碎石桩处理液化地基抗液化研究现状及存在问题
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摘要
就目前国内外碎石桩处理液化地基抗液化理论、动力分析以及液化判别等方面的研究作简要的归纳和评述。在加固机理研究方面,主要认为碎石加固砂土有以下几种作用:(1)挤密作用;(2)振密作用;(3)排水减压作用;(4)预震作用;(5)加筋作用。其次,在理论研究方面如排水效应和桩体效应方面的研究也取得了长足进展,已经从总应力法深入到有效应力法,从只对孔压的研究发展到对水土共同作用的研究。并且随着计算机的发展,数值计算为复杂条件下的问题解答开辟了一个新的途径,现在已经可以模拟地震时土体的变形和孔压变化情况。但是在碎石桩处理液化地基的判别标准研究方面发展较慢。最后,对高速公路碎石桩复合地基抗液化研究方面的一些不足之处提出了解决的思路,主要包括:(1)上部荷载对复合地基的影响;(2)碎石桩处理深度设计时应考虑的影响因素;(3)碎石桩加固区与周围环境的相互作用;(4)考虑碎石桩排水、应力集中和附加应力共同影响下的液化判别标准。
Since vibrosinking method was invented in 1937, gravel columns foundation has been widely applied in engineering . Up to now, great achievements have been attained in the research of gravel columns foundation. In this paper the recent advances in theoretical research and dynamic analysis and criteria for liquefaction resistance of gravel columns foundation are reviewed. Firstly, the reinforcement effects of gravel columns are recognized gradually; i.e.(1)densifing the soil by squeezing and vibrationg in the progress of forming columns;(2)draining away water through gravel columns and reducing waterpressure;(3)liquefing in advance in the progress of forming columns; (4) reinforcing soil. Secondly, many achievements in the theoretical research have been made, especially in the mechanisms of drainingawaywatercolumns and focusing stress by gravel. In the past, the research was mostly concentrated on the total stress method or only the waterpressure change, while at present the research has already turned to the effective stress method and combined action between soil and water. With the development of computer, numerical simulation is provided to solve complicated problems, thus deformation of soil and change of waterpressure during an earthquake can be simulated by computer. Thirdly, the development is very slow in the criteria for liquefaction resistance of gravel columns foundation, due to the slow development in the criteria for liquefaction resistance of sand foundation. Present criteria for liquefaction of sand foundation are based on insitu tests, such as standard penetration test(SPT), cone penetration test(CPT) or shearwave velocity measurements(VS). Corresponding criteria for liquefaction resistance of gravel columns foundation are obtained by that of sand foundation. At last a few deficiencies are pointed out in restraches of liquefaction resistance of gravel columns foundation. To overcome these deficienies, further studies are sugsested which includes:(1)influence of superstructure loads on gravel columns foundation;(2)some effective factors for the design of reinforce depth of gravel columns;(3)interact between reinforced foundation and surrounding;(4)criteria for liquefaction of gravel columns foundation considering influence of draningawaywater and focusing stress of gravel columns and additional stress for superstructure loads.
Since vibrosinking method was invented in 1937, gravel columns foundation has been widely applied in engineering . Up to now, great achievements have been attained in the research of gravel columns foundation. In this paper the recent advances in theoretical research and dynamic analysis and criteria for liquefaction resistance of gravel columns foundation are reviewed. Firstly, the reinforcement effects of gravel columns are recognized gradually; i.e.(1)densifing the soil by squeezing and vibrationg in the progress of forming columns;(2)draining away water through gravel columns and reducing waterpressure;(3)liquefing in advance in the progress of forming columns; (4) reinforcing soil. Secondly, many achievements in the theoretical research have been made, especially in the mechanisms of drainingawaywatercolumns and focusing stress by gravel. In the past, the research was mostly concentrated on the total stress method or only the waterpressure change, while at present the research has already turned to the effective stress method and combined action between soil and water. With the development of computer, numerical simulation is provided to solve complicated problems, thus deformation of soil and change of waterpressure during an earthquake can be simulated by computer. Thirdly, the development is very slow in the criteria for liquefaction resistance of gravel columns foundation, due to the slow development in the criteria for liquefaction resistance of sand foundation. Present criteria for liquefaction of sand foundation are based on insitu tests, such as standard penetration test(SPT), cone penetration test(CPT) or shearwave velocity measurements(VS). Corresponding criteria for liquefaction resistance of gravel columns foundation are obtained by that of sand foundation. At last a few deficiencies are pointed out in restraches of liquefaction resistance of gravel columns foundation. To overcome these deficienies, further studies are sugsested which includes:(1)influence of superstructure loads on gravel columns foundation;(2)some effective factors for the design of reinforce depth of gravel columns;(3)interact between reinforced foundation and surrounding;(4)criteria for liquefaction of gravel columns foundation considering influence of draningawaywater and focusing stress of gravel columns and additional stress for superstructure loads.
