In recent years, removal work of existing piles has been increasing, and many pulling-out methods for existing piles are being applied. As for the present situation, there is concern that the physical characteristics of the ground will deteriorate due to the holes that remain after pulling out the existing piles (pullout holes). In addition, the filler to be injected into these pullout holes has not yet been specified and the influence of the physical properties of the filler on the surrounding ground has not been elucidated. In this study, therefore, the authors evaluated the influence of pullout holes on the static physical characteristics of the ground by elasto-plastic analysis using a three-dimensional static FEM. As a result, the settlement of the ground surface was seen to increase as the number of pullout holes increased, but it was obvious that the region of the surrounding ground influenced by the settlement does not depend on the number of pullout holes. The authors also clarified that the strength characteristics of the filler injected into the pullout holes do not cause local settlement of the surrounding ground and that it is important to perform reliable filling to the bottom of the pullout holes.

中文翻译：

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抽拉孔状况对周围地面的影响

近年来，现有桩的清除工作一直在增加，并且许多用于现有桩的拉出方法正在被应用。对于目前的状况，担心的是，由于在拉出现有的桩之后残留的孔（拉出孔）会导致地面的物理特性恶化。另外，尚未确定要注入到这些拉出孔中的填充剂，并且尚未阐明填充剂的物理性质对周围地面的影响。因此，在这项研究中，作者通过三维静态FEM的弹塑性分析评估了拉拔孔对地面静态物理特性的影响。结果，随着拔出孔数量的增加，地面的沉降增加了，但是很明显，受沉降影响的周围地面区域并不取决于拉拔孔的数量。作者还阐明，注入到拉出孔中的填充物的强度特性不会引起周围地面的局部沉降，对拉出孔的底部进行可靠的填充非常重要。