基于现场液化试验的饱和砂土孔压增量计算模型
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摘要
采用现场液化试验,研究水平场地孔压增长模式,提出孔压增量计算模型。通过不同密实度砂土的液化试验,以加速度、埋深、砂土密实度等现场参数为指标构建孔压增量模型,发现现场和室内试验孔压增长模式的区别和联系,并验证该孔压模型的可靠性。研究结果表明:等幅循环荷载下,与现有动三轴等土单元试验的孔压增量随作用次数一直呈单调递减模式不同,现场试验孔压增量随作用次数呈现出先增大后减小的规律,中间存在阈值;通过参数分析和试验实例验证,构建的孔压增量计算模型,可更方便地用于随机荷载下水平场地的饱和砂土孔压计算。
Through in-situ liquefaction tests under dynamic artificial loading, the pore pressure variation of saturated sand in level ground is measured, and an incremental model of predicting pore pressure is proposed. Using the results of in-situ testing in different cases, a new incremental model is established considering acceleration, buried depth, density of sand, common properties used to describe soil characteristics in-situ. The correlation and difference of response for pore pressure increase between in-situ test and laboratory test are also analyzed. Parameter analysis and validation through in-situ liquefaction tests indicate that the new model is reliable. The number-of-cycle effect by in-situ tests is different from the results obtained from laboratory tests. The main conclusions are as follows:(1) Under uniform cyclic loading conditions, the variation of pore pressure increment in saturated sand in field is not monotonically decreasing with increasing numbers of cycles, but increasing at the beginning followed by decreasing after a specific number of cycles, which can be defined as a threshold number;(2) The proposed incremental model can also be used to predict pore pressure buildup of saturated sand under irregular loadings.
Through in-situ liquefaction tests under dynamic artificial loading, the pore pressure variation of saturated sand in level ground is measured, and an incremental model of predicting pore pressure is proposed. Using the results of in-situ testing in different cases, a new incremental model is established considering acceleration, buried depth, density of sand, common properties used to describe soil characteristics in-situ. The correlation and difference of response for pore pressure increase between in-situ test and laboratory test are also analyzed. Parameter analysis and validation through in-situ liquefaction tests indicate that the new model is reliable. The number-of-cycle effect by in-situ tests is different from the results obtained from laboratory tests. The main conclusions are as follows:(1) Under uniform cyclic loading conditions, the variation of pore pressure increment in saturated sand in field is not monotonically decreasing with increasing numbers of cycles, but increasing at the beginning followed by decreasing after a specific number of cycles, which can be defined as a threshold number;(2) The proposed incremental model can also be used to predict pore pressure buildup of saturated sand under irregular loadings.
引文
[1]SEED H B,MARTIN P P,LYSMER J.Pore water pressure changes during soil liquefaction[J].Journal of the Geotechnical Engineering Division,ASCE,1976,102(GT4):323-345.
[2]FINN W D L,BNATIA S K.Prediction of seismic pore water pressures[C]//Proceedings of 10th International Conference on Soil Mechanics and Foundation Engineering.Rotterdam:A.A.Balkema,1981.
[3]徐志英,沈珠江.地震液化的有效应力二维动力分析方法[J].华东水利学院学报,1981,(3):1-14.XU Zhi-ying,SHEN Zhu-jiang.2D dynamic analysis of effective stresses of seismic liquefaction[J].East China College of Hydraulic Engineering,1981,(3):1-14.
[4]魏汝龙,郭家禄,左元明.往复荷载下饱和粉砂中的孔隙压力[J].土木工程学报,1983,16(1):22-32.WEI Ru-long,GUO Jia-lu,ZUO Yuan-ming.Pore pressure in saturated silty sand under cyclic loading[J].China of Civil Engineering Journal,1983,16(1):22-32.
