深基坑地下连续墙支护结构侧向变形的改进指数平滑法预测

Prediction of Lateral Deformation of Diaphragm Wall Support Structures in the Deep Foundation Pit by Using Improved Exponential Smoothing Method

由于基坑开挖过程存在大量的不确定性,其支护结构在设计阶段无法根据现场环境的变化进行实时变形可靠度分析与预测.围护结构分布范围大,失效位置不可预测.工程监测数据由于监测点数量的限制难以直接反映围护结构连续变化的状态.采用穿越率法,提出一种适用于以地下连续墙为围护结构的深基坑工程的侧向变形预测与分析模型.利用MATLAB建立自适应指数平滑模型,自动计算和预测深基坑围护结构在不同深度的侧向变形.对比实测与预测的侧向变形数据,结果表明该自适应指数平滑模型在短期预测中具有精度较高、误差波动小的特点;同时采用预测数据的超越概率分析表明,深基坑侧向变形的分析模型同样适用于由自适应指数平滑法获得的预测数据,且随着位移限值远离最大监测位移值,分析精度将逐渐提高.通过利用椭圆搜索模式的反距离加权插值法,解决了样本点仅集中分布于深度方向的缺点,使插值结果更加平滑,结合基于深基坑侧向变形的分析模型,实现了围护结构空间曲面的变形预测,使评价反馈方式更加直观简洁.

Due to a large number of uncertainties in the excavation process of the foundation pit,the real-time deformation reliability analysis and prediction of its supporting structure can not be carried out according to the changes of the site environment in the design stage.The distribution range of enclosure structures is large,and the failure location is unpredictable.Due to the limitation of the number of monitoring points,the engineering monitoring data cannot directly reflect the continuous change of the retaining structures.Based on the method of up-crossing rate,was proposed for deep foundation pit engineering with an underground diaphragm wall.An adaptive exponential smoothing model is established by using MATLAB to automatically calculate and predict the lateral deformation of the deep foundation pit retaining structure at different depths.By comparing the measured and predicted lateral deformation data,the results show that the self-adaptive exponential smoothing model has the characteristics of higher accuracy and smaller error fluctuation in short-term field prediction,the transcendental probability analysis based on the prediction data shows that the analysis model based on the lateral deformation of deep foundation pit is also applicable to the measured data obtained by the self-adaptive exponential smoothing method,and the analysis accuracy will be improved as the displacement limit is far away from the allowed displacement.The inverse distance weighted interpolation method based on ellipse search mode solves the defect that the sample points are distributed in the depth direction,which makes the interpolation result smoother.Combined with the analysis model based on the lateral deformation of the deep foundation pit,the deformation prediction of the spatial surface of the retaining structure is performed,which makes the evaluation method more intuitive and concise.