Deformation Monitoring Analysis of Tongzilin Hydropower Station Dam Based on Vacuum Laser Alignment System

Dam deformation monitoring is a key technical means to ensure the safe operation of water conservancy hub projects. The vacuum laser collimation system, with its advantages of high measurement accuracy and strong anti-interference ability, is widely used in the monitoring of horizontal and vertical displacements of dams. Based on the vacuum laser collimation system renovation project of the Tongzilin Hydropower Station in the Yalong River Basin, this study systematically sorted out the key points of the renovation construction process and the variation patterns of monitoring data. The kurtosis index was used to evaluate the stability of the data before and after the system renovation, and the Spearman rank correlation coefficient was employed to explore the correlation between dam deformation and environmental factors. The results show that: (1) After the system renovation, the vacuum degree was optimized from around 80 Pa to a minimum of about 8 Pa. The kurtosis index of most monitoring data at 22 measurement points significantly decreased, and the data stability improved; (2) Compared with other dam sections, the spillway dam section had the largest amplitude of displacement in the river direction. The riverbed dam section was significantly negatively correlated with the concrete temperature, while the bank abutment dam sections on both sides were positively correlated with the concrete temperature; (3) Vertical displacement was negatively correlated with the water levels upstream and downstream. The power plant dam section, affected by the vibration of the generating units, had the largest amplitude of vertical deformation; (4) The temperature factor had the greatest impact on deformation. This study reveals the temperature-dominated mechanism of dam deformation and the regional differences among dam sections in a daily-regulated reservoir riverbed power plant hydropower station, providing technical references for the safety monitoring and vacuum laser collimation system renovation of similar gravity dams.