Abstract: A fractured rock model is established with discrete fracture network(DFN); and then the relationship between fracture frequency and the Hoek-Brown parameters is deduced. By using the particle flow code, the anisotropy of rock mass strength before and after grouting is calculated; and the stress-strain curve is acquired along different directions and with different cohesive forces. With analyzing the physical meaning of the Hoek-Brown parameters, rock mass strength curve after grouting is fitted; and the influencing rule of grouting effect is analyzed. Results show that, after grouting, the compressive strength is improved significantly and the anisotropic property is decreased. The mechanical property of the rock mass changed from ductile to brittle. When the confining force is low, the compressive strength calculated from the model is different from that of the Hoek-Brown criterion; and the difference decreases when confining force increase. Based on the quantitative relationship between JCond and the Hoek-Brown parameters, the influencing law of grouting reinforcement on rock mass strength is acquired. The parameters is influenced to a larger extent by grouting effect. Since the parameter mb represents the own strength property of rock mass, while s represents the broken degree, the performance of grouting effect and the physical meaning match with each other, which proves the rationality of this model.

Key words: fractured rock mass, grouting reinforcement, Hoek-Brown criterion, numerical simulation