Disaster characteristics and stability evaluation of the Hanjin Beishan landslide group in Linxia Basin, Gansu Province

On August 24, 2018, obvious cracks appeared in Beishan mountain, Hanji Town, Linxia County, Gansu Province, part of the mountain slide in different direction and landslide group formed.It is very urgent to carry out stability evaluation of the landslide groups.Field geological survey, limit equilibrium analysis and finite element numerical simulation were used to systematically evaluate the stability of each secondary landslide in Beishan landslide group.The results show that: ①Continuous rainfall or heavy rainfall was the main inducing factor that caused such a large area of deformation and the formation of multiple secondary landslides.The topography of the landslide area, the structure of the slope body and the unreasonable human engineering activities creat conditions for the formation of landslide.②According to the quantitative stability evaluation of different blocks of the landslide group, under the self-weight condition, the landslide group is in a better stable state.Under the rainfall condition, except for the H10 landslide, the rest of the secondary landslides will be further destabilized.If the area is subjected to an earthquake that exceeds its basic seismic intensity, the stability coefficient of the landslide group will decrease rapidly.All secondary landslides will experience rapid instability.③According to the deformation characteristics and disaster patterns of different secondary landslides in the landslide group, it is recommended to take targeted management measures such as retaining walls at the slope foot, slope cutting and load reduction, anchor frames, intercepting and draining channels, hanging ditches drainage anti-skid design.In order to ensure the safety of residents, buildings and traffic within the affected area of landslides, it is recommended to further strengthen the risk management and control of landslide groups, strengthen monitoring and early warning before landslide treatment, and dynamically grasp the stability of landslide groups.