Genesis and evolution mechanism of the Longmen Dangerous Rock Zone in the Three Gorges Reservoir Area, China

Abstract

Analysis of the genesis and evolution mechanism of High and Steep Dangerous Rocks (HSDRs) are crucial for enhancing the capability of geological disaster risk prevention and control in reservoir areas. This study focuses on the Longmen Dangerous Rock Zone (LDRZ) in the Three Gorges Reservoir Area (TGRA), China, and employs an integrated investigation system proposed. The genesis and evolution of the LDRZ can be attributed to the early influence of the Indosinian movement, Yanshan movement, and the Himalayan movement. The development of joint fissures in the Longmenxia Anticline led to the presence of stacked blocks in the steep cliffs, forming the early prototype of the LDRZ. The increased base pressure caused by natural rainfall affecting High and Steep Dangerous Rock Masses (HSDRMs) above the 175 m water level is recoverable, which reflects the situation of HSDRMs before the impoundment in the TGRA. The HSDRMs affected by the water in the TGRA are simultaneously influenced by natural rainfall and reservoir water level fluctuation. The reservoir water leads to the rock masses deterioration at the base, resulting in an irreversible increase in base pressure. With the annual cyclical rise and fall of the water level in the TGRA, forming the current LDRZ.