锈蚀锚杆与砂浆黏结机理试验研究

锚杆通常工作于软弱破碎的不良地质环境中,岩土介质及地下水中存在的腐蚀性介质、干湿交替、永久浸泡、密闭潮湿、杂散电流、双金属作用等各种因素,都会引发锚杆锈蚀。锈蚀使锚杆表面性状改变,从而影响杆体与砂浆之间的有效黏结,导致锚杆极限抗拔力下降。基于拉拔试验,研究了锈蚀及锈蚀部位对锚杆极限抗拔力和黏结性能的影响机理。结果表明:锚固段无锈蚀试件的极限抗拔力明显高于锚固段发生锈蚀的试件,并且锚固段前段锈蚀对锚杆极限抗拔力的不利影响最大,因此,锚固段前段是锚杆与砂浆黏结的关键部位。试验数据证实锈蚀在锚杆与砂浆界面间起"润滑"的不利作用,破坏了应力由锚杆到砂浆的有效传递路径,是导致锈蚀锚杆极限抗拔力下降,锚固端滑移量增大的主要原因。

Experimental study on bonding mechanism between corroded bolts and grout

Bolts are always subjected to corrosion due to complicated and unfavorable environmental factors such as aggressive medium,alternation of wetting and drying,permanent immersion,stray earth and bimetallic corrosion.Corrosion might make the bonding mechanical behavior inferior,and even make bolts disabled.Pullout tests were carried out to investigate the mechanism of influence on the bond property and uplifit resistance of bolts in terms of corrosion and its position.It was demonstrated that the ultimate uplifit resistance of non-corroded bolts was evidently greater than that of corroded bolts,and that of the corroded bolts in the front part along the anchor was obviously smaller than that in the middle and rear parts.Therefore,the front part along the anchor was the key region to the bonding mechanical behavior between bolts and grout.It was also shown that corrosion products acted as lubricant,resulting in the degradation of bonding mechanical behavior by breaking the effective transfer of stress from bolts to grout.