螺纹钢锚杆搅拌树脂锚固剂端部形态优化试验研究

Experimental study on optimization of end shape of mixed resin of rebar bolt

常用的树脂锚固剂是实现螺纹钢锚杆与围岩黏结的重要介质,其工作性能对锚固质量存在重要影响,螺纹钢锚杆端部搅拌树脂锚固剂是锚固的关键步骤。为明晰螺纹钢锚杆端部搅拌树脂锚固剂问题,基于已有成果分析了螺纹钢锚杆搅拌端部类型,重点对双楔形端部搅拌树脂锚固剂进行了力学分析,得到了加制“V”型槽双楔形搅拌端效果良好的理论基础。锚杆端部加制“V”型槽有助于锚杆端头刺入锚固剂封袋,增加锚固剂所受的旋转力,更好破坏锚固剂封袋,增强锚固剂的搅拌效果;拉拔实验发现,双楔形角在60°~75°,随着双楔形角的增大,锚杆的拉拔力有逐渐递增的趋势,在双楔形端部加制“V”型槽的螺纹钢锚杆锚固时,平均拉拔力峰值比未加制“V”型槽的提高了22%,比传统原型锚杆提高了62%,相比于锚杆有横肋双楔形搅拌端,无横肋双楔形搅拌端的平均拉拔力峰值下降了约16%;通过高速动态非接触全场应变测试系统观察搅拌过程发现,锚杆原型搅拌端搅拌锚固剂时其封袋是被搅拌端挤压、摩擦破坏的,且破坏过程中锚固剂封袋几乎没有发生扭曲;锚杆单楔形搅拌端搅拌锚固剂时锚杆单楔形尖端从锚固剂与孔壁之间的空隙插入,将锚固剂推入孔壁的一侧进行挤压、旋转,并从锚固剂侧面破袋;锚杆双楔形搅拌端搅拌锚固剂时,双楔形端部使锚固剂封袋顶部产生凹陷、挤压、扭曲,最终使锚固剂封袋破坏,在双楔形端部加制“V”型槽后,锚固剂封袋发生更大扭曲,更有助于破坏锚固剂封袋,使树脂胶泥与固化剂充分混合,提升搅拌效率。

The commonly used resin is an important medium for realizing the bonding between rebar bolt and surrounding rock,and its work performance has an important influence on anchoring quality.The key step of anchoring is to stir the resin with the end of bolt.In order to clarify the problem of mixing resin at the end of threaded steel bolt,based on the existing results,the types of the mixing end of rebar bolt are analyzed,and the mechanical analysis of the double-wedge-shaped end mixing resin is carried out.The theoretical basis for the good effect of adding“V”groove double wedge-shaped stirring end is obtained.The“V”-shaped groove added to the end of bolt helps the end of bolt to pierce the resin sealing bag,increasing the rotation force of resin,better destroying the resin bag,and enhancing the mixing effect of resin.Experiments have found that the cutting angle is in the range of 60°-75°,and the pull-out force of bolt has a gradually increasing trend with the increase of cutting angle.When the rebar bolt with“V”grooves are added to the double wedge-shaped ends,the average pull-out force peak is 22%higher than that without“V”grooves and 62%higher than the traditional prototype bolts.Compared with the double-wedge-shaped mixing end of bolt with transverse ribs,the average pull-out force peak of the double-wedge-shaped mixing end of bolt without transverse ribs has been reduced by about 16%.By observing the mixing process through the high-speed dynamic non-contact full-field strain test system,it was found that the mixing end of traditional bolt is mixed resin,resin bag is squeezed and frictionally damaged by the mixing end,and no twist occurred during the destruction of resin bag.The single-wedge-shaped mixing end of bolt is inserted into the gap between the resin and the borehole wall when the resin is mixed,and the resin is pushed into one side of the borehole wall to squeeze and rotate,and the bag is broken from the side of the resin.When the double-wedge-shaped mixing end of bolt mixes the resin,the double-wedge-shaped end of bolt causes the top of resin bag to be dented,squeezed and twisted.Finally the resin bag is destroyed.The“V”groove is cut at the double-wedge-shaped end of bolt,which makes resin bag more twisted,and is more helpful to destroy resin bag,so that resin can be mixed more fully and the mixing efficiency of resin can be improved.