[5]何广讷.砂土振动孔隙水压力的研究[J].水利学报,1983,(8):49-54.HE Guang-ne.Study on vibration pore pressure of sand[J].Journal of Hydraulic Engineering,1983,(8):49-54.
[6]LIYANAPATHIRANA D S,POULOS H G.A numerical model for dynamic soil liquefaction analysis[J].Soil Dynamics and Earthquake Engineering,2002,22(9):1007-1015.
[7]ISHIBASHI I,SHERIF M A,TSUCHIYA C.Porepressure rise mechanism and soil liquefaction[J].Soils and Foundations,1977,17(2):17-26.
[8]SHERIF M A,ISHIBASHI I,TSUCHIYA C.Pore-water pressure prediction during earthquake loadings[J].Soils and Foundations,1978,18(4):19-30.
[9]刘颖,仝筠,齐心.循环荷载作用下饱和砂土的残余孔压[J].土工工程学报,1981,14(3):49-55.LIU Ying,TONG Jun,QI Xin.Residual pore pressure in saturated sand under cyclic loading[J].China of Civil Engineering Journal,1981,14(3):49-55.
[10]KAGAWA T,KRAFT L M.Modeling the liquefaction process[J].Journal of the Geotechnical Engineering Division,ASCE,1981,107(GT12):1593-1607.
[11]丰万玲,石兆吉.判别水平土层液化势的孔隙水压力分析方法[J].工程抗震,1988,(4):32-35.FENG Wan-ling,SHI Zhao-ji.Pore pressure analysis method for estimating liquefaction potential of horizontal soil strata[J].Earthquake Resistant,1988,(4):32-35.
[12]王天颂,刘颖,同筠,等.地震荷载作用下饱和砂层孔隙水压力的增长与消散[J].岩土工程学报,1983,5(3):87-102.WANG Tian-song,LIU Ying,TONG Jun,et al.Generation and dissipation of pore pressure in saturated sand layer due to earthquake loading[J].Chinese Journal of Geotechnical Engineering,1983,5(3):87-102.
[13]孙锐,袁晓铭.非均等固结下饱和砂土孔压增量简化计算公式[J].岩土工程学报,2005,27(9):1021-1025.SUN Rui,YUAN Xiao-ming.Simplified incremental formula for estimating pore pressure of saturated sands under anisotropic consolidation[J].Chinese Journal of Geotechnical Engineering,2005,27(9):1021-1025.
[14]孟上九,刘添华.不规则荷载下饱和砂土孔压模型研究[J].岩石力学与工程学报,2014,33(增刊1):3050-3055.MENG Shang-jiu,LIU Tian-hua.Study of pore-pressure model of saturated sands under irregular load[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(Supp.1):3050-3055.
[15]佘跃心,刘汉龙,高玉峰.饱和黄土孔压增长模式与液化机理试验研究[J].岩土力学,2002,23(4):395-399.SHE Yue-xin,LIU Han-long,GAO Yu-feng.Study on liquefaction mechanism and pore-water pressure mode of saturated original loess[J].Rock and Soil Mechanics,2002,23(4):395-399.
[16]陈存礼,何军芳,胡再强,等.动荷载作用下饱和尾矿砂的孔压和残余应变演化特性[J].岩石力学与工程学报,2006,25(增刊2):4034-4039.CHEN Cun-li,HE Jun-fang,HU Zai-qiang,et al.Developing characteristics of pore water pressure and residual deformation of tailings sands under cyclic loading[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(Supp.2):4034-4039.
[17]王亚军,金峰,张楚汉,等.舟山海域海相砂土循环激振下的液化破坏孔压模型[J].岩石力学与工程学报,2013,32(3):582-596.WANG Ya-jun,JIN Feng,ZHANG Chu-han,et al.Liquefaction failure pore water pressure model of Zhoushan marine sandy soil under cyclic exciting loading[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(3):582-596.
