Research On The Influence Range And Limit Angle Of Surface Deformationinthewestareaof Chengchao Iron Mine

The mining of metal mines by sublevel caving often results in excessive surface deformation and damage to the buildings on the ground.Scholars mostly study the boundary of the acceptable deformation(movement curve)and the angle of the boundary of the acceptable deformation on the surface of the metal mine.The curve is the dividing curve that affects normal living or use due to damage to surface buildings or structures,but it still affect the area outside of the curve,and there are few studies on the actual affected area,Therefore,studying mining influence range and limit angle is of great significance to mining theory.This article takes the west area of Chengchao Iron Mine in Ezhou,Hubei as an example.Based on the monitoring data of surface horizontal displacement in the past 4 years(May 2016 to May 2020),the main research contents and results of the analysis of the impact range and limit angle of the mining area are as follows:(1)Author conduct survey records,research and analysis of engineering geology,hydrogeological conditions,ore body occurrence and mining conditions in the mining area.In-depth understanding of the field deformation of the mining area,the characteristics of the main geological mining factors and the potential impact on the surface deformation are analyzed.(2)According to the recent 4 years of surface GPS,leveling monitoring and other underground mining data in the west area of Chengchao Iron Mine,and on this basis,the measurement error is considered and the threshold is set,the influence curve is obtained through Kriging interpolation.The expansion of influence range and limit angle are made.(3)The expansion of influence curve is analyzed.The influence range of the hanging wall will have a sudden change.The mining level will play a leading role in the expansion of the influence curve.The influence curve can be a warning for the extension of the boundary of the dangerous deformation zone;A large structural crack will cause a larger range of influence curve in local area;In the end area,there is no apparent change between the influence curve and the moving curve due to the existence of ore pillars(4)The change of the limit angle is analyzed.In the footwall,the influence curve and the moving curve are all outside the area of the larger cracked structure surface,the limit angle and the moving angle change pattern will be the same.The limit angle mutation of the upper and lower disks is completely different due to the boundary difference effect of the upper and lower levels.The stability of the limit angle depends on whether there is a major change in the mining level.The limit angle will remain at53°?55° and is about 6° smaller than the moving angle.(5)We study the reasons of boundary deformation in the western area by UDEC.The influence range of the hanging wall is that the rock mass is deformed under the tensile action of an approximate horizontal force after the horizontal tectonic stress is released.the foot wall is a vertical cantilever beam model,with falling slip failure,and the rock mainly happens horizontal deformation;The end area is protected by the boundary of the strata and the pillars,making the deformation unable to continue to be transmitted to the distance.