土层BFRP锚杆现场拉拔试验研究

The Research of BFRP Anchor Drawing Test in Soil Layer

新型BFRP锚杆作为一种抗拉强度高、质量轻、耐腐蚀性强、抗震性与疲劳性俱佳的玄武岩纤维锚杆,现已走入土木工程的支护结构,有逐渐替换传统钢性锚杆的趋势。但其第一、二界面的力学传递性能研究还不够完善,针对这一问题,本文将从不同直径、不同成孔方式、是否带扩大头三方面展开研究,得出以下结论:(1)直径越大极限拉拔力越大。当锚杆较细时放置过程中容易出现偏心情况,且锚固体完整程度越差;(2)相同直径下不带扩大头,极限拉拔力挤风1#>取3#>挤1#,但是三种者差距很小,说明在考虑第一界面破坏的情况下成孔方式对BFRP锚杆极限拉拔力对基本没有影响;(3)对比挤密成孔和风钻成孔,第一界面强度带扩大头的锚杆要高于不带扩大头11~16%左右,风钻成孔下的第一界面强度无论锚杆是否带扩大头均大于挤密成孔;(4)挤密成孔条件下,由于锚固长度只有1m,且孔壁较光滑,第一界面的强度是第二界面强度的2.5~3倍,建议工程中适当加大锚固长度,采用高压注浆来增大第二界面的强度;(5)根据锚固体上的裂缝分布和破坏情况,从上至下依次将其分为拔出裂缝、应力集中裂缝和低强度裂缝。

As a kind of basalt fiber anchor with high tensile strength, light weight, strong corrosion resistance, good shock resistanceand fatigue resistance, the new BFRP anchor has now entered the support structure of civil engineering and has the trend of graduallyreplacing the traditional steel anchors. However, the study of the mechanical transfer performance of the first and second interfaces is notperfect enough. In view of this problem, this paper studies from different diameters, different pore-forming methods and whether haveenlarged head, and draws the following conclusions： 1 The larger the diameter, the greater the ultimate pull force. When the anchor rod isthin, the eccentricity is likely to occur during the placement process, and the integrity of the anchor is worse; 2Without the enlarged headat the same diameter, the sequence of ultimate drawing force is the wind 1#〉 take 3#〉 squeezes 1#, but the difference among the three issmall, indicating that the hole forming method has no effect on the ultimate drawing force of the BFRP bolt by in consideration of the firstinterface failure; 3Comparing the compacted holes and wind drilled hole, the anchor whose first interface strength with enlarged head ishigher 11~16% than that without enlarged head, and the first interface strength under the wind drilled hole is no matter whether the anchorhas enlarged heads are larger than the compacted holes; 4Under the condition of compacted holes, since the anchoring length is only 1mand the wall of the hole is smooth, the strength of the first interface is 2.5~3 times of the strength of the second interface. It is recommendedto increase the anchoring length appropriately in the project and uses high pressure grouting to increase the strength of the second interface;5according to the distribution and damage of the crack on the anchor, it is divided into the extraction crack, the stress concentration crackand the low strength crack from top to bottom.