Stability And Environmental Effect Evaluation Of Road Abandoned Slag Yard

As a special artificial accumulation deposit,abandoned slag yard will disturb and destroy the soil and vegetation during the process of dumping.Under the influence of rainfall and upstream water,it may not only cause serious soil erosion,but also cause geological disasters such as landslides and mudslides,posing a serious threat to downstream traffic,water conservancy and residents'lives and property.In recent years,incidents of destabilization of abandoned slag yard have emerged in endlessly.Therefore,It has become an urgent topic to carry out in-depth study of abandoned slag yard.In this paper,aiming at the stability and environmental effects of abandoned slag yard,a highway abandoned slag yard in Chongqing is taken as an example.Based on literature review and case study of a large number of abandoned slag yards,the engineering characteristics of abandoned slag yard is analyzed.The types,the disaster factors of abandoned slag yard and the mode of instability and destruction are summarized.Based on particle flow software PFC^2D,the correlation between the Micro-Parameters of particles and the Macro-Parameters of rock-soil body is studied.The Micro-Parameters of materials in each layer of abandoned slag yard is calibrated according to the Mohr-Coulomb criterion.On this basis,the particle flow model of abandoned slag yard is established.The principle of strength reduction in particle flow model is analyzed,and the stability analysis method based on particle discrete element theory is discussed,which is applied to the stability evaluation of abandoned slag yard.PFC^2D software is used to simulate the whole process of landslide,analyze the mechanism of landslide and disaster scope,and fish language is used to compile program to monitor and study the kinetic energy and impact force in the process of landslide.Based on a large number of cases of abandoned slag yard disasters,this paper summarizes the environmental problems and their environmental effects of abandoned slag yard disasters,puts forward the environmental effect chain of abandoned slag yard disasters,analyses the impact of soil erosion on the typical abandoned slag yard involved in the article and evaluates the severity of landslide disasters,and puts forward comprehensive control measures for the environmental effects of abandoned slag yard.The specific contents and research results are as follows:?1?The engineering characteristics of abandoned slag yard are analyzed,and the types of abandoned slag yard,the disaster factors and the mode of instability are summarized.According to the site selection,the road abandoned slag yard can be divided into ditch type,slope type,flat type and river-facing type.According to the source of the abandoned slag,it can be divided into the road abandoned slag yard,tunnel abandoned slag yard and building demolition abandoned slag yard.According to the composition of the abandoned slag,it can be divided into stone abandoned slag,soil abandoned slag and soil-rock mixed abandoned slag.There are four main factors affecting the slope instability and failure of abandoned slag yard:geological environmental factors,physical and mechanical properties of the abandoned slag soil,design factors of abandoned slag yard and induced factors of the slope instability and failure.The main failure modes of abandoned slag yard include three types,the abandoned material landslide,basement landslide and foundation landslide.?2?The study on the relationship between macro and micro parameters of materials shows that when the number of particles exceeds 3000,the peak strength of samples tends to be stable;with the increase of contact stiffness,the initial tangent modulus of the material increases and the peak stress decreases;with the increase of contact stiffness ratio,the initial tangent modulus of the material decreases and the peak stress increases;with the increase of friction coefficient between particles,the peak stress of the material increases.The peak stress increases with the increase of intergranular bond strength,and the cohesion is mainly affected by intergranular bond strength,while the internal friction angle is mainly affected by intergranular friction coefficient.?3?The strength reduction method based on particle flow theory is mainly aimed at the reduction of friction coefficient and bond strength between particles.The safety factor is the reduction factor.The stability of typical abandoned slag yard is analyzed.The minimum safety reserve factor is not satisfied in the case of heavy rain.The protection should be strengthened.The safety factor calculated by the limit equilibrium method is compared with that calculated by the limit equilibrium method.The simulation results are better.?4?The whole process of landslide is simulated.The results show that the instability of abandoned slag yard belongs to the landslide mode of the lower traction-upper pushing;the trend of change of landslide velocity and kinetic energy is the same on the whole,The initial stage increases and then decreases gradually after reaching the maximum.It is found that the farther the distance is,the smaller the impact force is.The main reason is that with the increase of sliding distance,the velocity and kinetic energy of the sliding body gradually decrease due to the friction resistance.?5?Environmental problems and environmental effects of abandoned slag yard can be divided into four categories:land resources damage effect,water resources damage effect,instability disaster effect and ecological and landscape damage effect.Moreover,the environmental effects of abandoned slag yard disasters do not exist in isolation.There are some causal links between them,forming a complex chain structure.In order to reduce the disaster environmental effect of abandoned slag yard,comprehensive treatment can be carried out from the aspects of early planning and control,protection of Engineering measures,improvement of ecological management and so on.