Method for determining long-term strength parameter of rock based on steady-flow variable-rate tangent line

Abstract

The invention discloses a method for determining a long-term strength parameter of rock based on a steady-flow variable-rate tangent line. The method comprises the steps: taking 0 to 90 degrees of a steady-flow variable-rate curve as an angle interval, making a tangent line every 10 degrees for the rock steady-flow variable-rate curve, obtaining an interval formed by intersection points of all tangent lines and a horizontal axis, selecting an interval with a smallest range in which an inflection point of a steady-flow variable rate is located, wherein a deviator stress value of the interval is a rock long-term strength parameter interval. By introducing the interval formed by the intersected points of the tangent lines of the steady-flow variable-rate curve and an X axis, the rock long-term strength parameter interval in which the inflection point is located is determined by controlling the angle of the tangent lines, so that the problem of a fuzzy inflection point in a rock sample with unconspicuous rheological properties in the traditional stress-strain isochronous curve cluster method and steady-flow variable-rate method can be solved, a specific interval number of the rock long-term strength parameter can be quantitatively determined by means of the tangent lines, and the interval of the tangent lines and a coordinate axis is used for representing the interval of the rock long-term strength parameters.

Description

technical field [0001] The invention relates to the field of rock mechanics and engineering, in particular to a method for determining long-term rock strength parameters. Background technique [0002] The long-term strength of rock is the focus of rock engineering long-term stability research, which has very important engineering background and significance. A more accepted definition of long-term rock strength is that the rock undergoes rheological phenomena under long-term constant external loads; when the external load is greater than or equal to a certain value, the rheological deformation of the rock will continue to increase and eventually fail. ; When the external load is less than a certain value, the rheological deformation rate of the rock will gradually decrease with time, and the rheological deformation will gradually converge, and the rock will not crack; the critical value of this stress level can be called the long-term strength of the rock. Theoretically, l...

AI Technical Summary

Problems solved by technology

The inflection point method widely used at present is to randomly select any one of the axial, circumferential or volume rheological rate curves for visual inspection of the sudden change point, so it is more random and inaccurate

In addition, when the stress-strain isochronous curve cluster method is obvious in rock rheological properties, the inflection points of the initial straight line segment and the later curve segment are more obvious, but if the rock rheological properties are not obvious, the curve inflection point is relatively vague. Difficult to get directly visually, the effect is not good

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