长螺旋钻孔压灌超流态混凝土桩基础的应用

Application of long spiral drilled press-grouting super-fluid concrete foundation pile

长螺旋钻孔压灌超流态混凝土施工技术是一种值得推广的新型成桩技术。与普通螺旋干钻孔桩相比 ,单桩承载力提高 30 %～ 5 0 % ,桩身混凝土量减少 30 %～ 5 0 % ;采取措施保证桩顶 (尤其是桩头部分 )混凝土强度 ,提高单桩容许承载力。采取适当措施 ,防止压灌混凝土时堵管。我们对 3根原体试验桩进行竖向静载试验 ,单桩极限承载力值 2 6 0 0～ 2 90 0KN ,为工程桩的成功作了准备 ;对 4 0 8根工程桩 ,根据规范要求 ,抽取 4根 ,进行竖向静载试验 ,承载力都超过设计要求。α反射波试验 36 6根 ,检测结果 :Ⅰ类桩 337根 (92 0 8% ) ,Ⅱ类桩 2 8根 (7 6 5 % ) ,Ⅲ类桩 1根 (0 2 7% )。节约资金 6 3 36万元 ,工期缩短 5 0 %以上。

The construction technology of long spiral drilled press-grouting super-fluid concrete pile is a new kind of pile-forming construction technology. Single bearing capacity of this pile increased 30～50% than normal concrete grouting pile, body concrete quantity of this pile is decreased 30～50%. The strength of top pile concrete, especially head part, ensured by taking measurement, Single allowable bearing capacity of this pile is enhanced. The measurements are taken to prevent blocking up pipe when super-fluid concrete is press-grouted. The allowable value of a single pile ultimate bearing capacity reaches 2 600～2 900KN by vertical quiescently loaded test with 3 in-situ pile to meet with success of construction pile. The single bearing capacity all surpass the demand of designed capacity by vertical quiescently loaded test with 4 piles among 408 construction piles in accordance with related code. The test result by α reflecting wave slows that Ⅰ type piles have 337 piles (92.08%),Ⅱ type piles have 28 piles (7.65%),Ⅲ type pile has 1 pile (0.27%). Investment save RMB 633,600 yuan,pile construction time shorten 50% than normal concrete grouting pile.