| Layered rock mass structure is common in geology.It is often encountered in tunnel excavation,coal mining,oil mining and other projects.Interlayer is a form of layered structure.The existence of interlayer has great and continuous effects on mechanical propertie of rock mass,which products cause inconvenience and harm to the construction of engineering.Therefore,it is necessary to study the influence factor of mechanical characteristics and stability of the interlayer.The mechanical properties of layered rock mass are not easy to calculate accurately for the complexity structure.So some hypotheses are necessary to make.and it is not easy to verificat the calculation results by experiments because of the difficulty of sampling and the possible destroyed during transportation.In order to study the internal stress and strain of rock.This paper take elastic mechanics as the theoretical basis,the theoretical analysis as the means,the composite rock mass with horizontal weak interlayer as the research object,and use artificial composite rock mass instead of natural rock mass to carry on the experiment.The mechanical properties of the material are studied.The main research contents and conclusions of this paper are as follows:(1)Theoretical deduction.Based on the axisymmetric theory of elastic mechanics,the standard cylinder specimen,which is commonly used in the field of rock mechanics research,is used as the research object,and the semi-inverse method is adopted.The three-dimensional stress function of cylinder standard rock specimen under uniform load and triaxial compression load is constructed.According to the stress function,the analytical solution of stress component,strain component anddisplacement component is derived,and then the principal stress and principal strain are obtained.The distribution of stress,strain and displacement at the interface between weak interlayer and interface is given,and the variation trend of rock mass stress,strain and displacement with the ratio of thickness to thickness of interlayer is studied.Predicted integration The failure form of a body rock mass.It is found that the destroy mode is different while the thickness ratio of soft-weak interlayer of composite rock mass and the loading condition is different.In generally,the interlayer is easier be destroyed under bigger thickness.The axial compressive capacity is higher while the rock is under higher confining pressure.(2)Sample preparation.Two kinds of laboratory sieving devices are developed in this paper: a scrolling graded screening device for particle and a non dynamic track type single layer drum screen.Multi-stage screening can be carried out at one time.The separation effect is good.The screening process is closed,and there is no dust pollution.Complete screening in exercise and play,reduce the traditional manual screening of labor and physical strain,and make,disassemble,carry convenient,suitable for laboratory,family and other small particle sieving.Two kinds of common sedimentary rocks,shale and sandstone,are selected as prototypes of soft rock and hard rock respectively.Selecting cement and gypsum as similar materials,appropriate similarity ratio is selected based on similarity theory and uniaxial compression experiment.Using existing dies and machines in the laboratory,artificial composite similar specimens of composite rock mass with soft-weak interlayer is prepared.(3)Experimental study.Through uniaxial experiments and triaxial compression tests under different confining pressure on artificial composite similar specimens.The influence of thickness ratio of soft-weak interlayer on the strength characteristics of composite rock mass is obtained.It is considered that the greater the soft interlayer thickness ratio is,the lower the compressive strength and elastic modulus of the rock mass will be.The larger the confining pressure is,the greater the uniaxial compressive strength of the rock mass and the smaller the slope of the stress-strain curve in the elastic deformation stage will be. |
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