液化场地群桩地震响应的三维数值分析
|
摘要
桩基是处理软弱基础的主要形式之一。然而历史桩基震害调查表明地震液化可加重桩基础破环程度,故当今液化场地桩基抗震性能研究已成为一个迫切解决的课题,开展液化场地群桩地震响应研究,对探讨液化场地桩土动力相互作用机制,提出合理有效的抗震措施具有重要的意义。
本文基于三维有限差分分析方法,构建了液化场地群桩地震响应的数值分析模型,数值研究分析了在相同的地震波作用下、有无上部荷载条件下两个模型的群桩动力响应特征,总结了土体加速度、桩土侧向位移、桩身弯矩和土体超孔隙水压力分布规律,进而探讨了液化场地群桩的地震响应特征和桩土动力相互作用机制。研究得出:
(1)液化场地群桩地震中水平位移随着埋深的加大而减少,液化现象有从上向下趋势;
(2)桩头是否固定对桩身的水平位移和弯矩计算结果的影响较大。桩头固定条件下桩身水平位移较桩头自由模型结果小,桩顶弯矩值则比桩头自由计算模型大;
(3)桩身的最大弯矩发生在桩底的1/3处,在桩头固定或自由时中心桩桩身的最大弯矩值则均小于外边角桩的最大弯矩值;
(4)本文计算模型中,超孔隙水压力的发展速度在一定程度上受群桩效应的影响,但较土层深度影响程度弱。
论文研究成果对液化场地群桩基础的抗震设计和饱和砂土液化评价具有一定的理论和现实意义,并为工程应用提供理论依据和技术支持。
Pile foundation is one main treatment method for soft foundation. Pile foundations in liquefiable soils are damaged seriously indued by earthquake liquefaction from many earthquake case. Consequently, in order to investigate the mechanism of pile-soil interaction and develop a rational seismic design of pile groups on liquefiable soils, the analysis of seismic responses of pile groups found on liquefiable soils are key problem earging to overcoming for geotechnical engineers.
Based on the Flac3D program, the numerical modelling for the analysis of seismic responses of pile-groups on liquefiable soils are described in this dissertation. Two cases of same input seismic wave, and with or without loading were carried out to investigate the seismic responses of pile groups in liquefiable soils. Moreover, the contribution principles of soil acceleration, excess pore water pressure, bending moments of pile are further discussed. And results are reached as shown in the following:
(1) The lateral displacement of pile groups decreases with in increase of burried pile depth. The phenomenon of liquefaction trending to downward are observed.
(2) The values of displacement and bending moments are influenced by the fixed or free pile top. The value of displacement in the fixed pile top model is larger than that in free pile top model.
(3) The bending moments of the piles are on 1/3 part from pile bottom. The bending moments of center piles are less than those of edge piles in both models.
(4) The burried depth of soil play role of the generation rate of pore water pressure in the discussed models, but the influence of effect of pile groups is little.
The results can provide references for the seismic design of pile-groups foundation found on liquefiable soils. Also some result can be used to direct reinforce and treatments of pile-groups on the liquefiable soils.
本文基于三维有限差分分析方法,构建了液化场地群桩地震响应的数值分析模型,数值研究分析了在相同的地震波作用下、有无上部荷载条件下两个模型的群桩动力响应特征,总结了土体加速度、桩土侧向位移、桩身弯矩和土体超孔隙水压力分布规律,进而探讨了液化场地群桩的地震响应特征和桩土动力相互作用机制。研究得出:
(1)液化场地群桩地震中水平位移随着埋深的加大而减少,液化现象有从上向下趋势;
(2)桩头是否固定对桩身的水平位移和弯矩计算结果的影响较大。桩头固定条件下桩身水平位移较桩头自由模型结果小,桩顶弯矩值则比桩头自由计算模型大;
(3)桩身的最大弯矩发生在桩底的1/3处,在桩头固定或自由时中心桩桩身的最大弯矩值则均小于外边角桩的最大弯矩值;
(4)本文计算模型中,超孔隙水压力的发展速度在一定程度上受群桩效应的影响,但较土层深度影响程度弱。
论文研究成果对液化场地群桩基础的抗震设计和饱和砂土液化评价具有一定的理论和现实意义,并为工程应用提供理论依据和技术支持。
Pile foundation is one main treatment method for soft foundation. Pile foundations in liquefiable soils are damaged seriously indued by earthquake liquefaction from many earthquake case. Consequently, in order to investigate the mechanism of pile-soil interaction and develop a rational seismic design of pile groups on liquefiable soils, the analysis of seismic responses of pile groups found on liquefiable soils are key problem earging to overcoming for geotechnical engineers.
