组合压浆增强风化岩大直径桩桩-土界面力学特性试验研究

Experimental study on mechanical properties of large diameter pile-soil interface reinforced by combined grouting in weathered rock

依托深圳某棚户区改造项目,对超高层建筑的两根超长大直径钻孔灌注桩进行了大吨位静载试验,同时结合室内剪切试验和数值模拟,研究了组合压浆对风化岩层灌注桩承载性状的影响。结果表明,组合压浆通过改善桩周土体弹性模量,可以有效控制桩基沉降并增强桩基的侧阻和端阻,组合压浆后试桩极限承载力最大增幅达127%。组合压浆可以增强风化岩桩-土界面的抗剪强度并提升剪切强度的发挥速度。最后,基于双曲线函数构建了荷载传递子程序模型,该模型能有效地模拟出压浆前后风化岩大直径钻孔灌注桩的竖向承载特性。研究成果可对深化组合压浆大直径嵌岩桩承载特性的认识提供理论依据。

Based on the renovation project of a shantytown in Shenzhen, the large tonnage static load test of two ultra-long and large diameter bored piles was carried out. At the same time, combined with indoor shear test and numerical simulation, the influence of combined grouting on the bearing behavior of bored piles in weathered rock was studied. The results show that the combined grouting can effectively control the settlement of the pile foundation and enhance the side resistance and end resistance of the pile foundation by improving the elastic modulus of the soil around the pile. The maximum increase of the ultimate bearing capacity of the test pile after the combined grouting is 127%. Combined grouting can enhance the shear strength of weathered rock pile-soil interface and improve the speed of shear strength. The calculation model established by the load transfer curve proposed in this paper effectively simulate the vertical bearing characteristics of large-diameter bored piles in weathered rock before and after grouting. The research results can help to deepen the understanding of bearing characteristics of composite grouting large diameter rock-socketed piles.