重塑饱和砂土的现场液化试验研究
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摘要
利用自行研发的动力加载系统,通过重塑饱和砂土的现场液化试验,分析不同水平向震动强度下砂土液化响应规律,探讨孔压增长模式、地表加速度与孔压发展之间的关系、现场和室内液化试验中孔压增长模式的异同.主要认识如下:实际场地下,砂土相对密度越大,上覆压力越大,孔压比就越小,砂土的液化水平越低,反之亦然;实际场地下,饱和砂土液化时的孔压增长梯度缓慢.这一孔压增长模式与他人现场液化试验结果一致,而与动三轴试验结果有显著不同,与振动台试验结果有一定差别;正弦波动荷载输入下,孔压比在液化与地表运动的关联性研究中是一个重要且平稳的指标,孔压比0.5~0.6是液化削减地表运动的临界值.本文结果表明,现有孔压计算模型在实际液化场地的适用性和可靠性有待验证.
Through a self-developed loading apparatus,in-situ liquefaction tests are carried out for reconstituted saturated sand. Dynamic responses of saturated sand are obtained under different horizontal loading. The relationship of pore pressure and surface acceleration are analyzed. The buildup patterns of pore pressure and comparison between laboratory and in-situ tests are also investigated. The main indications are:(1) In field tests,when the sands are dense that the overburden pressure is large,the pore pressure ratio is small and the liquefaction extent is low,and vice versa.(2) The pore-water pressure of saturated sand in field tests increases gradually,which stays consistent with results by other researchers,but is remarkably different from results of triaxial tests,and a little different from results obtained from shaking table tests.(3) Under sinusoidal loading,pore pressure ratio plays an important and stationary role correlating liquefaction with surface ground motion. When the soils starts to reduce ground acceleration,the critical pore water pressure ratio is around 0. 5 ~ 0. 6. The results from in-situ liquefaction tests indicate that the applicability and reliability of the current formulas for estimating pore pressure in actual liquefied site should be discussed and carefully recognized.
Through a self-developed loading apparatus,in-situ liquefaction tests are carried out for reconstituted saturated sand. Dynamic responses of saturated sand are obtained under different horizontal loading. The relationship of pore pressure and surface acceleration are analyzed. The buildup patterns of pore pressure and comparison between laboratory and in-situ tests are also investigated. The main indications are:(1) In field tests,when the sands are dense that the overburden pressure is large,the pore pressure ratio is small and the liquefaction extent is low,and vice versa.(2) The pore-water pressure of saturated sand in field tests increases gradually,which stays consistent with results by other researchers,but is remarkably different from results of triaxial tests,and a little different from results obtained from shaking table tests.(3) Under sinusoidal loading,pore pressure ratio plays an important and stationary role correlating liquefaction with surface ground motion. When the soils starts to reduce ground acceleration,the critical pore water pressure ratio is around 0. 5 ~ 0. 6. The results from in-situ liquefaction tests indicate that the applicability and reliability of the current formulas for estimating pore pressure in actual liquefied site should be discussed and carefully recognized.
引文
[1]孙锐,杨洋,袁晓铭.土体液化研究的新探索[J].地震工程与工程振动,2017,37(3):175-181Sun Rui,Yang Yang,Yuan Xiaoming.New exploration of soil liquefaction[J].Earthquake Engineering and Engineering Dynamics,2017,37(3):175-181
[2]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1):189-199Chen Longwei,Yuan Xiaoming,Sun Rui.An incremental pore-water pressure buildup model for horizontal soil strata[J].Journal of Basic Science and Enginering,2010,18(S1):189-199
[3]Ishihara K,Shinizu K,Yamada Y.Pore water pressures measured in sand deposits during an earthquake[J].Soils and Foundations,1981,21(4):85-100
[4]Ishihara K,Muroi T,Towhata I.In-situ pore water pressures and ground motions during the 1987 Chiba-Toho-Oki Earthquake[J].Soils and Foundations,1989,29(4):75-90
[5]Holzer T L,Hanks T C,Youd T L.Dynamics of Liquefaction during the 1987 Superstition Hills,California,Earthquake[J].Science,1989,244(4900):56-59
