采礦工程專業(yè)--外文翻譯-文庫吧
2025-11-02 00:45 本頁面
【正文】 re(m) and is the average weight of the volume of the overlying strata (kN/m3) ． calculation process According to the theory of elasticity on distributed loads on a semiinfinite plane，we can use Eq.(2) to calculate the vertical stresses σz(1) and σz(2) and the horizontal stresses σx(1) and σx(2) which are affected by the supporting pressures and ． The stress equations at point M(x, z) can then be obtained correspondingly by superposition (this calculation neglects the effect of the transferred load from the goaf and the overlying strata movement as well as the effect of the initial ground stress because it does not produce subsidiary stress at point M； largely we considered the action of the supporting pressure in front of the working face). The calculations are as follows： Therefore， σz = σz(1) + σz(2) (4) and σx = σx(1) + σx(2) (5). By coordinate transformation(x = x (n = 0， 1， 2， … ))， x is regarded as x0 in Eqs.(4) and (5) and the stress values of each section can be calculated， where the variable expresses the relative distance from the pushing position of the working face to the origin of the coordinate system. Given the related parameters of supporting pressures， the stress values， located at the relatively fixed floor section， (x = ) at different depths， can be calculated by puter when the working faces advance. When x = x ， Eqs.(4) and (5) can be represented as follows： analysis Given the actual geological conditions and mining technology at the 2702 working face of the Yangcun Colliery of the Yanzhou Mining Group Limited Company， the following related parameters are determined： =3， =5 m， =50 m， =25 kN/m3 and H=500 Eqs.(6) and (7)， the stress distribution curves are obtained on the relatively fixed floor section x= at different depths with the working face advancing by calculation. The results are shown means of puter in Figs. 3 and 4. Fig. 3 shows that vertical stress maintains its maximum at the interface between the coal seam and floor on the section x= from the original coordinates and then quickly decreases with the increasing depth and slowly decreases at a specific depth. A similar situation is obtained when the working face advances， .， the range of the vertical stress decreases with an increase in depth. From the results it can be seen that the range of depth, given the variation of vertical stress, is relatively large, ., within 40 m. The range of the vertical stress is clearly smaller after the working face advances 30 m. According to the relationship of the variation between vertical and horizontal stress, the multiplication of the variation of vertical stress and its corresponding coefficient of horizontal pressure (λ) is equal to the increment of horizontal stress at the point M[1]. Then the increment of horizontal stress and the horizontal stress at the point M continues to be superposed, which is inversed analysis when the working face advances 30 m. The results of the variation in stress show that the vertical stress is larger than the horizontal stress when the working face is at its original position: the maximum principal stress is the vertical stress。 the minimum principal stress is horizontal stress. Because the rate of decrease of the vertical stress is faster than the horizontal stress, the horizontal stress is larger than the vertical stress within 42 m when the working face advances 30 m (for details, see Fig. 4). Considering the effect of the variation in vertical stress, the horizontal stress is much larger than the vertical stress. The maximum principal stress is the horizontal stress and the minimum principal stress is the vertical stress. It agrees with the partial reasons of the mechanical p
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