【摘要】 综合运用静载试验、CT试验及取芯试验等试验方法,针对桩端后压浆对超长大直径钻孔灌注桩承载性能的影响进行研究,并对其作用机制进行分析。对同一根桩桩端压浆前后,以及同一场地上同样尺寸的未压浆桩与压浆桩,分别进行静载试验。试验结果表明:桩端后压浆可有效提高超长大直径钻孔灌注桩的桩端承载力,以及桩底截面以上一定范围的桩侧摩阻力,从而提高整桩承载力。桩端后压浆不仅可以提高桩承载力,还可以有效提高其刚度,有利于控制基础的沉降。CT试验及取芯试验明确了水泥浆在桩周的分布范围,证实了桩端后压浆的效果,并表明桩端持力层为砂性土层时效果较好。更多还原

【Abstract】 For the reason of construction,some deterring factors will be brought out such as residue and mud cake for bored pile. Post grouting under pile tip can reduce the deterring factor,and the bearing performance of the bored pile will be improved. Effect on the bearing performance of the super-long and large-diameter bored pile by post grouting under the pile tip was studied by a series of tests including the static loading test,CT test and coring test. The self-balanced method was adopted in the static loading test. The bearing performances of the same pile before grouting and after grouting were compared. In the same field,the bearing performances of the piles were compared. Dimensions of the piles were the same,one had been post grouted under the pile tip and the other had not been post grouted. According to the results of the static loading tests,the resistance of the pile tip was raised, and the friction of a finite scope of pile side above pile tip was also raised. So the whole bearing capacity of the pile was raised. By the post grouting under the pile tip,not only the bearing capacity of the whole pile was raised, but also the rigidity of the pile was raised which make the settlement of pile be easier to control. CT test and coring test both approved the effect of post grouting under pile tip. The effect of post grouting would be better when the grout was injected in the sand layer.更多还原