Experimental Research On Interface Characteristics Of Reinforced Tailings Sand

Tailings sand is the waste discharged after beneficiation which is the main components of tailings dam.Tailings dam as an important structure in mine,it's stability is very important to the safety of residents in mine zone.Reinforced earth technology has been widely used in the field of civil engineering since it was invented,and it has been continuously developed.The reinforcement technology applied to the tailings dam project can effectively improve the mechanical stability of the dam body,however,the study of the interface strength characteristics of reinforced soil is an important parameter in reinforced earth technologies.Geogrid has the characteristics of good stability,high strength,low elongation,light weight and strong interaction with soil as a widely used geosynthetic material in civil engineering field,it is always the first choice of reinforced materials.In this paper,in order to study the interface strength characteristics and interface strength parameters in detail,using the shear test of tailing sand,several commonly used geotextiles and geogrids,The specific work accomplished is as follows:(1)Analyzing the performance of geogrid,In order to describe the reinforcement mechanism of reinforced earth technology and the main research methods for the interface properties of reinforced soil,through comparing the interface strength curves of primary tailings with reinforced geotextiles and combining the test data.The direct shear test is used in this study.(2)Through screening test,compaction test,long-necked funnel method and drying test,physical indexes such as particle size gradation,maximum dry density,minimum dry density and moisture content of tailings were measured.(3)Shear tests of primary tailings,tailings and plastic geogrid,tailings and warp knitted geogrid are carried out with Shear Trac ?,so as to study the effects of different grille types,different shear rates,different compaction degrees and different vertical loads on the interfacial strength;And the concept of "absolute shear expansion" region is introduced to compare with the "relative shear expansion" region;The relationship between shear strength and shear dilatancy is further analyzed through understanding the region of "relative shear expansion".(4)Based on the experimental data,a new constitutive model is proposed,which can be used to simulate the interface strength curve of reinforced soil,this modelcontains four kinds of combinatorial relationships:1)shear strength envelope;2)the Duncan-chang hyperbolic model before peak intensity;3)logarithmic curve model before peak strength and 4)the constant Model of residual strength Stability.The combined model can fit the strength curve of test data well.