可以实现分布式、长距离、实时监测的BOTDR监测技术已在土木工程领域得到了较为广泛的应用,但在岩土工程领域的应用研究起步较晚,相关技术还有待于进一步完善。以布里渊BOTDR的巷道/隧道应变监测技术为基础,研究了沿巷道轴向进行一维布设的光纤应变测量值与隧道顶板沉降变形之间的关系。首先,根据巷道/隧道顶板的变形规律,建立了光纤沿巷道/隧道轴向发生的应变与巷道/隧道顶板的沉降变形之间的数学模型,即圆弧模型、抛物线模型和三角形模型。其次,对巷道/隧道顶板的沉降变形与光纤应变之间的关系进行了试验研究。对比分析表明,理论计算值与试验值具有很好的一致性。利用圆弧模型、抛物线模型和三角形模型等3个计算模型,可以将光纤应变与顶板沉降联系起来,这对于BOTDR技术的应用与推广具有重要的理论意义和工程实用价值。
Brillouin optical time-domain reflectometer(BOTDR) techniques have numerous advantages such as distributed measurement, long distance and real-time online, which are widely used in the structural engineering field and show extensive application prospects. However, the application of BOTDR is relatively limited in the field of geotechnical engineering, and thus some relevant technologies need to be improved. In this study, the relationship between strain measurements by the optical fiber distributed along the direction of axial tunnel and the deformation of tunnel roof subsidence is investigated based on the strain monitoring technology of BOTDR. Firstly, according to the deformation regularity of tunnel roof, three mathematical models, namely the circular arc model, the parabolic model and the triangle model, are established for the relationships between the strain along tunnel axial direction and the deformation of tunnel roof subsidence. Secondly, experiments are conducted to examine the relationship between the optical fiber strain and the deformation of tunnel roof subsidence. The final comparative analysis reveals that the theoretically calculated values show well agreement with experimental data. The optical fiber strain can be linked with the roof subsidence by using these three analytical models, which has theoretical significance and practical engineering value for the application and improvement of BOTDR technology.