¹⁰Be Exposure Age Study Of The Long-distance Landslide At The Luashibao High-speed In The Litang Maoyaba Basin, Western Sichuan

With the comprehensive improvement of China’s national strength,the construction of transportation network in Southwest China is gradually completing planning and implementation.The proposed Sichuan-Tibet Railway plan will pass through the Sichuan Basin and the eastern part of the Qinghai-Tibet Plateau from east to west.The planning and construction route in the middle section will pass through the Luanshibao high-speed remote landslide in the Maoyaba Basin on the southeastern edge of the Qinghai-Tibet Plateau(6.40×107-9.40×107m3).The landslide belongs to a typical high-speed remote landslide.Due to the complex geological structure background and special geographical location,the landslide may have a complex sliding process.The age of the landslide,the existence of the resurrection history,and the causes and stability of the landslide are closely related to the feasibility and engineering safety of the proposed Sichuan-Tibet railway scheme.It is also related to risk hazard assessment and disaster prediction and prevention of the same type of landslide in the region.At present,some scholars have carried out relevant theoretical research on the motion process and motion mode of high-speed long-distance landslide from the perspective of landslide dynamics.However,detailed research on the age of the landslide is rare,and whether the landslide has occurred excessively There was no relevant discussion in the second activity.The high-speed remote landslide of the Luanshibao landslide is suitable for the study of the 10Be exposure dating technique from the aspects of lithology and landslide properties.However,there is no discussion by researchers and the landslide causes and stability in combination with the chronological results.This paper takes the remote landslide of the Luanshibao high-speed in Maoyaba Basin as the direct research object,and uses the 10Be exposure dating technique to collect 8 granite samples from different altitudes(3 back wall samples,huge blocks on 5 piles).The stone sample was processed to obtain 7 sample data.Comprehensive analysis of the factors affecting the chronological data,through the calculation of the occlusion factor coefficient and the framed erosion rate,complete the chronological correction of the high-speed remote landslide.At the same time,combined with the geographical location of the sampling point and surrounding terrain analyzes the reliability of the age data and get on data selection.Combined with the age data and material,using the simple idealized stability analysis model tried to discuss the cause of the high-speed remote landslide and its process.In the end,the following progress and understanding were mainly achieved:(1)According to the corrected chronological results,it is found that the age of the back wall samples of the Luanshibao high-speed remote landslide from old to new corresponds to the altitude from high to low,and the analysis is the sample near the top of the back wall of the landslide cannot represent the real exposure period,because of the inheritance of nuclide,the period of large-scale high-speed sliding of the Luanshibao high-speed remote landslide of is about 3700a.(2)According to the data and data analysis,the sliding process of the landslide has multiple phases and complexity.Combined with the MYB-6 sample data and previous data,it was found that the high-speed remote landslide of the Luanshibao package had a second sliding around 2100a.(3)Based on the simple idealized calculation model with the safety factor of the landslide as the index,it is believed that the landslide has the first large-scale sliding under the action of the intra-regional earthquake during the 3700a period.The earthquake activity may be related to the fault zone activity from 1468±54a BC to 1340±25a BC.(4)Through the chronological data and literature,it is found that the landslide has only experienced two large-scale sliding in 4000a.After 2100a,multiple earthquakes with magnitudes greater than 6.5 in the region did not cause significant large-scale landslide activity.