Sensitivity Analysis and 3 D-displacement Inversion of Rock Parameters for High Steep Slope in Open-pit Mining
Due to the complexity of multiple rocks and multiple parameters circumstance, various parameters are often reduced to only one parameter empirically to generalize geological conditions, ignoring the really influential parameters. A developed method was presented as a complement to 3D displacement inversion to obtain the relative important parameters under complex conditions with limited computational work. Furthermore, this method was applied to a high steep slope in open-pit mining to investigate field applicability of the developed system. Back analysis was conducted in the reality of the east open-pit working area of Daye Iron Mine and propositional steps were presented for parameters solving in complex circumstance. Firstly, multi-factor and single-factor sensitivity analysis were carried out to classify rock mass and mechanical parameters respectively according to the extent of their effects on deformations. Secondly, based on the results, main influence factors were selected as inversion parameters and taken into a 3D calculating model to get the displacement field and stress field, all of which would be the artificial network training samples together with inversion parameters. Thirdly, taking the real deformations as input for the trained back propagation (BP) neural network, the real material mechanical parameters could be obtained. Finally, the results of trained neural network have been confirmed by field monitoring data and provide a reference to obtain the matter parameters in complicated environment for other similar projects.
Orthogonal back-analysis of geotechnical parameters and working state evaluation of lining of shallow buried tunnel
Based on site monitoring measurement data,orthogonal design theory,finite element theory and reinforced concrete structure theory,a new method of working state evaluation of lining was proposed.Firstly,according to the actually measured convergence and subsidence of vault,typical parameters of surrounding rock were selected to design orthogonal test scheme.The parameters of rock and soil were obtained by orthogonal back-analysis of FEM.Secondly,the internal forces of tunnel lining were calculated through FEM and the dangerous section was confirmed synthetically.Then,the designation internal force of lining was calculated based on reinforced concrete structure theory.The degree of safety was defined to evaluate the working state of tunnel lining.Moreover,the state of lining can be divided into security state,limit state and dangerous state.Finally,the working state of lining of Maanshan tunnel was evaluated.The results show that the degree of safety is 1.124,and the lining of Maanshan tunnel is in security state.The proposed new method of working state evaluation of lining can provide experiences and references for the designation and construction of tunnels.
Mineral element analyses of various tropical forages in Guatemala and their relationship to soil concentrations
Determination de la composition minerale de differents fourrages dans 3 regions d'elevage du Guatemala et etude des relations entre la chimie des sols et la composition minerale des fourrages