基于微观结构的碎石桩软基加固影响半径分析

Analysis on effective radius of gravel piles reinforcement in soft soil foundations based on microstructure

以珠江三角洲地区代表性软土地基为研究对象,通过在碎石桩周围一定范围内采取土样进行的微观结构分析,讨论了碎石桩软基加固影响半径问题。首先采取天然状态的原状土样,通过扫描电镜,取得其微观结构照片,提取其孔隙参数和颗粒参数;然后,在碎石桩成桩45天后,在距离碎石桩1d,2d,3d,…,6d处(d为碎石桩的直径)采取土样提取此时孔隙参数和颗粒参数;最后,通过比较不同空间位置处土样的微观结构及其参数变化特点,得到结果。

By choosing a representative soft soil foundation in the Pear River Delta Area, sampling around piles within a certain distance and analyzing their microstructure, the radius of reinforcement with gravel piles was discussed. At first, getting soft soil samples in their natural state and consolidation state after 45 days from the position located at 1d to 6d from piles (where d is the diameter of the gravel pile), obtaining and analyzing their microstructures by scanning electronic microscope, parameters describing pores and grains were extracted in deferent states. Then, by comparing the features of microstructures and the variation of parameters in different positions, the key point at 3d was gained, meaning that the microstructure would vary greatly within a distance of 3d (the porosities of soils around reinforcement were all larger than 50%), and then changed very small beyond 3d (the porosities of soils around reinforcement were all less than 50%, mainly distributing in the range of 50%-10%). According to the result, a conclusion is obtained that an effective radius of gravel piles in soft clays of Pearl River Delta is 3d. It provides a important reference for the reinforcement design of gravel pile.