[18]陈育民,张意江,王维国,等.爆炸液化场地中浅埋钢筋混凝土结构动力响应的现场试验研究[J].岩土力学,2016,37(12):3506-3519.CHEN Yu-min,ZHANG Yi-jiang,WANG Wei-guo,et al.Experimental investigation into dynamic response of shallow-buried reinforced concrete structure in blastinduced liquefied sandy foundation[J].Rock and Soil Mechanics,2016,37(12):3506-3519.
[19]付海清,袁晓铭,陈龙伟.基于重塑饱和砂土的现场液化试验方法[J].地震工程学报,2015,37(1):16-20.FU Hai-qing,YUAN Xiao-ming,CHEN Long-wei.A method for in-situ liquefaction test based on reconstituted saturated sand model[J].China Earthquake Engineering Journal,2015,37(1):16-20.
[20]付海清,陈龙伟,李雨润,等.人工激振下现场液化试验初步研究[J].世界地震工程,2010,26(增刊1):235-240.FU Hai-qing,CHEN Long-wei,LI Yu-run,et al.Preliminary study on in-situ liquefaction tests under artificial dynamic loading[J].World Earthquake Engineering,2010,26(Supp.1):235-240.
[21]付海清,袁晓铭.液化对地表运动影响的现场试验研究[J].地震工程与工程振动,2016,36(5):99-106.FU Hai-qing,YUAN Xiao-ming.Effect of soil liquefaction on ground motion using artificial vibration[J].Journal of Earthquake Engineering and Vibration,2016,36(5):99-106.
[22]SEED H B,IDRISS I M.Simplified procedure for evaluating soil liquefaction potential[J].Journal of the Soil Mechanics and Foundations Division,ASCE,1971,97(SM9):1249-1273.
[23]YOUD T L,IDRISS I M.Liquefaction resistance of soils:summary report from the 1996 NCEER and 1998NCEER/NSF workshops on evaluation of liquefaction resistance of soils[J].Journal of Geotechnical and Geoenvironmental Engineering,2001,127(4):297-313.
[24]付海清,袁晓铭.重塑饱和砂土的现场液化试验研究[J].应用基础与工程学报,2018,待刊.FU Hai-qing,YUAN Xiao-ming.In-situ liquefaction test on remoulded saturated sands[J].Journal of Basic Science and Engineering,2018,to be published.
[25]CHANG W J,RATHJE E M,STOKOE II K H,et al.In situ pore-pressure generation behavior of liquefiable sand[J].Journal of Geotechnical and Geoenvironmental Engineering,2007,133(8):921-931.
[26]COX B R,STOKOE II K H,RATHJE E M.An in-situ test method for evaluating the coupled pore pressure generation and nonlinear shear modulus behavior of liquefiable soils[J].ASTM Geotechnical Testing Journal,2009,32(1):11-21.
[27]陈龙伟,袁晓铭,孙锐.适应于水平场地孔压发展的增量计算模型[J].应用基础与工程科学学报,2010,18(增刊):189-199.CHEN Long-wei,YUAN Xiao-ming,SUN Rui.An incremental pore-water pressure buildup model for horizontal soil strata[J].Journal of Basic Science and Engineering,2010,18(Supp.):189-199.
[28]柏立懂.荷载历史对砂土最大剪切模量影响的共振柱试验研究[J].岩石力学与工程学报,2011,30(11):2366-2374.BAI Li-dong.Effects of loading history on maximum shear modulus of sand by resonant column tests[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(11):2366-2374.
[2]FINN W D L,BNATIA S K.Prediction of seismic pore water pressures[C]//Proceedings of 10th International Conference on Soil Mechanics and Foundation Engineering.Rotterdam:A.A.Balkema,1981.
[3]徐志英,沈珠江.地震液化的有效应力二维动力分析方法[J].华东水利学院学报,1981,(3):1-14.XU Zhi-ying,SHEN Zhu-jiang.2D dynamic analysis of effective stresses of seismic liquefaction[J].East China College of Hydraulic Engineering,1981,(3):1-14.