引文
1 任书考 .用动剪应变法确定饱和砂土的地震液化势 .振动水冲法加固地基学术讨论会资料选编 , 1 984.
[1] 叶书麟,韩 杰,叶观宝编.地基处理与托换技术(第二版)[M].北京:中国建筑工业出版社,1994.75-80.
[2] 刘松玉.公路地基处理[M].南京:东南大学出版社,2000.211-220.
[3] 周 健,白 冰,徐建平.土动力学理论与计算[M].北京:中国建筑工业出版社,2001.238.
[4] SeedHBandBookerR.Stabilizationofpotentiallyliquefialsanddepositsusinggraveldrains[J].J.ofGeotechnicalEngineeringDiv.JGED,1976,102(7):1-15.
[5] 顾卫华,王余庆.砾石排水桩与地面压重的抗液化效果[J].岩土工程学报,1985,7(4):34-43.
[6] 王余庆,孙建生.挤密桩法在加固可液化地基中的应用[J].岩土工程学报,1989,11(2):18-25.
[7] 徐志英.用砾石排水桩抗地震液化的砂基孔压计算[J].地震工程与工程振动,1992,12(4):88-92.
[8] 徐志英,沈珠江.土坝地震孔隙水压力的产生、扩散和消散的有限元动力分析[J].华东水利学报,1981,9(4):1-16.
[9] 徐志英,周 健.土坝地震孔隙水压力产生、扩散和消散的三维动力分析[J].地震工程与工程振动,1985,5(4):57-71.
[10] 邱 钰,黄 卫,刘松玉.干振碎石桩处理高速公路液化地基效果分析[J].公路交通科技,2000,17(4):19-21.
[11] 刘金韬,金晓媚.抗液化排水井(桩)间距确定方法的研究[J].岩土力学,2000,21(4):374-376.
[12] 林本海,谢定义.复合地基的液化检验理论及其应用[M].北京:中国水利水电出版社,1999.152.
[13] SeedHB,IdissIM.Simplifiedproceduresforevalu-atingsoilliquefactionpotential[J].J.ofSoilMe-chanicsandFoundationDiv.1971,97(9):1249-1273.
[14] MejiaLH,SeedHB.Threedimensionaldynamicre-ponseanalysisofearthdams[R].ReportEEPRC1987.81-15.
[15] 汪文韶.饱和砂土振动孔隙水压力试验研究[J].水利学报,1962(2):37-49.
[16] SeedHBandBookerR.Stabilizationofpotentiallyliquefialsanddepositsusinggraveldrains[J].J.ofGeotechnicalEngineeringDiv.JGED,1976,102(7):1-15.
[17] MartinGB,FinnWDL,SeedHB.Fundamentalsofliquefactionundercyclicloading[J].J.ofGeotechnicalEngineeringDivision.ASCE,1975,101(5):439-457.
[18] NematS,ShokoohA.Aunifiedapproachtodesifica-tionandliquefactionofcohesionlesssandincyclicshearing[J].J.ofCanadianGeotech,1979,16(4):659-678.
[19] DavisRO,BerrillJB.Energydissipationandseis-micliquefactioninsands[J].EarthquakeEngineer-ingandStructuralDynamics,1982,10(1):59-68.
[20] 何广讷,李万民.振动能量下的体变与孔隙水压力[J].地震工程与工程振动,1987,7(2):89-99.
[21] 谢定义,张建民.往复荷载下饱和砂土强度变形瞬态变化的机理[J].土木工程学报,1987,20(3):59-69.
[22] 陈国兴,胡庆兴,刘雪珠.关于砂土液化判别的若干意见[J].地震工程与工程振动,2002,22(1):141-151.
[23] 中华人民共和国建设部.建筑抗震设计规范(GB50011-2001)[S].北京:中国建筑工业出版社,2001,20-23.
[24] 郑建国.碎石桩复合地基液化判别方法的探讨[J].工程勘察,1999,(2):5-8.
[25] 张剑峰,华镇难.镇江500KV长江大跨越北岸塔基抗液化处理[J].岩土工程学报,1990,12(4):79-88.
