An Investigation on Stability of Clay Ground Improved by Sand Compaction Piles

通过一系列离心试验，研究了沉箱重量、压砂桩宽度及加固面积比对沉箱下加固地基稳定性的影响。本研究得出以下结论：在用sccp - 2改良的软土上建造回填沉箱时，水平变形比垂直变形占主导地位。对于改良地基，观察到明显的圆形滑动面。而对于改良地基，水平变形随水平荷载的增大而逐渐增大，达到一定荷载时水平变形突然开始增大，地表无滑移面。由此得出结论，对于这种类型的结构，考虑水平变形比考虑抗破坏稳定性更重要。3. 当修正费勒纽斯稳定分析计算的安全系数超过1.4时，会出现较大的水平变形。由此得出的结论是，此类问题的最小安全系数应为1.5。

A series of centrifuge tests was conducted in an attempt to study the effect of the weight of a caisson and the width and the area ratio of improvement by sand Compaction piles(S.C.P.) on the stability of improved ground under a backfilled caisson. Following conclusions are derived from this study. l.Horizontal deformations are much more dominant than vertical deformations when a backfilled caisson is built on soft clay improved with S.C.P. 2. For improved ground, a well-defined circular slip surface is observed. However for improved ground, horizontal deformations increase gradually with the increase of horizontal load and at a certain load the horizontal deformations suddenly start to increase, showing no slip surface in the ground. This leads to a conclusion that consideration of horizontal deformations is more important than that of stability against failure for this type of structure. 3. When the safety factor calculated by the modified Fellenius' stability analysis exceeds 1.4, considerable horizontal deformation appear. This leads to a conclusion that the minimum safety factor for this type of problem should be taken as 1.5.