包裹碎石桩加固的砂土液化机理试验研究
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摘要
通过分别开展包裹碎石桩加固、碎石桩加固以及未加固的饱和砂土液化振动台试验,对比分析不同加固类型下的抗液化性能,重点剖析包裹碎石桩加固的砂土液化机理。试验表明:振动加载过程中,包裹碎石桩始终保持桩体的完整性与良好的排水性能且其加固模型地基的总沉降量相较于未加固模型地基减少了50%,相较于碎石桩加固模型地基减少了31.8%。包裹碎石桩加固模型排出水量较未加固模型地基提高了33.3%,较碎石桩加固模型地基提高了16.6%;包裹碎石桩加固模型地基的超静孔压值下降显著且地基下层砂土出现未液化的现象;并进一步发现包裹碎石桩的排水加固作用沿土层竖向深度呈递增趋势。因此,可以发现包裹碎石桩加固砂土液化的抗震性能优于碎石桩。
Geo-encased stone columns are novel types of columns wrapped in layers of geosynthetics. They retain the excellent performance of stone columns and fully exploit the tensile properties of geosynthetics, which can improve the rigidity, shear resistance, and drainage effect of stone columns. However, few studies have focused on the liquefaction of sandy soil reinforced by geo-encased stone columns. In this work, shaking table tests on the liquefaction of sandy soil without reinforcement, reinforced with geosynthetic-encased stone columns, or reinforced with stone columns are carried out to investigate and compare the anti-liquefaction performances of the reinforcements. Results show that during vibration loading, the geo-encased stone columns consistently maintained their integrity and good drainage performance. Compared with those of the non-reinforced foundation and the foundation reinforced with stone columns, the total settlement values of the foundation reinforced with geosynthetic-encased stone columns decreased by 50% and 31.8%, respectively. Moreover, the amount of discharged water of the foundation reinforced with geosynthetic-encased stone columns increased by 33.3% and 16.6%, respectively, relative to those of the non-reinforced foundation and the foundation reinforced with stone columns. Excess pore water pressure in the foundation reinforced with geo-encased stone columns has drastically reduced, and sand liquefaction does not occur in lower portion of the foundation. The drainage performance of the foundation reinforced with geo-encased stone column tends to improve as the vertical depth of the soil increases. The seismic performance of geo-encased stone columns is better than that of stone columns.
Geo-encased stone columns are novel types of columns wrapped in layers of geosynthetics. They retain the excellent performance of stone columns and fully exploit the tensile properties of geosynthetics, which can improve the rigidity, shear resistance, and drainage effect of stone columns. However, few studies have focused on the liquefaction of sandy soil reinforced by geo-encased stone columns. In this work, shaking table tests on the liquefaction of sandy soil without reinforcement, reinforced with geosynthetic-encased stone columns, or reinforced with stone columns are carried out to investigate and compare the anti-liquefaction performances of the reinforcements. Results show that during vibration loading, the geo-encased stone columns consistently maintained their integrity and good drainage performance. Compared with those of the non-reinforced foundation and the foundation reinforced with stone columns, the total settlement values of the foundation reinforced with geosynthetic-encased stone columns decreased by 50% and 31.8%, respectively. Moreover, the amount of discharged water of the foundation reinforced with geosynthetic-encased stone columns increased by 33.3% and 16.6%, respectively, relative to those of the non-reinforced foundation and the foundation reinforced with stone columns. Excess pore water pressure in the foundation reinforced with geo-encased stone columns has drastically reduced, and sand liquefaction does not occur in lower portion of the foundation. The drainage performance of the foundation reinforced with geo-encased stone column tends to improve as the vertical depth of the soil increases. The seismic performance of geo-encased stone columns is better than that of stone columns.
引文
[1] IMPE VAN,W F.Soil Improvement Techniques and Their Evolution[J].Animal Science Papers & Reports,1989,20(1):169-178.
