钻孔灌注桩压浆后的承载性能研究

根据某大厦及邻近场地试桩的静载荷及桩身应力测试结果，对压浆后桩的承载性能进行了深入地分析。未压浆桩的荷载-沉降关系符合双曲线函数，而压浆后桩的荷载-沉降关系符合幂函数。在极限状态时桩端阻力占总荷载比例为6.4 %～ 18.4 %，桩侧阻力占总荷载比例为81.6 %～93.6 %，且随着桩顶荷载的增加，桩端阻力所占比例快速增长。根据极限承载力外推值, 桩侧、桩端压浆的极限承载力提高幅度为89.85 %～147.81 %, 桩端压浆的极限承载力提高幅度为30.08 %～81.78 %。根据灰色关联分析，无论哪种压浆工艺，起主要作用的是压浆总量，且桩端压浆的影响大于桩侧压浆。

Study on load bearing behavior of post-grouted bored piles

The load bearing behavior of post-grouted bored piles were analyzed deeply, according to the static load test and stress testing results of test piles in a building and its nearby site. The top load-settlement relationships of post-grouted bored piles can be represented with power models; those of un-grouted bored piles can be represented with hyperbolic models. The ratios of base bearing ranges over 6.4 %—18.4 % after grouting, and the ratio increased sharply with the increasing of top loads. According to the extrapolated values, the ultimate load bearing capacities of piles grouted in the base or the shaft were increased 89.85 %—147.81 %, those grouted only in the base were increased 30.08 %—81.78 %. According to the results of gray relational analysis, the total grout quantity is the most important factor no matter which grouting method is applied, and the effect of base grouting is better than that of shaft grouting.