Abstract:
The west open-pit coal mine at Fushun in Liaoning Province of China was opened in 1901 and closed in 2018.It formed a 420 meters bottomless pit due to stepped coal mining, therefore, is called the largest pit in Asia.The south side landslide in the open-pit coal mine is a giant bedding rock landslide with 3100 meters in length from east to west and 1500 meters in width from north to south.The volume of the landslide is about 452 million cubic meters.Rainfall seepage and excavation unloading at the bottom of the mine are the main factors that lead to the landslide and the continuous long-distance movement.The concrete manifestation includes interlayer softening, groundwater buoyancy, and pore water pressure in the middle and front parts of the slope.The monitoring data from 2012 to 2019 show that the maximum horizontal displacement of the landslide is 96.01 meters, the cumulative maximum subsidence is 56.65 meters, and the full raise of the front edge is 23.61 meters.The topographic feature of the landslide area is greatly changed.The landslide movement has experienced deformation and failure before 2013, step evolution from 2013 to 2016, and gradually stabilization since 2017.The three phases reflect the rapid development of the giant landslide from the complete destruction of the bedding mountain to a gradually stable process.Analysis of the sensibility reveals the uplifting of underground water level plays an important role in decreasing slope stability, and filling soil at the toe of the slope remarkably increase slope stability.Bedding sliding resistance in the middle and upper slope, cut-layers shear resistance in the lower slope, fill pressure in leading edge, boundary resistance of bilateral, and counterforce of the north side are major factors of the gradual braking of landslide.It is manifested as the "block effect" of the boundary and the "pressure arch effect" of the leading edge.Using boundary resistance, stowage, and resistance reaction force to control the landslide process is typical.The impact and vibration effects were avoided, and the soft landing was realized.