Research On The Development Characteristics Of The Saliva-ice In The Sichuan-tibet Traffic Corridor And Its Influence On The Sichuan-tibet Railway

The saliva-ice disease is a unique special engineering geological phenomenon in severe cold areas,especially in high latitudes and high altitudes.It is widespread in the cold winter areas of northern China and the Qinghai-Tibet Plateau,and is one of the geological diseases frequently encountered in the construction of these areas.The engineering geological conditions and hydrogeological conditions of the Kangding to Changdu section of the Sichuan-Tibet Railway crossing the area are very conducive to the formation of saliva-ice.This article takes the Kangding-Changdu section of the Sichuan-Tibet railway as the basis for research.Through the collation of relevant papers and engineering materials,the site survey,field test,theoretical analysis and finite element simulation of saliva-ice in the whole area of Kangding to Changdu,the saliva-ice is analyzed.Formation conditions,the influence of various factors on the formation of saliva-ice,and the development mechanism of different types of saliva-ice.Through collecting and reviewing and collating relevant literature data of typical saliva-ice in northeast and northwest regions,combined with the meteorological and geological conditions in the Kangding to Changdu area,a more detailed field research plan was formulated.The survey method for the saliva-ice in the Sichuan-Tibet traffic corridor is satellite image identification and field survey.The contents of the field investigation are mainly determined by the geographic location,topography,aspect,slope,and slope position of the salivating ice,the type,location,and scale of the saliva-ice,and the degree of damage to the proposed project.A total of 2,369 freezing points were investigated.Identify seven types of saliva-ice in the Sichuan-Tibet traffic corridor area,which are slope overflow type,slope foot seepage type,gully type,groove type,bedrock fissure type,soil-rock interface type and river type.Combined with the on-site investigation and study of saliva-ice in the Sichuan-Tibet traffic corridor area and the on-site observation and comprehensive analysis of the topography,geological structure,meteorology,and hydrology along the line,the development characteristics of the saliva-ice in the Sichuan-Tibet traffic corridor area are described,The hydrological conditions,meteorological conditions and topographic and geomorphic conditions required for the formation of saliva-ice.From the frozen-pressure effect of the enclosed body,the causes of the formation of saliva-ice and the factors affecting the development of saliva-ice were analyzed.Based on the development mechanism of saliva-ice,according to different types of water sources,the causes of formation of soil-rock interface saliva-ice,bedrock fissure saliva-ice,and valley-shaped saliva-ice were analyzed.Through the Midas-GTS numerical simulation software,the seepage of the slope with saliva-ice was simulated,and the effects of water sources and weak layers on the formation of saliva-ice were analyzed.The results show that there are 64 salivary ice sites that affect the subgrade of the proposed Sichuan Tibet railway,57 salivary ice sites that affect the bridge and 30 salivary ice sites that affect the tunnel.For the salivary ice point affecting the entrance and exit of the tunnel,it is suggested to adjust the route scheme to avoid the salivary ice development area;for the bridge engineering,it is suggested to bridge piers to avoid the salivary ice development area;for the subgrade section,it is suggested to strengthen the salivary ice prevention engineering measures.