Construction method for rock freeze-thaw damage constitutive model under action of constant confining pressure

Abstract

The invention discloses a construction method for a rock freeze-thaw damage constitutive model under the action of constant confining pressure. Based on a popularized strain equivalence principle, taking the joint action of two damage factors (freeze-thaw cycle and load) into consideration, the invention proposes an expression of a total damage variable. If the strength of a rock element body is subject to Weibull distribution, on the basis of a D-P failure criterion and geometrical conditions at peak points of a rock stress-strain curve, an expression of a random distribution variable F, a distribution parameter m and F0 is obtained, and a rock freeze-thaw damage constitutive model under the action of constant confining pressure is created. A triaxial compression experiment is carried out on a rock under the action of freeze-thaw cycle, and the experiment verifies the rationality of the model. The method disclosed by the invention is a method combined with theoretical derivation and experimental verification. The theoretical curve of the rock damage constitutive model created by the method is identical with the experimental curve, the mechanical behaviors of a rock under various confining pressures and freeze-thaw cycle numbers can be perfectly reflected, and a theoretical guidance is provided for designs and construction of cold-region projects.

Description

technical field [0001] The present invention relates to a rock damage constitutive model, specifically a method for constructing a rock freeze-thaw damage constitutive model under constant confining pressure, which is based on the generalized strain equivalence principle, assuming that the rock element body strength obeys the Weibull distribution, using A combination of theoretical derivation and experimental verification. Background technique [0002] my country's cold regions are widely distributed and rich in minerals, forests and land resources. Rock weathering caused by freeze-thaw cycles is one of the main geological disasters. With the intensification of resource development in cold regions in the west, railways, highways, During the construction and operation of civil engineering such as tunnels, more and more rocks under low temperature and temperature alternating conditions are touched. The rocks of engineering structures in cold regions are always in a certain str...

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Problems solved by technology

[0005] (1) At the experimental level, there are many studies on the macroscopic mechanical properties of freeze-thaw rocks, and there are few studies on damage mechanical properties through the establishment of rock constitutive models under freeze-thaw loads;

[0006] (2) Most of them are limited to unidirectional stress state, without considering the effect of confining pressure;

[0007] (3) Most of them only consider the conditions of external loads, and do not involve the effects of temperature effects and freeze-thaw cycles;

[0008] (4) In the previous studies, the rock constitutive model parameters were mostly based on test curve fitting, which not only had no clear physical meaning, but also could not reflect the internal mechanism of freeze-thaw damage and the general change law of the selected physical quantities. Versatility

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