[6]陈龙伟,袁晓铭,孙锐.2011年新西兰Mw6.3地震液化及岩土震害述评[J].世界地震工程,2013,29(3):1-9Chen Longwei,Yuan Xiaoming,Sun Rui.Review of liquefaction phenomena and geotechnical damage in the 2011 New Zealand Mw6.3 earthquake[J].World Earthquake Engineering,2013,29(3):1-9
[7]Youd T L,Carter B L.Influence of soil softening and liquefaction on spectral acceleration[J].Journal of Geotechnical and Geoenvironmental Engineering,2005,131(7):811-825
[8]Yuan X M,Sun R,Chen L W.A method for detecting site liquefaction by seismic records[J].Soil Dynamics and Earthquake Engineering,2010,30(4):270-279
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[10]Wang Lanmin,He Kaiming,Shi Yucheng,et al.Study on liquefaction of saturated loess by in situ explosion test[J].Earthquake Engineering and Engineering Vibration,2002,1(1):50-56
[11]常方强,贾永刚.黄河口粉质土海床液化过程的现场试验研究[J].土木工程学报,2012,45(1):121-126Chang Fangqiang,Jia Yonggang.In-situ test to study silt liquefaction at the subaqueous delta of Yellow River[J].China Civil Engineering Journal,2012,45(1):121-126
[12]刘晓磊,贾永刚,郑文杰.波浪导致黄河口海床沉积物超孔压响应现场试验研究[J].岩土力学,2015,36(11):3055-3061Liu Xiaolei,Jia Yonggang,Zheng Wenjie.In situ experiment of wave-induced excess pore pressure in the seabed sediment in Yellow River estuary[J].Rock and Soil Mechanics,2015,36(11):3055-3061
[13]王维国,陈育民,张意江,等.饱和砂土中浅埋单药包爆炸液化特性分析[J].岩土工程学报,2016,38(2):355-361Wang Weiguo,Chen Yumin,Zhang Yijiang,et al.Characteristics of liquefaction induced by single shallow-buried detonation in saturated sand[J].Chinese Journal of Geotechnical Engineering,2016,38(2):355-361
[14]Inazaki T.In situ measurement of the liquefaction potential of soils using a shear-wave vibrator[C/OL].The Proceedings of IWAM04,Mizunami,Japan,2004
[15]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
[16]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
[17]付海清,袁晓铭,陈龙伟.基于重塑饱和砂土模型的现场液化试验方法[J].地震工程学报,2015,37(1):16-20Fu Haiqing,Yuan Xiaoming,Chen Longwei.A method for in-situ liquefaction test based on reconstituted saturated sand model[J].China Earthquake Engineering Journal,2015,37(1):16-20
[18]付海清.现场液化试验方法及液化土体特征研究[D].哈尔滨:中国地震局工程力学研究所,2016Fu Haiqing.An approach of dynamic in-situ liquefaction test and characteristic of liquefied soil[D].Harbin:Institute of Engineering Mechanics,China Earthquake Administration,2016
[19]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):323-346
[20]Elgamal A,Yang Z H,Parra E.Computational modeling of cyclic mobility and post-liquefaction site response[J].Soil Dynamics and Earthquake Engineering,2002,22(4):1259-271
[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):99-106Fu Haiqing,Yuan Xiaoming.Effect of soil liquefaction on ground motion using artificial vibration[J].Earthquake Engineering and Engineering Dynamics,2016,36(5):99-106
[22]石兆吉,张廷军,郁寿松,等.土层液化对地面运动特征的影响[J].地震工程与工程振动,1994,14(4):15-23Shi Zhaoji,Zhang Yanjun,Yu Shousong,et al.Effect of liquefied soil layers on ground motion[J].Earthquake Engineering and Engineering Dynamics,1994,14(4):15-23
[23]苏栋,李相菘.砂土自由场地震响应的离心机试验研究[J].地震工程与工程振动,2006,26(2):166-170Su Dong,Li Xiangsong.Centrifuge model of seismic response of free sand ground[J].Earthquake Engineering and Engineering Dynamics,2006,26(2):166-170
[24]孙锐,袁晓铭,李雨润,等.循环荷载下液化对土层水平往返变形的影响[J].地震工程学报,2009,31(1):8-14Sun Rui,Yuan Xiaoming,Li Yurun,et al.Effect of liquefaction on cyclic deformation of soil layer[J].China Earthquake Engineering Journal,2009,31(1):8-14
[25]孙锐,袁晓铭.液化土层地震动特征分析[J].岩土工程学报,2004,26(5):684-690Sun Rui,Yuan Xiaoming.Analysis on feature of surface ground motion for liquefied soil layer[J].Chinese Journal of Geotechnical Engineering,2004,26(5):684-690
[2]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1):189-199Chen Longwei,Yuan Xiaoming,Sun Rui.An incremental pore-water pressure buildup model for horizontal soil strata[J].Journal of Basic Science and Enginering,2010,18(S1):189-199
[3]Ishihara K,Shinizu K,Yamada Y.Pore water pressures measured in sand deposits during an earthquake[J].Soils and Foundations,1981,21(4):85-100
[4]Ishihara K,Muroi T,Towhata I.In-situ pore water pressures and ground motions during the 1987 Chiba-Toho-Oki Earthquake[J].Soils and Foundations,1989,29(4):75-90
