高填方膨胀土作用下刚柔复合桩基挡墙结构数值模拟
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摘要
针对高填方膨胀土路基边坡的治理问题,提出了在膨胀土和挡墙之间设置EPS(聚苯乙烯泡沫)柔性垫层的刚柔复合桩基挡墙结构。采用FLAC~(3D)建立了刚柔复合桩基挡墙结构支护的高填方膨胀土路基数值模型,并基于热-力耦合模型实现了湿度变化后的高填方膨胀土变形模拟,进而对比分析了5种不同工况下刚柔复合桩基挡墙结构的受力变形特性及路面变形,并着重探讨了EPS垫层厚度和刚度对刚柔复合桩基挡墙结构墙背土压力和水平位移的影响。研究结果表明:刚柔复合桩基挡墙结构的墙背土压力、抗滑桩桩身弯矩和剪力、挡土墙和抗滑桩水平位移均明显减小,但路面沉降和水平位移有所增大;EPS垫层弹性模量越小或厚度越大,则EPS垫层压缩量越大,允许膨胀土发生的侧向变形也越大,刚柔复合桩基挡墙结构的受力和变形则越小;柔性EPS垫层减压作用的充分发挥,必须同时满足厚度和弹性模量2个方面的条件,单一采用垫层刚度指标不足以反映EPS垫层的影响。
A composite rigid-flexible pile-supported retaining wall(CRF-PSRW) including EPS cushion was proposed aiming for the treatment of high-filled expansive soil subgrade slope. The numerical model of CRF-PSRW used for high-filled expansive soil subgrade was established by FLAC~(3D). Based on the thermal-mechanical coupling model, the deformation of expansive soil was simulated with the change of humidity. The mechanical and deformation behaviors of CRF-PSRW in five different working conditions were compared and analyzed. The effects of thickness and stiffness of EPS cushion on the earth pressure and horizontal displacement of the CRF-PSRW were further investigated. The results show that the CRF-PSRW can obviously reduce the earth pressure of retaining wall, bending moment and shear force of anti-slide pile, and horizontal displacement of the structure. However, settlement and horizontal displacement of pavement are found to significantly increase. The compression amount of EPS cushion increases with the decrease of elastic modulus or increase of thickness. Then larger lateral deformation of the expansive soil is permitted, leading to reduction of the force and deformation of CRF-PSRW. In order to give full play to the decompression effect of flexible EPS cushion, the conditions of thickness and modulus of elasticity must be satisfied at the same time.The single cushion stiffness index is not enough to reflect the influence of EPS cushion..
A composite rigid-flexible pile-supported retaining wall(CRF-PSRW) including EPS cushion was proposed aiming for the treatment of high-filled expansive soil subgrade slope. The numerical model of CRF-PSRW used for high-filled expansive soil subgrade was established by FLAC~(3D). Based on the thermal-mechanical coupling model, the deformation of expansive soil was simulated with the change of humidity. The mechanical and deformation behaviors of CRF-PSRW in five different working conditions were compared and analyzed. The effects of thickness and stiffness of EPS cushion on the earth pressure and horizontal displacement of the CRF-PSRW were further investigated. The results show that the CRF-PSRW can obviously reduce the earth pressure of retaining wall, bending moment and shear force of anti-slide pile, and horizontal displacement of the structure. However, settlement and horizontal displacement of pavement are found to significantly increase. The compression amount of EPS cushion increases with the decrease of elastic modulus or increase of thickness. Then larger lateral deformation of the expansive soil is permitted, leading to reduction of the force and deformation of CRF-PSRW. In order to give full play to the decompression effect of flexible EPS cushion, the conditions of thickness and modulus of elasticity must be satisfied at the same time.The single cushion stiffness index is not enough to reflect the influence of EPS cushion..
引文
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[12]BATHURST R J,ZARNANI S.Earthquake load attenuation using EPS geofoam buffers in rigid wall applications[J].Indian Geotechnical Journal,2013,43(4):283-391.
