining wall on dam are made to verify the reliability of the proposed numerical method, and some credible conclusions about the computation of the lateral deformation of wall faces and the strain and stress of geogrids are obtained, which is a good test for the following numerical analysis of sensitivity of parameters.
Further more, a comparative study is conducted for a varied range of relevant parameters involved in the analysis such as deformation and strength properties of backfills and rigidity, length and vertical space of geogrids, the elastic modular of wall face. Based on the computed results, the effects of these factors on distribution and variation modes of stresses and
defonnations of the system are examined and performance behavior of geogrids-reinforced earth retaining walls is discussed, some regular conclusions which are benefic to the actual engineering are summed up. At the same time, the application of FEM is developed.
After above works, the author puts forward some questions required solved and expectations about the FEM of geogrids-reinforced earth retaining walls.
In summary, many works of this paper are with some actual meanings. The FEM analysis and the analysis of sensitivity of parameters are significant for the design of reinforced earth retaining walls.
本文首先在前人研究的基础上对土工格栅加筋挡土墙结构的应用研究进行了较为全面的总结与分析：深入探讨了加筋土的强度问题—土工格栅的加筋机理；在加筋挡土墙墙面板侧向变形模型分析所得到的变形参数的基础上，结合加筋挡土墙的工作机理分析选择了可能会影响挡土墙工作性能的敏感性参数。上述工作为后面的有限元数值分析及参数的敏感性数值计算提供了依据。
随后对于填土和填土—格栅接触面分别基于双曲线非线性弹性模型E-B模式和无厚度接触面单元模式，建立了能够模拟逐层填筑和分级加载过程的工程实用非线性有限元数值计算模型。以一座土工格栅加筋试验墙和一个坝上填筑的双面板土工格栅加筋挡土墙实际工程为数值分析的研究对象，进行了有限元数值计算，将计算结果与实测结果进行对比分析，验证了加筋挡二墙结构应力与变形有限元分析的合理性与可靠性，同时为后面的参数敏感性数值计算提供了实例验证。
进一步的，以加筋试验墙为数值计算对象，变动其填土的强度和刚度参数，加筋的刚度、长度和间距以及面板的弹性模量一系列参数，进行了参数的敏感性数值计算。通过对比分析探讨了填土、加筋和面板的性质对土工格栅加筋挡土墙工作性能的影响程度，总结得出了对工程实际有参考价值的规律性结论，从而深化了有限单元法对土工格栅加筋挡土墙结构的分析。
上述工作完成后，论文在最后对土工格栅加筋土结构有限元数值分析还有待于进一步研究的问题以及今后的发展方向进行了讨论与展望。
总之，本文所做的很多工作都是有实际意义的，有限元分析及加筋性能的参数敏感性分析结论为土工格栅加筋挡土墙的设计提供了有价值的参考依据。
The study of performance behavior of geogrids-reinforced earth retaining walls is an important and practical problem In practice of geotechnical engineering. At the present time, the application and study of ge ogrids-reinforced earth retaining walls mainly deals with several problems, such as strength(the mechanism of reinforcement), stability(the analysis based on limited-balance methods), deformation(the analysis of lateral deformation of wall face), the effect of reinforcing and so on. These problems are not well settled in practice.
Numerical analysis of FEM which is used to simulate the mechanism of geogrids-reinforced earth retaining walls is based on the mechanism of reinforcement, and makes up the deficiency of limited-balance methods to get the actual strain and stress of geogrids and deformation of construction. So it is closely related to the above several problems.
Based on the studies of predecessors, the author makes a comparatively general study about geogrids-reinforced retaining walls. The reinforcing mechanism of geogrids which belongs to the problem of strength is discussed particularly. Base on the parameters obtained by model analysis of lateral dsformation of wall faces, the author combines with the performance and mechanism of reinforced earth retaining walls to select a series of relevant parameters which are likely to affect the performance behavior of geogrids-reinforced earth retaining walls. The two studies provide some gist for the numerical analysis and the analysis of sensitivity of parameters.
