Abstract:

With the development of deep coal resources, research on the water stability of soft rocks containing coals becomes
very important. In Juye Coal field, the roof rocks and floor soft rocks, mainly consists of mudstone at 900-1200m below surface,
is typical soft rocks for deep coal. The macro features and micro cale degradation mechanism of deep coal soft rocks in water in
Juye Coal Field have been analyzed by water stability experiment, X-ray diffraction and scanning electron microscopy. The result
shows that the water stability of soft rocks is poor, and soft rocks startet to disintegrate in 30 minutes after being soaked. The
clay minerals of the rock samples, mainly kaolinite and illite/montmorillonite interstratified, show significantly osteoporotic and
alignment in structure. The degradation of deep coal soft rocks is due to the expansion of clay minerals inside and outside through the analysis, and the main factor that leads to poor water stability of rock samples is the structural features of soft rocks.

Key words: deep, coal-bearing soft rocks, water stability, micro-mechanism