Based on the Flac3D program, the numerical modelling for the analysis of seismic responses of pile-groups on liquefiable soils are described in this dissertation. Two cases of same input seismic wave, and with or without loading were carried out to investigate the seismic responses of pile groups in liquefiable soils. Moreover, the contribution principles of soil acceleration, excess pore water pressure, bending moments of pile are further discussed. And results are reached as shown in the following:
(1) The lateral displacement of pile groups decreases with in increase of burried pile depth. The phenomenon of liquefaction trending to downward are observed.
(2) The values of displacement and bending moments are influenced by the fixed or free pile top. The value of displacement in the fixed pile top model is larger than that in free pile top model.
(3) The bending moments of the piles are on 1/3 part from pile bottom. The bending moments of center piles are less than those of edge piles in both models.
(4) The burried depth of soil play role of the generation rate of pore water pressure in the discussed models, but the influence of effect of pile groups is little.
The results can provide references for the seismic design of pile-groups foundation found on liquefiable soils. Also some result can be used to direct reinforce and treatments of pile-groups on the liquefiable soils.
引文
[1]莫海鸥,杨小平.基础工程[M].北京:中国建筑工业出版社,2003.116-117.
[2]刘惠珊.桩基震害及原因分析—日木阪神大地震的启示[J].工程抗震,1999,3(1):37-43.
[3]孙锐.液化土层地震动和场地液化识别方法研究[博士学位论文][D].哈尔滨:中国地震局工程力学研究所,2006.
[4]刘惠珊.1995年阪神大地震的液化特点.工程抗震[J] .2001,3(1):25-26.
[5] Lok, M. Numerical modeling of seismic soil-pile-structure interaction in soft clay [D]. California: University of California, 1999.
[6] Seed, H. B. A simplified Procedure for Evaluating Soil Liquefaction Potential [J].Proc, ASCE, 1971, 93-97(SM9).
[7]韩英才,Novak M.,水平载荷作用下单桩的动力分析[J] .地震工程与工程振动,1989(6),97-106.
[8]韩英才,Novak M.,水平载荷作用下群桩动力特性的研究[J] .土木工程学报,1992(10):24-33.
[9]徐莜在,阎兴华,史玉良.桩基水平振动的特性.地基与工业建筑抗震[M] .北京:地震出版社,1984.
[10]王志良,王余庆.不规则循环剪切荷载作用下土的粘塑性模型[J] .岩土工程学报,1980,2(3):66-72.
[11] Liu. L. and Dobry. R. Effect of liquefaction on lateral response of piles by Centrifuge model texts, National Center for Earthquake Engineering Research Bulletin [J],1995, 9(l):7-11.
[12] Hudson Matlock. Correlation for Design of Laterally Loaded Pile in Soft Clay [J]. OTC, 1970, 25(1):577-594.
[13] Reese L C, Cox W R, Koop F D. Analysis of laterally loaded piles in sand[C]. Proceedings of OTC2080, 1974, 473-483.
[14] Grib, S, Behaviour of Pile Foundations Under Horizontal Seismic Action,Proc.5th European Conf. Earthquake Eng, Istanbul, Vol. 1, 1975.
[15] NOGAMI T, NOVAK M. Soil-pile interaction in vertical vibration. Earthq.Engng.Struct.Dyn.,1976, (4):277-293.
[16] Novak M. Vertical vibration of floating piles [J]. Journal of Engineering Mechanics Division, ASCE, 1977, 103(EMI):153-168.
[17] Novak M. Piles under dynamic loads[C]. Proceedings of 2nd International Conference Recent Advances in Geotechnical Earthquake Engineering and SoilDynamics, St. Louis, Missouri, 1991.2433-2456.
