采礦工程專(zhuān)業(yè)--外文翻譯-wenkub
2022-12-17 00:45:36 本頁(yè)面
【正文】 ess at a specific point inside a semiinfinite plane，such as point M ． Supposing the coordinate of point is (x， z)， the micro1ength dζ from the origin of coordinate is ζ on the AB segment， the microconcentration force dp=qdζ is regarded as its force and the state of stress of the microconcentration force at point is defined as follows． In order to calculate the stress at point M from all distributed loads， the stress which is caused by every microconcentration force is superposed． We need to integrate Eq.(1) from ζ= a to ζ= b and Eq.(1) then bees： 3 Stress calculation of coal seam floor of the mechanical model Based on the theory of underground pressure， the mechanical model of supporting pressure in front of the working face can be simplified， as shown in [911]． Where the OA segment is the plastic area， with a length of x0； the AB segment is the elastic area， with a length of L0 x0． In order to calculate easily the supporting pressure of both areas pz(1) ， pz(2)， without losing its rational， we can assume the following two linear functions： Where is the supporting pressure of the plastic area(kPa)， the supporting pressure of the elastic area(kPa)， the maximum stress concentration coefficient，the width of the plastic area(m)， H the buried depth of the coal floor(m)， the width of the area affected by the supporting pressure(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
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