基坑钢支撑轴力监测的优化及实践

Optimization and practice of axial force monitoring for steel support of foundation pit

针对基坑钢支撑轴力监测中因偏心受压导致数据“失真”现象,采用增加轴力计钢弦数量(3根),取平均值的方法进行优化,分别从理论分析、数值模拟和工程实践三方面阐述论证了优化方法的可行性。结果表明:三弦轴力计通过测量各弦频率,取均值后得出钢支撑的轴力;三种计算工况下,布置方式a、b的三弦轴力计相对误差均小于单弦轴力计,仅2/3面积偏压工况下布置方式c的三弦轴力计相对误差小于单弦轴力计;钢支撑实测轴力呈现在当前工况支撑下挖土,支撑轴力增大,后续工况架设的支撑下挖土,先行工况的支撑轴力发生适当调整,后续工况支撑轴力增长的规律;钢支撑实测轴力变化规律符合基坑支撑轴力的基本变化规律,也说明了增加钢弦数量,取平均值的优化方法可行。

By increasing the number of steel wire and using the average value,the influence of eccentric compression on the axial force monitoring was eliminated.The feasibility of the optimization method was demonstrated by theoretical analysis,numerical simulation and engineering verification.The results show that by measuring the chord frequency and taking the average value,three-string axial force meter obtains the axial force.Under the three different conditions,the relative error of three-string axial force meter under the arrangement of a and b is less than single-string axial force meter.The relative error of three-string axial force gauge under the arrangement of c is less than the single-string axial force meter,only under 2/3 area bias condition.Excavating under current support,the axial force of this steel support increases.Excavating under subsequent support,the axial force of the previous support is been properly adjusted,and the axial force of subsequent support is increased.The variation law of axial force of steel support conforms to the basic change rule,and it is also verified that the optimization method is feasible.