[18] Scott, R, Liu, H, Ting, J. Dynamic pile tests by centrifuge modeling[C]. Proceedings of 6th World Conference Earthquake Engineering, 1997, (2):1670-1674.
[19] Scott, R, Tsai, C, Steussy, D., et al. Full-scale dynamic lateral pile tests[C].Proceedings of 12th Offshore Technology Conference, OTC 4203, Houston, 1982, 435-450.
[20] Ting, J ,Scott, R .Static and dynamic lateral group action[C].Proceedings of 11th World Conference Earthquake Engineering, 1984,(3):641-648.
[21] Ohira A., Tazoh T., Dewa K., Shimizu K., and Shimada M., Observations of Earthquake Response Behaviors of Foundation Piles for Road Bridge,Proc.8th World Conf. Earthquake Eng., San Francisco, Vol.3, 1984, 577-584.
[22] Werner S., Beck J., and Levine M.,Seismic Response Evaluation of Meloland Road Overpass Using 1979 Imperial Valley Earthquake Records,Earthquake Eng.Struct.Dyn.,1987,15(2):249-274.
[23] Finn, W, Gohl, B Centrifuge model studies of piles under simulated earthquake lateral loading [J]. Geotechnical Special Publication 11, ASCE, 1987:21-38.
[24] Naggar E I, Novak M. Nonlinear model for dynamic axial pile response [J].Journal of Geotechnical Engineering, ASCE ,1994,120(2):308-329.
[25] Konder R L. Hyerbolic stress-strain response: cohesive soils[J]. Journal of the Soil Mechanics and Foundation Engineering Division, ASCE, 1963, 89(1):115-143.
[26] Chacko, M Analysis of dynamic siol-pile-structure interaction [D]. California, University of California, 1985.
[27] Imamura, A, Hijikata, K, Tomii, Y ,et al. Hasegawa. An experimental study on nonlinear pile-soil interaction based on forced vibration tests of a single pile and a pile group[C]. Proceedings of 11th World Conference Earthquake Engineering, 1996, Paper No.156.
[28] Wilson, D. W. Soil-pile-superstructure interaction in liquefying sand and soft clay[D]. California, University of California, 1998.
[29]刘宗贤,李玉亭.桩基础在阻尼与分层弹性地基场地土波动影响下的横向地震反应分析[J].地震工程与工程振动,1994,14(3):47-59.
[30]王慧,杨光辉,张鸿儒.桩土体系运动相互作用参数分析[J] .工程力学,1998,(增):527-533.
[31]胡昌斌,王奎华,谢康和.基于平面应变假定基桩振动理论适用性研究[J] .岩土工程学报,2003,25(5):595-601.
[32]俞载道,傅公康。桩-土-高层框剪结构动力相互作用分析[J] .同济大学学报,1984,12(1):66-79.
[33]俞载道,王荣昌,应稼年.地基土与非线性多层剪切型结构相互作用体系的动力分析[J].同济大学学报,1986,14(3):271-280.
[34]陈云敏,陈仁朋,朱斌.打桩过程中桩的横向振动分析[J].振动工程学报,2001,14(2):215-219.
[35]范敏,解明雨,邬瑞锋。土-桩-结构相互作用体系的非线性地震反应分析[J] .土木工程学报,1998,31(5):48-55.
[36]蒋建平,汪明武,高广运.桩端岩土差异对超长桩影响的对比研究[J] .岩石力学与工程学报,2004,23(18):3190-3195.
[37]徐攸在,阎兴华,史玉良.桩基水平振动的特性[M] .北京:地震出版社,1984.
[38]韩英才,李宝贵,首培侠.单桩的振动试验研究.岩土工程学报[J],1989,11(3):70-77.
[39]刘惠珊,乔太平.可液化土中桩基工作性能及其实用计算方法的探讨[M].北京:地震出版社,1984.
[40]刘惠珊,陈克景.液化土中的桩基试验[J].工程抗震,1991(2):19-23.
[41]陈文化,门福录,景立平等.有建筑物存在的饱和砂土的地基液化振动台模拟实验研究[J].地震工程与工程振动,1998,18(4):54-60.
