桩端后压浆灌注桩长期承载性能试验研究

为研究后压浆灌注桩的长期工作性能，以银川北京路延伸及滨河黄河大桥为工程背景开展试桩静载试验，通过对比不同时间后压浆桩承载力的实测结果，并结合数值模拟结果进行对比分析，研究了后压浆灌注桩的长期承载性能及桩基阻力随时间的变化规律。结果表明：桩端后压浆形成的水泥土加固体，其强度随时间的推移而增长，使桩端阻力进一步增强，桩端后压浆存在时间效应；桩端后压浆导致浆液上返而在靠近桩端的桩侧处形成浆土混合物，使桩侧摩阻力随时间推移不断增强，占极限承载力的比例逐渐增大；与未压浆桩相比，在相同荷载作用下，桩端后压浆桩基的沉降随时间增长而减小并趋于稳定。

Experimental study on long-term bearing behaviors of base post-grouting bored piles

To study the long-term bearing behavior of post-grouting bored piles, the static load test of test piles was carried out using Yinchuan Beijing Road extension and Binhe Yellow River Bridge as the engineering background. The variation of long-term bearing behavior and pile resistance of post-grouting bored piles at different time were studied by comparing the field test results with numerical simulation results. The results indicate that the strength of cement-stabilized soil formed by grouting at the pile tip increases with time, which further increases the tip resistance, and the pile tip grouting has time effect. The upward grout penetration along the pile side due to tip grouting forms a cement soil mixture at the pile side near the pile tip, which makes the side resistance increase continuously over time, thus the ratio of side resistance to the ultimate bearing capacity gradually increases. Compared with the non-grouted pile, the settlement of the tip grouting pile decreases with time and tends to be stable under the same load.