Q330
When does the first caving in long wall working starts?
A.
it usually starts when the tensile stress in a certain point of the roof over the gob exceeds its tensile strength
AnswerB.
it starts when rocks over the gob area are in compression
C.
it starts when the thickness of immediate roof increases
D.
it usually starts when the tensile stress remains less or equal to the tensile strength
Answer: Option A
Solution
Answer: Option A
No explanation is given for this question Let's Discuss on Board