Hyper-gravity experiment of solute transport in fractured rock and evaluation method for long-term barrier performance

Hyper-gravity experiment enable the acceleration of the long-term transport of contaminants through fractured geological barriers.However,the hyper-gravity effect of the solute transport in fractures are not well understood.In this study,the sealed control apparatus and the 3D printed fracture models were used to carry out 1 g and N g hyper-gravity experiments.The results show that the breakthrough curves for the 1 g and N g experiments were almost the same.The differences in the flow velocity and the fitted hydrodynamic dispersion coefficient were 0.97–3.12%and 9.09–20.4%,indicating that the internal fractures of the 3D printed fracture models remained stable under hyper-gravity,and the differences in the flow and solute transport characteristics were acceptable.A method for evaluating the long-term barrier performance of low-permeability fractured rocks was proposed based on the hyper-gravity experiment.The solute transport processes in the 1 g prototype,1 g scaled model,and N g scaled model were simulated by the OpenGeoSys(OGS)software.The results show that the N g scaled model can reproduce the flow and solute transport processes in the 1 g prototype without considering the micro-scale heterogeneity if the Reynolds number(Re)
critical Reynolds number(Recr)and the Peclet number(Pe)
the critical Peclet number(Pecr).This insight is valuable for carrying out hyper-gravity experiments to evaluate the long-term barrier performance of low-permeability fractured porous rock.