Analysis of anchor space-time effect and research of control technology considering creep of surrounding rock

Aiming at the failure mode of combined support of roadways between rock bolt and cable bolt,the constitutive model of surrounding rock and the constitutive model of anchorage body,which can reflect the accelerated creep of surrounding rock and the working characteristics of rock bolt respectively,are established based on the deformation characteristics of surrounding rock. The control effect of anchorage foundation location on the deformation of surrounding rock is analyzed by solving the creep equation of anchorage body. The result shows that the creep control mechanism of bolt support to surrounding rock can be summarized in two aspects:the first is to share the load of surrounding rock,the second is to increase the stiffness of surrounding rock and enhance the resistance to the deformation of surrounding rock. Giving a full play to the supporting performance of rock bolt,lengthening the supporting time of rock bolt and maintaining the stable working state of roadway need to meet two criteria:the load of rock bolt does not exceed the critical breaking load of rod,meanwhile,the anchorage foundation should be located beyond the plastic zone. It can maximize the bearing capacity of support system when the anchorage foundation of end-anchored form is located in the elastic surrounding rock. Under this circumstance,the end-anchored form,whose stress foundation locates in elastic rock mass and whose anchoring effect can occur rapidly after the deformation of surrounding rock,is better than a fulllength anchoring form. The butt long bolt has the advantages of large elongation and flexible anchor length,and it can solve the problems that the rock bolt of roadway,in the centralized transportation roadway of 3rd panel in western of Puhe coal-mine,is often pulled out and its cable bolt breaks easily.