Damage constitutive model and damage evolution characteristics of gangue cemented backfill with different moisture contents based on energy dissipation
Xiang Yu , Ke Yang , Xiang He , Yong-qiang Hou , Zhen Wei , Shu-xin He
Journal of Central South University ›› 2026, Vol. 33 ›› Issue (6) : 2651 -2681.
To reveal the influence of moisture content on the mechanical properties and damage of gangue cemented backfill, uniaxial compression tests were carried out on gangue cemented backfill with four different moisture contents (dry, natural, immersed, and saturated). The influence of moisture content on the characteristic parameters, energy evolution, distribution characteristics and peak point energy index of gangue cemented backfill was considered. The unit characteristic change rate and unit energy change rate were proposed to describe the degree of variation in the characteristic parameters and peak point energy indicators with moisture content. From the perspective of energy dissipation, a damage constitutive model considering the initial compaction closure and post-peak failure stages was established, and the model was revised to compensate for the shortcomings of the current damage constitutive model research. The stress – strain curve of the gangue-cemented backfill before reaching the saturated state exhibited a typical four-stage characteristic, whereas the gangue-cemented backfill in the saturated state lost the initial compaction closure stage. The characteristic parameters of the cemented gangue backfill decreased in the form of a quadratic function with the increase of moisture content. The unit characteristic change rate gradually decreased with the increase of moisture content, and the decreased amplitude gradually increased, indicating that the order of the influence of moisture state on the unit characteristic change rate of gangue cemented backfill was: drying effect < immersion effect < saturation effect. The energy evolution law of gangue cemented backfill with different moisture contents was consistent with the stage characteristics of the stress – strain curve. Before the saturated state, the elastic energy ratio curves of the gangue-cemented backfill all showed a trend of first increasing and then decreasing, whereas the dissipation energy ratio curves showed a trend of first decreasing and then increasing. The order of influence of the moisture state on the unit energy change rate of the total strain energy and elastic energy of the gangue-cemented backfill was as follows: drying effect < immersion effect < saturation effect, while the order of influence on the unit energy change rate of the dissipated energy was as follows: saturation effect < immersion effect < drying effect. With the increase in the moisture content of the gangue-cemented backfill, the failure mode of the backfill mainly underwent a transformation from tensile failure to tensile-shear mixed failure and then to “V” -shaped shear failure. The modified damage constitutive model based on energy dissipation considering the initial compaction closure stage and the post-peak failure stage has a high consistency with the test curve, and the energy dissipation curve and damage evolution curve of the cemented gangue backfill with different moisture content were also consistent. When the dissipation energy curve reached the threshold, the damage evolution curve also reached the threshold. These results provide a theoretical basis for studying the long-term stability of gangue-cemented backfill with different moisture contents in the goaf.
gangue cemented backfill / compressive strength / energy evolution / dissipation energy / damage constitutive model
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Central South University
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