APPLICATION OF PREDICTION MODEL FOR LAND SUBSIDENCE POTENTIAL BASED ON DFOS MONITORING

Land subsidence is one of the main geological disasters in China. It is necessary to evaluate and predict the development trend of land subsidence. In this paper, the hyperbolic subsidence model, exponential subsidence model and growth curve subsidence model are introduced into the measured subsidence mathematical model. Combined with the continuous deformation of different layers under the surface obtained by the full cross-section distributed fine monitoring system, the land subsidence prediction model based on the distributed optical fiber monitoring data is established. This new model can realize the potential evaluation of land subsidence. Taking the G06 optical fiber monitoring drilling results of Tianjin Binhai New Area as an example, the prediction results of three kinds of subsidence models are compared. The results show that: the land subsidence curve in Tianjin Binhai area presents nonlinear attenuation characteristics. From October 2017 to December 2019, the cumulative subsidence reached 52.4 mm, and the estimated limit subsidence was about 92.6 mm. There is still about 43.4% subsidence potential. There is still a large subsidence space, and it is expected to enter the stage of subsidence stability in 2050. The 3.4~18.4 m clayey silty sand and silty fine sand layers in this area have large subsidence amount. These layers are the main layers of land subsidence, namely "dominant layer". Although the current subsidence amount of 18.4~38.4 m silty clay and clayey silty sand layer is small, its residual subsidence is large and the subsidence duration is long, which is the "priority layer" for later monitoring.