基于弱反射布拉格光栅技术的海上钢管桩变形监测研究

Deformation Monitoring of Offshore Steel Pipe Piles Based on Weak Reflection Bragg Grating Technology

利用弱光栅应变监测原理,研究了两种不同封装方式的弱光栅传感器对钢梁的应变监测效果,并将其应用于海上钢管桩的变形监测。结果表明,弱光栅应变监测结果与分布式光纤结果以及理论计算结果都具有较高的一致性;推算的钢梁挠度与千分表测实值以及理论值误差在10%以内。海上钢管桩水平静载荷试验结果表明,桩身变形主要在海平面以下60 m的范围内,钢管桩挠度随着荷载的增加而增加,随着桩深的增加而减小,在50 m埋深后,钢管桩几乎不再受水平推力的影响;监测所得挠度与实际挠度平均误差为16 mm。通过室内模型及实际工程应用证明了弱光栅在钢结构监测中的可行性及准确性,并为同类项目提供了一定的技术支持。

Two types of weak grating sensors with different packaging methods were developed using the weak grating strain monitoring technology.The strain of the steel beam after loading is measured and compared with the distributed optical fiber sensor.The experimental results show that the strain monitoring results obtained using weak grating agree well with those obtained using distributed optical fiber and theoretical calculation.The error between the calculated deflection of the steel beam and measured and theoretical values of the dial indicator is within 10%.The horizontal static load test results of an offshore steel pipe pile show that the deformation of the pile is mainly within the range of 60 m below the sea level.The deflection of steel pipe piles increases with the increase of load and decreases with the increase in pile depth.After 50 m buried depth,the steel pipe pile is almost no longer affected by horizontal thrust,and the deflection value is 0.In the horizontal static load test,the average error between the monitored deflection and actual deflection is 16 mm.Through the indoor model and practical engineering application,the feasibility and accuracy of weak grating in steel structure monitoring are proved,which provides technical support for similar projects.