Study On The Formation Mechanism Of Subao Seismic Loess Landslide Induced By The 1920 Haiyuan Earthquake

A large number of landslide disasters have been induced by the 8.5 magnitude earthquake of Haiyuan in 1920.This seismic geological phenomenon has high academic value and engineering significance for the study of landslides in the loess region.In this paper,The development characteristics,failure modes,distribution rules and movement characteristics of large loess landslides are analyzed by means of comprehensive geological survey,remote sensing interpretation,wave velocity test,ground pulsation test and numerical simulation.On this basis,this paper chooses the Su Bao Village Landslide as an example.The formation mechanism is analyzed,and its dynamic stability is evaluated by GEO-Studio software.The main results are as follows:1.Based on a large number of field surveys,the development characteristics,distribution regularity and movement characteristics of the large loess landslides formed by the massive earthquake in Haiyuan were calculated,and the failure mode of large-scale landslide was summarized.According to the surface morphology,length,width of landslide,landslide volume,area,the original slope,slope higher,this paper index categorize large landslides,The results show that landslides was controled by ancient topography,landforms factors.2.This paper summarized the failure mode of the large-scale landslide.The earthquake landslide is divided into large collapse sliding,cracking collapse-shear slide,vibration shear,liquefaction,liquefaction-flow slide,composite six failure mode;The statistical relationships of large landslide in different intensity area,river,slope,slope and fault distance were given.The characteristic value of large landslide motion,the value of topographic block coefficient and the fitting relation between each element are given.3.The field survey tested the characteristics of the landslide in subao village and restored the original morphological form;The structure of landslide formation is established,and the rationality of formation structure is verified through the wave velocity test.The characteristics of sliding zone in different parts of the landslide are proved,and the failure mode of landslide is given as liquefaction-shear type.Through the ground pulsation test,the predominant period of the slope is given,and the test results show that there is a large difference between the sliding body and the pulsation test results of the slope.4.A typical landslide formation mechanism is proposed and the dynamic stability of slope model is simulated and analyzed.In the in-depth analysis of slope engineering,on the basis of geological background and characteristics of landslides,landslide formation mechanism are given;the soil at the bottom of the slope is liquefied,thus,the shearing strength of the slope zone is reduced,the upper soil was slide;The stability coefficient of the slope in static force and the method of quasi-static force are obtained by numerical simulation.