Effect of anchoring force by adding steel aggregate in resin anchoring agent
ZHANG Ming1 ,CAO Chen2,3 ,ZHANG Huaidong1 ,TRAN Vancong1 ,REN Ting2,3 ,MA Shuangwen1 ,HAN Jun1,3
本次实验研究对钢质骨料添加剂的外形、粒径和浓度进行了优化,以提高树脂锚固剂在破坏界面的抗剪能力和改变原锚固剂的直剪破坏方式来直接改善整个锚固系统的加固效果,进一步提高了钢质骨料对试件锚固力的增强程度。试验通过向散装慢速树脂锚固剂中分别添加粒径为1.5,2.0,2.8 mm的钢砂和1.4,2.0,2.5 mm的钢丸,每种粒径的钢质骨料又分为30,40,50共3种数量;使用矿业20 mm右旋螺纹钢锚杆和长度100 mm、内径30 mm、壁厚7.0 mm的钢套筒制作锚固试样;然后使用电液伺服万能试验机,加载方式为2 mm/min进行拉拔试验采集数据,并结合销栓作用相关理论分析不同钢质骨料添加剂对平均锚固力的影响。试验数据表明:与无添加钢质骨料的锚固试件相比,向树脂锚固剂中添加钢砂和钢丸对锚固试件的平均锚固力分别为125.6,129.0 kN,提高了6.4%和9.4%;其中,添加粒径为1.4~1.5,2.0~2.0和2.5~2.8 mm的试件平均锚固力分别为127.6,124.7和129.6 kN,提高了8.1%,5.7%和9.8%,呈现先减小而后增大的趋势;而添加钢质骨料的数量增加对锚固力的提升程度呈现逐渐减小的趋势,即添加骨料数量为30,40,50的试件平均锚固力分别为128.5,127.2和126.2 kN,提升约8.9%,7.8%和6.9%。本次实验中最大锚固力提升来自添加数量为30、粒径为1.4 mm的钢丸,平均锚固力为135.1 kN,增加了14.5%。试验中的锚固剂破坏方式为剪切破坏,且钢质骨料产生的销栓作用对锚固剂破坏表面造成划痕,并根据锚固段破坏机理分析,进一步讨论了锚固剂抗剪强度及残余抗剪强度参数对锚固效果产生的重要影响。
In this experimental study,the shape,particle size and concentration of the steel aggregate additive were op- timized to directly improve the strengthening effect of the anchorage system by increasing the shear resistance of the resin anchoring agent at the failure interface and changing the original direct shear failure mode of the anchoring a- gent. Furthermore,the study enhanced the degree of reinforcement of the steel ag-gregate to the anchoring force of the specimen. The test was conducted by adding steel grit with a particle size of 1. 5,2. 0,and 2. 8 mm and steel shot of 1.4,2. 0,and 2. 5 mm to the bulk slow resin anchoring agent,and each particle size was further divided into 30,40 and 50 kinds in total. A ϕ20 mm right-lateral rebar and steel sleeve with length of 100 mm,inner diameter of 30 mm and wall thickness of 7. 0 mm were used to make anchoring specimens. Then,an electro-hydraulic servo universal tes- ting machine with 2 mm / min of loading mode was used to collect data for the pullout test,and the effects of different steel aggregate additives on the average anchoring force were analyzed based on the theory of doweling effect. The test data showed that the average anchoring force of the anchoring specimens with the steel grit and steel shot is 125. 6 and 129. 0 kN,respectively,increasing by 6. 4% and 9. 4% ,comparing with the specimens without adding steel aggregate. Among them,the average anchoring force of specimens with particle sizes of 1. 4-1. 5,2. 0-2. 0 and 2. 5-2. 8 mm is 127. 6,124. 7 and 129. 6 kN,respectively,which increased by 8. 1% ,5. 7% and 9. 8% ,showing a trend of decreasing first and then increasing. While the increase in the amount of adding steel aggregates presents a gradual decrease in the degree of improvement of anchorage force,i. e. ,the average anchoring force of the specimens with the aggregate amount of 30,40,50 is 128. 5,127. 2 and 126. 2 kN, respectively, with an increase of about 8. 9% ,7. 8% and 6. 9% . In this experiment,the maximum anchorage force is increased by 14. 5% ,with an average anchorage force of 135. 1 kN,from steel shot with an added quantity of 30 and a particle size of 1. 4 mm. The failure mode of the ancho- ring agent in the test is shear failure,and the doweling effect produced by steel aggregate causes scratches on the fail- ure surface of the anchoring agent. According to the analysis of the failure mechanism of the anchorage section,the im- portant effects of shear strength and residual shear strength parameters of the anchoring agent on the anchoring effect are further discussed.
resin anchoring agent;steel aggregate;anchoring force;doweling effect
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会