锚杆托板与缓冲垫层组合结构静、动载力学性能试验研究

Experimental study on static and dynamic mechanical properties of composite structure of anchor plate and cushion

针对锚杆支护系统受到冲击载荷作用时,围岩与托板间作用力瞬间增加,造成托板过载弯折、撕裂及接触区域围岩破裂、塌落等问题,采用实验室试验的方法,搭建了托板与缓冲垫层组合试样静、动载测试试验台,分别测试了5种组合结构托板的静、动载力学性能,获取了组合结构的静载力-位移曲线、冲击力时程曲线及应变时程曲线;研究了不同冲击载荷下组合结构的力学响应规律,分析了缓冲垫层材质、厚度对组合结构抗冲击性能的影响。试验结果表明:静载作用下缓冲垫层对托板变形形态有一定影响,刚度高的缓冲垫层会增加托板的变形量,但也会降低组合结构的峰值载荷;垫层厚度主要影响组合结构的变形能力,对承载力影响不大。不同冲击能量下托板的冲击力峰值基本相同,托板在较低的冲击能量下已达到峰值承载力,动载峰值承载力与静载最大承载力基本相同。不同冲击能量下托板变形明显不同,托板对角线上部的变形相对较小,中线上部的变形相对较大;缓冲垫层能降低组合结构的冲击力峰值,与未使用缓冲垫层相比,采用松木、橡胶垫、废旧皮带及泡沫铝缓冲垫层时,组合结构冲击力峰值分别降低21.45%,17.55%,25.40%和2.80%,冲击力作用时间分别增加了41.94%,24.52%,47.74%和65.16%,缓冲垫层可降低冲击力峰值,延长冲击作用时间,有效吸收冲击能量;垫层厚度对试样冲击力和应变影响较大,垫层厚度越大,吸收的冲击能量越多,冲击力峰值越小,冲击力作用时间越长,垫层缓冲性能越好,合适的垫层材料和厚度能有效降低冲击载荷对托板结构的破坏效应。总体来看,与单独使用托板相比,4种缓冲垫层均能实现吸能减冲,不同缓冲组合结构的垫层对抗冲击性能影响不同,缓冲垫层吸能效果从优到劣分别为泡沫铝、松木、废旧皮带及橡胶垫。

When the bolt support system is subjected to the impact load, the impact load causes the instantaneous increase of the force between surrounding rock and supporting plate, resulting in the overload bending and tearing of supporting plate, and the fracture and collapse of surrounding rock in the contact area. Using the method of laboratory test, the static and dynamic load test bench for the composite structure of supporting plate and cushion is built. The static and dynamic load mechanical properties of five composite structures are tested respectively. The static load displacement curve, impact force time history curve and strain time history curve of the composite structure are obtained, and the mechanical response law of the composite structure under different impact loads is studied. The effects of cushion material and thickness on the impact resistance of composite structure are analyzed. The test results show that the cushion has a certain effect on the deformation shape of the supporting plate under static load. The high stiffness of cushion will increase the deformation of supporting plate and reduce the peak load of the composite structure. The thickness of cushion mainly affects the deformation capacity of the composite structure and has little effect on its bearing capacity. The peak value of the impact force of supporting plate is basically the same under different impact energy, the supporting plate has reached the peak bearing capacity under low impact energy, and the peak bearing capacity of dynamic load is basically the same as the maximum bearing capacity of static load. Under different impact energy, the deformation of supporting plate is obviously different. The deformation of the upper diagonal of supporting plate is relatively small, while the deformation of the upper midline of supporting plate is relatively large. The cushion can reduce the impact force peak value of the composite structure. Compared with the bolt support system without cushion, the impact force peak value of the composite structure increased by 21.45%,17.55%,25.40% and 2.80% respectively when the pine, rubber cushion, waste belt and foam aluminum cushion were used. The impact force time increased by 41.94%,24.52%,47.74% and 65.16% respectively. The cushion could reduce the impact force peak, prolong the impact time and effectively absorb the impact kinetic energy. The cushion thickness has a great impact on the impact force and strain of the composite structure. The greater the cushion thickness, the more impact kinetic energy absorbed, the smaller the impact force peak value, the longer the impact force action time, and the better the cushion performance. The appropriate cushion material and thickness can effectively reduce the damage effect of impact load on the supporting plate structure. Overall, compared with the use of pallets alone, the four cushions have a certain degree of energy absorption and impact reduction. However, different cushions have different effects on the impact resistance of composite structures, and the energy absorbing effect of cushion is superior to inferior foam aluminum, pine, worn belts and rubber mats.