[13]郑俊杰,吕思祺,曹文昭.刚柔复合抗滑桩受力与变形特性数值模拟分析[J].华中科技大学学报(自然科学版),2017,45(4):39-44.ZHENG Jun-jie,LüSi-qi,CAO Wen-zhao.Numerical analysis of mechanical and deformation characteristics of composite rigid-flexible anti-slide pile[J].Journal of Huazhong University of Science&Technology(Natural Science Edition),2017,45(4):39-44.
[14]曾仲毅,徐帮树,胡世权,等.增湿条件下膨胀土隧道衬砌破坏数值分析[J].岩土力学,2014,35(3):871-880.ZENG Zhong-yi,XU Bang-shu,HU Shi-quan,et al.Numerical analysis of tunnel liner failure mechanism in expansive soil considering water-increased state[J].Rock and Soil Mechanics,2014,35(3):871-880.
[15]丁金华,陈仁朋,童军,等.基于多场耦合数值分析的膨胀土边坡浅层膨胀变形破坏机制研究[J].岩土力学,2015,36(增刊1):159-168.DING Jin-hua,CHEN Ren-peng,TONG Jun,et al.Research on failure mechanism of shallow instability of expansive soil slope based on multifield coupling numerical analysis[J].Rock and Soil Mechanics,2015,36(Supp.1):159-168.
[16]郑健龙.公路膨胀土工程理论与技术[M].北京:人民交通出版社,2013.ZHENG Jian-long.Theory and technology for highway expansive soil engineering[M].Beijing:China Communications Press,2013.
[17]ZARNANI S,BATHURST R J.Numerical modeling of EPS seismic buffer shaking table tests[J].Geotextiles and Geomembranes,2008,26(5):371-383.
[18]顾慰慈.挡土墙土压力计算手册[M].北京:中国建材工业出版社,2006.GU Wei-ci.Computing manual of earth pressure for retaining wall[M].Beijing:China Building Materials Press,2006.
[19]中交第二公路勘察设计研究院有限公司.JTG D30-2015公路路基设计规范[S].北京:人民交通出版社,2015.Communication of China Second Highway Consultant Co.Ltd.JTG D30-2015 Specifications for design of highway subgrades[S].Beijing:People Communications Press,2015.
[2]郑俊杰,吴文彪,曹文昭,等.桩基挡墙支挡结构极限状态及稳定性分析[J].华中科技大学学报(自然科学版),2016,44(4):74-78.ZHENG Jun-jie,WU Wen-biao,CAO Wen-zhao,et al.Study on limit state and stability of retaining wall based on anti-slide pile retaining structure[J].Journal of Huazhong University of Science&Technology(Natural Science Edition),2016,44(4):74-78.
[3]KHATTAB S A,Al-SHAMAM M K,Al-JUARI K A.Model test on lateral earth pressure of highly expansive soil[C]//6th Asia-Pacific Conference on Unsaturated Soils.Guilin:[s.n.],2016:709-716.
[4]王年香,章为民,顾行文,等.膨胀土挡墙侧向膨胀压力研究[J].水利学报,2008,39(5):580-587.WANG Nian-xiang,ZHANG Wei-min,GU Xing-wen,et al.Lateral swelling pressure of expansive soil acting on retaining wall due to inundation[J].Journal of Hydraulic Engineering,2008,39(5):580-587.
[5]杨和平,王静,湛文涛,等.南宁外环膨胀土路基处治技术及设计方案研究[J].岩土力学,2011,32(增刊2):359-365.YANG He-ping,WANG Jing,ZHAN Wen-tao,et al.Study of treatment technology and design scheme of expansive soil subgrade for Naining outer ring expressway[J].Rock and Soil Mechanics,2011,32(Supp.2):359-365.
[6]孔令伟,陈正汉.特殊土与边坡技术发展综述[J].土木工程学报,2012,45(5):141-161.KONG Ling-wei,CHEN Zheng-han.Advancement in the techniques for special soils and slopes[J].China Civil Engineering Journal,2012,45(5):141-161.
