Anchorage Mechanism And Anchoring Effect Of Joint Rockmass And Their Applications

Anchor technique is widely used in geotechnical engineering, while the mechanism of anchorage is still not known well. Analogical method or semi-theoretical, semi-empirical method are often adopt in most of the anchoring designs in engineering practice. Furthermore, it takes more traditional empirical method into consideration during the engineering design indeed. In present, mainly two kinds of numerical simulation methods, which are commonly used in simulating the anchorage mechanism, do not consider the effect of the fracture toughness change of anchored joint rockmass. In this thesis, the problem presented above is studied based on fracture and damage mechanics theories.According to the theory that the bolt and the joint plane have the same distortion, the optimal anchoring angle and distortion angle are discussed, which are following with the changes of the tangential joint displacement and joint friction angle. Based on the theory analysis, a rock-like material is chosen and corresponding fracture toughness tests are carried out to model the effect of anchorage on fracture toughness increment and retardation of crack. The change of fracture toughness K1c according to the anchoring position coefficient is obtained. The results show that the fracture toughness of anchoring specimens can increase 50% ~ 135%. Thus effect is taken into consideration in a 3-D elastic-plastic damaged constitutive model for intermittent multi-cracks rockmass. Finally, the model is used to analyze the stability of a XIAMEN tunnel project is carried out. The results show that considering the effect of fracture toughness increment and retardation of crack of anchorage, better effect of anchorage is reflected in numerical fracture and damage simulation.