Discontinuity Layout Optimization Method And Its Application To Geotechnical Stability Analysis

The methods of geotechnical stability analysis are mainly divided into four categories,namely,limit equilibrium method,limit analysis method,displacement finite element method(including finite element strength reduction method and finite element force or external force loading method)and slip line method.Among them,limit equilibrium method,finite element strength reduction method and limit analysis method are widely used.The traditional limit analysis methods are mostly analytical limit analysis methods,so their application fields are limited due to the influence of geological conditions and boundary conditions.Discontinuity Layout Optimization is a recently developed new numerical limit analysis method by arranging grid points in the solution domain and creating discontinuities between the grid points and creating discontinuities between the grid points to planning potential slip paths in geotechnical materials.And then a standard linear programming problem is formed and solved using an efficient linear programming to determine the slip mode.The main research contents and conclusions of this article are as follows:(1)The basic theories of DLO are introduced and the optimization formulas of DLO external force loading method and strength reduction method are given.And the correctness of the above formula is verified by concrete examples.Program based on the Python language was developed to carry out Geotechnical stability analysis.(2)The effect of grid and discontinuities layout on the results of stability analysis in DLO method was discussed.Through comparative analysis of specific examples,it can be known that the DLO method has obvious grid-point dependence,so it is recommended to adopt a equal regular grid layout.By comparing the full connection scheme and the optimized connection scheme,it is found that the number of discs in the optimized connection scheme is optimized and significantly reduced.While ensuring the accuracy,the computational efficiency is significantly improved.Therefore,it is recommended to use the disc optimized connection scheme.(3)The DLO method was applied to the analysis of slope stability and subgrade bearing capacity and compared with the commonly used limit equilibrium method and finite element strength reduction method to confirm the effectiveness of the DLO method.In particular,compared with the limit equilibrium method,the DLO method does not need to specify the position of the slip surface and can accurately find the most dangerous position of slip surface and can clearly demonstrate the instability failure mode of block of geotechnical materials.And the DLO method can select more appropriate methods for targeted analysis based on different stability problems anddestabilizing mechanisms.(4)The numerical study also shows that for the DLO method,the denser the grids'layout is,the more accurate the calculation results are.However,as the grid density increases,the calculation amount also increases significantly.Especially when the density is large,the increasingly density calculation is further increased but the accuracy of the results is no longer obviously increased and the amount of calculations is significantly increased.It is recommended that when DLO is used for geotechnical stability analysis,the medium grid density can be used to ensure the calculation efficiency.