Study On The Stability And Safety Monitoring Of Backfill And Rock In The Pillar Recovery Process

The most important problem in pillar extraction is to control ground pressure reasonably, to prevent large-scale ground pressure activity, and recover the pillar safely. The paper discussed pillar backfill and rock stability and safety monitoring in the process of pillar recovery. Dynamic finite element method is adopter to analysis the ore cylinder’s response characteristics under the power disturbances and the variation of the stress field on the above basis. On the basis of the result of backfill compression testing, this paper establishes a damage model of cemented tailings backfill; then analyses tailings backfill damage and reasonable matching relationship between backfill and rock. and establish the stop ground pressure, ground surface settlement and deformation, displacement of surface rock, underground displacement monitoring model, put forward a set of complete recovery of ore pillar mining safety monitoring and warning system of comprehensive decision-making.This paper takes an example of the mine backfill and mining in Daye iron by collecting and reading a lot of literature, using field surveys and other methods of theoretical and empirical research, the numerical simulation of pillar mining process of selection, the filling method in Daye iron mine open mining pillar safety system research, the results are as follows.1.The dynamic finite element method is adopted to analyses ore columns’ response characteristics under dynamic disturbance, and draws conclusions that the greater the load pillar model is, the more obviously that dynamic disturbance has influence on pillar model. The model is becoming more and more unstable. It shows that the response for dynamic disturbance is becoming more and more obviously, and the pillar is more easily instability failure under dynamic disturbance.2. Studying on the mechanical action mechanism of filling body, tailings backfill is a kind of multiphase composite material which contains a variety of internal defects such as micro cracks, micro pores, bubbles and other defects. So, it’s fit to adopt damage mechanics to research failure law of backfill. Firstly, the paper gets the mechanical characteristics of cemented tailings backfill by compression testing of backfill in different proportions,then the paper makes a damage model of cemented tailings backfill base on the method of damage mechanics Then it analyses different proportions damage law of cemented tailings backfil. Finally, it also establishes backfill damage constitutive models in different proportions based on mechanical model, using the mutation theory to analysis tailings back fill’s damage and discuss a reasonable match between backfill and rock. It also provides a theoretical basis for mine backfill mined-out area strength design.3.The research contents covers monitoring methods, monitoring sites and monitoring requirements of pillar recovery mining, and the monitoring model of underground displacement and the safety monitoring and early warning colligation decision-making system of pillar recovery mining. This paper built integrated decision-making systems of pillar recovery mining safety monitoring and early warning according to the monitoring program; monitoring system is the digital communication network system which is based on the field of industrial control technology. Ground Monitoring Center sends the relevant instructions to multi-channel sub-station via wired communication network. Then each multi-channel acquisition underground sub-stations analysis received instruction and confirms communication module control via a communication network to upload data to complete exchange of data information between the multi-channel acquisition underground sub-stations and the central station. Real-time data which is received by the monitoring center ground station will real-time display on a computer screen, tabulation and storage after process. The client receives the data and displays it by curve or data timely, and put the data into warning mode, if there is a danger, it can inform audiences through sound, images, text and other forms of police. The research results could make safety assessment and hazard warning of the pillar recovery process true.4.The paper takes an example of the mine backfill and mining in Daye iron in which the deformation characteristics, stress characteristics and the stress state of the ore body in process of mining, surrounding rock and filling body are got on the numerical simulation analysis and comparison. Displacement field analysis shows that amount of deformation of mining roof of the relatively is larger when pillars and surrounding rock deformation in the recovery process is smaller. Stress Field Analysis showed that backfill effectively improves the stress conditions in the mined-out area, largely reducies the stress concentration, so that the environment of ore body and surrounding rock stress has been significantly improved. Plastic zone analysis showed that the effect of filling body supporting the surrounding rock and roof of mining process is very obvious. It shows that backfill full play a supporting role to avoid significant stress concentration in order to ensure the stability of the recovery process goaf surrounding rock.In short, the paper studies on stability and safety monitoring of backfill and rock in pillar recycling process, both for remedy its theoretical research defects, or for stress matching research of the backfill and rock, and design of pillar recovery filling body strength.The paper is very important in theoretical and practical significance.The main innovation of this paper is as follows:1. This paper establishes the damage model of cemented tailings backfill which is according to the compression testing result of backfill and the research methods of damage mechanics.using the mutation theory to analysis tailings back fill’s damage and discuss a reasonable match between backfill and rock. It also provides a theoretical basis for mine backfill mined-out area strength design.2. The paper develops a set of complete recovery of ore pillar mining safety monitoring and warning system of comprehensive decision-making which is in the process of pillar recovery’s stops ground pressure, ground surface settlement and deformation, displacement of surface rock. The system can determine the key part of ground pressure’s monitor to achieve safety assessment and hazard warning information in the pillaring process.3. Numerical simulationthe is used for that deformation characteristics, stress characteristics and the stress state of the ore body in process of mining, surrounding rock and filling body are got on the numerical simulation analysis and comparison. The results showed that the filling body effectively improves the stress conditions in the mined-out area, reduces the stress concentration. Filling body’s supporting effect on the surrounding rock, the roof is very obvious, it can guarantee the stability of the goaf surrounding rock in recovery process. Research result have guide meaning to safety of pillar recovery.