Performance Evaluation Of Multi-service Support And Application

Hydraulic support in 3-1 coal seam of Gaotouyao Coal Mine of China Huaneng Group has been in service at 101,102 and 104 working faces.103 working face is the fourth working face where support is continuously used.It is defined as multi-service support,referred to as multi-service support.Many coal mines insist on long-term service of support in multiple working faces,which will lead to potential safety hazards after performance degradation.At present,there is no scientific method to guide the replacement of support in coal mine.It is very important to establish a scientific method to judge whether the support has reached the service life.In this thesis,the ground pressure of 103 working face of 3-1 coal bed in Gaotouyao Coal Mine is observed,which is about 186m in advance.The observation contents include the working resistance of support,the shrinkage under movable pillar and the wall of coal,etc.Through analyzing the open pressure of safety valve and calculating the loss rate of support resistance,the total amount of cyclic subsidence of multi-cutter coal cutting during weighting period is calculated based on theory and field measurement.The roof control effect under support is judged at this stage,and the stability of coal wall can be maintained by checking the working resistance of support.It is found that the support safety valve has a high opening rate,a large dynamic load coefficient and an early opening of the safety valve.The actual rated working resistance of 19 supports monitored decreased by about 18%compared with the rated working resistance of the factory.The actual rated working resistance of 174 supports in the whole working face decreased by about 18%to 24.8%compared with the rated working resistance of the factory.The level of roof control effect is "medium",and the amount of coal wall slice exceeds the safety criteria formulated by the coal mine.All of the above indicators indicate that the support performance of multi-service support has declined significantly,reaching the lower limit of the support resistance requirement of the working face and replacing the new support for the mining of the new working face in the same coal seam.In addition to the evaluation of support performance by visual factors such as rock pressure,there are many mine fuzzy factors,but many fuzzy factors are difficult to accurately express in terms,and it is difficult to assess the impact of support performance.Therefore,it is necessary to quantify the fuzzy factors and get the evaluation value of support performance after quantification.In this chapter,FAHP+ EWM is introduced to evaluate the performance of multi-service bracket support system,and the quantitative value of multi-service bracket support system performance is obtained.The bracket support performance score is 63.31,and the corresponding grade is "general".Through two methods to evaluate the support performance of multi-service support,it shows that the support has reached the service life,103 working face can continue to use the support,but the performance continues to decline,the support may cause potential safety hazards.New brackets must be replaced in the mining of new working face in the same coal seam.The selection of reasonable working resistance of support is the main content to be studied in the selection of support type.In the initial stage,the support selection of No.3-1 coal seam in Gaotouyao Coal Mine can only be calculated by theoretical formula due to the lack of in-situ observation of rock pressure data.However,there are some discrepancies between theoretical analysis and practical engineering parameters.At the same time,with the increase of the service life of the support,the performance of the support declines.The service resistance of these supports may not be taken into account in the initial approval of work resistance.The rated resistance F=10500kN of the stent may not be the best choice for the proportion of stent performance deterioration.In order to increase the service life of the support and enhance the support performance,it is necessary to redefine the reasonable working resistance of the support in the new working face of 3-1 coal seam.The new working face is 105.Because 105 working face is located in the same coal seam as 103 working face,the mining geological conditions and design mining method are similar.According to the rock pressure law of 103 working face,the reasonable working resistance of support is determined F=12000kN by analogy estimation method.