Then a numerical nonlinear analysis model based on finite element method considering the filling of layers by layers and loading step by step is developed for the geogrids-reinforced earth retaining walls, which is based on the E-B mode of Duncan-Chang model of soils and the Goodman model of interfaces. Two cases studies for a large-scale test wall reinforced by geogrids and an actual geogrids-reinforced earth retaining wall on dam are made to verify the reliability of the proposed numerical method, and some credible conclusions about the computation of the lateral deformation of wall faces and the strain and stress of geogrids are obtained, which is a good test for the following numerical analysis of sensitivity of parameters.
Further more, a comparative study is conducted for a varied range of relevant parameters involved in the analysis such as deformation and strength properties of backfills and rigidity, length and vertical space of geogrids, the elastic modular of wall face. Based on the computed results, the effects of these factors on distribution and variation modes of stresses and
defonnations of the system are examined and performance behavior of geogrids-reinforced earth retaining walls is discussed, some regular conclusions which are benefic to the actual engineering are summed up. At the same time, the application of FEM is developed.
After above works, the author puts forward some questions required solved and expectations about the FEM of geogrids-reinforced earth retaining walls.
In summary, many works of this paper are with some actual meanings. The FEM analysis and the analysis of sensitivity of parameters are significant for the design of reinforced earth retaining walls.
引文
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[2] 杨果林，肖宏彬．现代加筋土挡土结构[M]．北京：煤炭工业出版社，2002，3．
[3] 南京水利科学院研究院主编．土工合成材料测试手册[S]．北京：水利电力出版社，1991．
[4] 龚晓南主编．土工计算机分析[M]．北京：中国建筑工业出版社，2000．
[5] 孙钧，迟景魁，曹正康，施建勇．新型土工材料与工程整治[M]．中国建筑工业出版社，1998，11．
[6] 周志刚，郑健龙．公路土工合成材料设计原理即工程应用[M]．北京：人民交通出版社，2001．
[7] 王瑁成，邵敏．有限单元法基本原理和数值方法[M]．北京：清华大学出版社，1997．
[8] Koemer M Robert, Soong Te-Yang. Geosynthetic reinforced segmental retaining walls[J] . Geotextiles and Geomembranes, 2001, 19(6): 359-386.
[9] 周志刚，张起森．土工加筋材料研究综述[J]．长沙交通学院学报，2001，17(2)：38-42．
[10] 贺丽．塑料土工格栅加筋挡土墙的应用研究[J]．昆明理工大学大学硕士学位论文，2001．
[11] 陈国芳．挡土墙与填土间接触面大型直剪试验[J]．路基工程，1995，58(1)：49-55．
[12] 高翔，石名磊，刘松玉．加筋粘性土筋土界面剪切特性的试验研究[J]．公路交通科技，2002，19(5)：8-10．
[13] 周志刚等．大型直剪仪试验的尺寸效应[J]．长沙交通学院学报，1999，15(1)：47-49．
[14] 周志刚，郑健龙，高燕希．土工格栅加固体抗压强度的极限平衡分析[J]．长沙交通学院学报，1998，14(1)：39-44．
[15] 李燕君．土工格栅加筋土支挡结构抗拔性能探讨[J]．铁道标准设计，1996，z1．
[16] 周志刚，郑健龙，张起森，高燕希．Netlon土工格栅与界面性能的研究[J]．长沙交通学院学报，1998，14(3)：34-39．
[17] 吴兴征，丁昌杰，朱文芳．土工格栅拉拔试验研究进展[J]．山东交通科技，1998，4(10)：6～9．
[18] Palmeira E A, Millgan G W E. Scale and other factors affecting the results of pull-out test of grids buried in sand[J] . Geotechnique, 1989, 39 (3): 511-524.
[19] Lopes M L, Ladeira, M. Influence of the confinement, soil density and displacement rate on soil-geogrid interaction[J] . Geotextiles and Geomembranes, 1996, 14(10): 56-69.
[20] Sugimoto M, Alagiyawanna A M N, Kadoguchi K. Influence of rigid and flexible face on geogrid pullout tests[J] . Geotextiles and Geomembranes, 2001, 19(7): 145-162.
[21] Bergado D T, Hardiyatimo H C, Cisneros C B, Chun C J, Alfaro M C, Balasubramaniam A S,
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