voussoir

12(a)) when the topography for working face advancing position corresponds to the valley while main roof moves in a mode of "voussoir beam" (Fig.

Add thin wedges of stone as needed so that each arch stone (called a voussoir) fits snugly into the structure.

The KS in a caved zone will collapse after mining while that in a fractured zone will bear the overlying load with the voussoir beam structure (VBS).

[9] revealed the alternated regularity of the interval and strength of weighting by using the combined mechanics models of voussoir beam and cantilever beam, and they pointed out that the premature rupture of the key strata and the step subsidence would result in the weighting of the alternated regularity of strong (weak) periodically.

established mechanical structure models of "short voussoir beam" and "step beam" of main roof, providing the basic method of supporting design for shallow coal seam working face [6].

True arches (also called voussoir arches) are created with wedge-shaped bricks or stones on either side of a keystone at the top middle.

Ju and Xu [15] analysed the strata behaviour during the operation of great mining height, studying the structural characteristics of key strata (cantilever beam and/or voussoir beam) as well as the movement law.

For example, detached roof block method [6, 7], yielding foundation model [8], design of powered support selection model [9], ground response curves [10], "Roof -support-floor" system model [11], and Voussoir beam theory [12].

However, past field observations have indicated that the main roof may continue to hang in the form of a voussoir beam and only collapse into the caved zone after the working face has been advanced further.

Local natural stone has been used to face the bridge and the arch "voussoir" stones have been re-used from the nearby Elland Bridge, which was damaged at the same time and reopened earlier this year.