刚性基础下筋箍碎石桩复合地基桩土应力比计算模型
|
摘要
桩土应力比是筋箍碎石桩复合地基沉降计算中最重要的参数,但由于其涉及到桩体、土体及筋材三者之间的复杂关系且影响因素众多,目前尚无明确的计算方法。基于此,根据刚性基础下筋箍碎石桩复合地基的受力变形特征,首先通过数值模型研究筋箍碎石桩复合地基桩土应力比与荷载、埋深、筋材刚度以及桩土弹性模量比的关系。根据数值模型揭示的桩土应力比变化规律,提出一个新的桩土应力比计算模型,并依据该模型在假设桩体、土体及筋材应变协调的基础上利用弹塑性分析方法推导刚性基础下筋箍碎石桩桩土应力比的解析公式;基于建立的模型及计算公式探讨桩土应力比与各主要影响因素之间的关系。研究结果表明:该解析公式基于弹塑性理论分析,但也能考虑现场桩土应力比实测值,能够综合反映桩体、土体、筋材、埋深及荷载之间的相互影响作用,并且形式简单,计算方便;刚性基础下筋箍碎石桩桩土应力比在相同荷载水平下随埋深、筋材刚度、面积置换率、桩土弹性模量比及桩体摩擦角的增大而增大,随着荷载水平的增加则会逐渐降低并趋于稳定值;在碎石桩复合地基沉降计算中不宜采取单一的桩土应力比参数,而是应该根据荷载水平以及计算深度分层选取合适的桩土应力比作为计算参数。
Stress concentration ratio is the most important parameter in the settlement calculation of a composite foundation reinforced by geosynthetic-encased stone columns. However, the calculation method of stress concentration ratio has not been well established due to the extremely complicated interactions in the stone column-soil encasement system. In this work, the stress concentration ratio of a composite foundation was calculated using both numerical and analytical methods, taking into account the load-deformation behavior of a composite foundation reinforced by geosynthetic-encased stone columns. A new calculation model for the stress concentration ratio was proposed based on the strain compatibility assumption of the stone column-soil encasement system, and its analytical solution was presented. The proposed model can reflect complicated interactions between the stone column, surrounding soil, geosynthetic encasement, and load. The stress concentration ratio increases with increasing depth, encasement stiffness, replacement ratio, stiffness ratio between the stone column and soil, and friction angle of the stone column under the same load, and decreases with an increase in the load. Therefore, a constant stress concentration ratio is not recommended for use in the settlement analysis of the composite foundation reinforced by geosynthetic-encased stone columns, and a suitable stress concentration ratio should be used taking the load and depth into account.
Stress concentration ratio is the most important parameter in the settlement calculation of a composite foundation reinforced by geosynthetic-encased stone columns. However, the calculation method of stress concentration ratio has not been well established due to the extremely complicated interactions in the stone column-soil encasement system. In this work, the stress concentration ratio of a composite foundation was calculated using both numerical and analytical methods, taking into account the load-deformation behavior of a composite foundation reinforced by geosynthetic-encased stone columns. A new calculation model for the stress concentration ratio was proposed based on the strain compatibility assumption of the stone column-soil encasement system, and its analytical solution was presented. The proposed model can reflect complicated interactions between the stone column, surrounding soil, geosynthetic encasement, and load. The stress concentration ratio increases with increasing depth, encasement stiffness, replacement ratio, stiffness ratio between the stone column and soil, and friction angle of the stone column under the same load, and decreases with an increase in the load. Therefore, a constant stress concentration ratio is not recommended for use in the settlement analysis of the composite foundation reinforced by geosynthetic-encased stone columns, and a suitable stress concentration ratio should be used taking the load and depth into account.
引文
[1] 龚晓南.广义复合地基理论及工程应用[J].岩土工程学报,2007,29(1):1-13.GONG Xiao-nan.Generalized Composite Foundation Theory and Engineering Application [J].Chinese Journal of Geotechnical Engineering,2007,29 (1):1-13.
