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冲击载荷下锚杆托板及组合构件力学性能试验研究

Experimental study on mechanical properties of anchor plate and combination components under impact load

  • 摘要: 为揭示冲击地压巷道锚杆支护系统中托板及组合构件的抗冲击性能,采用微机控制电液伺服试验机和自主研发的落锤冲击试验装置,对煤矿常用的拱形托板及其组合构件进行了力学性能研究,分别测试托板静载和正、反向及组合构件冲击力学性能,获取试样静载力-位移曲线、冲击力时程曲线、位移时程曲线及变形特征。研究结果表明:静载作用下,托板最大承载力为228~243 kN,最大变形量为14.10 mm,变形主要表现为拱高降低、四角翘起、连接部位向圆心转移;冲击载荷作用下,随着冲击能量增加,三种托板变形经历拱高逐渐降低,四角翘起量逐渐升高、拱高等于四角翘起量、拱高与四角翘起量同步降低等三个阶段。托板低能量冲击力时程曲线呈现急剧上升阶段、震荡作用阶段和迅速下降等3个阶段,高能量冲击震荡作用阶段可细分为震荡稳载阶段和震荡上升阶段;正、反向冲击力时程曲线轨迹线形态一致,组合构件时程曲线增加初期震荡和尾部震荡卸载阶段。三种试样冲击力逐渐增大,最大值分别为440、415.29、458.26 kN,均位于震荡作用阶段,此阶段作用时间逐渐增加且均不超过7.49 ms。试样位移时程曲线可分为弹塑性变形和回弹变形两阶段,弹塑性变形阶段变形量与作用时间呈现线性关系,正、反向及组合构件最大形变量平均作用时间占比分别为68.66%、69.25%、66.66%。总体来看,托板可抵抗2500 J冲击能量破坏,托板正、反向冲击力学性能及变形特征一致性较好,组合构件可实现吸能减冲、延长冲击力作用时间、改善托板承载特性等作用,研究成果为冲击地压巷道提供一定参考与借鉴意义。

     

    Abstract: In rockburst roadway, the impact load will cause the interaction force between the components of bolt support system and surrounding rock to increase sharply, and the supporting plate is prone to deformation and failure under high force. In view of the above problems, the mechanical properties of three kinds of arched supporting plates and their combined components commonly used in coal mines were tested by using a microcomputer-controlled electro-hydraulic servo testing machine and a self-developed drop hammer impact testing device. The static load-displacement curve, impact time-history curve, displacement time-history curve and deformation and failure characteristics of the samples were obtained, and the impact resistance of anchor supporting plates and combined components was analyzed. The results show that under the static load, the bearing capacity of the supporting plate is 228-243 kN, and the maximum deformation is 14.10 mm. The deformation characteristics are as follows: the arch height is reduced, the four corners are tilted, and the connecting parts are transferred to the center of the circle. Under dynamic load, the deformation of the supporting plates all experienced three stages: arch height reduction, four corners lifting and flattening. When the impact energy was 500-3 000 J, the impact time-history curve showed a sharp rising stage, a shock stage and a rapid decline stage, while when the impact energy was 3 500-5 000 J, the impact time-history curve showed a sharp rising stage, a shock steady load stage, a shock rising stage and a rapid decline stage. With the increase of impact energy, the peak values of impact force of the samples are gradually increased. Compared with its static load, the peak value of dynamic load of the supporting plate sample is obviously larger than its static load. The displacement time-history curve of the samples can be divided into two stages: elastic-plastic deformation and springback deformation. In the elastic-plastic deformation stage, the deformation is linearly related to the acting time, and the average acting time of the maximum deformation of the positive, negative supporting plates and combined components accounts for 68.66%, 69.25% and 66.66% respectively. In the springback stage, the average elastic deformation of the three samples is 1.71, 1.84 and 3.23mm respectively. In the whole impact process, the impact energy average conversion rates of the three samples are 96.82%, 97.33% and 93.78%. Generally speaking, the positive and negative impact mechanical properties and deformation characteristics of the supporting plate are consistent. Compared to single supporting plate, the combined components can achieve the functions of energy absorption, prolonging the overall impact time, shortening the impact time and improving the bearing characteristics of the supporting plate. The research results provide some reference for the selection of supporting plate and combined components for the bolt support of rock burst roadway.

     

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