The Stability Analysis Of Large Underground Cavern Group Of Zhangjiawan Iron Ore

With the shallow mineral resources gradually drying up,mining depth unceasingly increasing,the underground cavern engineering is also increasingly growing.Due to the complex geological conditions in the deep underground,large tectonic stress and multiple uncertain factors etc.,the stability of the underground cavern,especially the underground chambers and tunnels is under serious threat.Large cavern group’s lack of stability will even bring about a catastrophic result.This thesis studies systematically the stability of the underground cavern groups adopting the finite difference method FLAC3D software through field survey,indoor rock mechanical experiments,borehole camera and measurement of geostress set in the study background of the proposed Zhangjiawan iron ore.The thesis is finished smoothly based on the development of the following works:1、Rock mechanics experiment:The thesis obtains the basic mechanical properties of the rock in the Zhangjiawan through a series of indoor rock mechanical tests including uniaxial compression test,direct shear test and Brazilian split test etc.by acquiring the part of rock core sample on the spot.2、Borehole camera on the spot:The thesis gains such information as the joints occurrence,the geometrical characteristics and the joint distribution density of the rock in the Zhangjiawan diggings through the borehole camera on the spot and makes a complete evaluation of the rock mass in the mining area.3、Quality classification of rock:Getting geological strength index GSI throughing field drilling logging,the thesis carries out the quality classification of the mining rock based on the quantitative GSI surrounding rock classification indexes and gets the rock Mohr-Coloumb intensity parameter through revising Hoek-Brown intensity criterion with the experimental results in order to provide the parameter basis for the subsequent numerical calculation.4、Measurement of geostress:The author applies the hydraulic fracturing in testing the crustal stress of K3 borehole and identifies an initial crustal stress field and an original rock stress value in Zhangjiawan diggings.5、Numerical simulation:The thesis performs a simulation analysis of the surrounding rock stability of the large underground cavern group in Zhangjiawan applying FLAC3D and observes the stability situation of cavern group under the different working conditions thus providing certain technical reference for the engineering construction.