[2] 欧阳芳,张建经,付晓,等.包裹碎石桩承载特性试验研究[J].岩土力学,2016,37(7):1929-1936.OUYANG Fang,ZHANG Jian-jing,FU Xiao,et al.Experimental Analysis of Bearing Behavior of Geosynthetic Encased Stone Columns [J].Rock and Soil Mechanics,2016,37 (7):1929-1936.
[3] 赵明华,陈庆,张玲,等.加筋碎石桩承载力计算[J].公路交通科技,2011,28(8):7-12.ZHAO Ming-hua,CHEN Qing,ZHANG Ling,et al.Calculation of Bearing Capacity of Geosynthetic-encased Stone Columns [J].Journal of Highway and Transportation Research and Development,2011,28 (8):7-12.
[4] 何广讷.振冲碎石桩复合地基[M].2版.北京:人民交通出版社,2012.HE Guang-ne.The Composite Foundation of Vibro-replacement Stone Column [M].2nd ed.Beijing:China Communications Press,2012.
[5] BRAUNS J.Die Anfangstraglast Von Schottersaulen Im Bindigen Untergrund [J].Die Bautechnik,1978,55 (8):263-271.
[6] HUGHE J,WITHERS N J.Reinforcing of Soft Cohesive Soils with Stone Columns [J].Ground Engineering,1974,7 (3):42-49.
[7] WONG H Y.Field Instrumentation of Vibroflotation Foundation [J].Field Instrumentation in Geotechnical Engineering,1974,23 (4):475-487.
[8] 张玲,赵明华,马缤辉,等.土工格室-碎石桩双向增强复合地基大比例室内模型试验[J].中国公路学报,2013,26(6):1-8.ZHANG Ling,ZHAO Ming-hua,MA Bin-hui,et al.Large Scale Laboratory Experiments on Two-directional Composite Foundation Reinforced with Geocell and Stone Columns [J].China Journal of Highway and Transport,2013,26 (6):1-8.
[9] 赵明华,顾美湘,张玲,等.竖向土工加筋体对碎石桩承载变形影响的模型试验研究[J].岩土工程学报,2013,36(9):1587-1593.ZHAO Ming-hua,GU Mei-xiang,ZHANG Ling,et al.Model Tests on Influence of Vertical Geosynthetic-encasement on Performance of Stone Columns [J].Chinese Journal of Geotechnical Engineering,2013,36 (9):1587-1593.
[10] 陈建峰,王波,魏静,等.加筋碎石桩复合地基路堤模型试验[J].中国公路学报,2015,28(9):1-8.CHEN Jian-feng,WANG Bo,WEI Jing,et al.Model Test of Embankment on Composite Foundation Reinforced with Geosynthetic-encased Stone Columns [J].China Journal of Highway and Transport,2015,28 (9):1-8.
[11] 叶观宝,蔡永生,张振.加芯水泥土桩复合地基桩土应力比计算方法研究[J].岩土力学,2016,37(3):672-678.YE Guan-bao,CAI Yong-sheng,ZHANG Zhen.Research on Calculation of Pile-soil Stress Ratio for Composite Foundation Reinforced by Stiffened Deep Mixed Piles [J].Rock and Soil Mechanics,2016,37 (3):672-678.
[12] 赵明华,张玲,刘敦平.散体材料桩复合地基桩土应力比分析[J].中南大学学报:自然科学版,2007,38(3):555-560.ZHAO Ming-hua,ZHANG Ling,LIU Dun-ping.Bearing Capacity Calculating Method of Discrete Material Pile Composite Foundation [J].Journal of Central South University:Science and Technology,2007,38 (3):555-560.
