Study On Numerical Modeling Method Of Mining Excavation Method In Subway

Numerical modeling is affected by physical parameters, element divisions, constitutive equations, boundary conditions and failure criterions, so the results are different and oppugned. This paper puts forward the boundary numerical method and contrasts it with normal gravitational field method and load-construction method in order to apply numerical modeling soundly to practical projects. The major process and results are as follows.Firstly, this paper shows how to fix on the boundary conditions of three numerical modeling methods, especially on the interpolation fitting of boundary numerical method and selects the interpolation fitting function suitable for this example—cubic spline interpolation function.Secondly, this paper illuminates the criterion types, especially Mohr-Coulomb criterion, D-P criterion and L-D criterion and transforms them to ratios. If the ratio is less than 1, rock or soil will be destroyed and if greater than 1, it will be stable. Through analyzing, in this paper Mohr-Coulomb criterion is used on silt, L-D criterion is used on coarse sand and round gravel and D-P criterion is used on lining. The union of the three criterions is called M-D-L criterion.Thirdly, this paper shows the excavation results of each steps at Taoranting station with normal gravitational field method and boundary numerical method and theⅩstep result with load-construction method. Through contrasting displacements, M-D-L values, bending moment values, axis force values and shear force values, it can be seen that boundary numerical method is more practical, it can reflect the actual stress-strain distribution and the changing process and forecast the developing trend about stress-strain on underground engineering.Finally, through the results of normal gravitational field method and boundary numerical method, it can be seen that if middle pilot hole method and CRD method are used on mining excavation, stress concentration can be released effectively, and stress redistribution action is made the most of.