通过对龙羊峡拱坝垂直位移监测资料进行分析，总结其沉降变形的时间变化规律和空间分布规律，进一步 研究水压和温度等因素对龙羊峡坝体沉降变形的作用机理，并对变形中存在的一些特殊现象进行解释。研究表 明：水压和温度对龙羊峡拱坝不同高程的变形影响不同，导致坝体不同高程的垂直位移变化存在“相位差”；坝体 部分测点垂直位移有一定的持续变形趋势；2018 年以来的高水位运行期间，坝体各部位垂直位移测值变化趋势改 变；坝基扬压力对 7 号坝段坝基垂直位移影响较大；坝体高高程部位近右岸坝段的垂直变形规律与同高程其他坝 段垂直变形规律相反。

Monitoring data analysis is an important part of dam health monitoring to ensure the long-term safe operation of the dam. Vertical displacement is one of the main component in dam deformation monitoring. It can reflect the settlement deformation of the dam intuitively. The analysis of vertical deformation law and mechanism of the dam is a key content of data monitoring analysis. The main factors affecting the vertical displacement of the concrete dam are water pressure, temperature, and time-varying, and the influence degree of each factor is different. For the concrete dam with a low water head or little change of water level, the temperature has a greater influence on the vertical displacement, while for the high water head concrete dam, the water pressure has a greater influence than other factors. The effect of water pressure on the vertical displacement of a gravity arch dam is mainly manifested in two aspects: (1) The dam body tilts downstream due to the action of reservoir water pressure, which leads to the upstream surface of the dam body to lift and the downstream surface to sink. (2) The gravity action of the reservoir water causes the settlement of the reservoir plate and the dam foundation, which causes the dam body to tilt upstream, resulting in the upstream surface of the dam body sinking and the downstream surface lifting. The water pressure and temperature influence on deformation at different elevations of Longyangxia arch dam are different, which results in “phase difference” in the vertical displacement of the dam. The reservoir water pressure in the high elevation part is dominant, and the influence of temperature is comparatively small. The foundation of the dam is less affected by external air temperature and is mainly affected by upstream water pressure. Due to the complex interaction between water pressure and temperature in the middle part of the dam, the hysteresis phenomenon of water pressure effect and the abnormal phenomenon of temperature effect appears. The uplift pressure in the upstream and downstream of the curtain at the no.7 and no.8 dam sections foundation is larger than other dam sections, which leads to the large vertical displacement of the no.7 dam foundation. Therefore, the monitoring of seepage and deformation in this section should be strengthened. During the operation of high water levels since 2018, the deformation of the dam body has an obvious response, and the variation trend of the measured vertical displacement of the dam has changed significantly. Although Longyangxia arch dam has operated for more than 30 years, the vertical displacement of some measuring points of the dam still shows a trend of continuous deformation and has not reached a stable state. The settlement rate of no.6, 7 and 8 dam sections at 2 463m elevation is faster, so the observation of these sections should be strengthened. The vertical deformation of Longyangxia arch dam from the no.14 dam section to the right bank foundation is contrary to that of other dam sections at the same elevation, which sinks as the water level rises and lifts when the water level decreases.