[13] 赵明华,刘猛,马缤辉,等.路堤下“土工格室+碎石桩”双向增强复合地基桩土应力比及沉降计算[J].中国公路学报,2016,29(5):1-10.ZHAO Ming-hua,LIU Meng,MA Bin-hui,et al.Calculation for Stress Concentration Ratio and Settlement of Bidirectional Reinforced Consisting of Geocell Mattress and Stone Column under Embankment [J].China Journal of Highway and Transport,2016,29 (5):1-10.
[14] 赵明华,牛浩懿,刘猛,等.柔性基础下碎石桩复合地基桩土应力比及沉降计算[J].岩土工程学报,2016,39(9):1549-1556.ZHAO Ming-hua,NIU Hao-yi,LIU Meng,et al.Pile-soil Stress Ratio and Settlement of Composite Ground with Gravel Piles in Flexible Foundation [J].Chinese Journal of Geotechnical Engineering,2016,39 (9):1549-1556.
[15] 陈继彬,赵其华,彭社琴.路堤荷载下碎石桩处理软基沉降计算[J].工程地质学报,2015,23(3):505-510.CHEN Ji-bin,ZHAO Qi-hua,PENG She-qin.Settlement Evaluation of Soft Soil Foundation Reinforced with Stone Column Due to Embankment Load [J].Journal of Engineering Geology,2015,23 (3):505-510.
[16] CASTRO J,SAGASETA C.Deformation and Consolidation Around Encased Stone Columns [J].Geotextiles & Geomembranes,2011,29 (3):268-276.
[17] BOSTJAN P,BOJAN M,JANKO L.Geosynthetic-encased Stone Columns:Analytical Calculation Model [J].Geotextiles & Geomembranes,2011,29 (1):29-39.
[18] 蒋敏敏,肖昭然,蔡正银.高速公路碎石桩复合地基加固数值模拟[J].公路,2012(1):8-12.JIANG Min-min,XIAO Zhao-ran,CAI Zheng-yin.Numerical Simulation of Stone Columns Reinforced Foundation of Expressway [J].Highway,2012 (1):8-12.
[19] 刘洋,闫鸿翔,汪成林.复合振冲碎石桩加固机理及施工过程数值模拟[J].工程科学学报,2015(3):390-397.LIU Yang,YAN Hong-xiang,WANG Cheng-lin.Reinforcement Mechanism of Vibro-stone Columns with Additional Wicks and Numerical Analysis [J].Chinese Journal of Engineering,2015 (3):390-397.
[20] TAN X,ZHAO M H.Deformation and Failure Behavior of the Isolated Single Stone Column with and Without Geosynthetic Encasement [C] // CHEN R P,ZHENG G,OU C Y.Proceedings of the 2nd International Symposium on Asia Urban GeoEngineering.Hangzhou:Zhejiang University Press,2017:547-559.
[21] TAN X,ZHAO M,CHEN W.Numerical Simulation of a Single Stone Column in Soft Clay Using the Discrete-element Method [J].International Journal of Geomechanics,2018,18 (12):1-12.
[22] 谭鑫,赵明华,金宇轩,等.碎石桩单桩受荷模型试验的离散单元法数值模拟[J].湖南大学学报:自然科学版,2019,46(3):106-113.TAN Xin,ZHAO Ming-hua,JIN Yu-xuan,et al.Numerical Simulation of Loading Test on a Single Stone Column Using Discrete Element Method [J].Journal of Hunan University:Natural Sciences,2019,46 (3):106-113.
[23] LO S R,ZHANG R,MAK J.Geosynthetic-encased Stone Columns in Soft Clay:A Numerical Study [J].Geotextiles & Geomembranes,2010,28 (3):292-302.
[24] CHUNGSIK Y.Performance of Geosynthetic-encased Stone Columns in Embankment Construction:Numerical Investigation.[J].Journal of Geotechnical & Geoenvironmental Engineering,2010,136 (8):1148-1160.
[25] SEXTON B G,MCCABE B A,CASTRO J.Appraising Stone Column Settlement Prediction Methods Using Finite Element Analyses [J].Acta Geotechnica,2014,9 (6):993-1011.
