某3层(局部4层)钢筋混凝土结构办公楼(简称“N楼”,图1),建于日本鹿儿岛市内。该市地基多为火山灰浮石两次堆积土层,钻孔至-35m没有发现明确的持力层;在-20m,标准贯入度试验的N值在10以下,地下水位是-1.4m。N楼建设场地,三面与现存建筑物邻接,另一面临街,在占地区域内满建。因此不能来用压实加固方法。砾石排水法由于需要扩大地基处理范围, A three-story (partial four-story) reinforced concrete structure office building (referred to as “N building”, Fig. 1) was built in Kagoshima City, Japan. Most of the city’s foundations are pluice-pulverized rocks with twice-accumulated soil layers. There is no clear bearing stratum in the drilling to -35m; at -20m, the standard penetration test has N value below 10, and the groundwater level is -1.4m. The N building site is adjacent to the existing building on three sides, and the other side faces the street and is fully built within the occupied area. Therefore, no compaction reinforcement method can be used. The gravel drainage method needs to expand the scope of foundation treatment.