Study On The Interaction Mechanism And Deformation Evolution Law Of Cemented Filling Body And Surrounding Rock

The traditional filling method focuses on the strength of cemented backfills after filling downholes,while ignoring the different strength cemented backfills present at different ages having different effects on the stability of surrounding rocks.Both the common carrying capacity of cemented backfills and surrounding rock directly affects the downhole.The stope’s high-efficiency and safe mining and stable deformation of the overlying rock strata,and the filling of the stope are subjected to a complex multi-axial stress environment.With Chengchao Iron Mine as the engineering background,the filling method and sub-column-less sublevel caving method have been jointly exploited and ensured that the surface selection plant secure fill stope requirements for safe and efficient recovery.In order to ensure the efficient and safe mining,the stability of the contact zone is ensured through the study of joint bearing problems between the cemented backfill and the surrounding rock,thereby ensuring that the sublevel caving method without bottom pillars does not affect the safety of the filling and mining area,and at the same time,through cemented backfills and enclosures.The common bearing of the rock ensures the stability of the overlying rock formations,which in turn ensures the safety of the surface plant.For this reason,the deformation evolution characteristics and bearing capacity of the backfill body and the surrounding rock mass under load are the key scientific issues for the stability analysis and evaluation of the contact zone.Therefore,the rock mechanics test,theoretical analysis,numerical simulation test and physical similarity simulation test are adopted.And on-site monitoring and other research methods,systematically studied the impact of different strength cemented backfill on the stability of the surrounding rock of the stope,and the problem of the evolution of the deformation of the cemented backfill and the surrounding rock.(1)With the safety factor cloud images,the evolutionary rule of deformation damage of stalactites with stochastic joints was quantitatively characterized.Based on stochastic grouping function,a stochastic numerical simulation method for stochastic ore-rock distribution was established.Aiming at the characteristics of complex stress,tight joint development and large distribution of gravel in the contact area between the filling body and the surrounding rock,laboratory tests and numerical simulations on the deformation damage of the intact ore rock,random joint and gravelly ores in the contact area were carried out.A random joint numerical model was established by systematic tracing method.Combined with pigment extraction software,the evolution law of deformation damage of random jointed ore strata was quantitatively characterized by the cloud graph of safety coefficient.A random distribution function was used to simulate the random distribution of rock strata.With the elasto-plastic theory,the influences of the distribution of different joints and the content of gravel on the stability of surrounding rock was obtained,which provided theoretical guidance for the stability evaluation of surrounding rock under different geological conditions in the contact area.(2)The creep energy accumulation method was proposed,the energy accumulation and release response of cemented filling body was studied,and the instability criterion of cemented filling body is established.The cemented filling body was divided into early and late stages by the deformation characteristics of cemented filling body at different ages.The laboratory tests and numerical simulations on the mechanics and deformation of early cemented filling bodies were carried out.Combined with hydrostatic pressure theory,the mechanical model of interaction between early cemented filling bodies and ore rock was established,and the influence of early cemented filling bodies on the stability of surrounding rock was obtained.The creep energy accumulation method was proposed.By integrating and deriving the constitutive equations,the softening normal tension and strain energy tensor are used to characterize the energy variation of cemented filling body.The energy accumulation and release of cemented filling body was studied.In response,a post-cemented filling body instability criterion was builded.The effect of surrounding cemented backfill on the surrounding rock was simplified as the mechanical model of simply supported beam.The long-term stability of the cemented backfill has the creep property,which was reduced to the model of the Visco-elastoplatic model.The stability of the simply supported beam was evaluated by the deflection calculation.The results revealed that the different time cemented filling bodies can exert energy transfer,accumulation and release to influence the stability of the surrounding rock through different degrees of deformation and squeezing constraints on the surrounding rock.(3)The relationship between the damage variables and the strength proportion coefficient and the corresponding relationship between the damage and the attenuation of the ultrasonic wave value were established,and the internal damage situation co-carried by the filling body and the ore-rock complex was quantitatively characterized.The acoustic emission apparatus and sonicator were used to monitor the deformation,and evolution characteristics of co-supported composite body with cement-bounding and surrounding rock.The acoustic emission point locating during the loading process of the co-bearing complex was monitored.The number of acoustic emission rings and the acoustic emission energy were monitored,and the proportion of the damage variables and intensities count ratios was established to characterized the relationship between the internal damage and the overall stability by introducing the proportion of the ringing counts to the total ringing count ratios at different times.At the same time,the ultrasonic wave instrument was used to test the changes of acoustic wave before and after loading and unloading,and the corresponding relationship between damage and sound attenuation was established.Through the evaluation of the fractal characteristics of crack growth on the surface of the composite wall and the soft PVC plastic sheeting,the failure morphology of the contact surface was characterized and monitored,and the deformation and evolution characteristics of the composite bearing body was clarified.(4)Three-axis loading device was designed to co-carry the composite body with the surrounding rock to construct a multi-directional force model of the composite body.The damage and failure characteristics of the composite bearing body with surrounding rock under axial loading,bidirectional shear loading and self-designed three-axis loading were studied.The strain changes in the contact area of the composite bearing body with the surrounding rock were monitored by the strain gages and strain gauges.The initiation,propagation,pooling and penetration of the surface cracks of the composite under different loading conditions were monitored by the electronic microscope imaging equipment.The fractal dimension characterization method of different fracture surfaces was established by using damage mechanics and fractal theory.At the same time,the variation of strain in the contact area is validated by numerical simulation.The research results revealled different forms of stress on the overall stability when the cemented filling body and the surrounding rock were co-supported,which was beneficial to change the stress characteristics of the contact area through the adjustment of mining operations and reduced the co-bearing of the cemented filling body and the surrounding rock Adverse effects.(5)Chengchao Iron Mine was selected as the research object of the field project,guiding the stability of the contact zone under the common mining of caving and filling method.The contact zone under caving method and filling method was simplified as the mechanical model of simply supported beam with spring constraint to calculate the deflection and displacement,and to quantitatively analyze the deformation characteristics of the contact zone.Numerical simulation software was used to select the typical section of Chengchao Iron Mine to carry out numerical simulation research.The contact zone was stable and the caving method was reasonable optimization of the sequencewas studied to guide mine safety production by focusing on monitoring the stress distribution and safety factor changes of surrounding rock under different sequence of recovery.