[2] 欧阳芳,张建经,付晓,等.包裹碎石桩承载特性试验研究[J].岩土力学,2016,37(7):1929-1936.OUYANG Fang,ZHANG Jian-jing,FU Xiao,et al.Experimental Analysis of Bearing Behavior of Geosynthetic Encased Stone Columns [J].Rock and Soil Mechanics,2016,37 (7):1929-1936.
[3] 赵明华,陈庆,张玲,等.加筋碎石桩承载力计算[J].公路交通科技,2011,28(8):7-12.ZHAO Ming-hua,CHEN Qing,ZHANG Ling,et al.Calculation of Bearing Capacity of Geosynthetic-encased Stone Columns [J].Journal of Highway and Transportation Research and Development,2011,28 (8):7-12.
[4] 何广讷.振冲碎石桩复合地基[M].2版.北京:人民交通出版社,2012.HE Guang-ne.The Composite Foundation of Vibro-replacement Stone Column [M].2nd ed.Beijing:China Communications Press,2012.
[5] BRAUNS J.Die Anfangstraglast Von Schottersaulen Im Bindigen Untergrund [J].Die Bautechnik,1978,55 (8):263-271.
[6] HUGHE J,WITHERS N J.Reinforcing of Soft Cohesive Soils with Stone Columns [J].Ground Engineering,1974,7 (3):42-49.
[7] WONG H Y.Field Instrumentation of Vibroflotation Foundation [J].Field Instrumentation in Geotechnical Engineering,1974,23 (4):475-487.
[8] 张玲,赵明华,马缤辉,等.土工格室-碎石桩双向增强复合地基大比例室内模型试验[J].中国公路学报,2013,26(6):1-8.ZHANG Ling,ZHAO Ming-hua,MA Bin-hui,et al.Large Scale Laboratory Experiments on Two-directional Composite Foundation Reinforced with Geocell and Stone Columns [J].China Journal of Highway and Transport,2013,26 (6):1-8.
[9] 赵明华,顾美湘,张玲,等.竖向土工加筋体对碎石桩承载变形影响的模型试验研究[J].岩土工程学报,2013,36(9):1587-1593.ZHAO Ming-hua,GU Mei-xiang,ZHANG Ling,et al.Model Tests on Influence of Vertical Geosynthetic-encasement on Performance of Stone Columns [J].Chinese Journal of Geotechnical Engineering,2013,36 (9):1587-1593.
[10] 陈建峰,王波,魏静,等.加筋碎石桩复合地基路堤模型试验[J].中国公路学报,2015,28(9):1-8.CHEN Jian-feng,WANG Bo,WEI Jing,et al.Model Test of Embankment on Composite Foundation Reinforced with Geosynthetic-encased Stone Columns [J].China Journal of Highway and Transport,2015,28 (9):1-8.
[11] 叶观宝,蔡永生,张振.加芯水泥土桩复合地基桩土应力比计算方法研究[J].岩土力学,2016,37(3):672-678.YE Guan-bao,CAI Yong-sheng,ZHANG Zhen.Research on Calculation of Pile-soil Stress Ratio for Composite Foundation Reinforced by Stiffened Deep Mixed Piles [J].Rock and Soil Mechanics,2016,37 (3):672-678.
[12] 赵明华,张玲,刘敦平.散体材料桩复合地基桩土应力比分析[J].中南大学学报:自然科学版,2007,38(3):555-560.ZHAO Ming-hua,ZHANG Ling,LIU Dun-ping.Bearing Capacity Calculating Method of Discrete Material Pile Composite Foundation [J].Journal of Central South University:Science and Technology,2007,38 (3):555-560.
