Abstract
Aiming at the acid-etched freeze-thaw rock for geotechnical engineering in cold regions, chemical damage variables, freeze-thaw damage variables, and force damage variables were introduced to define the degree of degradation of rock materials, the law of damage evolution, the total damage variable of acid-corroded rock under the coupling action of freeze-thaw and confining pressure was deduced. The continuous damage mechanics theory was adopted to derive the damage evolution equation and constitutive model of acid-eroded rock under the coupling action of freeze-thaw and confining pressure. The theoretical derivation method was used to obtain the required model parameter expressions. Finally, the model’s rationality and accuracy were verified by the triaxial compression test data of frozen-thawed rocks. Comparing the test curve’s peak point with the peak point of the model theoretical curve, the results show that the two are in suitable agreement. The damage constitutive model can better reflect the stress-strain peak characteristics of rock during triaxial compression, verifying the rationality and reliability of the model and the method for determining the model parameters. The model extends the damage model of rock under the coupling action of freeze-thaw and confining pressure in the chemical environment and further reveals the damage mechanism and failure law of acid-corroded rock under the coupling action of freeze-thaw and confining pressure.
Highlights
In the construction process of cold region projects, more complex rock engineering problems have been encountered
Compare the peak points of the stress-strain curve under different freeze-thaw cycles and different confining pressures with the peak points of the model’s theoretical curve, as shown in Figures 1 and 2 By comparing the experimental curve’s peak points and the theoretical curve, the results show that the two are in suitable agreement, indicating that the established rock freeze-thaw-confining pressure coupled damage constitutive model can better reflect the stress-strain peak value of the rock during triaxial compression characteristic
The theoretical curve can reflect the trend of rock strength and deformation with the number of freeze-thaw cycles and confining pressure, indicating that the constitutive model established in this paper, including the coupled damage evolution equation of rock freeze-thaw-confining pressure, can fully reflect the characteristics that the strength of freeze-thaw rock depends on the confining pressure
Summary
In the construction process of cold region projects, more complex rock engineering problems have been encountered. There are still some shortcomings, mainly in the following three points: (1) the current research results mainly focus on the effects of chemical solutions and freeze-thaw cycles on the macroscopic mechanical properties of rocks; (2) there are few studies on the mechanical properties of rock damage through the establishment of freeze-thaw damage constitutive models, and most of them do not consider the effect of confining pressure and are limited to unidirectional stress; (3) there is a lack of research on constitutive models of acid-corroded rocks, and research on freezethaw damage models of acid-corroded rocks is rare. Taking the D-P criterion as rock strength criteria, and based on the Lemaitre strain equivalence assumption, the damage evolution equation and constitutive model of rock under the combined action of chemical-freeze-thawing-load were established. The damage model of the coupling of freezethaw and confining pressure under chemical corrosion was expanded, and the damage mechanism and failure law of acid-etched rock under the coupling of freeze-thaw and confining pressure were further revealed
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