[4]魏汝龙,郭家禄,左元明.往复荷载下饱和粉砂中的孔隙压力[J].土木工程学报,1983,16(1):22-32.WEI Ru-long,GUO Jia-lu,ZUO Yuan-ming.Pore pressure in saturated silty sand under cyclic loading[J].China of Civil Engineering Journal,1983,16(1):22-32.
[5]何广讷.砂土振动孔隙水压力的研究[J].水利学报,1983,(8):49-54.HE Guang-ne.Study on vibration pore pressure of sand[J].Journal of Hydraulic Engineering,1983,(8):49-54.
[6]LIYANAPATHIRANA D S,POULOS H G.A numerical model for dynamic soil liquefaction analysis[J].Soil Dynamics and Earthquake Engineering,2002,22(9):1007-1015.
[7]ISHIBASHI I,SHERIF M A,TSUCHIYA C.Porepressure rise mechanism and soil liquefaction[J].Soils and Foundations,1977,17(2):17-26.
[8]SHERIF M A,ISHIBASHI I,TSUCHIYA C.Pore-water pressure prediction during earthquake loadings[J].Soils and Foundations,1978,18(4):19-30.
[9]刘颖,仝筠,齐心.循环荷载作用下饱和砂土的残余孔压[J].土工工程学报,1981,14(3):49-55.LIU Ying,TONG Jun,QI Xin.Residual pore pressure in saturated sand under cyclic loading[J].China of Civil Engineering Journal,1981,14(3):49-55.
[10]KAGAWA T,KRAFT L M.Modeling the liquefaction process[J].Journal of the Geotechnical Engineering Division,ASCE,1981,107(GT12):1593-1607.
[11]丰万玲,石兆吉.判别水平土层液化势的孔隙水压力分析方法[J].工程抗震,1988,(4):32-35.FENG Wan-ling,SHI Zhao-ji.Pore pressure analysis method for estimating liquefaction potential of horizontal soil strata[J].Earthquake Resistant,1988,(4):32-35.
[12]王天颂,刘颖,同筠,等.地震荷载作用下饱和砂层孔隙水压力的增长与消散[J].岩土工程学报,1983,5(3):87-102.WANG Tian-song,LIU Ying,TONG Jun,et al.Generation and dissipation of pore pressure in saturated sand layer due to earthquake loading[J].Chinese Journal of Geotechnical Engineering,1983,5(3):87-102.
[13]孙锐,袁晓铭.非均等固结下饱和砂土孔压增量简化计算公式[J].岩土工程学报,2005,27(9):1021-1025.SUN Rui,YUAN Xiao-ming.Simplified incremental formula for estimating pore pressure of saturated sands under anisotropic consolidation[J].Chinese Journal of Geotechnical Engineering,2005,27(9):1021-1025.
[14]孟上九,刘添华.不规则荷载下饱和砂土孔压模型研究[J].岩石力学与工程学报,2014,33(增刊1):3050-3055.MENG Shang-jiu,LIU Tian-hua.Study of pore-pressure model of saturated sands under irregular load[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(Supp.1):3050-3055.
[15]佘跃心,刘汉龙,高玉峰.饱和黄土孔压增长模式与液化机理试验研究[J].岩土力学,2002,23(4):395-399.SHE Yue-xin,LIU Han-long,GAO Yu-feng.Study on liquefaction mechanism and pore-water pressure mode of saturated original loess[J].Rock and Soil Mechanics,2002,23(4):395-399.
[16]陈存礼,何军芳,胡再强,等.动荷载作用下饱和尾矿砂的孔压和残余应变演化特性[J].岩石力学与工程学报,2006,25(增刊2):4034-4039.CHEN Cun-li,HE Jun-fang,HU Zai-qiang,et al.Developing characteristics of pore water pressure and residual deformation of tailings sands under cyclic loading[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(Supp.2):4034-4039.
