Field study on axial bearing capacity and load transfer characteristic of waveform micropile

Abstract

The waveform micropile is an advanced construction method that combines the concept of the conventional micropile with the jet grouting method. This new form of micropile was developed to improve shaft resistance, and has enabled a higher bearing capacity and greater cost efficiency. Two field tests were conducted to examine field applicability and to verify the effects of bearing capacity enhancement. In particular, waveform micropile construction using the jet grouting method was performed to evaluate the viability of waveform micropile installation. After testing, the surrounding ground was excavated to check the shape of the waveform micropile. The result showed that waveform micropiles can be installed by adjusting the grouting time and pressure. In the loading tests, the bearing capacity of the waveform micropile increased by 1.4–2.3 times that of the conventional micropile, depending on the shape of the micropile. The load transfer analysis using the strain gauge data showed that the waveform micropile increases the shaft resistance in the soil layer. This not only decreases pile settlement, but also contributes to the increase of overall bearing capacity. The overall results clearly demonstrate that the waveform micropile is an enhanced construction method that can improve bearing capacity.