Mechanical Characteristics And The Shell Formation Mechanism Of The Force Chain Of Surrounding Rock In Stope

This paper adopts the research methods of indoor laboratory test,similar simulation test,numerical simulation and theoretical analysis,using the force chain as the research line,to systematic study the load pass path way,expecting to reveal the mechanism of load pass way and the mechanism of shell formation of the force chain.The research of this paper provides the theoretical basis for the scientific mining method of coal seam,the reasonable location of coal seam roadway and the support design,and provides the basic theory for the safe and efficient mining of coal mine,further enriches the theory of rock pressure.The mainly research results are as follows:The laboratory tests are carried out on the mechanical behavior of the surrounding rock.The physical and mechanical parameters of the surrounding rock are obtained and the evaluation of the mechanical environment of the surrounding rock is realized,which lays the parameter foundation for the analysis of the force chain of the surrounding rock.At the same time,it further reveals the response rules between rock damage and force chain evolution,microcrack propagation and energy evolution.Based on the particle discretization method,the mechanism of the force chain shell of the surrounding rock is analyzed.It is found that there is a force chain shell formed by strong contact force in the surrounding rock of the stope,which reveals the load transfer mechanism of the surrounding rock.Along the gob and the oblique direction,the roof of the stope shows the arched chain.With the working face advance,the strength and range of the chain arch gradually increased,and the back of the goaf gradually showed the weak chain distribution,the force chain concentration is formated by the overburden loads passing the strong chain of the force chain shell into the work around coal rock body,and then the shell base is informed,which is the mechanical nature of the support pressure formation.And the contact force chain of the surrounding rock of the stope is formed from the closed-chain structure of the original equilibrium state to the post-mining disturbance,and the quasi-linear arched chain structure is formed by the Fourier formula.The different key parts of the force chain shell(shell base,shell shoulder and shell top)when the deflection angle,revealing the stress shell is the chain of mass transfer.The stress field,displacement field and failure characteristics of the main mechanical parameters are described.It is found that there is stress concentration in the front and rear of the working face along the working face and the oblique direction,and the stress concentration is more obvious as the working face advancing.The area is gradually changing during the mining process.The stress arch is formed in the overlying strata of the stope,the stress shell is formed in the three-dimensional space of the stope.Based on the theory of three-dimensional stress shell,the mechanics analysis of the surrounding rock is carried out with the roof rock formation.Based on the plate-shell theory,the stress model of the elliptical rock(plate)formed by the stress shell and the basic top effect is established based on plate shell theory.The criterion and mechanism of "chain-stress-shell" instability of surrounding rock is analyzed,and the failure criterion of the stress shell and the failure mode of the stress shell crust damage are obtained.