Numerical Simulation Analysis On Stability Of Underground Large Section Chambers

In the process of deep mineral resources exploitation,the construction of underground mineral processing plant in large section has attracted extensive attention in the industry.Underground mineral processing plant is buried deep in the rock mass.Due to the complicated geological conditions,criss-crossed with chamber and the centralized layout,the overall stability control of the chamber group caused by excavation has become a major technical problem affecting the concentrator into deep underground.In this paper,Zhangjiawan Iron as engineering background,based on the analysis of engineering geological conditions of underground chambers,the geological model of three-dimensional visualization was builted by using of FLAC3 D software,simulated the excavation process of the chambers with existed design programme,to analyzes the deformation of surrounding rock,stress characteristics,yield zone and the stability of surrounding rock conditions about the whole process from excavation to support.The main research results are as follows:(1)The reasonable spacing of the main equipment chambers was determined through the numerical simulation calculation on the design case of the chambers with stepped arrangement.The expansion and coalescence of plastic zone in the surrounding rock,the catastrophe of the rate of curves of displacement and stress of the critical points are taken as criterion to investigate the reasonable spacing,it obtains 1.5 times of the width of the chambers in level and 0.5 times of that in vertical of the floors of the two chambers.(2)The stability of surrounding rock of chamber group with different buried depth is analyzed,and the distribution rules of secondary stress field,displacement field and plastic yield zone of surrounding rock in underground chambers is obtained.With the increase of the depth of the chambers,the shear plastic zone gradually increases,and the part of the bottom and the top also appears the shear plastic zone.(3)The corresponding reasonable excavation order of the chambers in different stress fields is determined.In the self weight stress field,the excavation sequence of first wall then arch should be adopted,while in the horizontal stress dominated field,the excavation order of the first arch then wall should be adopted.(4)The influence of the excavation of the chamber group on the stability of surrounding rock in the two kinds of initial stress fields including the self weight stress field and the horizontal stress dominated field are analyzed,where we can get the rules of the distribution of stress,displacement and plastic zone in different stress fields.(5)Through the study,under the engineering condition of underground chambers in Zhangjiawan Iron,the optimal solution to the stability of large chamber group is to arrange the chambers reasonably and determine the reasonable chambers excavation sequence and supporting scheme and supporting time.