Research on Strength Model of Cemented Tailings Deposit Body in Underground Tailings Reservoir

Due to the lack of clarity in the strength design of underground tailings reservoirs, it is imperative to investigate the interaction between the tailings deposit body (TDB) and surrounding rock. Taking the TDB as the subject of analysis, a differential equation for vertical stress on the TDB is proposed, considering the stresses from the hanging wall of the surrounding rock and physical and structural parameters of the TDB. Considering the similarity between the underground tailings reservoir and one-step subsequent filling, in situ data of the one-step subsequent filling body from a mine was utilized to compare calculated values of the theoretical model. The resulting theoretical prediction error was less than 10%, thus verifying the reliability of the proposed model. According to the theoretical model analysis, the height of the TDB exerts the most significant influence on vertical stress, while the width and length of the TDB have a negligible impact. Moreover, internal friction angle has a more pronounced effect on vertical stress than cohesion force. A case study for a lead-zinc mine in China is presented in this work. Through uniaxial compressive strength and triaxial shear experiments, the key mechanical parameters of TDB at different ratios of cement to tailings are obtained. According to the theoretical model proposed herein, the distribution law of vertical stress in the height direction of TDB is determined for various ratios of cement to tailings. The original technical scheme of the mine has been optimized by using uniaxial compressive strength greater than vertical stress as the evaluation index, achieving both storage safety and cost reduction goals.