深大基坑施工工艺及围护结构沉降预测解析方法研究

Research on Construction Technology of Deep and Large Foundation Pit and Analytical Method of Settlement Prediction of Retaining Structure

文章以盐城市铁路客运枢纽西广场工程为研究对象,对基坑施工过程中基坑围护结构的变形趋势进行预测研究。首先,根据现场监测数据研究分区分层开挖工艺对基坑稳定性的影响。其次,基于钢板桩支护结构监测数据,引入指数平滑法对钢板桩沉降变形进行预测并建立动态沉降预测函数。结果表明:随着监测时间的增加,基坑北侧及南侧坡体各测点的总沉降均呈先快速增大后逐步趋于稳定的变化规律;基坑西侧由于受到主要施工便道及地下市政管道迁移施工影响,导致其变形量大于北侧及南侧坡体;当平滑常数为0.4时,二次指数平滑法的预测精度要优于一次及三次指数平滑法,且随着平滑常数的增加,三次指数平滑值的波动范围要远大于一次及二次指数平滑值。

This paper takes the research object of the Western Plaza of the Yancheng Railway Passenger Transport Hub,and conducts predictive research on the deformation trend of the base pit encirclement structure during the construction of the foundation pit.Firstly,according to the field monitoring data,the influence of zonal excavation technology on the stability of the foundation pit is studied.Secondly,based on the monitoring data of steel sheet pile supporting structure,the exponential smoothing method is introduced to predict the settlement deformation of steel sheet pile and establish the dynamic settlement prediction function.The results show that:with the increase of monitoring time,the total settlement of each measuring point on the north and south sides of the foundation pit increases rapidly and then tends to be stable.The deformation of the west side of the foundation pit is greater than that of the north and south slopes due to the influence of the main construction access roads and the migration of underground municipal pipelines.When the smoothing constant is 0.4,the prediction accuracy of the quadratic exponential smoothing method is better than that of the first and third exponential smoothing methods,and with the increase of the smoothing constant,the fluctuation range of the third exponential smoothing value is much larger than that of the first and second exponential smoothing values.