Research On Stiffness Of Hydraulic Powered Shield Support Groups And Distribution Law Of Supporting Stress

According to the three-dimensional deformation of hydraulic powered shield support,the stiffness of the hydraulic powered shield support can be categorized as vertical stiffness,longitudinal stiffness,and transverse stiffness.By combining the methods of theoretical analysis and experimental test,this thesis particularly analyzed the vertical stiffness of the hydraulic powered shield support while the hydraulic powered shield support was working properly,found the equation for estimating the increased resistance stiffness of hydraulic powered shield support,and concluded that the increased resistance stiffness affected by the structure of powered shield support leg is proportional to the number of the legs and the leg diameters and is inversely proportional to the volume compressibility of emulsion and the height of liquid column.The estimating equation was proved by the coincidence of the experimental data and the theoretical result.Based on the assumption that the hydraulic powered shield support is a kind of elastomer when it works properly,the thesis proposed a mechanical model of independent elastic of hydraulic powered shield support groups bearing rock beam and a model of elastic foundation beam,analyzed the differences between two models under different application conditions.The first model specificly applied to the situation when stiffness of the hydraulic powered shield support is different.The second model was easy to calculate and required the stiffness of the hydraulic powered shield support to be absolutely the same.On the basis of two above-mentioned models,this thesis analyzed the bearing characteritics of the hydraulic powered shield support groups.The results of two methods were approaching to the same number while the length of mining face was increasing.Two results were almost the same when the ratio of the length of mining face to the width of single hydraulic powered shield support was over 100.The thesis established the stiffness matrix of hydraulic powered shield support groups by simplifying the powered shield support and the side of roadway as elastomer with a certain stiffness,derived the matrix equation of supporting resistance of powered shield support groups,found the quantitative relationship between the distribution law of supporting resistance of powered shield support groups and the length of mining face,analyzed the influence of different mining face parameters on supporting resistance and roof deflection,explained the change of three peaks supporting resistance of powered shield support groups in the ultra-long mining face,and provided a theoretical basis for defining ultra-long mining face.The thesis researched the distribution law of supporting stress of a single powered shield support,concluded the equation of supporting stress field of hydraulic powered shield support groups based on the quantitative relationship between the supporting resistance and the supporting stress of a single powered shield support,and analyzed the influence factors of the supporting stress field of hydraulic powered shield support groups.The results showed that supporting stress field of hydraulic powered shield support groups was uneven distribution in mining face and the distribution law of it was mostly related to the mining face parameters such as beam end conditions,mining height,and roof thickness,and related to the structure patterns of powered shield supports such as the length of canopy,the position of prop cap in canopy.Based on the measured data of 43303-2 mining face in Yujialiang coal mine and 42102–1 large-height mining face in Buertai coal mine,the thesis researched the distribution law of the supporting resistance of powered shield support groups.The results showed that the measured data coincided with the theoretical results,and the calculation method was proved to be reasonable and accurate.