[17]王亚军,金峰,张楚汉,等.舟山海域海相砂土循环激振下的液化破坏孔压模型[J].岩石力学与工程学报,2013,32(3):582-596.WANG Ya-jun,JIN Feng,ZHANG Chu-han,et al.Liquefaction failure pore water pressure model of Zhoushan marine sandy soil under cyclic exciting loading[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(3):582-596.
[18]陈育民,张意江,王维国,等.爆炸液化场地中浅埋钢筋混凝土结构动力响应的现场试验研究[J].岩土力学,2016,37(12):3506-3519.CHEN Yu-min,ZHANG Yi-jiang,WANG Wei-guo,et al.Experimental investigation into dynamic response of shallow-buried reinforced concrete structure in blastinduced liquefied sandy foundation[J].Rock and Soil Mechanics,2016,37(12):3506-3519.
[19]付海清,袁晓铭,陈龙伟.基于重塑饱和砂土的现场液化试验方法[J].地震工程学报,2015,37(1):16-20.FU Hai-qing,YUAN Xiao-ming,CHEN Long-wei.A method for in-situ liquefaction test based on reconstituted saturated sand model[J].China Earthquake Engineering Journal,2015,37(1):16-20.
[20]付海清,陈龙伟,李雨润,等.人工激振下现场液化试验初步研究[J].世界地震工程,2010,26(增刊1):235-240.FU Hai-qing,CHEN Long-wei,LI Yu-run,et al.Preliminary study on in-situ liquefaction tests under artificial dynamic loading[J].World Earthquake Engineering,2010,26(Supp.1):235-240.
[21]付海清,袁晓铭.液化对地表运动影响的现场试验研究[J].地震工程与工程振动,2016,36(5):99-106.FU Hai-qing,YUAN Xiao-ming.Effect of soil liquefaction on ground motion using artificial vibration[J].Journal of Earthquake Engineering and Vibration,2016,36(5):99-106.
[22]SEED H B,IDRISS I M.Simplified procedure for evaluating soil liquefaction potential[J].Journal of the Soil Mechanics and Foundations Division,ASCE,1971,97(SM9):1249-1273.
[23]YOUD T L,IDRISS I M.Liquefaction resistance of soils:summary report from the 1996 NCEER and 1998NCEER/NSF workshops on evaluation of liquefaction resistance of soils[J].Journal of Geotechnical and Geoenvironmental Engineering,2001,127(4):297-313.
[24]付海清,袁晓铭.重塑饱和砂土的现场液化试验研究[J].应用基础与工程学报,2018,待刊.FU Hai-qing,YUAN Xiao-ming.In-situ liquefaction test on remoulded saturated sands[J].Journal of Basic Science and Engineering,2018,to be published.
[25]CHANG W J,RATHJE E M,STOKOE II K H,et al.In situ pore-pressure generation behavior of liquefiable sand[J].Journal of Geotechnical and Geoenvironmental Engineering,2007,133(8):921-931.
[26]COX B R,STOKOE II K H,RATHJE E M.An in-situ test method for evaluating the coupled pore pressure generation and nonlinear shear modulus behavior of liquefiable soils[J].ASTM Geotechnical Testing Journal,2009,32(1):11-21.
[27]陈龙伟,袁晓铭,孙锐.适应于水平场地孔压发展的增量计算模型[J].应用基础与工程科学学报,2010,18(增刊):189-199.CHEN Long-wei,YUAN Xiao-ming,SUN Rui.An incremental pore-water pressure buildup model for horizontal soil strata[J].Journal of Basic Science and Engineering,2010,18(Supp.):189-199.
[28]柏立懂.荷载历史对砂土最大剪切模量影响的共振柱试验研究[J].岩石力学与工程学报,2011,30(11):2366-2374.BAI Li-dong.Effects of loading history on maximum shear modulus of sand by resonant column tests[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(11):2366-2374.