A soil investigation was conducted to determine the extent and degree of loosening of the surrounding ground due to removal of existing piles and backfilling of the area. The area affected by ground loosening was approximately 2 to 3m from the edge of the casing, and the decrease in N-value etc., was more pronounced closer to the edge of the casing. The tendency of decrease by soil type was more pronounced for sandy soil. Based on the investigation results, we proposed a soil investigation plan to determine the effects of ground loosening caused by the removal of the existing piles.
