螺纹钢与圆钢锚杆工作机理对比试验研究

为深入研究以螺纹钢为杆体的全长粘结砂浆锚杆锚固机理，进行了螺纹钢锚杆与圆钢锚杆对比试验研究。试验结果表明拉拔条件下螺纹钢受力范围相对圆钢小且衰减快；螺纹钢周边浅部粘结物应力水平高于圆钢周边粘结物应力，且其变形破坏更显著：螺纹钢以屈服形式破坏而圆钢则整体拔出。通过试验分析了螺纹钢由于存在螺纹起伏使其与粘结物之间存在明显挤压、剪胀、剪断等作用从而较大地提高了锚固强度。

TESTING STUDY ON WORKING MECHANISM OF FULLY GROUTED BOLTS OF THREAD STEEL AND SMOOTH STEEL

In order to study the bolting mechanism of full grouted bolt,a pull-out test of thread steel and smooth steel is carried out. The test results show that the depth of load distribution along thread steel is lower than that along smooth steel and the stress in thread steel attenuates quickly under tensile load. At the same time the test results show that the load distribution along the bolt of thread steel is the same with the result of elasticity theory under lower loads. The stress in superficial part concrete around thread steel is higher than that around smooth steel and the failure in superficial part of concrete around thread steel is more obvious. The thread steel bolt yields and the smooth steel bolt is pulled out under tensile loads of 280 and 300 kN,respectively. At last it is pointed out that there are compression,dilatancy and shear failure at the thread tendon and grouting interface and bond strength is enhanced significantly,which is the reason why the bond strength of thread steel bolt is higher. But there are only cohesion and friction at the smooth steel and grout interface,so that the bond strength is lower.