TESTING STUDY ON WORKING MECHANISM OF FULLY GROUTED BOLTS OF THREAD STEEL AND SMOOTH STEEL
螺纹钢与圆钢锚杆工作机理对比试验研究

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.