Over Riding Of The Pillars

If there is hard sand stone in the roof or if roof does not comes down timely and hanging at roof at long time these type of hanging roof when fall at once time there is pressure on the near - bye pillars and it does not takes the load and pillar collapse or crushed. This is called "over riding of pillar"

The weight of the strata is transferred, before the fall takes place, over the pillars on the outbye side. If the pillars are not strong enough, they may be crushed due to such sudden heavy pressure. This phenomenon is known as overriding of pillars and stooks and results ultimately into premature collapse in the area.

Causes of over - riding of pillar :

1. Weak and small pillar

2. Pillar robbing

3. Width and height of the gallery is more

4. Not well supported of exposed roof .

5. Not maintaining a straight breaking line of face.

6. Nature of immediate roof and floor

7. Compressive strength of coal