Proceeding of the 2018 DFI-EFFC International Conference on Deep Foundations and Ground Improvement, Rome, Italy, (DFI, EFFC)
Performance of a New Driven Battered Micropiles System in Sand
Amirhassan Mehdizadeh, Mahdi M. Disfani, Dr., Chin F. Tsang, Guillermo A. Narsilio, Robert Evans and Emad Gad
A new concrete-free driven micropile footing system that consists of a steel pile cap and a number of inclined small diameter steel micropiles has been tested. This new footing system is light enough to be manually handled and can be installed in a short time-frame using small jackhammers. There is minimal soil disturbance and no need for any excavation making it a smart solution for supporting light structures. This paper presents the performance of this new footing system in a medium dense sand formation under vertical compressive and tensile pull-out forces. Two different combinations (with different embedment depths) were tested. Ultimate bearing and pullout capacities were determined using a range of methods. A plate load test was also performed as a benchmark for shallow foundation capacity. The recorded pullout capacity was approximately 27 per cent of the bearing capacity showing that there are other parameters such as the reinforcing effect of battered micropiles enclosing the soil in between that contribute to the improved bearing capacity. These influential parameters need to be applied in the current engineering approach as the ultimate bearing capacity is underestimated. A negative group effect was also found that needs to be considered in estimating both tensile and compressive loads.
|article #3054; publication #1040 (ROME-2018)|