The prevention and control of geological disasters in the Three Gorges reservoir area provides a strong guarantee for the stability of the reservoir bank.

China geological survey bureau Wuhan geological survey center

Since the preliminary work of the Three Gorges Project was carried out, the geological work of various departments has focused on finding out the engineering suitability and basic geological problems such as regional stability and seismic geological conditions, hydrogeological conditions in the reservoir area and dam site area, classification and distribution characteristics of nearby rock and soil bodies. Since the start of the Three Gorges Project in 1993, the geological work has gradually turned to the construction geological guarantee, and emergency investigations have been carried out on particularly serious geological disasters such as Lianziya dangerous rock mass and Huanglashi landslide at the head of the reservoir. On June 25, 2002, the State Council officially approved the Master Plan for the Prevention and Control of Geological Disasters in the Three Gorges Reservoir Area (hereinafter referred to as the Plan), which marked the official start of the prevention and control of geological disasters in the Three Gorges Reservoir Area. According to the guiding principles of the Plan, the relevant departments have carried out the investigation and evaluation, exploration and management, monitoring and early warning of geological disasters in the reservoir area in stages, which has provided technical support for the stability of the reservoir bank after the impoundment of the Three Gorges Reservoir and contributed to the safety of people's lives and property and even the stable economic and social development of the reservoir area.

1. Geological hazard investigation and scientific research provide technical support for bank slope stability evaluation.

In view of the unclear distribution of high and steep rocky slopes and dangerous rocks in the Three Gorges reservoir area, Wuhan Geological Survey Center has carried out the "Environmental Geological Survey of Yichang-Jiangjin Section in the Middle Reaches of the Yangtze River", taking 1 1 towns with relatively concentrated population as the main survey area, and screened out 232 typical dangerous rocks, and determined unstable slopes such as Gongjiafang-Dulong, Chuanjiandong and Wanzhou Jihazhai, which pose great threats to the safety of the Yangtze River channel. For example, in 2007, the Xianshuijing landslide was found in Shazhenxi Town, Zigui County, and the 500 kV transmission tower of the State Grid on the landslide was threatened. According to the nameplate address on the tower, the technicians informed and wrote to the relevant departments of the national trunk power grid, and the State Grid immediately organized and implemented the landslide investigation and treatment to ensure the safe operation of the power grid. At the beginning of April, 2009, investigators found many signs of deformation in the rock mass of Gongjiafang-Dulong high-steep slope, and reported to Chongqing Municipal Government in time and suggested strengthening monitoring. At the same time, the channel from Daning Hekou to Hengshi Xikou will be moved to the center of the river100m. The Chongqing municipal government immediately adopted the proposal of transferring the navigation channel and brought the unstable slope from Gongjiafang to Dulong into the monitoring and early warning system of geological disasters in Chongqing.

On July 20 10, after the China Meteorological Bureau released the forecast of extreme rainstorm weather in the Three Gorges reservoir area, Wuhan Geological Survey Center, Hubei Geological Environment Monitoring Station and Chongqing Geological Environment Monitoring Station urgently carried out the work of "geological disaster investigation in flood season in the Three Gorges reservoir area of the Yangtze River" to investigate the main hidden dangers of geological disasters in more than 20 counties and cities from Jiangjin City in the upstream to Zigui County in the downstream. Dispose of hundreds of hidden dangers with deformation and major threats in time, and compile more than 0/00 geological disaster emergency disposal reports, which provide a technically safe and economically feasible decision-making scheme for local governments to do a good job in sudden geological disasters.

Second, the monitoring and early warning work successfully predicted many geological disasters, avoiding casualties and property losses.

According to the spirit of relevant documents of the State Council and the Three Gorges Project Construction Committee, the Geological Disaster Prevention and Control Headquarters of the Three Gorges Reservoir Area of the Ministry of Land and Resources, the Geological Environment Monitoring Institute of China and the Geological Environment Monitoring Stations of Hubei and Chongqing took active actions to establish a relatively perfect geological disaster monitoring and early warning system in the reservoir area, and introduced GIS, GPS, rs and other technologies into the field of geological disaster monitoring and early warning. At present, professional monitoring has been carried out on nearly 200 important geological hazards in the reservoir area, and group monitoring and prevention work has been carried out on nearly 2,000 general hazards, initially realizing the network management of geological hazard monitoring data and early warning information. The Ministry of Land and Resources also cooperated with China Meteorological Bureau to carry out meteorological early warning and prediction of sudden geological disasters in flood season, and released early warning information of geological disasters through TV, Internet, SMS and other media, which successfully predicted the occurrence of many geological disasters represented by Qianjiangping landslide in Zigui County, effectively reducing casualties and property losses.

Since 2003, the Hydrogeological Environmental Geological Survey Center of China Geological Survey, in conjunction with Wushan County Land and Resources Bureau of Chongqing and Chongqing Geological Environmental Monitoring Station, has carried out projects such as "Research and demonstration of key technologies and methods of geological disaster early warning", "Real-time monitoring of groundwater pore water changes under reservoir water level fluctuation and prediction and evaluation of geological disasters". A monitoring and early warning demonstration station based on borehole inclinometer deep displacement monitoring, GPS surface deformation monitoring, time domain reflection technology (TDR) and pore water pressure monitoring was established, which realized the optimization and integration of geological disaster monitoring technology, remote transmission of monitoring data and real-time release of monitoring information on the Internet, and played an important role in promoting geological disaster monitoring and early warning technology and disaster information management in China.

In 2009, Wuhan Geological Survey Center launched "Study on Disaster Mechanism of Rock High and Steep Slope in Three Gorges Reservoir Area", which has achieved initial results, established the instability mode of high and steep slope, determined the instability criterion of slope, and predicted and simulated the surge that may be caused by slope instability.

Figure 1 Schematic diagram of the distribution of important dangerous rock deformation bodies in Wuxia section of the Three Gorges of the Yangtze River