[7]滕珂,杨果林,易岳林.膨胀土路堑柔性护坡整体稳定性计算方法[J].中南大学学报(自然科学版),2015,46(10):3907-3913.TENG Ke,YANG Guo-lin,YI Yue-lin.Global stability analysis method of flexible cutting slope protection[J].Journal of Central South University(Science and Technology),2015,46(10):3907-3913.
[8]鲜少华,许英姿,姚海林,等.锚固加强植被系统约束膨胀土变形模型试验研究[J].岩土力学,2017,38(增刊1):158-166.XIAN Shao-hua,XU Ying-zi,YAO Hai-lin,et al.Model test study of constraint to deformation of expansive soil by anchor reinforced vegetation system[J].Rock and Soil Mechanics,2017,38(Supp.1):158-166.
[9]张颖钧.裂土挡土墙模型试验缓冲层设置的研究[J].岩土工程学报,1995,17(1):38-45.ZHANG Ying-jun.Study on the buffering cushion installed in retaining wall model test with expansive soil as backfill[J].Chinese Journal of Geotechnical Engineering,1995,17(1):38-45.
[10]IKIZLER S B,AYTEKIN M,NAS E.Laboratory study of expanded polystyrene(EPS)geofoam used with expansive soils[J].Geotextiles and Geomembranes,2008,26(2):189-195.
[11]TSUKAMOTO Y,ISHIHARA K,KON H,et al.Use of compressible expanded polystyrene blocks and geogrids for retaining wall structures[J].Soils and Foundations,2002,42(4):29-41.
[12]BATHURST R J,ZARNANI S.Earthquake load attenuation using EPS geofoam buffers in rigid wall applications[J].Indian Geotechnical Journal,2013,43(4):283-391.
[13]郑俊杰,吕思祺,曹文昭.刚柔复合抗滑桩受力与变形特性数值模拟分析[J].华中科技大学学报(自然科学版),2017,45(4):39-44.ZHENG Jun-jie,LüSi-qi,CAO Wen-zhao.Numerical analysis of mechanical and deformation characteristics of composite rigid-flexible anti-slide pile[J].Journal of Huazhong University of Science&Technology(Natural Science Edition),2017,45(4):39-44.
[14]曾仲毅,徐帮树,胡世权,等.增湿条件下膨胀土隧道衬砌破坏数值分析[J].岩土力学,2014,35(3):871-880.ZENG Zhong-yi,XU Bang-shu,HU Shi-quan,et al.Numerical analysis of tunnel liner failure mechanism in expansive soil considering water-increased state[J].Rock and Soil Mechanics,2014,35(3):871-880.
[15]丁金华,陈仁朋,童军,等.基于多场耦合数值分析的膨胀土边坡浅层膨胀变形破坏机制研究[J].岩土力学,2015,36(增刊1):159-168.DING Jin-hua,CHEN Ren-peng,TONG Jun,et al.Research on failure mechanism of shallow instability of expansive soil slope based on multifield coupling numerical analysis[J].Rock and Soil Mechanics,2015,36(Supp.1):159-168.
[16]郑健龙.公路膨胀土工程理论与技术[M].北京:人民交通出版社,2013.ZHENG Jian-long.Theory and technology for highway expansive soil engineering[M].Beijing:China Communications Press,2013.
[17]ZARNANI S,BATHURST R J.Numerical modeling of EPS seismic buffer shaking table tests[J].Geotextiles and Geomembranes,2008,26(5):371-383.
[18]顾慰慈.挡土墙土压力计算手册[M].北京:中国建材工业出版社,2006.GU Wei-ci.Computing manual of earth pressure for retaining wall[M].Beijing:China Building Materials Press,2006.
[19]中交第二公路勘察设计研究院有限公司.JTG D30-2015公路路基设计规范[S].北京:人民交通出版社,2015.Communication of China Second Highway Consultant Co.Ltd.JTG D30-2015 Specifications for design of highway subgrades[S].Beijing:People Communications Press,2015.