The Instability Mechanism And Stability Control Technology Research On Loess Substrate Dump

The South Dump landslide at Antaibao Opencast Coal Mine is a severe geological hazard which is caused by the reservoir water-rock interaction in reservoir area. Rainfall and the fluctuation of reservoir water are the master factors which effect on the stability of landslides. The study on the geotechnical rheological properties under the action of water is significant for the forecast and reinforce of similar dump landslide.The Antaibao Opencast Coal Mine is located in the southwest145km from Datong City, Shanxi. The coal mine is formally put into operation in1987, the annual production capacity is15million tons, and the total amount of the two dump is229million m3. The abandoned slope angle is22°37, and the pile height is150m. At0:10on October29,1991, the south dump massive landslide took place. The maximum strike length of the slippery body was1095m, the altitude was1315～1450m, the slipeed volume was10million m3. That caused huge economic losses.In this paper, the loess substrate dump landslide is as a case for research. Applied method of combining physics experiments, field surveys and monitoring and numerical simulation, in-depth study of loess base dump mechanism of instability and stability control technology is started. The micro concept structure evolution characteristics under the load basal loess is achieved, that has important theoretical and practical value. The main tasks contain the following three aspects:At first, it is cleared that the engineering geological conditions, hydrogeological conditions, weather conditions of the loess substrate dump. The influencing factors of the dump stability are grasped, and the influencing factors of the loess substrate dump to determine the landslide mode are determined.Second, it is based on a large number of field and laboratory tests, that the weak layer mechanical parameters of the dump were determined. The failure mechanism of the loess substrate dump is studied through the mechanical properties of the dump base structure and the rheological properties of the loess structure weak layer. It was revealed that is the law of substrate saturated loess pore water pressure dissipation and the mechanical properties which is high-speed load lead to the loess strength reduction induced low confining pressure embrittlement damage instantly. Numerical simulation model of the evolution of a loess base dump weak layer was established. Based on systematic study of the mechanical properties of the dump base structure and the rheological properties of the loess structure weak layer, the overload destruction of the dump loess structure, water storage structure caused by rainwater infiltration, collapsible, water softening, forming a large area evolution weak layer, The mechanism is revealed that the abandoned quickly lead to substrate loess excess pore pressure, and intensity dropped suddenly, and the huge gravitational potential energy conversion landslide kinetic energy in an instant, then released In the manner of overall landslide to form the basement loess landslides.Finally, through the study on rheological properties and strength parameters of the weak layer and simulated dump stability evaluation under the action of hydrodynamic, the time-varying characteristics of rock mass strength under the action of water-rock mechanics was studied in-depth. The whole analysis from qualitative stage to quantitative stage formed a systemic way on dump landslide deformation mechanism and stability evaluation. The concept of dynamic stability coefficient was introduced. Loess base dump design and stability control technology was put forward.Therefore, the product of this paper revealed the reasons of dump landslide, that may provide scientific bases for the treatment of landslide in similar conditions on a certain degree.