硬土场地基坑变形监测与分析

Deformation monitoring and analysis of foundation pits on stiff clay

南京阳光雅居4期基坑工程处于硬土场地中,基坑开挖深度5.7 m,局部7.0 m,围护体系采用了人工挖孔灌注桩和土钉墙2种支护结构形式.施工过程中分别对桩顶圈梁水平位移、土钉墙墙顶水平位移、围护桩桩侧土体深层水平位移、邻近建筑物沉降、邻近道路沉降进行了长达8个月的监测.依据硬土的物理力学特性和本次基坑变形监测结果,分析表明:硬土场地中快速挖土卸载,可致使基坑支护结构产生明显水平位移,而周围土体水平位移相对较小,由于两者变形不协调,通常导致支护结构和土体间出现裂缝;硬土场地中基坑开挖引起的邻近建筑物和道路沉降较小,对周围环境影响不明显.

The fourth foundation pits of Nanjing Sunny Community were in stiff-clay area, and its foundation pits were 5.7 m deep, and some parts were excavated to 7.0 m. The excavation support system was column pile wall or braced wall. In construction, pile top perphery beam horizontal displacement, braced wall top horizontal displacement, displacement of deep soil by piles, settlements of adjacent buildings and adjacent roads were monitored, and the monitoring time was over 8 months. Based on the physical and mechanical character of stiff soil, the analysis of field measured data shows that, in stiff clay the big wall deflections are observed in fast-excavating construction, but horizontal displacement of adjacent soil is relatively small, so the cracks often appear between the supporting structure and soil due to both deformations uncoordinated. However, the influence of excavation on settlements of adjacent buildings and roads is little.