上海市深基坑工程地面沉降评估理论与方法

Theory and methodology on assessment of land subsidence caused by excavation engineering for deep foundation pit in Shanghai

深基坑工程是高层建筑、地铁隧道、地下空间开发利用等城市建设中的重要基础工程。随着土地节约集约化利用不断加强，基坑的深度与规模目渐提高。深基坑工程对区域地面沉降有明显影响。但针对性的地面沉降危险性评估尚属空白。根据深基坑工程地面沉降效应的理论分析与案例剖析，不同的设计施工方案对地面沉降有直接影响。含水层的疏干或降压是主要因素。地面沉降主要集中在开挖深度2倍的平面范围内，最远可达10—15倍开挖深度。地面沉降基本呈指数型衰减。现行的技术规程将2倍开挖深度范围作为基坑工程沉降监测与控制的重点。因此深基坑工程对区域地面沉降的影响评估应着重于15倍的开挖深度区间范围。提出了深基坑工程地面沉降评估的技术准则与主要技术环节的工作要点。

The deep excavation is an important foundation engineering for high building, subway and tunnel, underground space exploitation and others in city construction. With the intensive usage of land exploitation, the depth and dimension of excavation are improved. The deep excavation engineering has striking effect on regional land subsidence, but no one risk assessment of land subsidence existed so far. According to the theory and case analysis, engineering device have immediate effect on land subsidence, and the aquifer unwater or abase is predominant factor. The paper proposes that the influence assessment of deep excavation engineering to land subsidence should be 15 times the depth of excavation, also suggests the technical rules and wok points of risk assessment of land subsidence on deep excavation engineering.