Numerical Analysis for Ground Subsidence Caused by Extraction Holes of Removed Piles

Abstract

Around the world, and especially in Japan, the tearing down of social infrastructure, including civil engineering structures, has been increasing due to the aging of these constructions, which were built during a period of high economic growth, and a decrease in their utilization caused by a recent drop in the population. The number of existing pile foundations being pulled out has gradually risen to a higher number than that of pile foundations being newly installed. However, after the pulling-out of a pile foundation, the mechanical characteristics of the surrounding ground are of great concern due to the existence of the holes that form when the existing piles are removed (extraction holes). In this study, a three-dimensional elasto-plastic consolidation analysis was performed to examine the effect of the extraction holes of removed piles on the static properties of the surrounding ground. As examples of the results of the analysis, if an extraction hole of a removed pile is left as it is, large ground subsidence will occur near the extraction hole of removed pile, especially at the lower part of the clay layer near the hole. The greater the number of extraction holes of removed piles, the greater the compressive stress acting on the extraction holes after the pile removal. Therefore, the filler should exhibit strength early as the number of extraction holes of removed piles increases.

Ground Vibration Response to Vibratory Sheet Pile Driving and Extraction

“…Geometry Length (m) Testing Process Main Soil Type [11] Pipe pile 5 Vibratory driving London clay [12] Pipe pile 10 Vibratory driving Sandy clay [21] H-type 16.8 Impact driving Sand, silt [22] Z-type 13 Recently, sheet piles are commonly used as temporary supports in engineering practice and will be removed after the completion of construction, which leads to issues associated with pile extraction. However, to date, documented cases of the pile extraction process are still relatively limited [23,24]. Therefore, thorough investigation of the ground vibration behavior during pile extraction and assessment of the potential impacts of these vibrations is essential.…”