Research On Energy-Absorption And Anti-Impact Of Roadway O-Shed Support Based On Shell Surface Negative Stiffness Structure

The research on the prevention and control of rock burst disaster is an important engineering and scientific problem in the safe mining of coal.The energy-absorbing support of roadway is an effective means to prevent rock burst.The energy-absorbing components of traditional support do not have the characteristics of repeatable energy absorption.Therefore,a shell surface negative stiffness structure is proposed.The combination of the shell structure and the telescopic U-shaped support can form an O-shaped shed support with repeated energy absorption and impact prevention characteristics.In this paper,theoretical analysis,numerical simulation and experimental research are combined to analyze.Firstly,the deformation characteristics,energy absorption and cyclic tension and compression characteristics of the proposed shell structure are analyzed.The results show that the shell structure possess negative stiffness and bistable characteristics,and the bistable state is controllable.Compared with the traditional negative stiffness structure,it is found that the shell structure has better deformation stability and energy absorption.The cyclic tension and compression tests show that the shell structure has experienced 9 and 4 times of repeated tension and compression during the tension and compression displacement of 3.75 mm(half of the maximum stroke)and 7.5 mm(maximum stroke),respectively,and the compression force and tensile force before failure appear obvious sudden drop.At the same time,compared with 7.5mm cyclic tension and compression displacement,the total energy absorption of the structure under 3.75 mm displacement is increased by 21 %.The shell structure has a certain number of repeatable energy absorption characteristics.Secondly,the energy absorption,impact response characteristics and partial load characteristics of the multi-cell shell structure are analyzed.The results show that the energy absorption of the series combination is 5.3 % and 11.1 % more than that of the parallel combination and the series-parallel combination respectively.At the same time,the strain rate of the series combination changes smoothly and the comprehensive performance of shock absorption and shock isolation is better.The gradient processing of the surface thickness of the series combination is carried out.It is found that the larger the gradient interval is,the more energy is absorbed,which is helpful to improve the buffering performance of the structure.The arrangement order of different cell bodies under gradient treatment is analyzed,and the anti-scour performance of the structure under the arrangement of thin-thick-thin-thick is better.The partial load analysis shows that the higher the total height of the structure,the more prone the structure is to flip instability.Adding a guide sleeve to the multi-cell structure can alleviate such problems to a certain extent.Finally,based on the theoretical analysis,the energy-absorbing support with energy-absorbing structure can effectively dissipate the impact energy,suppress the dynamic response of the roof and the support body,and maintain the stability of the surrounding rock support system.On the basis of the retractable U-shaped support,the shell energy-absorbing structure is added to form the roadway O-shaped shed support.The results show that the bearing capacity of the support is greatly improved,and the maximum,minimum and average values of the bearing capacity are 3 times,7.6 times and 5.7 times of the retractable U-shaped support,respectively.Under the shell structure given in this paper,the O-shaped shed support can achieve repeated energy absorption for at least three cycles of surrounding rock disturbance,and under different impact energy,speed and position,the deformation of the key parts of the support and the control of the surrounding rock are superior to the traditional retractable U-shaped support.There are commonalities between the two supports when they are impacted : The internal energy of the two supports is larger at 45° impact,and the kinetic energy,internal energy of connecting cable and shrinkage displacement of surrounding rock of the two supports are larger at 90°impact.