Research On The Zoning Index Of Collapsible Loess Engineering Geology

Loess has caused various geological disasters due to its collapsibility.Therefore,the collapsibility of loess has received key attention in engineering.Yili is an area where the loess is relatively concentrated in Xinjiang.With the development of the regional economy and the increase of people's travel demand,the highway construction in the Yili area has developed rapidly.The utilization of loess resources in Yili area is also gradually increasing,in order to prevent it from hindering the development of highway construction,the demand for research results of loess is gradually increasing.This article selects the G578 highway Dunmaza-Nileke section of the Yili area as the research area,and conducts an in-depth and systematic study of the engineering properties of the loess along the line,with a view to the later road construction and other infrastructure construction in this area in terms of loess quality survey.It has certain practical guiding significance.The paper has achieved the following knowledge and results:(1)The east,south,and north sides of the study area are surrounded by the Tianshan Mountains.The terrain is generally high in the east and low in the west,and the route is approximately east-west.The loess along the route is mainly distributed in valley landforms,river alluvial plain landforms,piedmont alluvial plain landforms,and low mountain and hilly landforms.The distribution thickness is mostly 4m to 10 m,and vertical cleavage is developed.(2)Through the understanding of the collapsibility mechanism of loess,the relationship between collapsibility and engineering properties,natural moisture content,void ratio,natural density,dry density,saturation,compressibility,plasticity index,plastic limit,and liquid limit are used as research Indicators are explored.The relationship between the research index and the collapsibility coefficient is demonstrated,and the regression equation of the two indexes is established for the index that has a linear relationship with the collapsibility coefficient.The distribution rules of the above indicators and the collapsibility coefficient in the study area were explored.The collapsibility coefficient was not found in the study area.The compressibility and plasticity index were distributed along the route in the study area.However,the same sampling point varies with the depth of loess.Increase,there is no major change between the two.(3)Applying the basic idea of regression prediction method,a variety of collapsibility prediction equations were established by stepwise method and factor analysis method,and the F value was tested,and the models were all meaningful.Comparing the fit and independent variables of each model,the optimal model was selected to predict the collapsibility coefficient of loess.(4)In combination with external factors such as climate and hydrology,geological characteristics are used as the main indicators,and the site collapsibility level is used as an auxiliary indicator to classify the entire study area;based on the morphological characteristics of the geomorphology,the geomorphic features are used as the main indicator,supplemented by plasticity.The index classifies the loess and the compressibility of the soil classifies the classification of the soil in the second division;through the establishment of the division index system,the study is divided into 3first-level regions and 9 second-level regions.Combining the prediction of collapsibility of loess with engineering geological zoning,it provides the prediction equation of loess collapsibility coefficient for the first-level area of the study area,and uses the site collapsibility grade and collapsibility prediction equation to describe the collapsibility of the loess in the study area.It has carried out a useful exploration on the research work of the zoning of loess.