基坑分段支护设计及变形监测分析

以长春某深基坑支护工程为背景，对基坑支护体系设计与基坑变形监测进行论述和分析。根据基坑周边环境的复杂程度，基坑采用分段设计。在临近既有建筑和道路侧，分别采用桩锚、微管桩＋土钉墙＋预应力锚索的复合土钉墙支护及土钉墙支护3种形式。从基坑开挖监测角度，对支护结构顶部水平位移进行监测，对周围建筑进行了水平、沉降位移的观测，并对土体深部位移进行了监测。通过对监测结果的分析，证明复合土钉墙可有效控制变形，但在快速开挖的情况下，土钉墙对该基坑变形的控制效果较差，通过监测，及时处理了支护结构存在的危险，避免了事故的发生，证明了基坑监测的必要性。

The design to foundation pit sectional supporting and analysis to the deformation monitoring

Based upon the bracing engineering of a deep foundation pit in Changchun ,the design for foundation pit supporting system and deformation monitoring are discussed and analyzed .According to the complexity of the surroundings ,subsection design is adopted .Near the side of existing buildings and roads ,there are three forms of supporting respectively :pile‐anchor bracing ,composite soil nailing wall with micro pile and soil nailing and prestress anchorage cable ,and soil nail wall supporting .From the perspective of excava‐tion monitoring ,it monitors the top horizontal displacement of retaining structure ,observes the x‐offset and subsidence of the surrounding buildings ,and monitors the displacement of deep soil .By analyzing the monitoring results ,it proves that the composite soil nail wall can control the deformation effectively except for the condition of rapid excavation .By monitoring ,the dangers of supporting structure are timely trea‐ted ,avoiding the accident and effectively proving the necessity of the foundation pit monitoring .