Study On The Shear Strength And Distintegration Characteristics Of Coal-bearing Soil Under Dry-wet Circulation

Along the Chang-Li Highway,multi-generation coal strata was wide distribution,which stratum structure and lithology was complicated.Due to the coal-bearing soil is prone to softening and disintegrating,the surface coal-bearing cutting slope landslides are often occurred at many points after rains.That not only increases the project cost,but also affect the traffic safety seriously.Currently,the study about coal-bearing soil is still in the early stages.The most study were focus on the technique of cutting slope,and the study of physical properties,disintegration,shear strength characteristics of coal-bearing soil is rarely.Therefore,taking coal-bearing soil ranges along with Chang-Li Highway for example,the compositions,microstructure,basic physical properties,disintegration and shear strength characteristics under dry-wet circulations were studied.The main work of the thesis and achievements are summed up as follows:Firstly,the compositions of coal-bearing soil was studied by using X-ray diffraction,scanning electron microscopy and geotechnical test in laboratory,the results show that this kind of soil was mainly consist of quartz,muscovite,kaolinite,illite.By combining its basic physical properties,the soil can be defined as the product of strong weathered mother rock.Then,by watching the disintegration progress and analysis of disintegration pellets,the disintegration progress can be divided into three stages.And an criteria was put forward that the content of 0.5~5mm particles can be used as an evaluation standard of disintegration stability.Finally,the effects of various dry density,water contents and dry-wet circulation times on its shear strength of soil is measured through direct shear test,the cohesive force was linear to dry density,but segmented to water contents and dry-wet cycles,moisture content 9.2% and three cycles were the cut-off points.But the internal friction angle was still linear to above conditions.Research results can provide reference for slope protection and road design.