摘要
单桩竖向抗拔静载试验采用地基反力法时,试验桩的受力工况和抗浮结构中工程桩的实际受力工况有明显差异。静载试验时的附加应力效应、软土中还有的挤压隆起效应,两种效应共同作用会使桩承载力发生改变。基于实际工程,采用数值分析手段研究了桩长较短的PHC管桩,在两种桩周土层分布、不同支墩压力、不同桩—支墩净距下的抗拔承载力。结果显示:支墩压力会使抗拔承载力增大;桩头区域有软土层时,土体受挤压产生明显隆起会引起桩承载力波动;在满足规范规定的净距时,附加应力效应和挤压隆起效应均对试验结果影响不大;和规范规定的桩墩净距2.0m、有支墩压力相比,净距1.5m和1.0m、无支墩压力时承载力降低4%~6%;试验场地地表是混凝土筏板时,试验测得的承载力略高、桩顶上拔位移加大。
When the foundation reaction method is used for the vertical uplift static load test of pipe piles,the stress condition of the test pile is significantly different from the actual condition of the engineering pile in the anti-floating structure.There would be an additional stress effect and a squeezing uplift effect generating in the soft soils for static load test.The combination of these two effects will change the uplift bearing capacity of the pile.Based on an engineering example,the numerical analysis method is used to study the uplift bearing capacity of PHC short-pipe pile considering the two types of soil layer distribution around the pile,the different pier pressures and the dfferent net distances between the pile and pier.The results show that the uplift bearing capacity of the pile increases due to the effect of pier pressures.When a weak soil layer distributes around the pile,the squeezing uplift effect of the soil will cause the variation of the uplift bearing capacity of the pile.When the net distance specified in the code is satisfied,the additional stress effect and the squeezing uplift effect have lttle influence on the test results.Compared with the net distance of 2.Om specified in the code with pier pressure,the bearing capacity reduces by 4%~6%while the net distance is 1.5m or 1.Om without pier pressure.When the test field is treated with concrete raft,the bearing capacity measured by the test is slightly higher,and the pull-up displacement of pile heads also increases.
作者
邓涌
杨立
Deng Yong;Yang Li(Shenzhen Building Safety and Construction Quality Testing and Appraisal Center,Shenzhen 518052,China)
出处
《工程勘察》
2023年第4期18-24,共7页
Geotechnical Investigation & Surveying
关键词
管桩
抗拔静载
数值分析
附加应力
pipe pile
uplift static load test
numerical analysis
additional stress
