A quasi-distributed monitoring method for ground settlement using pulse pre-pump Brillouin optical time domain analysis

Abstract

In geotechnical engineering, it is critical to measure and control ground settlement. A new method is proposed in this work for quasi-distributed ground settlement monitoring. This method is based on the pulse pre-pump Brillouin optical time domain analysis (PPP-BOTDA). The optical fiber is arranged on the monitoring poles through special supports, forming a zigzag pattern. Based on geometric principles, the formulas converting strains in fibers to displacements of supports are derived. Afterwards, the feasibility of the method is verified through laboratory tests. The results show that the proposed method can achieve accuracy within 1 mm. Compared with traditional discrete-point measurement methods, the proposed method can monitor settlement up to 100 points simultaneously with satisfactory precision, facilitating remote and large scale ground settlement monitoring in geotechnical engineering applications.