采礦外文翻譯---受開(kāi)采影響地表橫向剪切變形-文庫(kù)吧
2024-12-24 11:44 本頁(yè)面
【正文】 were clearly visible 4. Importantly, horizontal shear deformations of ground surface as indicated in 3D survey data obtained from a number of collieries across all NSW Coalfields (to be further discussed). However, rigorous definition, in accordance with the principles of continuum mechanics (. Jaeger, 1969), of horizontal shear strains is not possible using 3D survey data from a straight line of survey follows that if warranted considering the significance of the surface features and their capacity to resist or acmodate shear deformations, the current surveying practices may need to be changed to obtain properly defined horizontal shear strains (or principal strains). To utilise the large amount of subsidence data in existence in the mining industry, an alternative (and approximate) Shear Index is suggested in order to gain an understanding of the general characteristics of mininginduced horizontal shear deformations. This Shear Index is derived based on the ponent of horizontal movements perpendicular to a survey line or a line of interest. The formula for deriving this index is the same as that for the conventionally defined tilt. Physically, this index reflects angular changes in the horizontal plane but it is not possible to tell what causes such changes, being either shear or rigid body rotation or both. However, the distribution pattern of this index can help to understand the development of shear deformations and to find trouble spots (refer to further discussions presented in the Section below). FURTHER DISCUSSIONS ON HORIZONTAL SHEAR DEFORMATIONS Figure 2 shows the distribution pattern of horizontal movements perpendicular to a survey line across a longwall panel and the corresponding Shear Index as discussed above. Although the site is located in the Hunter Coalfield with shallow cover depths, this case is selected as it provides a clear demonstration of the following observations mon to the studied cases from all NSW Coalfields: ? A plex history of the horizontal movements perpendicular to the cross line (Figure 2a) involving a reversal of movement direction after the extraction face passed the survey site by a certain distance. This distance varied from site to site. Similar findings were reported by Holla and Thompson (1992) and Mills (2022)。 ? Indications of horizontal shear deformations (near both solid ribs in this case, as shown by the Shear Index plotted in Figure 2b), noting the reversal in the sense of shearing after the extraction face has passed the survey site. The reversal in the sense of shearing has a potential to enhance the effects of shear deformations, and ? The occurrences of permanent horizontal deformations. IMPLICATIONS From the 3D survey data collected from a number of collieries across all NSW Coalfields, the characteristics (. the magnitude, nature, distribution and timing of occurrences) of the conventionally defined subsidence parameters are pared with those of the following horizontal deformational parameters: (i) Mininginduced horizontal movements perpendicular to survey grid lines, and (ii) The corresponding Shear Index as discussed above. Implications from the findings of the current study so far are summarised as foll
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