METHOD FOR DETERMINING CONSTANT MI AND INTENSITY ENVELOPE IN HOEK-BROWN CRITERION BASED ON DIGITAL DRILL PARAMETERS

The invention discloses a method for determining a constant mi and a strength envelope line in a Hoek-Brown criterion based on digital drill parameters, which comprises the following steps of: firstly, carrying out a digital drill experiment to obtain the digital drill parameters, obtaining a relation curve of cutting force Ft and thrust Fn according to the relation between the Hoek-Brown criterion and the digital drill parameters, and determining the constant mi and the strength envelope line in the Hoek-Brown criterion according to the relation curve of the cutting force Ft and the thrust Fn. Calculating a front angle alpha of the drill bit and a rock contact friction angle theta of a cutting surface and an end surface of the drill bit; calculating a friction angle between a compression area and a complete rock and an internal friction angle of the rock, drawing a relation curve of a cutting force Ft relative to a thrust Fn, obtaining a curve intercept b, and calculating a constant mi in a Hoek-Brown criterion; the theta and the intercept b are substituted into an equation of the cohesive force c of the rock to calculate the cohesive force c, and then the uniaxial compressive strength UCS of the rock is calculated; and substituting the calculated constant mi and the uniaxial compressive strength UCS into an H-B criterion, and further calculating the triaxial compressive strength TCS of the rock. The problem that the accuracy, scientificity and simplicity of an existing constant mi calculation method cannot be guaranteed is solved.