| Shenfu-Dongsheng coal field,as the seventh largest coal field in the world,accounts for about 1/3 of coal reserves in China.It will lay the good foundation for the national energy to the strategy of“the Belt and Road Initiatives”,with the construction and development of it.It shows that roof disaster is very serious,as a typical shallow seam in the area,which due to the severe pressure under the stoping process.Meanwhile,strata and surface movement caused by mining,which leads to surface subsidence so that it exacerbates the surface soil erosion and desertification.Therefore,it is an important subject that urgent needs to be solved,which is about to study on failure mechanism of overlying strata structures in shallow seam,and to establish a reasonable surface subsidence model and prediction theory of shallow seam mining area.In this paper,in order to study on the failure of the overlying strata structures in shallow seam and the laws of surface movement,taking the strata movement and surface subsidence which causes by mining face in Shenfu-Dongsheng coal field as an object,and using the methods of field observation,theoretical analysis,mathematical modeling,measurement and verification.The main research contents and conclusions are as follows:(1)Based on the theory of elastic thin plate,according to the boundary conditions about the initial pressure and periodic weighting of the stope,the mechanical model of roof under different boundary conditions was established.The deformation and mechanical characteristics of the old roof before and after the roof fracture were analyzed.The prediction formula of step distance about the initial pressure and periodic weighting was given,and the influence factors of the initial pressure step distance of the roof was analysed.According to the measured data of different working face mine pressure,the theoretical calculation value and the measured value were compared and analyzed,and the reliability and applicability of the model were verified.(2)According to the characteristics about the influence of the abutment pressure in the later stage of the working face on stress distribution of surrounding rock of withdrawal channel,the concept of the final mining stage was defined;Based on the deformation mechanism of the old roof and direct roof,the mechanical analysis model of the direct roof in the final mining stage was established,and the formula for calculating the roof pressure in the final mining stage was given;The relationship between the step distance of periodic weighting on the old roof and the direct roof parameter in the final mining stage was analyzed.(3)Based on the monitoring of the mine pressure of the 15201 working face in Zhang Jia Mao coal mine,the dynamic process and distribution characteristics of the initial support force and the final resistance of the working face during mining were analyzed,and the supporting characteristics of the stope support were also analyzed and evaluated.And the basic law of mine pressure behavior in shallow coal seam was also mastered.(4)According to the surface subsidence model of three-dimensional elastic thin plate,the prediction formula of surface movement caused by underground excavation was deduced;The dynamic surface subsidence prediction model based on Schnute time function was established;The characteristics and laws of surface subsidence at different speeds and times were analyzed.(5)According to the dynamic distribution characteristics of the advance support pressure in the final mining stage,the influence process of the advance support pressure on the withdrawal channel was analyzed.The initial distance of withdrawal channel in the impact of the dynamic mining effect was determined.The influence range of final mining stage was given quantitatively;According to the characteristics of the mining pressure in the final mining stage,the pressure control measures were put forward. |
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