[42]楼梦麟,王文剑,马恒春等.土-桩-结构相互作用体系的振动台模型试验[J] .同济大学学报,2001,29(7):763-768.
[43]郭金童,王建华.松散砂土中桩-土相互作用的试验研究[J] .勘察科学技术,2004,(4):3-5.
[44]汪明武,Tobita T, Iai S.强震动力条件下的桩土相互作用动态土工离心试验研究[J] .岩石力学与工程学报,2005,24(S2):5555-5560.
[45]黄春霞,张鸿儒,隋志龙等.饱和砂土地基液化特性振动台试验研究[J] .岩土工程学报,2006,28(12):2098-2013.
[46]苏栋,李相菘.可液化土中单桩地震响应的离心机试验研究[J] .岩土工程学报,2006,28(4):423-427.
[47]王成雷,王建华,冯士伦.土层液化条件下桩土相互作用p-y关系分析[J] .岩土工程学报,2007,29(10):1500-1505.
[48]汪明武,Iai. S.地下RC结构物地震响应特征土工离心试验的模拟[J] .地震工程与工程振动,2007,27(3):150-155.
[49]王建华,戚春香,余正春等.弱化饱和砂土中桩的p-y曲线与极限抗力研究[J] .岩土工程学报,2008,30(3):309-315.
[50]茜平一,周洪波.水平荷载群桩三维有限元分析研究[J] .岩土工程技术,1999,(4):44-48.
[51]马远刚,茜平一.横向土运动作用下群桩的性状研究[J] .岩土力学,2000,21(4):377-380.
[52]汪明武,井合进,飞田哲男.栈桥式构筑物抗震性能动态离心模型试验的数值模拟[J] .岩土工程学报,2005,27(7):738–741.
[53]陈鹏,李文华,范涛等.土体冲刷对桥梁桩基影响的三维差分模拟计算分析[J] .山东科技大学学报自然科学版,2007,26(4):23-26.
[54]朱英明.下卧液化土层堤坝的强震动力反应特性研究[硕士学位论文][D].合肥:合肥工业大学土木建筑工程学院,2007.
[55]吴大国.液化场地群桩地震响应有效应力分析[硕士学位论文][D]合肥:合肥工业大学土木建筑工程学院,2007.
[56]范君宇,刘全林.门字形锚桩围护结构参数对深基坑工程水平位移的影响[J] .科技信息(建筑与工程),2008,(16):154-155.
[57] Wang M. W., Li L. Numerical modeling of seismic performances of passive pile groups adjacent to soil slope[C]. Geotechnical Engineering for Disaster Mitigation and Rehabilitation, Science Press Beijing, Springer, 2008: 446-451.
[58]刘波,韩彦辉. FLAC原理、实例与应用指南[M].北京:人民交通出版社,2005.
[59] Itasca. FLAC-Users’Manual[M]. Minneapolis, Itasca Consulting Group, 2005.
[2]刘惠珊.桩基震害及原因分析—日木阪神大地震的启示[J].工程抗震,1999,3(1):37-43.
[3]孙锐.液化土层地震动和场地液化识别方法研究[博士学位论文][D].哈尔滨:中国地震局工程力学研究所,2006.
[4]刘惠珊.1995年阪神大地震的液化特点.工程抗震[J] .2001,3(1):25-26.
[5] Lok, M. Numerical modeling of seismic soil-pile-structure interaction in soft clay [D]. California: University of California, 1999.
[6] Seed, H. B. A simplified Procedure for Evaluating Soil Liquefaction Potential [J].Proc, ASCE, 1971, 93-97(SM9).
[7]韩英才,Novak M.,水平载荷作用下单桩的动力分析[J] .地震工程与工程振动,1989(6),97-106.
[8]韩英才,Novak M.,水平载荷作用下群桩动力特性的研究[J] .土木工程学报,1992(10):24-33.
[9]徐莜在,阎兴华,史玉良.桩基水平振动的特性.地基与工业建筑抗震[M] .北京:地震出版社,1984.
[10]王志良,王余庆.不规则循环剪切荷载作用下土的粘塑性模型[J] .岩土工程学报,1980,2(3):66-72.
