Model experimental study of landslides based on combined optical fiber transducer and different types of boreholes

Using a model box for laboratory model experiments on a slope is one of the most effective and acceptable methods for studying the occurrence and development of landslides. However, there have been no studies involving model experiments in which different types of combined optical fiber transducer (COFT) materials are buried in boreholes with different sizes and forms. Moreover, there have been no previous reports on the mechanism of a landslide being determined using the COFT we designed. Based on our previous studies, we designed a new model experimental box (with an interior space size of 4.5 × 2 × 1.7 m). A sliding bed was constructed of brick, with sliding surfaces made by layering cement mortar and stainless steel plates. The friction coefficients of these sliding surfaces were 0.63 and 0.27, respectively. Three loading schemes were designed: a stack load, jack, and jack and stack load combination. A landslide model experiment with two types of boreholes (inclined and vertical) was designed, and two laboratory model experiments were successfully conducted under the same soil conditions. During the test, the model slopes were cut, the COFTs were broken, and the corresponding data were collected, thus verifying the accuracy of the established experimental model. The results showed that the COFT measurements of the load movement direction were identical to previous research results. The friction coefficient of the sliding surface was a critical factor for the imposed load. The jack and stack load combination is recommended for this type of experiment. An inclined borehole model with a small inclination angle is not recommended for use in the model experiment, and an appropriate COFT material and borehole size should be selected according to the actual circumstances. The four stages of the land-sliding mechanism (compaction, gradual sliding, slightly faster sliding, and rapid sliding) could be determined from the tests.