Rock deformation modulus is one of the key parameters for the design and construction of underground rock engineering. Obtaining accurate rock deformation modulus is crucial for a comprehensive analysis of the deformation behavior of the surrounding rock in deep rock engineering. To achieve this goal, the commonly used methods for calculating rock deformation modulus are systematically sorted out and summarized. Furthermore, the rock deformation modulus is inverse-calculated by simulating in-situ tests using the finite element method, and the results are verified and analyzed by comparing them with the in-situ test results. For the actual project of deep shaft, a numerical calculation model is established to conduct an inversion analysis of rock deformation modulus of different lithologies in the deep strata. Additionally, a sensitivity analysis is performed on different strength criteria, Poisson's ratio and rock cohesion on rock deformation modulus. Finally, the numerical simulation inversion results are compared and discussed with the empirical formula calculation results. The results show that the values of rock deformation modulus obtained from numerical inversion using finite element method are in good agreement with those calculated based on the experimental rigid plate load test; While Poisson's ratio does have some influence on rock deformation modulus, the sensitivity of rock deformation modulus to Poisson's ratio is generally low; When the cohesion of the rock mass is small, the choice of strength criterion has a significant influence on the inversion results of deformation modulus, and vice versa; the sensitivity of the rock deformation modulus to the changes of the rock cohesion varies depending on the depth and lithology of the strata; the deformation modulus of the rock mass obtained by numerical inversion has a good correlation with some empirical equations. Therefore, the numerical simulation and empirical formulae are useful during planning, design and development of deep rock projects to perform the inversion calculation of rock deformation modulus, thereby ensuring greater safety and economy.
Cemented paste backfill is a suspension composed of solid-liquid-gas three-phase.For a long time,the focus has been mostly on the rheological behavior of solid-liquid two-phase,while the effect of gas phase on slurry with com-plex rheological behavior remains obscure.The gaseous phase components can significantly reduce the yield stress and viscosity of high-concentration backfilling slurry,which plays a significant role on improving pipeline transportation per-formance and reducing pipeline wear.In order to reveal the mechanism of bubbles to its rheological properties of slurry,the gas content of slurry was controlled by adjusting the content of air entrainment agent(TTAB),and tests such as sur-face tension,air content and rheological properties were carried out to find out the influence of bubbles on the rheological behavior of slurry,and capillary force(Fcay)and the bubble evolution model of dimensionless yield stress(τref/τy)were in-troduced to analyze the bubble evolution characteristics in the slurry and reveal the mechanism of bubbles on the rheolo-gical properties of slurry.The results showed that under the low gas content(＜12.5％),the gas phase had little effect on the rheological behavior of the suspended slurry.As the increase of gas content,the effect of bubbles on the rheological behavior of backfilling slurry was immense.Under the action of the air-entraining,the bubble surface had a repulsive force on the fine particles in the slurry,and could reduce the adsorption capacity of cement and solid waste,resulting in a de-creasing trend of slurry yield stress and increasing fluidity.Based on capillary force(Fcay)and dimensionless yield stress theory(τref/τy),evolutional mechanism of rheological properties of slurry in different gas content was analyzed.It could be seen that as the gas content increased(12.5％-27.7％),the surface tension and yield stress of slurry decreased,and the bubble would be deformed by extrusion.When the gas content(28.6％)was high,the bubbles in the slurry were easy to burst.In addition,bubbles,retained inside the backfilling body,leading to strength degradation,so the effect of bubbles on the mechanical properties of the backfilling body and its solution were explored and three effective measures were pro-posed.By revealing the effect of bubbles on the rheological properties of suspension slurry and its evolution characterist-ics,it provides theoretical support for the development of high bubble filling,which can achieve the goal of drag reduc-tion and friction reduction.
With the increase in the depth of metal resource development,the layout of the mining project is affected by the complex geomechanical environment,and serious ground pressure disasters such as large deformations and rock bursts are prone to occur.Aiming at the typical characteristics of deep mines in the Jiaodong area,this article summarizes several support theories commonly used in the field of metal mines,summarizes the failure modes of deep mine support systems,and analyzes existing problems and deficiencies.It is proposed that the future support design of deep mines should be based on mine geological information and rock mechanics data,and the energy-absorbing support technology research should be carried out according to the high stress characteristics of deep rock masses.At the same time,attention should be paid to the evaluation of the support system,using evaluation data and basic geological data of the mine as training samples,and establishing an intelligent decision-making system for support based on deep learning and artificial intelligence technology.