[2] 闫卫泽.散体材料砂桩加固液化砂土的振动台试验研究[D].太原:太原理工大学,2007.YAN Weize.The Shaking Table Experimental Study on Liquefiable Sand Soil Improved by Granular Sand Pile[D].Taiyuan:Taiyuan University of Technology,2007.
[3] AYADAT T,HANNAA M.Encapsulated Stone Columns as a Soil Improvement Technique for Collapsible Soil[J].Proceedings of the Institution of Civil Engineers - Ground Improvement,2005,9(4):137-147.
[4] WU C S,HONG Y S,LIN H C.Axial Stress-Strain Relation of Encapsulated Granular Column[J].Computers &Geotechnics,2009,36(1):226-240.
[5] ZHANG Yiping,LI Tao,WANG Yang.Theoretical Elastic Solutions for Foundations Improved by Geosynthetic-Encased Columns[J].Geosynthetics International,2011,18(1):12-20.
[6] 张仪萍,王洋,李涛.复合地基等效弹性参数研究[J].岩土力学,2011,32(7):2106-2110.ZHANG Yiping,WANG Yang,LI Tao.Study of the Equivalent Elastic Parameters of Composite Foundations[J].Rock and Soil Mechanics,2011,32(7):2106-2110.
[7] 张仪萍,饶勤波,王洋,等.复合地基单元体弹性解析解与Priebe法的比较[J].岩土力学,2011,32(8):2397-2401.ZHANG Yiping,RAO Qinbo,WANG Yang,et al.Comparison Between Priebe's Method and Elastic Analytical Solution of Unit Cell for Composite Foundations[J].Rock and Soil Mechanics,2011,32(8):2397-2401.
[8] ZHANG Y P,CHAN D,WANG Y.Consolidation of Composite Foundation Improved by Geosynthetic-Encased Stone Columns[J].Geotextiles and Geomembranes,2012,32:10-17.
[9] BALAAM N P,BOOKER J R.Analysis of Rigid Rafts Supported by Granular Piles[J].International Journal for Numerical and Analytical Methods in Geomechanics,1981,5(4):379-403.
[10] Priebe H.Abschatzung des Setzungsverhaltens Eines Durch Stopfverdichtung Verbesserten Baugrundes[M].Die Bautechnik.1976,5:160-162.
[11] 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 Minghua,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.
[12] 赵明华,张赞威,刘猛,等.筋箍碎石桩复合地基极限承载力计算[J].水文地质工程地质,2014,41(1):67-73.ZHAO Minghua,ZHANG Zanwei,LIU Meng,et al.Calculation of Ultimate Bearing Capacity of Composite Foundation with Geosynthetic Encased Stone Columns[J].Hydrpgeology & Engineering Geology,2014,41(1):67-73.
[13] 段园煜.土工袋装桩桩型复合地基受力变形特性研究[D].杭州:浙江大学,2012.DUAN Yuanyu.Mechanicaland Deformation Performance of Composite Foundation with Geosynthetics Encased Columns[D].Hangzhou:Zhejiang University,2012.
[14] 欧阳芳,张建经,韩建伟,等.包裹碎石群桩模型试验分析[J].东南大学学报(自然科学版),2015,45(5):952-957.OUYANG Fang,ZHANG Jianjing,HAN Jianwei,et al.Model Test Analysis on Group of Geosynthetic Encased Stone Columns[J].Journal of Southeast University (Natural Science Edition),2015,45(5):952-957.
[15] 欧阳芳,张建经,韩建伟,等.包裹碎石桩和碎石桩复合地基抗震性能对比试验研究[J].岩土力学,2016,37(4):998-1004.OUYANG Fang,ZHANG Jianjing,HAN Jianwei,et al.Comparison of a seismic Behavior Between Geo-encased Stone Columns Composite Foundation and Stone Columns Composite Foundation[J].Rock and Soil Mechanics,2016,37(4):998-1004.
[16] GNIEL J,BOUAZZA A.Improvement of Soft Soils Using Geogrid Encased Stone Columns[J].Geotextiles and Geomembranes,2009,27(3):167-175.
