基于光纤位移传感器的桥梁基坑沉降监测的试验研究

Experimental Research on Settlement Monitoring of Bridge Foundation Pits Based on Fiber Optic Displacement Sensors

文中以某大型桥梁深基坑工程为例,利用光纤位移传感器对基坑施工过程中冠梁和行车道的水平位移、地表沉降、锚索轴力、地下水位等进行动态监测和分析,以研究深基坑的开挖变形规律。结果表明,随着基坑的开挖,基坑的冠梁和行车道向基坑方向倾斜,最终趋于稳定,且随着开挖深度的增加,第一层的预应力锚杆轴向力随深度的增加而增加。两个开挖面的地下水有不同的发展规律,但均在短期之内逐渐趋于平稳。基坑各个部位的累积沉降均处于控制之中,但由于其北部和邻近一栋建筑的地面沉陷还没有得到控制,因此,需对该地区进行进一步的沉降监控。

Taking a large bridge deep foundation pit project as an example,a fiber optic displacement sensor is used to dynamically monitor and analyze the horizontal displacement,surface settlement,anchor cable axial force,groundwater level,etc.of the crown beam and traffic lane during the foundation pit construction process.Analyze the excavation deformation law of deep foundation pits.The experimental results indicate that as the excavation of the foundation pit progresses,the crown beams and traffic lanes of the foundation pit tilt towards the direction of the foundation pit and eventually stabilize.The variation of axial force of prestressed anchor cables on the first floor of the foundation pit is basically consistent with the variation of horizontal displacement time.The trend of groundwater level changes on both sides of the foundation pit is different,but tends to stabilize in a short period of time.Throughout the entire monitoring period,the cumulative settlement values in each area of the foundation pit were within a controllable range,but the surface settlement of a building on the north side and surrounding area of the foundation pit has not yet reached stability.It is recommended to extend the settlement monitoring time in the relevant areas.