Simulation of the water level influence on the difference within the water-tube tiltmeter in Shuangyang Lake

Abstract

This article analyzes the relationship between the water level and the water-tube tilting in Shuangyang lake, based on the differential deformation features reflected by the NS and EW components of the water-tube tiltmeter. The results show a good spatiotemporal consistency between the variation of water level and the NS tilt component, which is considered to be affected by the magnitude and duration of the water level variation in Shuangyang Lake. The article uses Landsat remote sensing image data to extract the water boundary of Shuangyang Lake, and takes advantage of the finite element numerical simulation method to build three-dimensional models for different geological structural conditions of the Shuangyang seismostation. The simulation results show that when the underground medium is granite, the effect of water level variation on the vertical displacement of the surface is non-directional. With a 50-m soil layer in Model 2, the simulated NS tilt variation is equivalent to the actual observed water-tube tiltmeter NS component when the water level variation is 0.44 m and 0.8m. When the variation of water level reaches 2.0m, the simulation result of the NS component is 79.6 ​ms, which is slightly larger than the observed result of 60.32 ​ms. However, the simulation results show that the variation of the EW component is significantly smaller than that of the NS one. Due to the fact that the Shuangyang lake is long in the NS direction and short in the EW direction, the existence of the soil layer tends to generate ground deformation along the NS direction in the vicinity of the lake after the increase of water level, thereby resulting in the difference of the ground deformation in the two directions.