Model test for evaluating deformation and weighting of overlying strata by distributed optical fiber sensing

To examine the deformation law of overlying strata in the excavation of the working face, BOTDA is applied to the three-dimensional model test. The three-dimensional model, internally embedded with three vertical optical fibers, which measures 3 600 mm (L) by 2 000 mm (W) by 2 000 mm (H), simulates the excavation of the working face 60 times with a cumulative advance of 2 400 mm.And 180 groups of Brillouin frequency shift test data of the three-distributed optical fibers are obtained.The concept of average variation of distributed optical fiber frequency shift is proposed to evaluate the initial weighting and period weighting in the working face, and the optical fiber frequency shift is used to characterize the deformation and collapse of the overlying strata. A comparison is made on the test results with those of the internal displacement indicating that the average variation of the distributed optical fiber frequency shift is an accurate reflection of the deformation, pressure and changes of the overlying strata, and that the popularization and application of this technology may provide a reliable basis for intelligent mining in the future.