抗液化刚性排水桩振动台试验的数值模拟研究
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摘要
抗液化刚性排水桩的基本原理是,在桩身部分范围内设置排水体,以便形成良好的排水通道,在地震作用下,桩周土体积累的超孔隙水压力可以由桩身的排水体快速排出,从而增大桩周土体的有效应力,达到抗液化的目的。利用小型振动台,对刚性排水桩和未设置排水体的普通桩在振动荷载作用下的抗液化性状进行研究,得到抗液化刚性排水桩的基本特性。基于试验结果,建立排水桩和普通桩振动台试验的三维数值分析模型,通过振动台试验与数值分析的比较,发现两者在土体超孔隙水压力发展和分布的主要规律方面表现一致,进一步验证了抗液化刚性排水桩的抗液化特性。数值分析结果还表明,在动力作用下,排水桩工况由于排水体的存在,形成良好的排水通道,孔隙水得以及时排出,桩身附近一定范围内土体的超孔隙水压力得到及时有效的消散,其消散作用随着与桩体距离的增大而逐渐减弱。桩周土体的孔压分布呈漏斗状,渗流矢量指向桩体,桩身附近土体的超孔压比峰值较小且在达到峰值后有明显的下降趋势。
Principle of rigidity-drain pile was setting vertical drains in part of the rigidity-drain pile so as to form an effective drainage channel.Small shaking table tests were conducted to investigate behaviors of anti-liquefaction of the rigidity-drain pile and common pile in liquefiable ground.The basic characteristics of anti-liquefaction mechanism were confirmed based on the test results.3D numerical model of the common pile and drain pile were built and simulations of the shaking table tests were performed.Comparing the small shaking table test with numerical simulations,it is found that the main rule of development and distribution of excess pore water pressure is consistent in both.Under dynamic loading,rigidity-drain pile can decrease the peak of excess pore water pressure ratio obviously and also has a significant effect on dissipating excess pore water pressure and maintaining effective stress and strength with certain distance to the pile.Rigidity-drain pile can reduce the possibility of soil liquefaction greatly and its behaviors of anti-liquefaction are proved.
Principle of rigidity-drain pile was setting vertical drains in part of the rigidity-drain pile so as to form an effective drainage channel.Small shaking table tests were conducted to investigate behaviors of anti-liquefaction of the rigidity-drain pile and common pile in liquefiable ground.The basic characteristics of anti-liquefaction mechanism were confirmed based on the test results.3D numerical model of the common pile and drain pile were built and simulations of the shaking table tests were performed.Comparing the small shaking table test with numerical simulations,it is found that the main rule of development and distribution of excess pore water pressure is consistent in both.Under dynamic loading,rigidity-drain pile can decrease the peak of excess pore water pressure ratio obviously and also has a significant effect on dissipating excess pore water pressure and maintaining effective stress and strength with certain distance to the pile.Rigidity-drain pile can reduce the possibility of soil liquefaction greatly and its behaviors of anti-liquefaction are proved.
引文
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[9]Orense R P,Morimoto I,Yamamoto Y,et al.Study onwall-type gravel drains as liquefaction countermeasure forunderground structures[J].Soil Dynamics and EarthquakeEngineering,2003,23(1):19-39
[10]刘汉龙.一种抗液化排水刚性桩:中国,ZL200520076660.4[P].2007
[11]刘汉龙,陈育民,赵楠.刚性排水桩的技术开发与抗液化特性试验研究[C]//第一届全国工程安全与防护学术会议论文集.北京:中国岩土力学与工程学会,2008
[12]Orense R P,Morimoto I,Yamamoto Y,et al.Study onwall-type gravel drains as liquefaction countermeasure forunderground structures[J].Soil Dynamics and EarthquakeEngineering,2003,23(1):19-39
[2]刘恢先.唐山大地震震害[M].北京:地震出版社,1985
[3]中国赴日地震考察团.日本阪神大地震考察[M].北京:地震出版社,1995
[4]曹振中,袁晓铭,陈龙伟,等.汶川大地震液化宏观现象概述[J].岩土工程学报,2010,32(4):645-650(Cao Zhenzhong,Yuan Xiaoming,Chen Longwei,et al.Summary of liquefaction macrophenomena in WenchuanEarthquake[J].Chinese Journal of GeotechnicalEngineering,2010,32(4):645-650(in Chinese))
[5]袁晓铭,曹振中,孙锐,等.汶川8.0级地震液化特征初步研究[J].岩石力学与工程学报,2009,28(6):1288-1296(Yuan Xiaoming,Cao Zhenzhong,Sun Rui,etal.Preliminary research on liquefaction charecteristics ofWenchuan 8.0 Earthquake[J].Chinese Journal of RockMechanics and Engineering,2009,28(6):1288-1296(inChinese))
[6]杜国云,邢秀臣.龙门山山前砂土液化初步研究[J].水文地质工程地质,2010,37(1):108-112(DuGuoyun,Xing Xiuchen.Research on the soil liquefactionin the piedmont region of the Longmen Mountain[J].Hydrogeology and Engineering Geology,2010,37(1):108-112(in Chinese))
[7]Harada N,Towhata I,Takatsu T,et al.Development ofnew drain method for protection of existing pile foundationsfrom liquefaction effects[J].Soil Dynamics andEarthquake Engineering,2006,26(2/3/4):297-312
[8]Pamuk A,Gallagher P M,Zimmie T F.Remediation ofpiled foundations against lateral spreading by passive sitestabilization technique[J].Soil Dynamics and EarthquakeEngineering,2007,27(9):864-874
[9]Orense R P,Morimoto I,Yamamoto Y,et al.Study onwall-type gravel drains as liquefaction countermeasure forunderground structures[J].Soil Dynamics and EarthquakeEngineering,2003,23(1):19-39
[10]刘汉龙.一种抗液化排水刚性桩:中国,ZL200520076660.4[P].2007
[11]刘汉龙,陈育民,赵楠.刚性排水桩的技术开发与抗液化特性试验研究[C]//第一届全国工程安全与防护学术会议论文集.北京:中国岩土力学与工程学会,2008
[12]Orense R P,Morimoto I,Yamamoto Y,et al.Study onwall-type gravel drains as liquefaction countermeasure forunderground structures[J].Soil Dynamics and EarthquakeEngineering,2003,23(1):19-39
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