Arch - structures

For the second step, we need an estimate of a0, which is the unconditional variance if there are no ARCH effects. We computed this based on the ARCH specification by a regression of et2 - (8/36)et j2 -. .. -(l/36)et s2 on just a constant term. This produces a negative estimate of do, but this is not the variance, so we retain the result. We note, the problem that this reflects is probably the specific, doubtless unduly restrictive. ARCH structure assumed. 

Sectional dimensions according to the theory of loose circle, the sectional dimensions for semicircular arch structure were as follows the clear width of main chamber was 4.2 m, the diameter of semicircular arch was 2.1 m, and the height of chamber wall (including chamber floor) was 1.6 m the clear width of auxiliary chamber was 3.0 m, the diameter of semicircular arch was 1.5 m, and the clear height of chamber wall was 1.3 m. 

From figure 4 and 5, it is known that when working face advanced to 200 m (when achieves fully mining), the bearing arch structure has already had an instability failure. The bedrock layers of the middle working face have already been broken along the inclination direction of working face... 

As the length of 316-04 working face is rather large, the bedrock layers over the middle working face have been all broken, and bearing arch structure has an instability failure. Then, synchronous falling of surface unconsolidated layers and the bedrock layers will severely affect the 316-04 working face. 

Lu Xueping, Zhang Linhong, FanYong. The quadratic parabola hingeless internal force calculation under the action of arch feet displacements and arch structure [J], Journal of Subgrade Engineering, 2010,06 (3) 68-70. 

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