1. Between each block voussoir iron connected by bite.

2. Vertical stress makes rock stratum reforming voussoir beam, horizontal in-situ stress is the main source to cause the voussoir beam crushed.

3. Theoretical Analysed the roof without voussoir beam structure in shallow seam mining under thick unconsolidated layers, thus, cann't use voussoir beam theory to compute the force of supports.

4. It is built of large blocks of travertine stone and the arch has two concentric rings of radiating voussoirs.

5. The relieving platform limits the sliding plane, and the sliding mass at this time is no longer a voussoir, so, Rankine theory and Coulomb theory cant be applied to calculate the earth pressure.

6. The major factors that affect the stability of the structure are rotational angle of the voussoir beam, ratio of length and height, rock type and height of carrying rock strata.

7. The paper also gives the range of stability of key block of voussoir beam and measures to be taken in various conditions.