Sensitivity Analysis Of Factors Affecting Deformation And Instability Of Roadway Composite Roof And Research On Surrounding Rock Control Technology

There are many factors affecting the deformation instability of the composite roof of the roadway,and there are also interactions between the factors.The paper studies the problem through numerical simulation and statistical analysis.The main research results are as follows:（1）Through reviewing relevant literatures,the main influencing factors affecting the deformation instability of composite roof are 6 kinds of composite roof lithology characteristics,roadway section size,original rock stress,composite roof layer thickness,weak interlayer position and weak interlayer thickness.（2）The orthogonal design and principal component analysis of 25 groups of these factors were carried out by orthogonal design method using FLAC^3D numerical simulation software.（3）In order to overcome the shortcomings of strong linear correlation between data columns,a complex collinearity diagnosis was performed between the normalized data columns using the conditional exponential+variance decomposition ratio method（CIVDP）.It was found that there are two sets of complex collinearity between the normalized data.The relationship between the two groups is determined by multiple linear regression analysis.The important influencing factors of the deformation instability of the composite roof are obtained by modifying the principal component comprehensive evaluation function.There are original rock stress,roadway section size and composite roof.3 layers,etc.（4）Taking the deformation of the N3702 transportation lane（upper）composite roof in the Xiangyang coal mine during the excavation process as the engineering background,through the analysis of the mine pressure monitoring data,it is found that the main reason for the failure of the roadway support is the ground stress of the roadway.The environment is unclear,the position of the soft and hard stratification in the composite roof of the roadway is unclear,and the shape of the section of the roadway is not suitable.The research results are highly consistent with the results of the principal component analysis based on the complex collinearity diagnosis.（5）Based on the test of the stress state of the N3702 transport lane（top）,the determination of the specific location of the soft roof of the composite roof and the improvement of the shape and size of the tunnel section,combined with long-term practical experience,the support of the N3702 transport lane（upper）is optimized.The protection program;the on-site engineering application shows that the optimized support scheme makes the deformation of the top plate and the two gangs of the N3702transportation lane（upper）stable within 20 days,and the relative displacement of the top and bottom plates is reduced by 107 mm.