上海某深基坑开挖变形及对环境影响监测研究

结合大量现场实测数据,通过对基坑开挖过程中围护墙体测斜、周边地表沉降以及围护墙顶变形进行了监测。监测结果显示:在开挖过程中围护墙体的整体变形形状呈中间大、两头小,随着基坑开挖深度的不断增加,围护墙体变形不断增大,且变形呈现持续、缓慢的变化态势;周边地表沉降监测点累计垂直变化基本呈现下沉,虽然有部分地表沉降监测点有累计下沉量超出报警值范围而报警的情况发生,但从地表沉降监测点的沉降变化曲线看,沉降呈现持续、缓慢的变化态势,未见突变情况发生,沉降变化曲线较平稳;围护墙顶垂直方向沉降呈现持续、缓慢的变化态势,沉降变化曲线较平稳,水平方向围护墙顶监测点的累计平面位移基本呈现向基坑内侧位移,且各监测点水平位移变化范围在0~+9 mm之间。结论对在密集建筑群中软土地基上基坑设计和开挖具有一定的实用价值和借鉴意义。

Research on monitoring of the deformation of a deep foundation pit excavation and its impact on the environment in Shanghai

Based on a large number of field data, this paper monitors the deformation of the retaining wall during the excavation of the foundation pit, the settlement of the surrounding surface and the deformation of the wall roof. The monitoring results show that the overall deformation of the retaining wall during excavation is large in the middle and small in the two ends. With the increasing excavation depth of the foundation pit, the deformation of the wall is increasing and the monitoring hole shows a continuous and slow change trend. The cumulative vertical changes of the surface subsidence monitoring point basically show a sinking trend. Although there is a partial subsidence monitoring point where the accumulated subsidence amount exceeds the alarm value range and the alarm condition occurs, from the settlement curve of the surface subsidence monitoring point, the monitoring point shows a continuous and slow change trend, and no mutation occurs. And the sedimentation curve is stable. The vertical monitoring points of the roof are showing a continuous and slow change trend, and the sedimentation curve is smooth. The cumulative plane displacement of the monitoring points in the horizontal direction of the wall is basically displaced toward the inside of the foundation pit, and the horizontal displacement of each monitoring point ranges from 0 to + 9mm. The conclusion is of practical value and provides reference for the design and excavation of foundation pit on soft soil foundation in intensive buildings.