A monitoring method based on the characteristics of weak grating sensors is proposed for long-term monitoring of the uneven settlement and horizontal displacement of segments in shield subway tunnels during the op-eration period.The cable type weak grating sensor is fixed on the wall of the shield tunnel in a diamond patten after prestretching.By monitoring the deformation of the weak grating sensor,the tunnel deformations corresponding to dif-ferent tunnel structure modes can be distinguished and calculated to meet the real-time and precision requirements for engineering.According to the similarity ratio principle,a 1∶5 tunnel displacement model is designed and manufac-tured to simulate the local expansion,settlement and horizontal displacement of the tunnel segments.The grating sen-sors are also fixed on the wall surface of the tunnel model.Sensitivity tests of the weak grating sensors are first con-ducted before displacement monitoring.Then,the weak grating monitoring results with different diamond layout angles are compared.The following step is to monitor the vertical settlement and horizontal displacement of the tunnel mod-el,which are compared with the actual displacement values.The results show that the strain of weak grating with the diamond layout is larger than that with a linear layout under the same settlement condition,which means the sensitivi-ty of the diamond layout method to settlement change is better than that of traditional linear layout.Furthermore,10°～20° is the optimal angle interval of the diamond layout for weak grating,for the monitoring result error is low.Additionally,the inversion equation of weak grating wavelength change and segment displacement is established based on the test data of diamond layout with an angle of 15°.
关键词
盾构管片/位移变形/弱光栅传感器/菱形布设/地铁/运营期
Key words
shield segment/deformation/weak grating sensor/diamond layout/subway/operation period
维普
万方数据