[11] Liu. L. and Dobry. R. Effect of liquefaction on lateral response of piles by Centrifuge model texts, National Center for Earthquake Engineering Research Bulletin [J],1995, 9(l):7-11.
[12] Hudson Matlock. Correlation for Design of Laterally Loaded Pile in Soft Clay [J]. OTC, 1970, 25(1):577-594.
[13] Reese L C, Cox W R, Koop F D. Analysis of laterally loaded piles in sand[C]. Proceedings of OTC2080, 1974, 473-483.
[14] Grib, S, Behaviour of Pile Foundations Under Horizontal Seismic Action,Proc.5th European Conf. Earthquake Eng, Istanbul, Vol. 1, 1975.
[15] NOGAMI T, NOVAK M. Soil-pile interaction in vertical vibration. Earthq.Engng.Struct.Dyn.,1976, (4):277-293.
[16] Novak M. Vertical vibration of floating piles [J]. Journal of Engineering Mechanics Division, ASCE, 1977, 103(EMI):153-168.
[17] Novak M. Piles under dynamic loads[C]. Proceedings of 2nd International Conference Recent Advances in Geotechnical Earthquake Engineering and SoilDynamics, St. Louis, Missouri, 1991.2433-2456.
[18] Scott, R, Liu, H, Ting, J. Dynamic pile tests by centrifuge modeling[C]. Proceedings of 6th World Conference Earthquake Engineering, 1997, (2):1670-1674.
[19] Scott, R, Tsai, C, Steussy, D., et al. Full-scale dynamic lateral pile tests[C].Proceedings of 12th Offshore Technology Conference, OTC 4203, Houston, 1982, 435-450.
[20] Ting, J ,Scott, R .Static and dynamic lateral group action[C].Proceedings of 11th World Conference Earthquake Engineering, 1984,(3):641-648.
[21] Ohira A., Tazoh T., Dewa K., Shimizu K., and Shimada M., Observations of Earthquake Response Behaviors of Foundation Piles for Road Bridge,Proc.8th World Conf. Earthquake Eng., San Francisco, Vol.3, 1984, 577-584.
[22] Werner S., Beck J., and Levine M.,Seismic Response Evaluation of Meloland Road Overpass Using 1979 Imperial Valley Earthquake Records,Earthquake Eng.Struct.Dyn.,1987,15(2):249-274.
[23] Finn, W, Gohl, B Centrifuge model studies of piles under simulated earthquake lateral loading [J]. Geotechnical Special Publication 11, ASCE, 1987:21-38.
[24] Naggar E I, Novak M. Nonlinear model for dynamic axial pile response [J].Journal of Geotechnical Engineering, ASCE ,1994,120(2):308-329.
[25] Konder R L. Hyerbolic stress-strain response: cohesive soils[J]. Journal of the Soil Mechanics and Foundation Engineering Division, ASCE, 1963, 89(1):115-143.
[26] Chacko, M Analysis of dynamic siol-pile-structure interaction [D]. California, University of California, 1985.
[27] Imamura, A, Hijikata, K, Tomii, Y ,et al. Hasegawa. An experimental study on nonlinear pile-soil interaction based on forced vibration tests of a single pile and a pile group[C]. Proceedings of 11th World Conference Earthquake Engineering, 1996, Paper No.156.
[28] Wilson, D. W. Soil-pile-superstructure interaction in liquefying sand and soft clay[D]. California, University of California, 1998.
[29]刘宗贤,李玉亭.桩基础在阻尼与分层弹性地基场地土波动影响下的横向地震反应分析[J].地震工程与工程振动,1994,14(3):47-59.
[30]王慧,杨光辉,张鸿儒.桩土体系运动相互作用参数分析[J] .工程力学,1998,(增):527-533.
[31]胡昌斌,王奎华,谢康和.基于平面应变假定基桩振动理论适用性研究[J] .岩土工程学报,2003,25(5):595-601.
[32]俞载道,傅公康。桩-土-高层框剪结构动力相互作用分析[J] .同济大学学报,1984,12(1):66-79.
