Research On Key Technology Of Arch Structure Grouting Control Surface Subsidence Of Mining Worked-out Area

The problem of surface subsidence of mining worked-out area has been becoming a hot topics in geotechnical engineering field.It involved in traffic engineering,and municipal engineering,and mineral engineering,and constructional engineering,and land resources management,and many other engineering field.In recent years,the scale of engineering construction and funding increasing with deepening and implementation of “The Belt and Road” in the field of high-speed rail and expressway and urban construction and land reclamation.The mined-out area surface subsidence isn't a disregardful obstacle in engineering construction.The Jiaozuo city of Henan province has been teemed with coal once.The multitudinous coal mined-out areas resulted in mining underground for decades in the city.The usually govern cost of them is expensive.which problem stymied urban construction and economic development for long time.Propsing reasonable and workable and economic and performable goaf treatment method,which is a important research topic to effectivity solve the geological environment of a mine according to local stratum geologic characteristic.This dissertation focus on the research of mined-out area in Liangma burg of Yanmazhuang mine,Jiaozuo city.The new arch structure grouting method was propsing to control subsidence with local thick alluvium geologic characteristic of mined-out area.The characteristic of surface destruction was analysed by field investigation and data collection.Research on the mechanism of subsidence of Liangma burg goaf was performed by basing on the key stratum theory.The dissertation investigated the mechanics principles of arch structure grouting by mathematics and mechanics analysis method.The method of internal force and deformation of arch structure and section design of arch springing were proposed.The parameter optimization of arch structure grouting project was studyed based on numerical simulation and orthogonal experimental design.The design of mix proportion of a new type grouting material was developed based on uniform design.Ultimately,the research result obtained the arch structure grouting project and land consolidation measure in the study area.The main research content and results of this paper are as follows:1.Through collection and field investigation,the geological background andsurface deformation behaviour and influence factor of Liangma burg mined-out area in Yanmazhuang mine field,Jiaozuo city.The maxmium value of subsidence and incline and horizontal deformation is larger in six collapse basins of study area.The maximum and minimum coefficient of subsidence is 1.38 and 0.92(q2=1.38,and q1=0.92)respectively.The coefficient approach 1 or greater than 1 and larger than other goaf.The influence factor of subsidence main is mining and geological conditions.The surface of study area belong to thickness unconsolidated formation and collapse basins more are gentle style.2.Estimating key stratums based on the key stratum theory for the mined-out area and resulted one main and two secondary key stratums.The shapes of investigativing six collapse basins was fitted by surface movement computational formula based on the key stratum theory.The fitted result relatively conformed to field investigation and appeared that the range of subsidence influence is widely and surface is more gently.3.Research on surface deformation influenced by the thickness of unconsolidated formation with discrete element method(UDEC)software.The results indicated that the deformation greater influenced by thickness and major performanced that more thickness and more larger range of surface subsidence basin;the maximum value of surface subsidence increased then decreased and keep up with increasing of thickness of unconsolidated formation.The maximum value of subsidence attained maximum when the thickness of unconsolidated formation equal to 90 m.The horizontal deformation maximum value increased with the thickness and trended to constant value.4.The optimal arch axis equation under uniform load and trapezoid soil pressure was established by mathematics and mechanics and structural mechanics and arch bridge design philosophy.Considering movement deformation of overlying rock and soil after destruction of goaf roof strata,theoretical analysis of internal force calculation of arch was performed under bearing deformation load.It included that axial force of arch moving and stress of relatively horizontal and vertical deformation and ratation of skewback.When arch axis close to pressure line,the vertical deformation of vault.Accroding to the design principle of ultimate bearing capacity and introducing to safety factor,arch springing section design method was proposed as shear failure under horizontal thrust.5.The optimal combination of parameters of arch structure and grouting material were obtained for the mined-out area through UDEC computation by using orthogonalexperimental design to arrange parameters.And then,numerical verification of reducing subsidence effect was performed for assigning the optimal combination of parameters under Liangma burg mined-out area.The results indicated that the reducing subsidence effect was best and the reducing rate reached 99.28% under the optimal combination of above parameters.6.The design of mix proportion testing program was formulated by uniform design.Through testing the viscosity and concretion rate and dry density and compressive strength and tensile strength of grouting material,the physical and mechanics parameters of sample was obtained.The functional expression was computed between viscosity,concretion rate,dry density expression,compressive strength expression,tensile strength expression,cohesive force expression and mix proportion by MATLAB software.The optimum material mix proportion design scheme(w_g=0.4598 and cg=0.4183 and s_c=0.3137%)was resulted combining with multiple objective function optimization method.