微破损拔出法测试喷射混凝土强度

Shotcrete Strength Measured with Micro Failure Drawn Method

论述拔出法测定喷射混凝土的工作原理，测定基本参数，测试仪表和机具，拔出测试过程。

The micro failure drawn method is a method to measure the strength fc of concrete with the measured drawn force of anchored part out from the shotcrete.The principle of the drawn measuring method is based on a certain relationship between the drawn force f (drawn strength)and the compressive strength of the concrete cubic.And the drawn strength of the concrete is close to the compressive strength of the concrerte.There are two drawn measuring methos.One is a drawn measuring method with preset anchored material and the other is a method with later bore hole set anchored material.The later bore hole set anchored material drawn method is to make a bore hole,mill and set a swelling spring in the shotcrete having a final strength,then to make a drawn and failure test.The diameter of the bore hole is 16 mm and the depth of the hole is 40 mm.At the depth of 25 mm in the hole,a slot ring should be made and then a swelling spring should be set in the slot ring.After measured the drawn force,the strength of the concrete can be calculated.This method has been put a trial in the Hebi Coal Mining Administration.The regression formula of the shotcrete strength measured fc cu is fc cu =2 95f+0 07(Mpa).F is a drawn force (kN).