卵石层中灌注桩桩端压力灌浆及桩承载特性分析

ANALYSIS OF PRESSURE GROUTING AT PILE TIP OF BORED PILES IN PEBBLE STRATUM AND ITS BEARING CHARACTERISTICS

结合某高速公路工程中的两座特大桥梁桩基的现场静载试验,研究了桩端压力灌浆技术对卵石地层中灌注桩的适应性以及卵石地层中的灌注桩采用桩端压力灌浆技术后的承载特性。结果表明:桩端压力灌浆技术对卵石地层中的灌注桩具有较好的适应性,能显著的提高桩基的承载能力,减小桩基的变形,具有显著的经济效益和社会效益。桩端压力灌浆后,桩的弹性工作范围延长,有利于桩承受重复荷载和动力荷载。同时,桩端压力灌浆后,灌注桩有可能发生材料强度破坏的失效模式,在设计中应引起重视。

Based on field dead load test for two supergiant bridges of a expressway project, this paper studied the applicability of the technology of pressure grouting at pile tip to bored piles in pebble stratum, and the bearing characteristics of bored piles after applying this technology. The findings show that the bored piles using pressure grouting at pile tip have good adaptability to strata and can remarkably improve the bearing capability and decrease the settlement of pile foundations, and consequently acquire remarable economic and social benefit. After pressure grouting on pile tip, elastic working range of piles will be extended and be in favour of pile to boar repeated loads and dynamic loads. At the same time, for bored pile using pressure grouting at pile tip, failure mode of material strength damage is likely to occur and attention should be paid to their design.