Study On The Bearing Capacity Of The Combined Single Compression Pillar

China is rich in underground mineral resources.According to statistics,in 2022,China will produce 4.5 billion tons of raw coal,890 million tons of iron ore,1.874 million tons of copper,and the number of other non-ferrous metals also ranks among the top in the world.The mining of these mineral resources requires supporting equipment,and the pressure pillar is an essential supporting equipment in mineral production.At present,the commonly used pressure pillar has wood pillar,steel pipe pillar,reinforced concrete pillar and other forms,wood pillar due to low strength,low turnover rate,more waste of wood resources,single steel pipe pillar and reinforced concrete pillar bearing capacity is large,but the quality is also large;Due to the restrictions of the working face in mineral production,the installation and maintenance of the pressure pillar need manual operation,and according to the safety code,the pillar must be repaired regularly.Too large quality has brought great challenges to the handling and installation.Therefore,the research and development of high bearing capacity,light weight,easy to operate monomer compression pillar has been a research focus.In view of the function and characteristics of the current pressure relief pillar,this thesis proposes the multi-section steel pipe composite monomial pressure relief pillar in the form of series splicing of multi-section steel pipe.The steel pipe is equipped with spiral mechanical jack at the bottom and digital display pressure sensor at the top.Through the multi-section decomposition of a single steel pipe,the characteristics of light weight,easy handling and installation are realized.At the same time,on this basis,the multi-limb composite steel tube monomer pressure column or multi-limb composite concrete filled steel tube monomer pressure pillar is proposed,which is a single large diameter steel pipe or concrete filled steel tube with a number of smaller steel pipe or concrete filled steel tube parallel combination to realize,also realize the characteristics of light weight,easy to carry,and more convenient than the multi-section combination of steel pipe.Due to the better bearing capacity of concrete-filled steel tube(CFST),finite element simulation analysis is carried out on the multi-limb composite compression pillar.In this thesis,the bearing performance of the pressure pillar is studied.The main contents are as follows:(1)Combined with the function and characteristics of the existing monomer pressure release pillar and the actual situation of the production face of mineral resources,a kind of multi-section steel pipe composite monomer pressure release pillar is proposed,and the bearing performance test under axial load is carried out,and the ultimate bearing capacity of the pillar and the whole failure process of the pressure release pillar are obtained,and the steel pipe wall thickness is taken as the parameter to analyze the change of the bearing performance of the pillar.(2)A multi-limb composite concrete filled steel tube(CFST)single compression pillar is proposed.A multi-limb compression pillar is composed of small diameter concrete filled steel tube(CFST)which is easy to transport.The proper constitutive relation is selected and analyzed by finite element software.(3)Taking the number of limbs,outer diameter of limbs,height of limbs,wall thickness of steel tubes and strength of concrete as the main parameters,the effects of the above parameters on the bearing properties of the columns were analyzed by simulating the axial compression process of the three-limb and four-limb composite compression columns.The results show that: The multi-section steel pipe combination makes the pressure pillar simple in structure and convenient in installation compared with the ordinary single hydraulic pillar,and shows better bearing effect and deformation ability under the design load.The yield load and peak load at 5mm,5.5mm and 6mm increased by 9.27%,18.51%,36.54% and 6.38%,16.36% and 32.37%,respectively,compared with the steel pipe wall thickness of 4mm,which also shows that the increase of steel pipe wall thickness can significantly improve the bearing capacity of the compression column members.On this basis,a multi-limb concrete-filled steel tube composite compression pillar is proposed,using finite element method to analyze the bearing performance and failure form of the column part,and taking the outer diameter,wall thickness,height and concrete strength grade of the column as parameters,to analyze its influence on the bearing performance of the column.Although the final failure form of the column is bending failure,the bearing capacity and deformation capacity of the component make the compression pillar more excellent than that of the multi-section steel pipe combination,and the four-limb combination pillar is more stable than that of the three-limb component.Among them,the increase of outer diameter and wall thickness has a more significant effect on the improvement of bearing performance.Compared with the multi-stage combination,the structure form of the column is more conducive to the operation and installation of workers in the underground environment.