Creep behaviour in rocks is a typical mechanical property that is directly linked to the stability of underground engineering. The deformations and rate of rocks creep are not only influenced by time but also by the loading and unloading history. To more accurately predict creep mechanical behaviour of salt rocks, the rocks hardening is described by introducing a state variable. A new three-dimensional creep constitutive model of salt rocks was established to describe the loading and unloading history effect of the rheological properties. In this paper, salt rocks creep tests under various loading and unloading histories were conducted to investigate how different loading routes affect the creep behaviour of salt rocks. The effects of the model state variables were analysed through different indicators. An example verification was carried out with the results of plastic deformation tests performed at different loading paths. The findings indicated the creep rate of stepped loading and the stepped unloading under the same stress level were significantly affected by the loading history. The proposed constitutive model can accurately fit the creep test curves of different loading paths, indicate that it can provided a prediction of the historical effect of the creep behaviour of salt rocks. Different parameters affect the different phases of the creep curve. The parameter k primarily affects the overall shape of the creep curves. Parameters m and c primarily influence the steady-state creep length and creep rates, excluding the initial cycle.

The stability of the bottom structure and the scientific management of ore drawing are critical to the successful application of the block caving method. In view of the engineering conditions of the Lower Orebody of the Cukaru Peki Copper-Gold Mine operated by Serbia Zijin Copper Doo Bor characterized by great burial depth, high in-situ stress, and large-scale mechanized ore extraction. This study systematically optimizes the layout form and key geometric parameters of the bottom structure through a comprehensive approach combining engineering analogy, theoretical analysis, numerical simulation, and orthogonal experimental design. The results indicate that, in terms of the layout at the extraction level, the branching herringbone configuration is the optimal scheme. It not only ensures sufficient overlap of draw zones and stability of the sill pillar, but also better accommodates the efficient operation of electric load–haul–dump (LHD) machines. Regarding key parameter determination, coupled analyses of vertical and planar geometric relationships demonstrate that the optimal vertical distance between the extraction level and the undercut level is 20 m. The spacing of drawpoint crosscuts and drifts is determined to be 32 m and 18 m, respectively. The optimized dimensions of the ore pass are identified as 5.0 m for the lower opening width and 14 m for the upper opening width, which significantly reduce the incidence of drawpoint hang-ups. For the undercutting scheme, an advancing undercut method combined with an inclined narrow-section layout is recommended, with an undercut height of 6 m. Furthermore, numerical simulations reveal the influence of the advanced undercut distance on stress redistribution. It is recommended that a reasonable distance of 30–36 m be maintained between ore pass operations and the advancing undercut front to effectively mitigate structural damage caused by high stress concentrations in the bottom structure. The parameter system established in this study provides a scientific basis for the safe and efficient exploitation of the Cukaru Peki deposit operated by Serbia Zijin Copper Doo Bor and offers important engineering guidance for bottom structure design in similar deep block caving mines.