Owing to the the fact that the difficult-to-work seams account for over 90% of these worked by hydromines,tbe coal roadway bolting technique has made slow progress.

• 由于煤层地质构造复杂，煤厚变化大等难采煤层条件在水采矿区占90%25以上，故水采矿井煤巷钻杆支护技术发展缓慢。