Research On Residual Deformation Characteristics And Subgrade Soil Dynamic Characteristics Test Of Deep Goaf

At present,the goaf area formed by coal mining in China has exceeded 8000 km~2,and it is still growing rapidly.Domestic and foreign scholars have been quite skilled in the research of ground subsidence question of goaf in different mining depths,but in the research of residual deformation question of goaf in different mining depths,scholars are still in the initial stage.Especially there is no specialized research of residual deformation question of goaf in deep mining.There are 58 coal mining working faces totally in Gucheng coal mine in Yanzhou city Shandong province,and the average floor altitude of 58 coal mining working faces is-970.00 m,and the average mining depth of 58 coal mining working faces is 1017.79 m.All the goafs formed by 58 coal mining working faces belong to deep goafs.The paper takes 58coal mining working faces in Gucheng coal mine in Yanzhou city Shandong province as geology background and research object:Firstly,based on the probabilistic integral method,a specialized calculation table set called"the calculation program of subsidence by the probabilistic integral method for Gucheng coal mine"is programmed,and the quantitative and qualitative prediction of ground subsidence question of goaf is carried out for 58 coal mining working faces in Gucheng coal mine.The main results:the maximum subsidence is1783.40 mm,and"subsidence 0-500 mm"area is 9493600 m~2,and"subsidence500-1000 mm"area is 7076500 m~2,and"subsidence 1000-1500 mm"area is 5680900m~2,and"subsidence>1500 mm"area is 702200 m~2.Secondly,based on the prediction of ground subsidence question of goaf,field monitoring and indoor data analysis,the time influenced parameter of residual deformation is introduced.Through a comparative research of a deep goaf instantiation(1209 working face in Gucheng coal mine)and a shallow goaf instantiation(9304 working face in Yangzhuang coal mine),a series of characteristics of residual deformation in deep goaf compared with shallow goaf are obtained.The main results:in deep goaf,the"beginning"of the residual deformation stage needs a longer duration,and reaching a certain proportion of subsidence value needs a longer duration,and the residual deformation stage"itself"needs a longer duration,and the total residual subsidence value is larger.Further,based on the research results of residual deformation in 1209 working face in Gucheng coal mine,the quantitative and qualitative prediction of residual deformation question for 58 coal mining working faces in Gucheng coal mine is carried out.The main results:the maximum residual subsidence is 195.69 mm,and"residual subsidence 0-50 mm"area is 19537800 m~2,and"residual subsidence 50-100 mm"area is 2079600 m~2,and"residual subsidence100-150 mm"area is 1081100 m~2,and"residual subsidence>150 mm"area is 254700 m~2.In addition,through the numerical simulation software called FLAC3D,a double constitutive model geology body with Kelvin model and Moore-Coulomb plastic model is constructed.It said that,the verifiable and supplementary research on the residual deformation question of single working face and 58 working faces in Gucheng coal mine is carried out by the method of numerical simulation.The main verifiable results:in Gucheng coal mine,“the 0-value contour profile and position of zz-direction residual displacement in west of the ground”,“zz-direction residual displacement is between-50.00 mm?-25.00 mm in east of the ground”and“actual positions and values(them are 90.29 mm,82.05 mm)of tow points of the maximum zz-direction residual displacement in the ground”are conformed with the monitoring research results of the introduction of the time influenced parameter of residual deformation.The main supplementary results:in Gucheng coal mine,zz-direction,xx-direction and yy-direction residual stresses are between-5.41×10~7Pa?3.68×10~5Pa,-4.30×10~7Pa?5.83×10~4Pa and-4.32×10~7Pa?3.03×10~4Pa respectively,and at the same time,the detailed residual stress analyses of the western and eastern roof(and overburden rock mass),floor(and rock mass below)and direct surrounding rock mass in Gucheng coal mine are realized respectively.Finally,based on the determining that the residual deformation of goaf in Gucheng coal mine is not enough to cause some subsidence damages that more than200 mm at some points of Beihuancheng road attached to Gucheng coal mine,dynamic characteristics of subgrade soil samples in Beihuancheng road are researched by dynamic three-axis test of soil.Results show:the maximum residual subsidence is297.55 mm under the condition of"one year dynamic load"for 3 boreholes subgrade soil and foundation soil in Beihuancheng road,and the increasing of residual subsidence of subgrade soil and foundation soil can be restrained by increasing dynamic modulus and increasing dynamic damping ratio by increasing confining pressure.Therefore,it is feasible to use the measure that setting retaining tube and taking dynamic compaction at some points.The paper can provide some references of methods and ideas for future research on residual deformation question of deep goaf,and it also can provide some theories and data references for geology disaster management in Gucheng coal mine and maintenance in Beihuancheng road.The paper contains 78 figures,18 tables and 68 references.