Research On Deformation And Failure Mechanism And Key Technology Of Grouting In Goaf Beneath Expressway

With the increasing mining intensity of coal,iron ore and other mineral resources,many underground goaf with different depths and complex conditions have been produced.When railway,highway,subway and other transportation facilities are built in this area,it is easy to cause major natural disasters such as roof caving,collapse and even surface subsidence in goaf under the overburden load of roads and vehicles.Research on the deformation and failure characteristics and treatment methods of the underlying goaf can effectively reduce the occurrence of engineering disasters and ensure the safety of people's life and property.At home and abroad for the highway of mined-out area deformation failure mechanism underlying the research focused on the research of damage characteristics of overburden rock of mined-out area,for the outer loads and old goaf ground residual deformation caused by the "activation" study is less,for the working condition of old goaf treatment under different geological conditions and treatment scheme selection,there is no clear disposal standards.In addition,as an effective treatment method of goaf,drilling grouting has the advantages of good reinforcement effect and short construction period.However,at present,drilling layout of goaf is mainly based on experience or single geophysical data,resulting in great blindness in construction.At the same time,most of the existing grouting materials do not consider the impact of moving water or static water environment in goaf,which is easy to cause slurry loss,slurry waste,and secondary disasters in goaf or groundwater pollution.According to the above problem,this study arashi luo fu large mined-out area under highway road linyi Luo Zhuang engineering as the backing,through theoretical analysis,numerical simulation,laboratory test and field test of the combination of means,to optimize the goaf grouting strengthening design and construction,clear influence highway underlying key factors of deformation and failure of mined-out area,research and development new type quick-setting grouting materials as the goal.The following research contents were carried out:1.Based on the results of geophysical exploration and fine supplementary exploration of goaf,the 3D visualization model of goaf is constructed by BIM technology,and the visualization and parameter optimization of grouting reinforcement design and construction of goaf are realized.2.In view of the haze,high speed under different embedded depth of goaf roadway roadway layers,layout,size,location and other factors,by building a three-dimensional numerical analysis model,analyzed the overlying load down v deformation and failure characteristics of mined-out area has been clear about the underlying impact highway key factors of deformation and failure of mined-out area,need treatment condition and threshold,It lays a foundation for the selection of treatment scheme of goaf in practical engineering.3.Considering the problems such as static water segregation resistance and poor dynamic water dispersion resistance of traditional grouting materials under the influence of dynamic water in goaf roadway,long grouting time and failure to start pressure,and taking into account grouting treatment effect and engineering material cost,a new cement-flyash-modified sodium silicate(C-FA-MS)grouting material was developed.Based on the initial setting time and final size,fluidity,the uniaxial compressive strength and other indicators to determine the optimal mixture ratio,the grouting material have short gel time,fluidity big,meet the demands of the engineering performance of the compressive strength advantages,can satisfy the arashi high-speed linyi Luo Zhuang period of underlying goaf water tunnel grouting reinforcement requirements,can provide the reference for similar engineering design and construction.4.Based on laboratory test and goaf roadway visualization analysis results,with haze,high-speed linyi Luo Zhuang section of a highway construction project as the backing,to carry out the grouting hole construction parameters and double liquid grouting construction technology optimization,ensure the goaf grouting effect under complex conditions,and based on geophysical exploration methods is proposed under the goaf grouting effect evaluation method.