咸阳机场高速公路桥梁桩端后压浆承载特性研究

针对西安咸阳国际机场专用高速公路段的K3+966.50渭河特大桥，采用钻孔灌注桩桩端后压浆技术和常规灌注桩两种不同方法对其桩基进行了现场静载试验，并根据实测数据分析探讨了各桩在不同等级荷载作用下的桩—土相互作用、桩端后压浆技术的增强机理，以及桩端压力注浆和常规钻孔灌注桩两种不同的桩基承载特性，结果发现，与未压桩的桩基相比，桩端后压浆桩基的竖向极限承载力至少提高了40%，沉降量减少25mm，说明桩端后压浆技术能够显著提高桩基的承载能力和稳定性。最后，根据现场实测数据和桩端后压浆的注浆机理，提出了后压浆单桩极限承载力的计算公式，为类似地区的桩基设计提供借鉴。 Two different techniques, pile-end post-grouting technology of bored piles and conventional cast-in-place piles, were used to conduct the in-situ static loading tests on the pile foundation of the Weihe Bridge K3+966.50 of Xi'an Xianyang International Airport Expressway. The measured data were used to analyze the interaction between the pile and soil of each pile under different loadings , the enhanced mechanism of technique, and the bearing characteristics of the two different techniques. The research results showed that the vertical ultimate bearing capacity of the pile-end post-grouting piles increases by at least 40% and the settlement decreases by about 25mm compared with that of the non-grouting piles, which suggested that the pile-end post-grouting technology can increase the bearing capacity and stability of pile foundation significantly. This paper proposed a calculation formula of the ultimate bearing capacity of a post-grouting single pile based on the observed data and grouting mechanism of pile-end post-grouting, which can provide valuable references for the pile foundation design in similar areas.