风化岩地基CFG桩复合地基承载特性现场试验

Field Test of Bearing Behavior of CFG Pile Composite Foundation on Weathered Rock Foundation

为研究嵌岩短桩复合地基的承载性状与沉降变形的主要影响因素,以7根CFG嵌岩短桩复合地基的静载荷试验为依托,并结合场地勘察报告对试验结果进行分析.研究结果表明,在青岛地区采用CFG短桩加固软土地基可取得良好的效果,两个试验区CFG桩复合地基承载力特征值分别为430,450kPa,均满足设计要求且其承载力仍有发挥余地;CFG嵌岩短桩(3~7m)P-s曲线为缓变形,呈s型变化,表现出半刚性端承型桩的特性;该嵌岩短桩复合地基的沉降变形主要来自桩身的压缩量,对于嵌岩灌注短桩(3~6m),其桩长增长60%~67%,沉降量可增长52%~78%,对于嵌岩灌注短桩(7~8m),桩长增长1%~4%,沉降量可增长36%~106%,但总沉降量仍较小,不超过14.5mm,满足工程变形要求.研究结果可为类似工程CFG桩的设计和应用提供参考依据,提高经济效益.

In order to study the main influencing factors of bearing behavior and settlement deformation of rock-socketed short pile composite foundation,the static load tests of seven CFG rock-socketed short pile composite foundation were carried out,and the test results were analyzed in combination with site investigation reports.The results show that the CFG short pile can be used to reinforce the soft soil foundation in Qingdao,and the bearing capacity characteristic values of the CFG composite foundation in the two test sites are 430,450 kPa,respectively,which satisfy the design requirements and still have room to exert its bearing capacity.The P-s curve of the CFG pile socket into rock,with length from 3~7 m,showing“s”type change,appearing the characteristics of semi-rigid end-bearing pile.The deformation of the composite foundation is mainly stemmed from the compression of the pile.For the pile with length ranging from 3~6 m,the settlement increases by 52%~78%as the length increased by 60%~70%,while the settlement increases by 36%~106%as the pile length increases by 1%~4%for pile with length ranging from 7~8 m.Even so,the whole settlement does not exceed 14.5 mm,which meets the need of construction.The results provide design and application references for the similar CFG pile,and improve the economic benefits of similar projects.