[17] DASH S Kumar,BORA M Chandra.Influence of Geosynthetic Encasement on the Performance of Stone Columns Floating in SoftClay[J].Canadian Geotechnical Journal,2013,50(7):754-765.
[18] MURUGESAN S,RAJAGOPAL K.Performance of Encased Stone Columns and Design Guidelines for Construction on Soft Clay Soils[M].Geosynthetics in Civil and Environmental Engineering.Springer Berlin Heidelberg,2009:729-734.
[19] 李雨润,强东峰,邹泽,等.不同厚度饱和砂土中群桩结构动力响应试验研究[J].地震工程学报,2018,40(4):625-630.LI Yurun,QIANG Dongfeng,ZOU Ze,et al.Experimental Study on the Dynamic Response of Pile-group Structure in Saturated Sand with Different Thicknesses[J].China Earthquake Engineering Journal,2018,40(4):625-630.
[20] 潘永庆,孙立强,王吉超,等.碎石桩加固液化粉土地基的数值模拟分析[J].地震工程学报,2014,36(3):540-543.PAN Yongqing,SUN Liqiang,WANG Jichao,et al.Analysis of Numerical Simulation of Liquefiable Silty Soil Reinforced by Gravel Pile[J].China Earthquake Engineering Journal,2014,36(3):540-543.
[21] 孙锐.液化土层地震动和场地液化识别方法研究[D].哈尔滨:中国地震局工程力学研究所,2006.SUN Rui.Study on Seimic Ground Motion on Liquefiable Soil Layer and Site Liquefaction Detection[D].Harbin:Institute of Engineering Mechanics,China Seismological Bureau,2006.
[22] 中华人民共和国行业标准编写组.建筑地基基础设计规范:GB50007-2011[S].北京:中国建筑工业出版社,2012.The Professional Standard Compilation Group of People′s Republic of China.Technical Code for Building Foundation Design:GB50007-2011[S].Beijing:China Architecture and Building Press,2012.
[2] 闫卫泽.散体材料砂桩加固液化砂土的振动台试验研究[D].太原:太原理工大学,2007.YAN Weize.The Shaking Table Experimental Study on Liquefiable Sand Soil Improved by Granular Sand Pile[D].Taiyuan:Taiyuan University of Technology,2007.
[3] AYADAT T,HANNAA M.Encapsulated Stone Columns as a Soil Improvement Technique for Collapsible Soil[J].Proceedings of the Institution of Civil Engineers - Ground Improvement,2005,9(4):137-147.
[4] WU C S,HONG Y S,LIN H C.Axial Stress-Strain Relation of Encapsulated Granular Column[J].Computers &Geotechnics,2009,36(1):226-240.
[5] ZHANG Yiping,LI Tao,WANG Yang.Theoretical Elastic Solutions for Foundations Improved by Geosynthetic-Encased Columns[J].Geosynthetics International,2011,18(1):12-20.
[6] 张仪萍,王洋,李涛.复合地基等效弹性参数研究[J].岩土力学,2011,32(7):2106-2110.ZHANG Yiping,WANG Yang,LI Tao.Study of the Equivalent Elastic Parameters of Composite Foundations[J].Rock and Soil Mechanics,2011,32(7):2106-2110.
[7] 张仪萍,饶勤波,王洋,等.复合地基单元体弹性解析解与Priebe法的比较[J].岩土力学,2011,32(8):2397-2401.ZHANG Yiping,RAO Qinbo,WANG Yang,et al.Comparison Between Priebe's Method and Elastic Analytical Solution of Unit Cell for Composite Foundations[J].Rock and Soil Mechanics,2011,32(8):2397-2401.
[8] ZHANG Y P,CHAN D,WANG Y.Consolidation of Composite Foundation Improved by Geosynthetic-Encased Stone Columns[J].Geotextiles and Geomembranes,2012,32:10-17.
[9] BALAAM N P,BOOKER J R.Analysis of Rigid Rafts Supported by Granular Piles[J].International Journal for Numerical and Analytical Methods in Geomechanics,1981,5(4):379-403.
