柔性荷载刚性桩复合地基修正密度法稳定分析改进
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摘要
基于柔性荷载下刚性桩复合地基绕流滑动时的桩土作用分析,改进了用于稳定分析的修正密度法。滑动面圆心外侧填料密度不作修正,拉中性面以上的正摩擦力增大桩间土密度,拉中性面以下的负摩擦力减小桩间土的密度,并考虑了桩身抗拉强度对拉中性面位置和桩间土修正密度的影响,将端阻力的反力换算到桩端土密度中。分析表明,滑动面圆心外侧填料和桩间土密度修正方法的变化对稳定安全系数影响较小,存在软土下卧层时,桩端土密度修正对稳定安全系数影响较大。工程实例证明改进后的修正密度法分析结果与工程实际符合较好。
The revised density method is improved based on analysis of interactions between ground soil, fill and piles in flow sliding. The density of fill outside the center of sliding surface needn't be revised. The density of soils among piles outside the center of sliding surface is increased due to the positive frictional stress over the tensile neutral plane and decreased due to the negative frictional stress below the tensile neutral plane. The influences of tensile strength of piles on position of the tensile neutral plane and the revised density of soils among piles are taken into account. The counterforce of end resistance of piles is transformed into the soil density below piles. It is shown by analysis that the safety factor of stability is affected little by change of the revised method for density of fills and soils among piles outside the center of sliding surface, but is obviously affected by the revision of density of soils below piles when there is soft substratum. It is shown that the results of stability analysis of a sliding project by the improved revised density method for rigid-pile composite foundation coincides with the project practices.
The revised density method is improved based on analysis of interactions between ground soil, fill and piles in flow sliding. The density of fill outside the center of sliding surface needn't be revised. The density of soils among piles outside the center of sliding surface is increased due to the positive frictional stress over the tensile neutral plane and decreased due to the negative frictional stress below the tensile neutral plane. The influences of tensile strength of piles on position of the tensile neutral plane and the revised density of soils among piles are taken into account. The counterforce of end resistance of piles is transformed into the soil density below piles. It is shown by analysis that the safety factor of stability is affected little by change of the revised method for density of fills and soils among piles outside the center of sliding surface, but is obviously affected by the revision of density of soils below piles when there is soft substratum. It is shown that the results of stability analysis of a sliding project by the improved revised density method for rigid-pile composite foundation coincides with the project practices.
引文
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[2]刘吉福,郑刚,安关峰.折减荷载法分析刚性桩复合地基路基绕流滑动稳定性[J].广西大学学报,2013,38(1):176-181.(LIU Ji-fu,ZHENG Gang,AN Guan-feng.Load reduction method for stability analysis of flow-slide of embankment on rigid-piles composite foundation[J].Journal of Guangxi University:Nat.Sci Ed,2013,38(1):176-181.(in Chinese))
[3]刘吉福,郭舒洋,肖昌建.修正密度法分析混凝土桩复合地基路基绕流滑动稳定性[J].广东公路交通,2016(5):12-20.(LIU Ji-fu,GUO Shu-yang,XIAO Chang-jian.Revised density method for stability analysis of flow slide of embankment with concrete-pile composite foundation[J].Guangdong Highway Communications,2016(5):12-20.(in Chinese))
[4]陈云敏,贾宁,陈仁朋.桩承式路堤土拱效应分析[J].中国公路学报,2004,17(4):1-6.(CHEN Yun-min,JIA Ning,CHEN Ren-peng.Soil arch analysis of pile supported embankments[J].China Journal of Highway and Transport,2004,17(4):1-6.(in Chinese))
[5]莫景逸,黄向平.某矿料堆场地基失稳原因分析[J].水运工程,2013(10):212-217.(MO Jing-yi,HUANGXiang-ping.Analysis of foundation failure of mineral ore yard[J].Port&Waterway Engineering,2013(10):212-217.(in Chinese))
[6]龚晓南.土塑性力学[M].杭州:浙江大学出版社,1990.(GONG Xiao-nan.Soil plastic mechanics[M].Hangzhou:Zhejiang University Press,1990.(in Chinese))