New improvement of the combined optical fiber transducer for landslide monitoring

Abstract

Abstract. Landslide monitoring is important in predicting the behavior of landslides, thereby ensuring environmental, life, and property safety. On the basis of our previous studies, we conducted the double shear test by using a third-generation optical fiber transducer that uses expandable polystyrene (EPS) as base material. However, the thirdgeneration transducer has poor performance when cohesive force is present between the grout and capillary stainless steel pipe of the transducer. Thus, the fourth-generation optical fiber transducer was invented. Similar to the third-generation transducer, the fourth-generation transducer also used EPS as its base material. Single shear test was conducted on the fourth-generation transducer after being grouted with cement mortar (1 : 1 mix ratio). The micro-bend loss mechanism of the optical fiber was considered, and the optical time domain reflectometry instrument was used. The fact that the loss sequence of optical fibers subjected to loading is different at various locations is found. The relationship of the loadingpoint displacement vs. optical fiber sliding distance and optical loss were measured. Results show that the maximum initial measurement precision of the newly proposed device is 1 mm, the corresponding sliding distance is 21 mm, and the dynamic range is 0-20 mm. The fourth-generation transducer can measure the movement direction of loadings, thus making this transducer applicable for landslide monitoring.

Experimental Study on Slope Deformation Monitoring Based on a Combined Optical Fiber Transducer

“…These indicate that the monitoring performance of transducers with EPS as the base material are better for sandy clay slopes. This is the same as our previous study [14,15].…”

“…Figure 1 shows a schematic diagram of the transducer. Based on our previous studies, the cross-section of the base material, both EPS and PVC, are 40 × 40 mm and 1# optical fiber was only studied in this paper (direction determining of 2#, 3#, and 4# optical fiber has been studied [14,15]).…”

“…This transducer has obtained a Chinese patent [13]. The fourth generation of the transducer has been invented, with improvements being made to the transducer and the effects of different mortar strength, different types, and dimensions of base materials on the performance of the transducer were studied [14,15]. These studies verify that the transducer has a relatively high initial measurement accuracy, a large measuring range, cheap paving, and the ability to determine the landslide direction and can realize real-time, remote monitoring.…”

Recent Phenomenal and Investigational Subsurface Landslide Monitoring Techniques: A Mixed Review

“…The most effective material and the best cement-to-sand ratio in mortar were expandable polystyrene (EPS) and 1:5, respectively. The following are the capabilities of COFT fibers: (1) accurately predict the slide direction; (2) low cost; (3) remote, long-term, and real-time monitoring; (4) data collection takes seconds; and (5) distributed across numerous kilometers with great strain accuracy [47,58,84,85].…”