| Slag dump is a common artificial disaster body.In the construction of highways and railways in mountainous areas,the excavation of tunnels and roadbeds is necessary due to the limitation of topographic conditions.Due to the imperfection of construction technology and construction management conditions,as well as the limitation of traffic,terrain conditions and engineering investment,abandoned slag is often chosen to be dumped and piled in the valley terrain around the construction site,thus forming a slag dump site of different sizes.The stability of the slag dump is related to the road traffic in the region,and the potential geological disasters caused by the slag dump will do harm to the production and life of the people in the downstream areas.The slope of slag dump site is formed by a large amount of slag dump piled on the original slope.In the process of slag dump,the slag particles with different particle sizes are naturally sorted under the action of gravity,and the final accumulation body has obvious particle size grading characteristics and uneven internal structure.In this paper,based on the practical engineering of the slag dump of the Syrian railway line,the grading characteristics of the grain size of the slag dump in the slope of the slag dump,the basic characteristics and physical and mechanical properties of the slag dump,as well as the stability and deformation instability process of the slag dump considering the grain size grading are studied.Data collection,field investigation,sampling,field test,laboratory test,model test and numerical simulation were carried out for the slag dump in the area along the line.The main work completed and corresponding results are as follows:(1)According to the survey and statistics of 25 slag dump sites in the study area,a set of survey method for the slope of slag dump site is proposed.The investigation found that there were signs of deformation and failure in several slag dump sites in the study area,and there was a risk of instability disaster in the slag dump site in the study area.In dalingshan tunnel research district imported tunnel abandon slag field and cool water Wells abandon slag field and walnut bay tunnel abandon slag field three typical abandon slag field launched a detailed investigation,find out the various typical abandon slag field of geometry,boundary features,bedrock and abandon slag characteristics such as conditions,to abandon slag field slope provides information and basis for the establishment of the numerical model.(2)Based on the investigation and statistics of the abandoned slag in each abandoned slag yard in the region,the basic characteristics of the deposited slag in each abandoned slag yard are obtained,including the lithology of abandoned slag,the composition and distribution of particle size,the filling in the abandoned slag body,the natural resting Angle,the degree of weathering and the cementation situation.In this paper,the undisturbed sample of the surface slag-abandoned body of slope was prepared by raw gum,and the in-situ structural characteristics of the slag-abandoned body were analyzed.(3)The physical and mechanical properties of abandoned slag body were studied in the field and in the laboratory,including bulk density,void fraction,natural resting Angle,particle size distribution characteristics,particle size and shear strength characteristics of abandoned slag produced by different rock grades.The density and voidage of the slag accumulation body were measured by means of drainage,sand filling and image recognition.The relationship between the natural repose Angle and shear strength was studied from the point of equilibrium of the particles.The size gradation of abandoned slag was measured by sieving component in the field.The shear strength characteristics of abandoned slag were studied by shear strength mechanism and direct shear test.The results can be used as a reference for the calculation of the stability of the slag dump.(4)Quartz sand and gravel particles with different particle sizes were used as similar materials to carry out dumping and stacking tests of abandoned slag particles in the generalized model.The results show that the formation of the accumulation body is a dynamic process with obvious grading characteristics of particle size,strong heterogeneity and special structural characteristics.(5)Based on particle size classification feature,the inhomogeneity of abandon slag volume parameter values,in three typical abandon slag field research district using limit equilibrium method to calculate the stability coefficient under three different conditions,and separately for each abandon slag field stress and shear strain fields in the cases of the most dangerous analysis,obtained the stability status of typical abandon slag field.(6)According to the laws of the particle size distribution of different elevation,established considering particle size distribution of particle flow model,dalingshan abandon slag field by shear test parameter calibration in combination with experience value determines the abandon slag and mesoscopic parameters of coating particles and take the critical condition of reduction factor to reduction of material strength parameters,simulates the deformation process of instability of abandon slag field,analyzes the buckling mode.The instability mode of the abandoned slag field is as follows: the whole abandoned slag body slides along the weak overburden;the middle and lower parts of the abandoned slag body show the characteristics of bedded landslide;the middle and upper parts show the characteristics of traction landslide. |
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