[26] 何广讷.振冲碎石桩复合地基液化势的判别[A].辽宁工程结构[C].沈阳:东北大学出版社,2000.79-86.
[27] 刘松玉.高速公路液化地基及桥梁抗液化研究总报告[R].南京:东南大学出版社,1999.47-66.
[1] 叶书麟,韩 杰,叶观宝编.地基处理与托换技术(第二版)[M].北京:中国建筑工业出版社,1994.75-80.
[2] 刘松玉.公路地基处理[M].南京:东南大学出版社,2000.211-220.
[3] 周 健,白 冰,徐建平.土动力学理论与计算[M].北京:中国建筑工业出版社,2001.238.
[4] SeedHBandBookerR.Stabilizationofpotentiallyliquefialsanddepositsusinggraveldrains[J].J.ofGeotechnicalEngineeringDiv.JGED,1976,102(7):1-15.
[5] 顾卫华,王余庆.砾石排水桩与地面压重的抗液化效果[J].岩土工程学报,1985,7(4):34-43.
[6] 王余庆,孙建生.挤密桩法在加固可液化地基中的应用[J].岩土工程学报,1989,11(2):18-25.
[7] 徐志英.用砾石排水桩抗地震液化的砂基孔压计算[J].地震工程与工程振动,1992,12(4):88-92.
[8] 徐志英,沈珠江.土坝地震孔隙水压力的产生、扩散和消散的有限元动力分析[J].华东水利学报,1981,9(4):1-16.
[9] 徐志英,周 健.土坝地震孔隙水压力产生、扩散和消散的三维动力分析[J].地震工程与工程振动,1985,5(4):57-71.
[10] 邱 钰,黄 卫,刘松玉.干振碎石桩处理高速公路液化地基效果分析[J].公路交通科技,2000,17(4):19-21.
[11] 刘金韬,金晓媚.抗液化排水井(桩)间距确定方法的研究[J].岩土力学,2000,21(4):374-376.
[12] 林本海,谢定义.复合地基的液化检验理论及其应用[M].北京:中国水利水电出版社,1999.152.
[13] SeedHB,IdissIM.Simplifiedproceduresforevalu-atingsoilliquefactionpotential[J].J.ofSoilMe-chanicsandFoundationDiv.1971,97(9):1249-1273.
[14] MejiaLH,SeedHB.Threedimensionaldynamicre-ponseanalysisofearthdams[R].ReportEEPRC1987.81-15.
[15] 汪文韶.饱和砂土振动孔隙水压力试验研究[J].水利学报,1962(2):37-49.
[16] SeedHBandBookerR.Stabilizationofpotentiallyliquefialsanddepositsusinggraveldrains[J].J.ofGeotechnicalEngineeringDiv.JGED,1976,102(7):1-15.
[17] MartinGB,FinnWDL,SeedHB.Fundamentalsofliquefactionundercyclicloading[J].J.ofGeotechnicalEngineeringDivision.ASCE,1975,101(5):439-457.
[18] NematS,ShokoohA.Aunifiedapproachtodesifica-tionandliquefactionofcohesionlesssandincyclicshearing[J].J.ofCanadianGeotech,1979,16(4):659-678.
[19] DavisRO,BerrillJB.Energydissipationandseis-micliquefactioninsands[J].EarthquakeEngineer-ingandStructuralDynamics,1982,10(1):59-68.
[20] 何广讷,李万民.振动能量下的体变与孔隙水压力[J].地震工程与工程振动,1987,7(2):89-99.
[21] 谢定义,张建民.往复荷载下饱和砂土强度变形瞬态变化的机理[J].土木工程学报,1987,20(3):59-69.
[22] 陈国兴,胡庆兴,刘雪珠.关于砂土液化判别的若干意见[J].地震工程与工程振动,2002,22(1):141-151.
[23] 中华人民共和国建设部.建筑抗震设计规范(GB50011-2001)[S].北京:中国建筑工业出版社,2001,20-23.
[24] 郑建国.碎石桩复合地基液化判别方法的探讨[J].工程勘察,1999,(2):5-8.
[25] 张剑峰,华镇难.镇江500KV长江大跨越北岸塔基抗液化处理[J].岩土工程学报,1990,12(4):79-88.
[26] 何广讷.振冲碎石桩复合地基液化势的判别[A].辽宁工程结构[C].沈阳:东北大学出版社,2000.79-86.
[27] 刘松玉.高速公路液化地基及桥梁抗液化研究总报告[R].南京:东南大学出版社,1999.47-66.
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