基于测斜的软土地铁深基坑地下连续墙估算弯矩精度研究

Accuracy of Estimated Bending Moment of Diaphragm Wall of Deep Foundation Pit of Subway in Soft Soil Based on Lateral Deformation

通过数值分析获得了不同工况下软土地铁深基坑的侧向变形值及计算弯矩值,基于6次多项式对侧向变形进行拟合,并结合弯矩估算方法确定估算弯矩值。同时对比了估算最大正弯矩值、最大负弯矩值与计算最大正弯矩值、最大负弯矩值之间的误差。研究结果表明:采用6次多项式拟合基坑侧向变形的平均绝对误差最大值仅为0.25 mm,拟合精度较高;采用最小二乘法曲线拟合的弯矩估算方法会高估地下连续墙受到的弯矩值,平均高估4.5%左右,因此可以采用估算弯矩值进行安全预警,但结论是偏于保守的,同时也要注意其可能导致的虚警、假警情况。

Through numerical analysis,the lateral deformation and calculated bending moment of a deep foundation pit for a soft soil subway are obtained.The lateral deformation is fited using a polynomial of sixth degree,and the estimated bending moment is calculated by applying the bending moment estimation method.Comparing the maximum estimated positive bending moment and maximum estimated negative bending moment to the calculated ones.The results demonstrate that the fitting accuracy is great,with the maximum average absolute error in fiting the lateral deformation of the foundation pit being just 0.25 mm by 6th degree polynomial.The moment of the diaphragm wall will be overestimated by the bending moment estimation approach employing least square curve fitting,on average by roughly 4.5 percent.As a result,the projected bending moment value can be employed for safety early warning although the conclusion is conservative.At the same time,the possible false alarm and false alarm should be paid attention.