挡土墙与土界面摩擦角为负的地震被动土压力解析解
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摘要
目前大多数被动土压力问题研究的是挡土墙背与土界面摩擦角为正的情况(墙身相对土体向下移动),而挡土墙与土界面摩擦角为负(墙身相对土体向上移动)的被动土压力问题则研究的较少。在平面滑裂面假设的基础上,利用散粒体Ktter方程得到破裂面土抗力的分布,结合拟静力法通过极限平衡分析得到了挡土墙与土界面摩擦角为负时的地震被动土压力系数、被动土压力合力和被动土压力合力作用点高度的理论公式。在地震荷载作用下,竖向地震加速度系数总是减小被动土压力,水平向地震加速度系数或减小或增加被动土压力系数取决于挡土墙倾角、挡土墙背与填土界面摩擦角、填土摩擦角。随地震加速度系数的增加,地震被动土压力系数变化越明显。利用破坏土楔弯矩平衡条件得到了地震被动土压力的作用点高度,且土压力作用点高度随水平向地震加速度系数的增加而减小。地震被动土压力系数和土压力作用点高度与相关文献结果吻合较好,可为锚、输电线路等基础受上拔荷载时设计所采用。
Most of the existing analyses of passive earth pressures behind retaining walls deal with the case of positive wall-soil interface friction angles(the wall moves downwards relative to the backfill),while the researches on passive earth pressures for the negative wall-soil interface friction angle case(the wall moves upwards relative to the backfill) are still lacking.Based on the planar rupture surfaces hypothesis,a theoretical formula for the seismic passive earth pressure coefficient,the resultant force of earth pressure and the application point of the resultant is obtained by using the Ktter equation and the combination of pseudo-static approach with the limit equilibrium method of analysis for the negative wall-soil interface friction angle case.The seismic passive earth pressure coefficients always decrease with the increase of the vertical seismic acceleration,but the horizontal seismic acceleration results in either an increase or a decrease in the earth pressure coefficients,depending on the combinations of the wall batter angles,wall-soil interface friction angles and soil friction angles.The variation of seismic passive pressure coefficients increases with the increase of the magnitude of the earthquake acceleration.The proposed analysis lies in its ability to compute the point of application of the passive thrust,for which moment equilibrium condition of failure wedge is effectively utilized.The application point of the passive thrust decreases with the increasing values of horizontal seismic acceleration coefficients.The computed values of the seismic passive pressure coefficients and the point of application of passive thrust agree with the available results,which can be served for anchor and transmission line foundations under uplift loading.
Most of the existing analyses of passive earth pressures behind retaining walls deal with the case of positive wall-soil interface friction angles(the wall moves downwards relative to the backfill),while the researches on passive earth pressures for the negative wall-soil interface friction angle case(the wall moves upwards relative to the backfill) are still lacking.Based on the planar rupture surfaces hypothesis,a theoretical formula for the seismic passive earth pressure coefficient,the resultant force of earth pressure and the application point of the resultant is obtained by using the Ktter equation and the combination of pseudo-static approach with the limit equilibrium method of analysis for the negative wall-soil interface friction angle case.The seismic passive earth pressure coefficients always decrease with the increase of the vertical seismic acceleration,but the horizontal seismic acceleration results in either an increase or a decrease in the earth pressure coefficients,depending on the combinations of the wall batter angles,wall-soil interface friction angles and soil friction angles.The variation of seismic passive pressure coefficients increases with the increase of the magnitude of the earthquake acceleration.The proposed analysis lies in its ability to compute the point of application of the passive thrust,for which moment equilibrium condition of failure wedge is effectively utilized.The application point of the passive thrust decreases with the increasing values of horizontal seismic acceleration coefficients.The computed values of the seismic passive pressure coefficients and the point of application of passive thrust agree with the available results,which can be served for anchor and transmission line foundations under uplift loading.
引文
[1]MONONOBE N,MATSUO H.On the determination of earth pressure during earthquakes[C]//In Proceedings World Engineer Congress,Tokyo,9:176,1924[C].
[2]OKABE S.General theory of earth pressure[J].Journal of the Japanese society of civil Engineers,Tokyo,Japan,12(1),1926.
[3]MORRISON E E,EBELING R M.Limit equilibrium computation of dynamic passive earth pressure[J].Canadian Geotechnical Journal,1995,32:481-487.
[4]SUBBA RAO K S,CHOUDHURY D.Seismic passive earth pressures in soils[J].Journal of Geotechnical and Geoenvironmental Engineering,2005,131(1):131-135.
[5]SOUBRA A H.Static and seismic passive earth pressure coefficients on rigid retaining structures[J].Canadian Geotechnical Journal,2000,37:463-478.
[6]CHENG Y M.Seismic lateral earth pressure coefficients for c-?soils by slip line method[J].Computers and Geotechnics,2003,30:661-670.
[7]KUMAR J.Seismic passive earth pressure coefficients for sands[J].Canadian Geotechnical Journal,2001,38:876-881.
[8]BENMEBAREK S,KHELIFA T,BENMEBAREK S.Numerical evaluation of 3D passive earth pressure coefficients for retaining wall subjected to translation[J].Computer and Geotechnics,2008,35:47-60.