[13] 赵明华,刘猛,马缤辉,等.路堤下“土工格室+碎石桩”双向增强复合地基桩土应力比及沉降计算[J].中国公路学报,2016,29(5):1-10.ZHAO Ming-hua,LIU Meng,MA Bin-hui,et al.Calculation for Stress Concentration Ratio and Settlement of Bidirectional Reinforced Consisting of Geocell Mattress and Stone Column under Embankment [J].China Journal of Highway and Transport,2016,29 (5):1-10.
[14] 赵明华,牛浩懿,刘猛,等.柔性基础下碎石桩复合地基桩土应力比及沉降计算[J].岩土工程学报,2016,39(9):1549-1556.ZHAO Ming-hua,NIU Hao-yi,LIU Meng,et al.Pile-soil Stress Ratio and Settlement of Composite Ground with Gravel Piles in Flexible Foundation [J].Chinese Journal of Geotechnical Engineering,2016,39 (9):1549-1556.
[15] 陈继彬,赵其华,彭社琴.路堤荷载下碎石桩处理软基沉降计算[J].工程地质学报,2015,23(3):505-510.CHEN Ji-bin,ZHAO Qi-hua,PENG She-qin.Settlement Evaluation of Soft Soil Foundation Reinforced with Stone Column Due to Embankment Load [J].Journal of Engineering Geology,2015,23 (3):505-510.
[16] CASTRO J,SAGASETA C.Deformation and Consolidation Around Encased Stone Columns [J].Geotextiles & Geomembranes,2011,29 (3):268-276.
[17] BOSTJAN P,BOJAN M,JANKO L.Geosynthetic-encased Stone Columns:Analytical Calculation Model [J].Geotextiles & Geomembranes,2011,29 (1):29-39.
[18] 蒋敏敏,肖昭然,蔡正银.高速公路碎石桩复合地基加固数值模拟[J].公路,2012(1):8-12.JIANG Min-min,XIAO Zhao-ran,CAI Zheng-yin.Numerical Simulation of Stone Columns Reinforced Foundation of Expressway [J].Highway,2012 (1):8-12.
[19] 刘洋,闫鸿翔,汪成林.复合振冲碎石桩加固机理及施工过程数值模拟[J].工程科学学报,2015(3):390-397.LIU Yang,YAN Hong-xiang,WANG Cheng-lin.Reinforcement Mechanism of Vibro-stone Columns with Additional Wicks and Numerical Analysis [J].Chinese Journal of Engineering,2015 (3):390-397.
[20] TAN X,ZHAO M H.Deformation and Failure Behavior of the Isolated Single Stone Column with and Without Geosynthetic Encasement [C] // CHEN R P,ZHENG G,OU C Y.Proceedings of the 2nd International Symposium on Asia Urban GeoEngineering.Hangzhou:Zhejiang University Press,2017:547-559.
[21] TAN X,ZHAO M,CHEN W.Numerical Simulation of a Single Stone Column in Soft Clay Using the Discrete-element Method [J].International Journal of Geomechanics,2018,18 (12):1-12.
[22] 谭鑫,赵明华,金宇轩,等.碎石桩单桩受荷模型试验的离散单元法数值模拟[J].湖南大学学报:自然科学版,2019,46(3):106-113.TAN Xin,ZHAO Ming-hua,JIN Yu-xuan,et al.Numerical Simulation of Loading Test on a Single Stone Column Using Discrete Element Method [J].Journal of Hunan University:Natural Sciences,2019,46 (3):106-113.
[23] LO S R,ZHANG R,MAK J.Geosynthetic-encased Stone Columns in Soft Clay:A Numerical Study [J].Geotextiles & Geomembranes,2010,28 (3):292-302.
[24] CHUNGSIK Y.Performance of Geosynthetic-encased Stone Columns in Embankment Construction:Numerical Investigation.[J].Journal of Geotechnical & Geoenvironmental Engineering,2010,136 (8):1148-1160.
[25] SEXTON B G,MCCABE B A,CASTRO J.Appraising Stone Column Settlement Prediction Methods Using Finite Element Analyses [J].Acta Geotechnica,2014,9 (6):993-1011.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |