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Groundwater inrush within faults is an important issue in underground engineering. The process of water permeation through the soil-rock mixture has been numerically investigated. The simulated soil-rock mixture was presented with rock blocks, and filled with selected types of soil particles. The Euler-Euler method was employed with multiphase interaction. Meanwhile, the filling soil was assumed to be Bingham fluid with additional user-defined function. Then the detailed evolutions of water permeation through the soil-rock mixture were presented visually, including water distribution, water velocity field, permeation time, and penetration time. It is shown that water permeation changes with time and space in the soil-rock mixture, and the overall process of water permeation can be divided into three different stages. Moreover, major variables including water velocity, size of soil particles, and yield stress of soil were considered, which clearly influenced water permeation. Soil density showed little effect on water permeation, and the permeation time decreases with increasing water velocity. Water permeation through the soil-rock mixture is easier when the filling soil consists of smaller particles. The permeation rate of water obviously decreases with increasing yield stress. Meanwhile, different types of soils were considered with corrections on the dynamic viscosities. We found that sand and soil behave differently when water permeates through the soil-rock mixture. Furthermore, selected results on water permeation were compared with the relevant studies, and reasonable agreements were reached. The presented stimulation results provide detailed information for further understanding on the mechanical mechanism of water permeation through the soil-rock mixture used in underground engineering.
Boron (B) is an essential microelement for the growth and development of plants. B-deficient radish plants grew slowly compared to B-sufficient controls. Soluble B and cell wall-bound B decreased in young leaves on removal of B from culture medium. In old leaves, B deficiency reduced soluble B content but there was no significant effect on cell wall-bound B content compared to controls. The mesophyll cells in the middle of leaves were enlarged abnormally and had greater cell wall thickness under B-deficient conditions. B deficiency reduced the stomata frequency, inhibited the stomata aperture, and guard cells had thickened cell walls. B-starved leaves showed decreased photosynthesis and stomatal conductance. These indicate that B deficiency could interfere with cell wall development, especially irregular guard cell walls as a result of B deficiency severely affected the rhythmic stomatal closing and opening, preventing the normal functioning of stomata. Correspondingly, photosynthesis was indirectly affected, and plant growth decreased.
Water inrush is one of the typical geological hazards of tunnel construction in karst areas. It is necessary to predict water inrush more accurately for karst tunnels. Firstly, we created a model on risk evaluation of water inrush based on the efficacy coefficient method. Then karst hydrologic and engineering geological conditions were considered in detail, and several typical factors were selected as evaluation indexes, including formation lithology, unfavorable geology, groundwater level, and so on. Moreover, the weight coefficients of the selected evaluation indices were calculated using the analytic hierarchy process method. Furthermore, the total efficacy coefficient was presented to specify the risk grade of the evaluation samples. Finally, the risk grade of water inrush for karst tunnels is divided into four levels: severe (red), high (orange), elevated (yellow), and guarded (blue). Additionally, the model of risk assessment of water inrush was applied to Jigongling tunnel along the Fanba Expressway in China. The results show that the present evaluation results agree well with the construction situation, which also agree with the relative analysis results of attribute mathematical theory. The presented work with the efficacy coefficient method is relatively simple with strong operability, which has potential for predicting water inrush in karst tunnels.
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