Model Test Study On The Failure Mode Of Seasonal Coarse Granular Frozen Soil Slope In Sichuan Tibet Railway

The new Sichuan Tibet railway is affected by the slope and terrain,The mountains in the crossing as the representative of the Sichuan Tibet railway to Xinduqiao mostly only by embankment,The line is located in the thick and thick seasonal frozen soil slope,Observations show that This kind of coarse granular frozen soil slope will slip or flow slowly under the action of seasonal freezing and thawing.Model test is the best choice for those who have not yet been able to establish mathematical models.Becase the less study of coarse granular frozen soil slope model,in this paper,a set of experimental method for the study of seasonal coarse granular frozen soil slope model is presented.In this paper,the following work is done in the process of establishing the model experimental research method.The 3 2 slopes of the site are investigated,and the failure modes and failure factors are summarized.The similarity ratio of frozen soil slope model is derived by integral analogy method.Combined with the theoretical calculation and the actual test method,the heat insulator of model test is determined.The model monitoring scheme is designed and the monitoring element is selected.The method of data acquisition is studied.Finally,the feasibility of the model test method is proved by field monitoring results.In the process of model test,the following conclusions are drawn.According to the investigation of the site slope,it is shown that the most failure of the seasonal coarse granular frozen soil slope is on the surface of the slops,The damage ranges from 0.2 meters to 1.5 meters of the slope surface.When the soil is used as the main material,we can obtain the time scale is 225 when the length scale is 15.The resistance value in soil is inversely proportional to the soil moisture content.It is feasible to use the self-made resistance sensor to monitor the slope humidity field.Photogrammetric method is successfully used for monitoring the frost heave displacement of the slop.The model test results show that the maximum frost heave displacement is on the top of slop,the frost heave displacement decreases from the top to the foot of the slope,the position of minimum displacement is toe.At the same time,it is concluded that the slope failure is caused by the melting of the snow infiltrates into soil which causes the increase of frost heave.By comparing with the results of field monitoring,it is found that the model test results are in good agreement with the field monitoring results.The deficiency of the model test is that the model is only used for the test of the slope with or without snow covering,it is suggested to carry out further study on the model test according to the different conditions.