Deformation Characteristics And Protection Technology Of Radio And Television Tower Under Influenced By Undermining

The mining of coal resources not only causes a large area of surface subsidence,but also causes the destruction of ground railways,highways,water bodies,bridges and culverts,pipelines,cultivated land,radio and television towers and other buildings（structures）.Therefore,the research on mining technology under buildings（structures）has important theoretical and practical significance for green mining of coal mines,improving the recovery rate of coal resources,enriching and developing the protection theory of buildings（structures）in mining areas.Based on the radio and television tower of 13031 working face of Baiping Coal Industry Company,combined with the knowledge of mining subsidence and structural mechanics,this paper analyzes the movement and deformation law between the radio and television tower and the ground under the influence of mining,and systematically studies the feasibility of mining under the radio and television tower by using the combination of probability integral method,numerical simulation,theoretical analysis and field observation.The main conclusions are as follows:（1）Through the calculation and analysis of geological mining conditions and overburden lithology of Baiping Coal Industry Company,the predicted parameters of surface movement in this area are obtained.The probability integral method is used to accurately predict and analyze the surface movement and deformation near the radio and television tower after mining of 13031 working face.The thickness of coal in 13031working face covered by radio and television tower is limited under the mining height of2.5m,The maximum subsidence value of the radio and television tower caused by the mining of the working face is about 1600mm,the maximum inclination value is about6mm/m,the maximum horizontal movement value is about 450mm,the maximum horizontal deformation value is about 3mm/m,and the curvature is less than 0.05×10^-3/m。By comparing the allowable and ultimate deformation values of buildings,it can be seen that except for the inclination value,the other deformation values are within the safe range.（2）Taking the radio and television tower above the 13031 working face of Baiping Coal Industry Company as the prototype,the numerical model is established by using FLAC3D numerical simulation software.Through the comparison of different mining schemes,it is concluded that the subsidence value and horizontal movement value of each foundation of the radio and television tower change obviously under different mining thickness.The 13031 working face is subject to thickness Limited mining.When the mining thickness is 2.5m,the inclination of the tower foundation is 5.25mm/m,which is very close to the limit deformation value of 6mm/m in the specification,and the rest deformation is within the safe range.Therefore,in order to protect the safe operation of the radio and television tower,it is necessary to timely monitor the radio and television tower and adopt necessary transformation and maintenance measures on the premise of thickness Limited mining.（3）Through the sorting,calculation and analysis of the observation data of the radio and television tower,the dynamic change curves of the subsidence,subsidence rate and inclination curve of the radio and television tower foundation during the measurement period are obtained.The cumulative subsidence of tower foundation measurement points tj1～tj4 are 375.8mm,401.2mm,386.8mm and 348.3mm respectively.The maximum height difference between four tower foundations occurs between tj3 and tj4,and the maximum height difference is 39.3mm;During the survey,the radio and television tower foundation sank three times with large amplitude.The distance between the advancing position of the working face and the center of the tower is 165m,67m and-82m respectively（positive before reaching the tower,negative when crossing the tower）.The maximum sinking rate is the tj2 measuring point closer to the goaf,which is 2.54mm/d,3.12mm/d and 2.75mm/d respectively;Due to the long-term shutdown of 13031 working face at the key propulsion position recently,the inclination of the tower foundation has increased sharply to 4.91mm/m,which is close to the limited inclination of the tower foundation.Therefore,it is necessary to take maintenance measures such as adjusting the inclination of the tower.（4）Based on the discussion of the common protection and maintenance measures for coal mining under high-rise structures at home and abroad,and in view of the mining deformation prediction of the radio and television tower of Baiping Coal Industry Company,the implementation scheme of transforming the split foundation of the tower into a combined foundation and precise grouting combination of the foundation of high-rise structures is put forward.The core content of precise grouting reinforcement technology for high-rise structure foundation based on foundation"settlement grouting pressure"is condensed,including grouting basis,grouting timing,grouting position,grouting effect and grouting mechanism.The precise grouting reinforcement technology for high-rise structure foundation is applied to coal mining under the radio and television tower of Baiping Coal Industry Company,combined with tower foundation inclination adjustment measures to effectively protect the safe operation of radio and television tower.Through the above research,this paper finally realizes the accurate prediction of the safety of radio and television tower under the influence of mining,achieves the expected goal,and provides a reference for the safe mining under radio and television tower and the construction and safe operation of tower buildings in mining subsidence area.