Stress Distribution and Optimum Spacing Determination of Double-Withdrawal-Channel Surrounding Rocks: A Case Study of Chinese Coal Mine

Table 1

Characteristics of coal roof and floor.

Roof/floor	Rock name	Min–Max	Lithology
		Average (m)
Main roof	Fine-grained sandstone, sandy mudstone	10.13–23.13	Grey, off-white, argillaceous cement with wavy bedding containing plant leaf fossils. Flat fracture, containing plant fossil fragments, microwave-like bedding, with a slippery surface
		16.63
Immediate roof	Fine-grained sandstone, sandy mudstone	1.48–10.07	Light grey, argillaceous silt-like structure, lenticular bedding, and horizontal texture, containing mica plant fossils
		5.78
Immediate floor	Sandy mudstone	9.97–13	Dark grey, uneven sand content, mica plant fossils, flat and conchoidal fractures, horizontal texture
		11.5