收稿日期:2013-08-08;修回日期:2013-12-02作者简介:赵文强(1980—),男,河南濮阳人,2004年毕业于石家庄铁道学院,土木工程专业,本科,工程师,现从事城市轨道交通设计研究工作。上软下硬复合地层条件下深基坑支护设计探析赵文强(中铁第五勘察设计院集团有限公司,北京102600)摘要:近年来,常出现在深基坑开挖支护中的吊脚桩存在一定的安全隐患。为此,以青岛地铁某长条形基坑为载体,对上软下硬地质条件下遇到的吊脚桩问题展开研究。首先,根据地质条件及周边工程概况,给出基坑开挖及支护思路和方案;然后,结合支护方案采用弹性抗力法和等效被动土压力法分别对上部桩撑(锚)体系和下部岩石边坡稳定性进行分析计算。实际应用结果表明:1)青岛地区上部土层适合采用桩+支撑,下部岩石边坡采用锚喷支护的组合支护方案;2)直壁开挖的岩石边坡中,微型钢管桩具有超前支护、预裂及减振作用;3)推荐算法适合于吊脚桩支护体系的设计。关键词:土岩复合基坑;吊脚桩;基坑支护;微型钢管桩;桩撑体系DOI:10.3973/j.issn.1672-741X.2014.02.011中图分类号:U45文献标志码:A文章编号:1672-741X(2014)02-0153-05DesignofSupportofDeepFoundationPitsinHardsoftHeterogeneousGroundZHAOWenqiang(ChinaRailwayFifthSurveyandDesignInstituteGroupCo.,Ltd.,Beijing102600,China)Abstract:Recentlysuspendedpilesalwaysexistindeepfoundationpits,whichcouldcausepotentialsafetyrisks.Inthispaper,the“suspendedpiles”ofastripshapedfoundationpitofQingdaoMetrolocatedinhardsoftheterogeneousgroundisstudied.First,excavationandsupportschemeisproposedfortheprojectonbasisofthegeologicalconditionsandthesurroundingenvironment;Secondly,thestabilityoftheupperpilestrutbracingsystemandthelowerrockslopeofthefoundationpitisanalyzedbymeansofelasticresistancemethodandequivalentpassiveearthpressuremethod.Thepracticeshowsthat:1)InQingdao,the“pilestrut”supportsystemissuitablefortheuppersoilstrata,andtheboltingandshotcretingsupportsystemissuitableforthelowerrockslope;2)Themicrosteelpipepilesadoptedinthecuttingoftheverticalrockslopesofthefoundationpitplaytheroleofadvancesupport,presplittingandvibrationreduction;3)Thecalculationmethodproposedissuitableforthedesignofthesuspendedpilesupportsystem.Keywords:foundationpitinsoilrockground;suspendedpile;foundationpitsupport;micros...