[10] Priebe H.Abschatzung des Setzungsverhaltens Eines Durch Stopfverdichtung Verbesserten Baugrundes[M].Die Bautechnik.1976,5:160-162.
[11] 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 Minghua,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.
[12] 赵明华,张赞威,刘猛,等.筋箍碎石桩复合地基极限承载力计算[J].水文地质工程地质,2014,41(1):67-73.ZHAO Minghua,ZHANG Zanwei,LIU Meng,et al.Calculation of Ultimate Bearing Capacity of Composite Foundation with Geosynthetic Encased Stone Columns[J].Hydrpgeology & Engineering Geology,2014,41(1):67-73.
[13] 段园煜.土工袋装桩桩型复合地基受力变形特性研究[D].杭州:浙江大学,2012.DUAN Yuanyu.Mechanicaland Deformation Performance of Composite Foundation with Geosynthetics Encased Columns[D].Hangzhou:Zhejiang University,2012.
[14] 欧阳芳,张建经,韩建伟,等.包裹碎石群桩模型试验分析[J].东南大学学报(自然科学版),2015,45(5):952-957.OUYANG Fang,ZHANG Jianjing,HAN Jianwei,et al.Model Test Analysis on Group of Geosynthetic Encased Stone Columns[J].Journal of Southeast University (Natural Science Edition),2015,45(5):952-957.
[15] 欧阳芳,张建经,韩建伟,等.包裹碎石桩和碎石桩复合地基抗震性能对比试验研究[J].岩土力学,2016,37(4):998-1004.OUYANG Fang,ZHANG Jianjing,HAN Jianwei,et al.Comparison of a seismic Behavior Between Geo-encased Stone Columns Composite Foundation and Stone Columns Composite Foundation[J].Rock and Soil Mechanics,2016,37(4):998-1004.
[16] GNIEL J,BOUAZZA A.Improvement of Soft Soils Using Geogrid Encased Stone Columns[J].Geotextiles and Geomembranes,2009,27(3):167-175.
[17] DASH S Kumar,BORA M Chandra.Influence of Geosynthetic Encasement on the Performance of Stone Columns Floating in SoftClay[J].Canadian Geotechnical Journal,2013,50(7):754-765.
[18] MURUGESAN S,RAJAGOPAL K.Performance of Encased Stone Columns and Design Guidelines for Construction on Soft Clay Soils[M].Geosynthetics in Civil and Environmental Engineering.Springer Berlin Heidelberg,2009:729-734.
[19] 李雨润,强东峰,邹泽,等.不同厚度饱和砂土中群桩结构动力响应试验研究[J].地震工程学报,2018,40(4):625-630.LI Yurun,QIANG Dongfeng,ZOU Ze,et al.Experimental Study on the Dynamic Response of Pile-group Structure in Saturated Sand with Different Thicknesses[J].China Earthquake Engineering Journal,2018,40(4):625-630.
[20] 潘永庆,孙立强,王吉超,等.碎石桩加固液化粉土地基的数值模拟分析[J].地震工程学报,2014,36(3):540-543.PAN Yongqing,SUN Liqiang,WANG Jichao,et al.Analysis of Numerical Simulation of Liquefiable Silty Soil Reinforced by Gravel Pile[J].China Earthquake Engineering Journal,2014,36(3):540-543.
[21] 孙锐.液化土层地震动和场地液化识别方法研究[D].哈尔滨:中国地震局工程力学研究所,2006.SUN Rui.Study on Seimic Ground Motion on Liquefiable Soil Layer and Site Liquefaction Detection[D].Harbin:Institute of Engineering Mechanics,China Seismological Bureau,2006.
[22] 中华人民共和国行业标准编写组.建筑地基基础设计规范:GB50007-2011[S].北京:中国建筑工业出版社,2012.The Professional Standard Compilation Group of People′s Republic of China.Technical Code for Building Foundation Design:GB50007-2011[S].Beijing:China Architecture and Building Press,2012.