Based On Time Series InSAR Tailings Dam (reservoir Area) Monitoring And Disaster Identification

Tailings dam is a high potential energy of man-made mudslide hazard source,once the dam will seriously threaten the life safety of downstream residents,and the current tailings reservoir monitoring mainly uses traditional measurement methods,monitoring costs are high,and it is difficult to achieve large-area overall deformation monitoring.With the continuous development of In SAR technology,time series In SAR technology has matured in Earth observation.Therefore,this paper uses time series In SAR technology to process Sentinel-1A images in the research area,extracting the KF tailings dam from October 2014 to July 2018,and the JM tailings depot in Tibet from February 2017 to June 2019.Deformation information for the corresponding time period of the YS tailings depot from March 2017 to May 2019.The acquired deformation is evaluated by the internal precision evaluation model provided by time series In SAR,and the deformation accuracy evaluation values of the three tailings reservoirs are between 0-3,and the results are reliable.Combined with field investigation and tailings dam construction data,the time-series deformation law of the three tailings dams was studied.The results show that:(1)The acceleration time of the first abnormal deformation of KF tailings dam detected by SBAS-In SAR is in perfect agreement with the height of the construction time node of the sand and stone laying project of the dam,which indicates that the SBAS-In SAR technology is highly sensitive to the deformation monitoring of the dam affected by man-made engineering.After the construction of the dam body,the trend of the dam body deformation did not ease,and the phenomenon of two times of acceleration,it is believed that the laying of about 1m-2m thick gravel in the dam body greatly increased the load of the dam body,breaking the original stress balance state of the dam body.The whole body of KF tailings dam is deformed,but the shape variables in the north and south are greater than other parts of the dam,and the deformation rate is larger,indicating that the north and south of the dam are potential danger areas.It is also recognized that the rainy season has a significant effect on the dam deformation,which indicates that the laying of sand and gravel will prolong the stagnation time of rainfall in the dam and further cause the dam deformation to be intensified during the non-rainy season.(2)the shape variable in the middle of JM tailings reservoir dam body is larger than other locations,and the deformation rate is larger,indicating that the middle area of the dam body is the potential danger area of the dam body.The slope B and C in JM tailings reservoir area have large shape variables,serious rock weathering and fragile geological conditions.The deformation rate is much higher than the slope instability threshold of 10mm/a,the slope is between 37.7° and 77.5°,while the C region is on a sunny slope,the sunshine time is long,the snow melt water infiltration is serious,and the C region has a large number of cracks and glacial erosion valleys.Although area B is an overcast slope,the deformation rate of area B is relatively high,and a number of fractures,glacial erosion valleys and gullies are developed on the site,which proves that the probability of landslide in areas B and C is relatively high.The deformation of JM tailings dam body is not significantly affected by freezing-thawing phenomenon,while the slope in the reservoir area is significantly affected by freezing-thawing phenomenon.The influence of freezing-thawing phenomenon on the slope will reduce the rock strength and increase the probability of landslide in regions B and C.(3)The area east of the central axis of the dam body of YS tailings pond is formed by the evolution of the dry beach of the original tailings pond and the area where the water is stored.After a large amount of water is discharged from the reservoir area,the gap between the particles of the dam body decreases,the stability is weakened,and the deformation of the dam body is intensified.The regional shape variable and deformation rate east of the central axis of the dam body are greater than the rest of the dam body,which is the potential danger area of the dam body.At the same time,the negative correlation between rainfall and dam deformation was identified,and the rainy season in 2018 coincided with the time of massive drainage,which caused the dam deformation to be intensified.The deformation in the southeastern part of the dam body is relatively large,but there is no abnormality during the drainage period.This study shows that the time-series In SAR technology can not only monitor the tailings reservoir as a whole,but also accurately identify the impact of artificial engineering on the dam body,and can also analyze and demonstrate the internal factors that cause abnormal deformation,which has important guiding significance for guiding the tailings dam disaster identification,analysis and treatment.