均质砂土中桩端后注浆抗压桩室内模型试验研究

在参考现场桩端后注浆工艺的基础之上，利用自行研发的注浆装置和注浆工艺，在均质砂土中进行了不同注浆压力和不同注浆量下的共计7根模型桩的桩端后注浆抗压承载特性的室内模型试验。结果表明：相对于未注浆桩，注浆桩的极限承载力均有明显提高，提高范围为213%~347%，同时桩端上返的浆液对桩侧摩阻力也有加固效果；在一定的注浆量下，存在一个最佳注浆压力，使整体的注浆加固效果最好，此试验中是0.3MPa；在最佳注浆压力0.3MPa下，桩的承载能力随着注浆量的增大而提升，但提高效果随注浆量的增大而减弱，以单位注浆量计算，注浆量从1L提升至4L，每升浆液带来的极限承载力增量从200%降至106.8%；随着注浆量的提升，浆液上返高度也从0.65m增加至1.0m。

The experimental model pile test study of post grouting compressive pile in homogeneous sandy soil

On the basis of the post-grouting process of the field pile test, the self-developed grouting device and grouting technics are used to carry out the indoor model pile tests of post-grouting with 7 pile models in homogeneous sandy soil, to study the bearing characteristics under different grouting pressure and different grouting volume. The test results show that after grouting, ultimate bearing capacity of the pile is significantly improved, the range of improvement is 213%~347%, and the effect of grout back from the end of the pile also enhances the shaft resistance of piles; there is an optimum grouting pressure under the same grouting amount and it is 0.3MPa in this test; under the optimum grouting pressure, the bearing capacity of the pile becomes higher with the increase of the quantity of grouting, but the increment decreases. Calculated by unit grouting quantity, the strength increment per liter slurry decreases from 200% to 106.8% with the grouting volume increasing from 1L to 4L, but the height of grout back from the end of pile increases from 0.65m to 1.0m.