Study On The Initiation Mechanism Of Xinmo High-Speed Rockslide In Mao Xian,Sichuan

On June 24,2017,a large scale high-speed landslide occurred in Xinmo Village,Mao Xian County,Sichuan Province.The horizontal displacement of the landslide exceeded 2500 m in two minutes,and the mean value of the movement velocity exceeded 40 m/s.Based on a detailed analysis of the geological environmental conditions of the Xinmo landslide,this paper is mainly focused on the sudden departure mode of the Xinmocun landslide,and proposes that the locked segment ruptures and releases energy to cause sudden departure.Through the method of model test,theoretical calculation and numerical simulation,the important effect of rock mass rupture and vibration on the high-speed departure of the landslide is analyzed.The main contents of this thesis are as follows:1.Through field geological investigation and material collection,the regional geological conditions of Xinmo Village landslide were studied,the movement area of the landslide is divided into the source area,the track area,and the deposition area.The reason for the sudden departure of the landslide is analyzed,and it is proposed that the anti-tilting joint zone that acts as locked segment in the source area has brittle shearing,the strong vibration generated by the energy release at the moment of rupture caused the originally broken rock mass to be thrown out,the landslide reaches high speed departure.2.The model of failure and instability of the landslide has been studied through model tests.The test phenomenon has proved that the rock mass rupture vibration in the locked segment makes the landslide sudden departure along the potential rupture surface.The acceleration monitoring data shows that the sliding mass is subjected to a force in the free face at the moment when the locked segment ruptures,resulting in an acceleration of 0.94 g.And discusses the impact of sudden departure of different strength sliding mass.3.Combining with the model test data,the theoretical results show that the sliding mass in the source area of Xinmo Village starts with a angle of 27.36 ° and an acceleration of 0.91 g.The Rockfall software is used to simulate the movement path of the sliding mass.After the sliding mass sudden departure,throws "flying",tracks at high speed,and finally decelerates and deposits,calculating the average velocity of the sliding mass during the whole process is39.4 m/s,and the total time of the whole process is 63.7 s.4.The stability of the source area was analyzed using the stereographic projection.Using Flac3 d software to analyze the stress field of Xinmocun landslide.Through the 3DEC software,the whole process of deformation and failure of the Xinmocun landslide was simulated,and the failure mechanism of the sudden departure and natural sliding were compared,the rock mass sudden departure started faster and moved farther.The track stage and deposition stage of the landslide were simulated,and the landslide motion process was reconstructed.