Abstract：By field observation in three longwall faces with different shallow overburden，the ground pressure behavior and the basic law of roof weighting are revealed. It is found that the strata breaking runs though whole roof，and there are big roof steps pushing in face during roof weighting. Shallow seam roof can not form stable roof block structure，and it will cause obvious roof pressure. It is also found that there are only two zones forming after strata collapse，the caving zone and the cracked zone. Speeding up face advancing is propitious to roof stability. Finally，the shallow seam definition for strata control is put forward by use of three key index，the key stratum，the thickness ratio of rock to soft overburden and the depth of coal seams.
2002, Vol. 21 
