扩径位置对CEP抗拔双桩承载性能影响的试验研究

Experimental study on influence of expanding position on bearing performance of CEP uplift double pile

在竖向拉力作用下,扩径位置为影响CEP(混凝土扩盘桩)群桩基础承载性能的关键因素。采用CEP双桩半截面小模型原状土抗拔试验,以扩径位置为变量,设计五种模型,完成七组试验。基于试验结果,分析扩径位置对桩周土体破坏状态的影响,并对每组CEP双桩的极限承载力和桩周土体受力状态进行分析。结果表明,CEP双桩扩径位置上方桩长d1应大于4R0(R0悬挑径),且扩径位置要尽量相同,扩径位置越靠近桩端时,极限承载力越强;扩径位置不同时,扩径位置的竖向距离(大于4R0为宜)满足互不影响要求即可。

Under the action of vertical tension,the expansion position is the key factor affecting the bearing performance of CEP(concrete expansion pile)group pile foundation.Using CEP double pile half-section small model undisturbed soil uplift test,five models were designed with the expansion position as the variable,and seven sets of tests were completed.Based on the test results,the influence of the expansion position on the failure state of the soil around the pile was analyzed,and the ultimate bearing capacity of each CEP double pile and the stress state of soil around the piles were analyzed.The results show that the pile length d1 above the expansion position of CEP double pile should be greater than 4R0(R0 be cantilevered diameter).The expanding position should be the same as far as possible,and the closer the expanding position is to the pile end,the stronger the ultimate bearing capacity is.When the expanding position is different,the vertical distance of the expansion position(greater than 4R0 be appropriate)can meet the requirement of the non-influence.