软土地基预加固对桩基竖向承载特性的影响研究  

Influence of soft soil foundation pre-reinforcement treatment on verticalbearing characteristics of pile foundation

作　　者：王丽欢 郜帆 任亚宁 李楚 WANG Lihuan;GAO Fan;REN Yaning;LI Chu(State Grid Hebei Economic Research Institute,Shijiazhuang 050000,China)

机构地区：[1]国网河北省电力有限公司经济技术研究院,河北石家庄050000

出　　处：《人民长江》2023年第4期190-197,共8页Yangtze River

基　　金：国网河北省电力有限公司科技项目“桩基础的机械清孔工艺研究与改进”(kj2017-026)。

摘　　要：针对目前软土地基预加固处理对桩基竖向承载特性影响的定量分析不足的问题,依托大型围垦工程案例,就软土地基预加固处理对桩基竖向承载力提高、桩顶沉降控制及负摩擦阻力减小等方面产生的影响进行了定量研究,给出了桩基极限侧摩擦阻力定量计算的α法、API-2000法及λ法,同时给出了桩基极限端阻力及桩顶沉降计算公式。通过工程案例,分别对原状淤泥土、预加固处理后的地基土中的试验桩进行竖向静载试验,并依据前述3种计算方法进行对比验证分析。分析结果表明:根据《建筑桩基技术规范》提出的建议值计算的桩基竖向极限承载力比现场试桩值偏保守,而采用α法计算的桩基竖向极限承载力更接近现场试桩值;对深厚淤泥软土地基进行预加固处理,可以有效提高桩基竖向承载力,但工程案例中竖向承载力提高近50%,同时对桩基负摩擦阻力及桩基沉降控制效果显著。研究成果可为类似软土地基加固工程提供参考。There are insufficient quantitative analyses on the impact of pre-reinforcement on vertical bearing characteristics of soft soil foundations.Relying on a case of a reclamation project in Zhejiang Province,we studied the improvement of vertical bearing capacity,pile top settlement control and reduction of negative friction resistance of the pile foundation after pre-reinforcement to the soft soil foundation.Theαmethod,API-2000 method andλmethod were given for the quantitative calculation of ultimate lateral friction resistance of the pile.At the same time,the calculation formulas for ultimate end resistance of pile foundation and settlement of pile top were given.Finally,through typical engineering cases,vertical static load tests were carried out on the test piles in the original silt soil and the pre-reinforced foundation soil respectively,and their results were compared,verified and analysed.It is concluded that the vertical ultimate bearing capacity of the pile foundation calculated by the recommended code was more conservative than the field test,while the results calculated by theαmethod were closer to the field test values.Pre-reinforcing the soft soil foundation can effectively improve the vertical bearing capacity of the pile foundation.In the engineering case,the vertical ultimate bearing capacity was increased by 50%,and the pre-reinforcement was also effective for control of negative friction resistance and pile top settlement,which provides a reference for the construction of similar reinforcement projects in soft soil.

关 键 词：软土地基 预加固处理 极限侧阻力 桩基竖向承载力 桩顶沉降 静载试验 

分 类 号：TV223[水利工程—水工结构工程]