[5]Holzer T L,Hanks T C,Youd T L.Dynamics of Liquefaction during the 1987 Superstition Hills,California,Earthquake[J].Science,1989,244(4900):56-59
[6]陈龙伟,袁晓铭,孙锐.2011年新西兰Mw6.3地震液化及岩土震害述评[J].世界地震工程,2013,29(3):1-9Chen Longwei,Yuan Xiaoming,Sun Rui.Review of liquefaction phenomena and geotechnical damage in the 2011 New Zealand Mw6.3 earthquake[J].World Earthquake Engineering,2013,29(3):1-9
[7]Youd T L,Carter B L.Influence of soil softening and liquefaction on spectral acceleration[J].Journal of Geotechnical and Geoenvironmental Engineering,2005,131(7):811-825
[8]Yuan X M,Sun R,Chen L W.A method for detecting site liquefaction by seismic records[J].Soil Dynamics and Earthquake Engineering,2010,30(4):270-279
[9]石兆吉,郁寿松,丰万玲,等.地震时孔隙水压力观测和估算[R].哈尔滨:中国地震局工程力学研究所,1989Shi Zhaoji,Yu Shousong,Feng Wanling,et al.Observation and prediction of pore water pressure during earthquakes[R].Harbin:Institute of Engineering Mechanics,China Earthquake Administration,1989
[10]Wang Lanmin,He Kaiming,Shi Yucheng,et al.Study on liquefaction of saturated loess by in situ explosion test[J].Earthquake Engineering and Engineering Vibration,2002,1(1):50-56
[11]常方强,贾永刚.黄河口粉质土海床液化过程的现场试验研究[J].土木工程学报,2012,45(1):121-126Chang Fangqiang,Jia Yonggang.In-situ test to study silt liquefaction at the subaqueous delta of Yellow River[J].China Civil Engineering Journal,2012,45(1):121-126
[12]刘晓磊,贾永刚,郑文杰.波浪导致黄河口海床沉积物超孔压响应现场试验研究[J].岩土力学,2015,36(11):3055-3061Liu Xiaolei,Jia Yonggang,Zheng Wenjie.In situ experiment of wave-induced excess pore pressure in the seabed sediment in Yellow River estuary[J].Rock and Soil Mechanics,2015,36(11):3055-3061
[13]王维国,陈育民,张意江,等.饱和砂土中浅埋单药包爆炸液化特性分析[J].岩土工程学报,2016,38(2):355-361Wang Weiguo,Chen Yumin,Zhang Yijiang,et al.Characteristics of liquefaction induced by single shallow-buried detonation in saturated sand[J].Chinese Journal of Geotechnical Engineering,2016,38(2):355-361
[14]Inazaki T.In situ measurement of the liquefaction potential of soils using a shear-wave vibrator[C/OL].The Proceedings of IWAM04,Mizunami,Japan,2004
[15]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
[16]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
[17]付海清,袁晓铭,陈龙伟.基于重塑饱和砂土模型的现场液化试验方法[J].地震工程学报,2015,37(1):16-20Fu Haiqing,Yuan Xiaoming,Chen Longwei.A method for in-situ liquefaction test based on reconstituted saturated sand model[J].China Earthquake Engineering Journal,2015,37(1):16-20
[18]付海清.现场液化试验方法及液化土体特征研究[D].哈尔滨:中国地震局工程力学研究所,2016Fu Haiqing.An approach of dynamic in-situ liquefaction test and characteristic of liquefied soil[D].Harbin:Institute of Engineering Mechanics,China Earthquake Administration,2016
[19]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):323-346
[20]Elgamal A,Yang Z H,Parra E.Computational modeling of cyclic mobility and post-liquefaction site response[J].Soil Dynamics and Earthquake Engineering,2002,22(4):1259-271
[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):99-106Fu Haiqing,Yuan Xiaoming.Effect of soil liquefaction on ground motion using artificial vibration[J].Earthquake Engineering and Engineering Dynamics,2016,36(5):99-106
[22]石兆吉,张廷军,郁寿松,等.土层液化对地面运动特征的影响[J].地震工程与工程振动,1994,14(4):15-23Shi Zhaoji,Zhang Yanjun,Yu Shousong,et al.Effect of liquefied soil layers on ground motion[J].Earthquake Engineering and Engineering Dynamics,1994,14(4):15-23
[23]苏栋,李相菘.砂土自由场地震响应的离心机试验研究[J].地震工程与工程振动,2006,26(2):166-170Su Dong,Li Xiangsong.Centrifuge model of seismic response of free sand ground[J].Earthquake Engineering and Engineering Dynamics,2006,26(2):166-170
[24]孙锐,袁晓铭,李雨润,等.循环荷载下液化对土层水平往返变形的影响[J].地震工程学报,2009,31(1):8-14Sun Rui,Yuan Xiaoming,Li Yurun,et al.Effect of liquefaction on cyclic deformation of soil layer[J].China Earthquake Engineering Journal,2009,31(1):8-14
[25]孙锐,袁晓铭.液化土层地震动特征分析[J].岩土工程学报,2004,26(5):684-690Sun Rui,Yuan Xiaoming.Analysis on feature of surface ground motion for liquefied soil layer[J].Chinese Journal of Geotechnical Engineering,2004,26(5):684-690