Bench stability in open pit mines : a methodology for jointed rock masses
The methods used to determine the overall gradients of the slopes in open pit workings aim to sufficiently eliminate all risk of failure on a scale comparable wich the pit walls. For this the slopes musc be made shallow gradual and reinforcing measures must generally be applied. Most often these consist of ensuring the drainage of the slopes and in limiting the effects of blasting (reinforcement is generally too costly in the case of very high slopes and deep planes of failure).
Fractures network analysis and interpretation in carbonate rocks using a multi-criteria statistical approach. Case study of Jebal Chamsi and Jebal Belkhir, South-western part of Tunisia
Abstract The quantitative analysis of fractures in carbonate rocks across termination folds is important for the understanding of the fractures network distribution and arrangement. In this study, we performed a quantitative analysis and interpretation of fracture network to identify the fracture networks type. For this reason, we used a multi-criteria statistical analysis. The distribution of directional families in all measured stations and their elemental distribution are firstly examined. Then we performed the analysis of directional criteria for each of the two and three neighbouring stations. Finally, the elemental analyses of fracture families crossing others were carried out. This methodology was applied to the folds of Jebal Chamsi and Jebal Belkhir areas located in south western Tunisia characterized by simple folds of carbonate geological formations. The application of the global and the elemental statistical analysis criteria of directional families show a random arrangement of fractures. However, elemental analysis of two and three neighbouring stations for families crossing one another shows a pseudo-organization of fracture arrangements.
Effects of thyrotropin-releasing hormone and a thyrotropin releasing hormone analog on growth and selected plasma hormones in lambs.
An 8-wk growth trial was conducted to assess the effects of continuous infusion of thyrotropin-releasing hormone (TRH) and an active TRH analog less than Aad-His-Pro-NH2 (the less than Aad is L-pyro-alpha-aminoadipic acid) on growth trial performance, carcass composition and hormone profiles of growing lambs. Both drugs were infused at 600 micrograms X lamb -1 X d -1 with 16 lambs/treatment. Both TRH and less than Aad-His-Pro-NH2 decreased average daily gain (ADG; P less than .01) and increased feed conversion (FC; P less than .01) compared with saline infused controls. Average daily feed intake was not altered. Carcasses of lambs given TRH or less than Aad-His-Pro-NH2 contained fewer kilograms of moisture (P less than .05) and appeared to contain fewer kilograms of protein. Thyrotropin-releasing hormone and less than Aad-His-Pro-NH2 increased thyroid gland weights (P less than .05), but pituitary gland weights were not different. Plasma thyrotropin (TSH) concentrations were increased by both drugs compared with control lambs, peaking at 4 to 7 d after initiating infusion. However, by 14 d, TSH concentrations returned to control levels. Triiodothyronine (T3) and thyroxine (T4) were elevated by both drugs over the entire 8-wk trial, with peak levels reached at 10 d and maintained for the duration of the study. Both TRH and less than Aad-His-Pro-NH2 increased prolactin over the entire period. Growth hormone levels were not altered by either drug. The effects of less than Aad-His-Pro-NH2 infusion on growth trial performance, carcass composition and hormone profiles of growing lambs were very similar to TRH. The negative effects of TRH and less than Aad-His-Pro-NH2 infusion on ADG, FC and carcass protein appear to be the result of elevated T3 and T4 levels.