[9]DAY R A,POTTS D M.The effect of interface properties on retaining wall behaviour[J].International Journal for Numerical and Analytical Methods in Geomechanics,1998,22:1021-1033.
[10]MEYERHOF G G and Adams J I.The ultimate uplift capacity of foundations[J].Canadian Geotechnical Journal,1968,5:225-244.
[11]MEYERHOF G G.Uplift resistance of inclined anchors and piles[C]//In proceedings of the 8th international conference on soil mechanics and foundations engineering,Moscow,1973.
[12]朱大勇,钱七虎,姜弘道.挡土结构中土体被动临界滑动场及被动土压力的数值计算[J].水利学报,2000,31(11):15-20.(ZHU Da-yong,QIAN Qi-hu,JIANG Hong-dao.Passive critical slip field of soils in retaining structures and numerical calculation of passive earth pressure[J].Journal of Hydraulic Engineering,2000,31(11):15-20.(in Chinese))
[13]CHOUDHURY D,SUBBA RAO K S.Seismic passive resistance in soils for negative wall friction[J].Canadian Geotechnical Journal,2002,39:971-981.
[14]KUMAR J,SUBBA RAO K S.Passive pressure coefficients,critical failure surface and its kinematic admissibility[J].Geotechnique,1997,47(1):185-192.
[15]DEWAIKAR D M and HALKUDE S A.Seismic passive/active thrust on retaining wall-point on of application[J].Soils and Foundations,2002,42(1):9-15.
[16]陈震.散体极限平衡理论基础[M].北京:水利电力出版社,1985.(CHEN Zhen.Limit equilibrium theory of granular structures[M].Beijing:Water Resources and Electric Power Press,1985.(in Chinese))
[17]张楚汉.水利水电工程科学前沿[M].北京:清华大学出版社,2002.(ZHANG Chu-han.Frontier of science in hydraulic and hydro-power engineering[M].Beijing:Tsinghua University Press,2002.(in Chinese))
[2]OKABE S.General theory of earth pressure[J].Journal of the Japanese society of civil Engineers,Tokyo,Japan,12(1),1926.
[3]MORRISON E E,EBELING R M.Limit equilibrium computation of dynamic passive earth pressure[J].Canadian Geotechnical Journal,1995,32:481-487.
[4]SUBBA RAO K S,CHOUDHURY D.Seismic passive earth pressures in soils[J].Journal of Geotechnical and Geoenvironmental Engineering,2005,131(1):131-135.
[5]SOUBRA A H.Static and seismic passive earth pressure coefficients on rigid retaining structures[J].Canadian Geotechnical Journal,2000,37:463-478.
[6]CHENG Y M.Seismic lateral earth pressure coefficients for c-?soils by slip line method[J].Computers and Geotechnics,2003,30:661-670.
[7]KUMAR J.Seismic passive earth pressure coefficients for sands[J].Canadian Geotechnical Journal,2001,38:876-881.
[8]BENMEBAREK S,KHELIFA T,BENMEBAREK S.Numerical evaluation of 3D passive earth pressure coefficients for retaining wall subjected to translation[J].Computer and Geotechnics,2008,35:47-60.
[9]DAY R A,POTTS D M.The effect of interface properties on retaining wall behaviour[J].International Journal for Numerical and Analytical Methods in Geomechanics,1998,22:1021-1033.
[10]MEYERHOF G G and Adams J I.The ultimate uplift capacity of foundations[J].Canadian Geotechnical Journal,1968,5:225-244.
[11]MEYERHOF G G.Uplift resistance of inclined anchors and piles[C]//In proceedings of the 8th international conference on soil mechanics and foundations engineering,Moscow,1973.
[12]朱大勇,钱七虎,姜弘道.挡土结构中土体被动临界滑动场及被动土压力的数值计算[J].水利学报,2000,31(11):15-20.(ZHU Da-yong,QIAN Qi-hu,JIANG Hong-dao.Passive critical slip field of soils in retaining structures and numerical calculation of passive earth pressure[J].Journal of Hydraulic Engineering,2000,31(11):15-20.(in Chinese))
[13]CHOUDHURY D,SUBBA RAO K S.Seismic passive resistance in soils for negative wall friction[J].Canadian Geotechnical Journal,2002,39:971-981.
[14]KUMAR J,SUBBA RAO K S.Passive pressure coefficients,critical failure surface and its kinematic admissibility[J].Geotechnique,1997,47(1):185-192.
[15]DEWAIKAR D M and HALKUDE S A.Seismic passive/active thrust on retaining wall-point on of application[J].Soils and Foundations,2002,42(1):9-15.
[16]陈震.散体极限平衡理论基础[M].北京:水利电力出版社,1985.(CHEN Zhen.Limit equilibrium theory of granular structures[M].Beijing:Water Resources and Electric Power Press,1985.(in Chinese))
[17]张楚汉.水利水电工程科学前沿[M].北京:清华大学出版社,2002.(ZHANG Chu-han.Frontier of science in hydraulic and hydro-power engineering[M].Beijing:Tsinghua University Press,2002.(in Chinese))
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