[33]俞载道,王荣昌,应稼年.地基土与非线性多层剪切型结构相互作用体系的动力分析[J].同济大学学报,1986,14(3):271-280.
[34]陈云敏,陈仁朋,朱斌.打桩过程中桩的横向振动分析[J].振动工程学报,2001,14(2):215-219.
[35]范敏,解明雨,邬瑞锋。土-桩-结构相互作用体系的非线性地震反应分析[J] .土木工程学报,1998,31(5):48-55.
[36]蒋建平,汪明武,高广运.桩端岩土差异对超长桩影响的对比研究[J] .岩石力学与工程学报,2004,23(18):3190-3195.
[37]徐攸在,阎兴华,史玉良.桩基水平振动的特性[M] .北京:地震出版社,1984.
[38]韩英才,李宝贵,首培侠.单桩的振动试验研究.岩土工程学报[J],1989,11(3):70-77.
[39]刘惠珊,乔太平.可液化土中桩基工作性能及其实用计算方法的探讨[M].北京:地震出版社,1984.
[40]刘惠珊,陈克景.液化土中的桩基试验[J].工程抗震,1991(2):19-23.
[41]陈文化,门福录,景立平等.有建筑物存在的饱和砂土的地基液化振动台模拟实验研究[J].地震工程与工程振动,1998,18(4):54-60.
[42]楼梦麟,王文剑,马恒春等.土-桩-结构相互作用体系的振动台模型试验[J] .同济大学学报,2001,29(7):763-768.
[43]郭金童,王建华.松散砂土中桩-土相互作用的试验研究[J] .勘察科学技术,2004,(4):3-5.
[44]汪明武,Tobita T, Iai S.强震动力条件下的桩土相互作用动态土工离心试验研究[J] .岩石力学与工程学报,2005,24(S2):5555-5560.
[45]黄春霞,张鸿儒,隋志龙等.饱和砂土地基液化特性振动台试验研究[J] .岩土工程学报,2006,28(12):2098-2013.
[46]苏栋,李相菘.可液化土中单桩地震响应的离心机试验研究[J] .岩土工程学报,2006,28(4):423-427.
[47]王成雷,王建华,冯士伦.土层液化条件下桩土相互作用p-y关系分析[J] .岩土工程学报,2007,29(10):1500-1505.
[48]汪明武,Iai. S.地下RC结构物地震响应特征土工离心试验的模拟[J] .地震工程与工程振动,2007,27(3):150-155.
[49]王建华,戚春香,余正春等.弱化饱和砂土中桩的p-y曲线与极限抗力研究[J] .岩土工程学报,2008,30(3):309-315.
[50]茜平一,周洪波.水平荷载群桩三维有限元分析研究[J] .岩土工程技术,1999,(4):44-48.
[51]马远刚,茜平一.横向土运动作用下群桩的性状研究[J] .岩土力学,2000,21(4):377-380.
[52]汪明武,井合进,飞田哲男.栈桥式构筑物抗震性能动态离心模型试验的数值模拟[J] .岩土工程学报,2005,27(7):738–741.
[53]陈鹏,李文华,范涛等.土体冲刷对桥梁桩基影响的三维差分模拟计算分析[J] .山东科技大学学报自然科学版,2007,26(4):23-26.
[54]朱英明.下卧液化土层堤坝的强震动力反应特性研究[硕士学位论文][D].合肥:合肥工业大学土木建筑工程学院,2007.
[55]吴大国.液化场地群桩地震响应有效应力分析[硕士学位论文][D]合肥:合肥工业大学土木建筑工程学院,2007.
[56]范君宇,刘全林.门字形锚桩围护结构参数对深基坑工程水平位移的影响[J] .科技信息(建筑与工程),2008,(16):154-155.
[57] Wang M. W., Li L. Numerical modeling of seismic performances of passive pile groups adjacent to soil slope[C]. Geotechnical Engineering for Disaster Mitigation and Rehabilitation, Science Press Beijing, Springer, 2008: 446-451.
[58]刘波,韩彦辉. FLAC原理、实例与应用指南[M].北京:人民交通出版社,2005.
[59] Itasca. FLAC-Users’Manual[M]. Minneapolis, Itasca Consulting Group, 2005.